7. The anatomy, histology and development of the pharynx, larynx and thyroid gland.

7. The anatomy, histology and development of the pharynx, larynx and thyroid gland.

Anatomy of pharynx, larynx and thyroid gland.

Thyroid gland

Location = deep to sternothyroid, and sternohyoid m, @ level of C5-T1, isthmus located b/w 2nd & 3rd rings of trachea

Parts:
2 lobes – L and R, w. isthmus (small linking piece) b/w the two

Covered by fibrous capsule, which sends CT septa into gland (more info in HISTO)

Function: endocrine gland, produces

• thyroid hormone – controls rate of metabolism
• calcitonin – controls calcium level

CLINICAL NOTE -Tumor of thyroid gland can cause excess weight gain, or excess resorption of Ca, causing bone fractures more likely

Blood supply:

• sup thyroid a (ext carotid a)
• inf thyroid a (thyrocervical trunk of subclavian)
• a run b/w fibrous capsule, and pretracheal cervical fascia
• both split into ant/post branches

Veins drain a venous plexus that covers ant surface of gland  –> sup thyroid v, middle, inf thyroid v

• sup & middle –> IJV
• inf thyroid –>brachiocephalic v

Lymph Drainage: network of lymph vessels –> prelaryngeal, pre tracheal, paratracheal l.n., inf deep cervical l.n. –> brachiocephalic lymph nodes, thoracic duct

Innervation:
SNS: post ggl fibers from sup/mid/inf cervical ggl –> run via cardiac arterial plexus  w/ thryroid a –> cause VC (vaso constriction)
*NOTE-  Thyroid reg. by hormones of hypophysis (pituitary)

Parathyroid glands:
Location: located just outside of fibrous capsule of thyroid gland

• Sup glands = 1 cm above entry of inf thyroid a, @ level of inf border of cricoid cart
• Inf glands = 1 cm below entry of inf thryoid a

Blood Supply: inf thryroid a, or br of esophageal, tracheal, laryngeal a
v –> venous plexus of thyroid gland

Lymph drainage: deep cervical and paratracheal l.n.

Nerves: see thyroid

Larynx:

Location: Bodies of C3 –> C6, leading from pharynx –> trachea

Function: regulate flow of air to and from lungs for vocalization = voice production, guard air passages, so food and liquids don’t enter it

Part of Larynx: Cartilages, Membranes, Ligaments, Joints, Muscles

Cartilages:

• Thyroid – single hyaline cartilage
  
  • forms the laryngeal prominence aka Adam’s apple,
  • has oblique line on lat surface of its lamina where inf pharyngeal constrictor, sternohyoid, thryrohyoid attaches,
  • has a superior/inf horn
    • superior horn attaches to hyoid bone = thyrohyoid membrane
    • medial part of membrane = median thyrohyoid ligament
    • lateral part of membrane = lateral thyrohyoid ligament

• Cricoid cartilage – single hyaline cartilage
  • only one that encircles the entire larynx,
  • articulates w/ thryroid cartilage,
  • lower border of it marks end of pharynx/larynx
  • attaches to thyroid via median cricothyroid ligament
  • attaches to 1st ring of trachea via cricotracheal ligament

• Arytenoid (2) – paired hyaline/elastic cartilages,
  • shaped like pyramids w/ attachment to vocal ligaments and vocalis m to  their vocal processes (ant part of cart)
• Cunieform (2) – paired elastic cartilages that lie in aryepiglottic folds ant to corniculate cartilages
• Corniculate (2) – paired elastic cart that lies on arytenoid cartilages, w/ aryepiglottic folds of mucous membrane
• Epiglottis – single elastic cartilage, spoon shaped extension from sup/ant wall of larynx
  • Vallecula epiglottica – the areas b/w the the folds of the epiglottis, the median and lateral glossoepiglottic folds
  • attached to thyroid cartilage via thyroepiglottic lig

Membranes & Ligaments of Larynx:

• Thyroid membrane – b/w hyoid and thyroid cart
• Cricothyroid ligament – thryroid and cricoid cartilage
• Quadrangular membrane – thyroid and arytenoid cart –> epiglottis, upper part of aryepiglottic folds, inf margin of this membrane makes the ventricular folds
• Thryoepiglottic lig – epiglottis –> thyroid cart lamina
• Hyoepiglottic lig – epiglottis –> hyoid bone
• Conus elasticus –  elastic membrane from cricoid cart –> line interconnecting inner surface of thyroid cartilage and vocal process of arytenoid cartilage, closes off the laryngeal inlet, except for at rima glottidis

Joints:

1. Cricothyroid Joint – tense vocal fold

• b/w inf horn of thyroid cartilage and lamina of cricoid cart
• fibrous capsule
• Movement: ant/post tilting of cricoid rt – when cart tips ant, tenses the cords, and post, loosens cords, rotation & gliding of thyroid cartilage
• Associated Muscles = vertical and oblique cricothryroid m

2.  Cricoarytenoid Joint

• b/w cricoid and base of arytenoid
• fibrous capsule
• Movement:  Rotation, sliding, ant/post tilting – help tense and relax vocal folds
• Associate muscles = transverse arytenoid, post cricoarytenoid, lat cricoarytenoid, oblique arytenoid, thryroarytenoid m vocalis m

Muscles of Larynx: – all innervated by recurrent laryngeal n, except cricothryroid = ext laryngeal n, both from CN X

Intrinsic Muscles: move the laryngeal parts, makes changes in the length and tension of the vocal folds

Adductors:

1. Lat cricoarytenoid
2. Oblique arytenoid
3. Transv arytenoid
4. Vocalis

Abductors:

1. Post cricoarytenoid m

Tensors of vocal fold:

1. Vertical and oblique cricothyroid m
2. Vocalis m

Relaxers of vocal fold:

1. Aryepiglottic
2. Vocalis m
3. Thyroarytenoid m

NOTE – ONLY 1 ABDUCTOR,  so if inf  laryngeal n is damaged, say bye to abducting – paralysis of larynx

Extrinsic Muscles: move the larynx as a whole
Elevators of Larynx: (Mainly Suprahyoid m)
Digastric

1. Mylohyoid
2. Genioglossus
3. Stylohyoid
4. Stylopharyngeus
5. Thyrohyoid

Depressers of Larynx: (mainly infrahyoid m)

1. omohyoid
2. sternohyoid
3. sternohyoid

Cavity (Internal Structure) of Larynx:
3 parts:
1. Vestibule of larynx = laryngeal inlet –>the ventricular folds

• ventricular folds = mucus membrane folds elevated by lower free edge of quadrangular membrane, run from thyroid cartilage above vocal ligament –> arytenoid cart
• laryngeal inlet = upper border of epiglottis, ary epiglottic folds, interarytenoid notch

2. Ventricle of larynx = b/w ventricular and vocal folds

• Vocal folds = from angle of thyroid –> vocal process of arytenoid cartilage,
  
  • IMPORTANT in voice production, b/c the control the stream of air thru rima glottidis
  • alter the shape and size of rima glottidis, by movement of artyenoids to faciliate respiration and phonation
  • Vocal folds made of:
    • vocal ligament = upper free edge of conus elasticus
    • vocal cords = fold of mucus membrane elevated by vocal lig
    • vocalis m = medial part of thyroarytenoid m

3. Subglottic (Infraglottic) space = rima glottidis –> lower border of cricoid cartilage

• Rima glottidis – narrow space b/w vocal folds
  • During inspiration = wide, expiration = narrow, wedge shaped
• Glottis =  Rima glottidis + vocal folds + vocal processes
• Piriform recess = part of cavity of laryngopharynx on each side of laryngeal inlet

Breathing/Phonation (making noises):
The more tensed the vocal folds are, the more narrow the rima glottidis is.
Normal respiration – rima is narrow & wedge shaped
Forced respiration – wide and kite shaped
Phonation – narrow , slitlike
Whispering – almost not open

Blood Supply:
Arteries:
Sup laryngeal a – thru thyrohyoid membrane = internal surface of larynx
Inf laryngeal a – mucus mem and m. in inf part of larynx
enter w/ nerves of same name (Int br of sup laryngeal n/inf laryngeal n)

Veins: venis w/ arteries
Sup laryngeal v –> sup thyroid v –> IJV
Inf laryngeal v –> inf thyroid v, thyroid venous plexus –> L brachiocephalic v

Lymph Drainage:
Above vocal fold – upper deep cervical nodes
Below vocal fold – lower deep cervical nodes

Innervation: CN X

1. Superior Laryngeal n – splits into int laryngeal (SS, ANS) /ext laryngeal n (SM)

• = mucus membrane above vocal fold, taste buds on epiglottis
• enters w/ sup laryngeal a thru thryrohyoid mem
• int laryngeal n – SS to laryngeal mucosa above vocal folds
• ext laryngeal n – SM to inf constrictor m, cricothyroid m,  runs w/ sup thyroid a

2. Recurrent Laryngeal n –

• (end branch of recurrent laryngeal n) all intrinsic m of larynx, except cricothyroid (ext laryngeal br of CN X)
• SS = below vocal fold
• terminates in int laryngeal n @ just above lower border of cricoid cart

Pharynx

funnel shaped fibromuscular tube from base of skull –> to inf border of cricoid cartilage
Layers of Pharyngeal wall:

• Mucus membrane
• Submucosa
• Pharyngobasilar fascia
• Muscular layer
• Buccopharyngeal fascia

Has 3 parts:
Nasopharynx, Oropharnx, Laryngeopharynx

Nasopharynx: from base of occiput –> soft palate & isthmus of fauces
Structures w/in
1. Choana – post opening of nasal cavity
2. Pharyngeal fornix – angle b/w roof of nasopharynx and post wall of pharynx, location of pharyngeal tonsils* (aka adenoids)
3. Opening of auditory tubes
– roof of auditory tube covered w/ torus tubarius
– ant bordered by salpingopalatine fold
– post bordered by salpingopharyngeal fold – has salpingopharyngeus m, opens pharyngeal opening of auditory tube during swallowing
– around tube opening = tubal tonsils*
4. Pharyngeal recess – b/w salpingopharyngeal fold and post wall of pharynx

Oropharynx: b/w soft palate, root of tongue –> epiglottis
Structures w/in
1. Root of Tongue
2. Lingual tonsils*
3. Palatoglossal & palatopharyngeal folds – w/ tonsillar bed b/w,

• that holds palatine tonsils*
• tonsillar bed = formed by superior constrictor of pharynx, and pharyngobasilar fascia

Opening to Oropharynx = Faucial isthmus

• Exit of oral cavity –> pharynx
• bordered laterally by palatoglossal/palatopharyngeal folds

Isthmus of Pharynx (diff than Fauces)

• Narrowest part of pharynx b/w soft palate & post wall of pharynx
• b/w nasal and oral parts of pharynx
• closed by elevation and tightening of soft palate and contraction of sup constrictor of pharynx & palatopharyngeus m
• Prevents food -> nasopharynx

Act of Swallowing:
1. Bolus of food pushed back by elevating tongue (styloglossus) into fauces
2. Palatoglossus & palatopharyngeus m contract to squeeze the bolus backward into oropharynx. Tensor veli palatini & levator veli palatini eleavate soft palate & uvula to close entrance into nasopharynx
3. Wall of pharynx raised by palatopharyngeus & stylopharyngeus to receive food, Suprahyoid m elevate hyoid bone & laynx to close opening into larynx, passing over the epiglottis, prevent food from entering respiratory pathway
4.Action of sup,mid,inf constrictor move food through oropharynx and laryngopharynx –> esoph, where propelled by peristalsis

Blood Supply:

• tonsillar br of facial a
• asc pharyngeal a
• asc palatine br of facial a
• desc palatine a
• pharyngeal br of maxillary a
• br of sup/inf thyroid a

Innervation:

• lies on middle pharyngeal constrictor
• formed by pharyngeal br of CN IX, X, SNS br from sup cervical ggl
• Vagal br = all m of pharynx, w/ exception of stylopharygeus m (CN IX), and tensor veli palatini (V2)
• Glossopharyngeal br = sensory fibers of pharyngeal mucosa

Laryngopharynx: epiglottis –> cricoid cartilage (C4-C6)
1. Piriform recess – b/w larynx (aryepiglottic fold) & lat wall of pharynx (medial surface of thyroid cartilage & thyrohyoid membrane), contains sup laryngeal a, int laryngeal n
2. Med/Lat glossoepiglottic folds
3. Valleculae epiglottica – b/w med and lat glossoepiglottic folds on sup side of epiglottis
4. Post/lat walls = middle and inf constrictor m,
5. Internal wall = palatopharyngeus, stylopharyngeus m

Muscles: all innervated by Pharyngeal plexus, except stylopharyngeus m (IX)

Elevators:

• Stylopharyngeus m
• Palatopharyngeus m
• Salpingopharyngeus m

Constrictors:
Sup/middle/Inf constrictors
each one is thicker than the one above and cover the lower end of it

* To see Parapharyngeal space & Retropharyngeal space, refer to cards above

Histology: Pharynx, larynx and thyroid gland.

Slide #28  Larynx *H&E

Structures to Identify:

• vestibule
• true vocal folds
• false vocal folds
• cricoid cart
• vocal ligaments
• str columnar epith
• epiglottis
• rima glottidis
• quadrangular membrane
• vocalis m
• str. sq epith
• ventricles
• thryoid cartilage
• conus elasticus
• psuedo str. epith

Lower power:
can see greater horn of hyoid bone
hyaline cartilages:
cricoid cartilages
thyroid cartilages

b/w cartilages = laryngeal musc – str. musc fibers
on outer side of thyroid cart = infrahyoid m can be seen

Vertical section thru larynx:
show 2 vocal folds, supporting cartilages & muscles
vestibule –> vestibular folds –> ventricle –> true vocal fold —> subglottic region

Function:
conducts air
origin of speech
helps in swallowing
sound production & resonance

Mucosa:
false vocal fold = made by mucosa,
lined pseudostr. columnar epith w/ ciliae & goblet cells  = respiratory epith

vocal fold= str. squamous non  epith, more resistant to strain bacteria
vocal ligament located just deep to it
rich in a/v, esp capillaries

subglottic region = respiratory epith again

Lamina Propia
in LP = mixed glands (mostly mucus)
excretory ducts from glands, open @ epith
lymphatic nodules on ventricular side of fold
is thinner in area of vocalis m = no glands or a/v

Fibromuscular layer = quadrangular membrane
cartilages = become ossified to bone w/ age
cricoid cart = perichondrium + chondrons surrounded by matrix (PGs) + type II collagen fibers
ext pharyngeal m =  responsible to move & elevate larynx during swallowing
musc = thyroarytenoid m

Adventia – external layer of CT

Slide #34 Thyroid Gland *H&E

Structures to Identify:
CT septa
follicles
colloid
follicular cells
parafollicular cells
arterioles
capillaries
venules

General Info:
unique exocrine gland b/c stores large amounts of secretory products extracellularly
has R & L lobe that are connected in middle via isthmus

CT septa separate thyroid gland into lobules
contain a/v, capillaries (from sup/inf thyroid a)

Follicular cells = prinicipal cells
follicular cells stores their secretory products in the cytoplasm
arranged into spherical shapes = follicles
surrounded by reticular fibers, and a/v – so thyroid hormones can enter blood
follicular epithelium = squamous, cuboidal, low columnar
structural and functional unit of thyroid gland

follicular cells can also release secretory products into lumen of follicles
stores their secretory products in the cytoplasm = colloid
made of thyroglobulin = GP w/ iodine acids
active thyroid hormones liberated from thyroglobulin
released into fenestrated capillaries that surround follicle

secretion of thyroid hormones = T3 + T4

• regulate  cell & tissue base metabolism, heat production, influence body growth & development
• inc fat/prot synthesis/degradation
• inc rate of carb use absorption
• inc heat production
• regulated by TSH

Production of Thyroid Hormones:
Thyroxine (3,5,3′,5′-tetra­iodothyronine) is produced by follicular cells of the thyroid gland. It is produced as the precursor thyroglobulin (this is not the same as TBG), which is cleaved by enzymes to produce active T4.

Thyroxine is produced by attaching iodine atoms to the ring structures of tyrosine molecules. Thyroxine (T4) contains four iodine atoms. Triiodothyronine (T3) is identical to T4, but it has one less iodine atom per molecule.

Iodide is actively absorbed from the bloodstream by a process called ‘iodine trapping’ and concentrated in the thyroid follicles. (If there is a deficiency of dietary iodine, the thyroid enlarges in an attempt to trap more iodine, resulting in goitre.) Via a reaction with the enzyme thyroperoxidase, iodine is covalently bound to tyrosine residues in the thyroglobulin molecules, forming monoiodotyrosine (MIT) and diiodotyrosine (DIT). Linking two moieties of DIT produces thyroxine. Combining one particle of MIT and one particle of DIT produces triiodothyronine.

* DIT + MIT → r-T3 (biologically inactive)
* MIT + DIT → triiodothyronine (usually referred to as T3)
* DIT + DIT → thyroxine (referred to as T4)

parafollicular cells
larger, pale staining cells
either peripherally, in follicular epith or w/in follicle
synthesize & secrete calcitonin =

• reg Ca2+ metabolism, and decreases its level in blood
• stimulate absorption of Ca2+ by bone
• regulated by concentration of Ca in blood

Embryology: Development of the pharynx, larynx and thyroid gland.

Pharynx:

Components of branchial/pharyngeal apparatus:

• Pharyngeal arches
• Pharyngeal pouches
• Pharyngeal clefts/grooves

Pharyngeal (branchial) arches:

• Derived from neural crest cells
• Resemble fish gills (branchia)
• Begin to develop early in the 4th week
• By end of 4th week, four pairs of arches are visible on the surface (not 5th and 6th ) and a buccopharyngeal membrane ruptures forming communication between primitive oral cavity and foregut
• Contribute to the formation of the neck as well as the face.

Pharyngeal Arch Derivatives:

Each arch has a core of mesenchymal tissue (mesoderm) covered by surface ectoderm (outside) and by endodermal epithelium (inside)

• Ectoderm -> skeletal
• Mesoderm -> muscles with accompanying nerve
• Arterial component (aortic arches) – each pharyngeal arch has an aortic arch running w. it
• Therefore, each arch carries nerve, muscle, bone and blood supply

First pharyngeal arch:

• Maxillary process (dorsal): Premaxilla, maxilla, zygomatic bone, portion of temporal bone
• Mandibular process (ventral): Contains Meckel’s cartilage which disappears except for dorsal end (incus & malleus) and mandible
• Muscles of mastication, digastric (ant belly), mylohyoid, tensor tympani and tensor palatini
• Therefore, the accompanying motor nerve is the mandibular branch of trigeminal (V2) and sensory are V1, V2, and V3
• 1st aortic arch practically disappears but forms the maxillary artery

Second pharyngeal arch:

• Reichert’s cartilage – stapes, styloid process, stylohyoid ligament, lesser horn and upper part of the hyoid
• Muscles include: stapedius, stylohyoid, digastric (post belly), auricular, and those of facial expression
• Facial nerve (CN VII)
• 2nd aortic arch – stapedial & hyoid arteries

Third pharyngeal arch:

• Cartilaginous contributions include greater horn and lower part of hyoid
• Sole muscle: stylopharyngeus
• CN IX (Glossopharyngeal nerve)
• 3rd aortic arch (quite large): common carotid, 1st portion of internal carotid (remainder dorsal aorta), and external carotid

Fourth & sixth pharyngeal arch:

• Cartilaginous contributions to larynx derived from fusion: thyroid, cricoid, arytenoid, corniculate, and cuneiform
• Muscles of 4th: cricothyroid, levator palatini, and pharyngeal constrictors are innervated by SLN (CN X)
• Muscles of 6th: intrinsics of larynx are innervated by RLN (CN X)
• 4th aortic arch: L->arch of aorta & R->subclavian
• 6th aortic arch: L & R pulmonary with ductus arteriosus on left

Pharyngeal pouches (5):

• 1st:tubotympanic recess-> middle ear & eustacian tube -> TM
• 2nd palatine tonsil/fossa
• 3rd: inferior parathyroid (dorsal), thymus (ventral)
• 4th: superior parathyroid
• 5th: ultimobranchial body  -> calcitonin producing C cells (parafollicular)

Pharyngeal clefts/grooves (4):

• 1st: external auditory meatus
• 2nd-4th : epicardial ridge and cervical sinus (disappears)

Larynx:

• Int lining from endoderm, as well as the laryngeal epithelium & glands
• musc & cartilage from 4th & 6th pharyngeal arch = thyroid, cricoid, arytenoid cartilages – therefore innervated by CN X
  • superior laryngeal n – above the vocal fold
  • recurrent laryngeal n = below the vocal fold
• @ wk 4, on the ventral side of the primitive gut, a pocket forms that bulges out from the gut = laryngotracheal diverticulum
• distal end of diverticulum to form lung bud
• then, 2 folds of tracheo-esophageal folds, push medially and push together to midline to form a wall “septum”
  • ant (ventrally) = laryngealtracheal tube
  • post (dorsally) = esophageal tube
• opening of laryngeal diverticulum = orifice

Thyroid gland:

• endoderm lining @ midline of floor in pharynx – forms pocket = diverticulum
• @ 7th wk = this pocket moves downward – and passes ventral to hyoid & laryngeal cart
• remain connected to tongue by thyroglossal duct — remains foramen cecum
• functional @ 3rd month

The anatomy of the nasal cavity and paranasal sinuses. The skeletal and smooth muscle tissues. The development of the pharyngeal gut.

The anatomy of the nasal cavity and paranasal sinuses. The skeletal and smooth muscle tissues. The development of the pharyngeal gut.

The anatomy of the nasal cavity and paranasal sinuses.

Nasal Cavity:

*For step by step amazing pictures of the nasal cavity: http://home.comcast.net/~WNOR/lesson9.htm

Borders:

• ant = nasal bone (ant nasal aperture = piriform aperture)
• sup =
  
  • (ant) nasal part of frontal bone
  • (middle) body of sphenoid,
  • (post) body of sphenoid,
    
  • the roof of the nasal cavity also has the cribriform plate of ethmoid bone, conveying fibers of CN I
• med = septum nasi – made by perpendicular plate of ethmoid sup/post, vomer inf/post, and septal cartilage ant
• inf = hard palate, made of palatine process of maxilla (ant), and horizontal plate of palatine bone (post)
• post border = outlet = choanae, that lead to nasopharynx
  • lat = med pterygoid plate
  • med = vomer
  • sup = body of sphenoid
  • inf = horizontal plate of palatine bone

There are two parts to the nasal cavity, the nasal vestibule, and the nasal cavity itself

The line that divides the vestibule from the rest of the nasal cavity is limen nasi, which is the alse the line between the cutaneous and mucosal part of the nasal cavity

On the sagittal section of the head, you can find limen nasi, by looking for where the nose hairs stop – and you will be transitioning into the mucosal part.

Medial Wall
The nasal cavity itself is further subdivided into two regions:
upper 1/3 = olfactory part, for smelling
lower 2/3 = respiratory part, for breathing

The medial wall of the nasal cavity is pretty lacking in any features, just mention what makes up the septum.
CLINCIAL NOTE – the nasal septum can be deviated (bent) to one side or the other, if bent so far that it touches the lateral wall, can require surgery, because will affect breathing.

Lateral Wall
The lateral wall is much more complicated, having three projections coming from it, the nasal concha.

There are 3 nasal concha – sup, mid, inf.
Function of the nasal concha: is to spin the air within the nasal cavity, in order to:

• to help warm the air,
  
• as well as aid in filtering it
  
• adding moisture to the air.

Above the superior nasal concha, is the sphenoethmoid recess – the sphenoid sinus opens into this space

between each concha, are the nasal meati.
Superior nasal meatus – B/w the superior and middle concha
2 things open here :

1. the posterior ethmoid air cells (one of the paranasal sinuses)
2. sphenopalatine foramen – thru it, go the sphenopalatine a, and post/ sup nasal n

Middle nasal meatus = B/w middle and inf concha
This area is a bit more complicated.
There is a bony projection (bulge) into this area, made by middle ethmoid air cells – called the ethmoidal bulla.
Below the ethmoidal bulla is the uncinate process, a horn shaped bony projection.
Leading into the uncinate process is the ethmoidal infundibulum, that contains the fronto nasal duct. This duct leads from the frontal sinus, and allows it to empty into the middle nasal meatus.

B/w the ethmoidal bulla and the uncinate process is a half moon shaped space = semi lunar hiatus.
3 Things open here:

1. Into the hiatus, the frontal sinus opens ( via the fronto nasal duct),
   
2. maxillary sinus opens into the post part of the hiatus,
   
3. ant/ mid ethmoid air cells also open here.

So all together that is 4 things that open in the middle nasal concha.

Inf nasal meatus =  below the inf nasal concha,
2 things open here:

1. Nasolacrimal duct opens here in to the ant part of the meatus, draining excess tears into the inf nasal meatus – this is  why your nose runs when you cry a lot.
2. Incisive canal – we mentioned this before in the oral cavity, is the connection b/w nasal and oral cavity, has nasopalatine n/a here.

Blood Supply of Nasal Cavity:

• post lat nasal and post septal br (sphenopalatine a)
• ant post/ethmoid a (ophthalmic a)
• Gr palatine a (desc palatine a)
• Septal br of sup labial a (facial a)
• Lat nasal br (facial a)

Huge venous plexus drains the nsals mucosa —> flow into sphenopalatine, facial, and ophthalmic v, plays a major role in warming air before it goes to lungs

Innervation of Nasal Cavity:
Respiratory region: SS

• Post/inf part of nasal cavity = nasopalatine n (V2) to septum, post lat nasal branches (gr palatine n) to lat wall
• ant /sup part = ant/post ethmoidal n (nasociliary n of V1)

Olfactory region = CN I

* For innervation of mucosal glands of Nasal Cavity, please see topic #3

4 Paranasal sinuses:

Function:

• decrease the weight of the facial skeleton
• vocal resonance – why your voice changes when you have a cold/sinus infection, and your sinuses fill
• moisten and warm air

1. Frontal Sinus – located w/ the frontal bone, behind the root of nose, innervated by supraorbital n of V1

2. Maxillary sinuses –  largest paranasal sinuses
Borders:
roof = floor of orbit
floor = alveolar process of maxilla
apex = zygomatic bone
base – inf/lat wall of nasal cavity

CLINICAL NOTE – maxillary sinus drains by an opening maxillary ostium in to middle nasal meatus, but this opening is located high on the walls, so sinus does not fully drain – can get infected easier = sinusitis

Blood supply = sup alveolar a (Maxillary a)
Innervation = br of ant/mid/post superior alveolar n (V2)

3. Ethmoidal sinuses (air cells)
located lat to most superior part of nasal cavity. If you pinch the bridge of your nose, the ethmoid sinuses would be located post to your fingers.

Innervation = by ant/post ethmoid n (nasocilary n of C1)

4. Sphenoid sinus
located in sphenoid bone, part of roof of nasal cavity
Clincial NOTE – b/c of this sinus, the roof of nasal cavity is weak. If broken in a fight, can cause to the leakage of sinus contents or even CSF out of the nose
Innervation = by post ethmoidal a and post ethmoid n

Histology: The skeletal and smooth muscle tissues.

Smooth Muscle

all musc tissue consist of elongated cells = fibers
cytoplasm of musc cells = sarcoplasm
contains a # of myofibrils, made of actin & myosin
surrounding cell membrane = sarcolemma

Smooth muscle

found in numerous organs = uterus, SI, LI, stomach, a/v, trachealis
contain contractile actin and myosin filaments
not arranged in regular cross striated pattern
appear smooth and non striated
involuntary motion
small, spindle, fusiform in shape – single central nucleus
actin/filaments attach dense bodies (adheron aggregates) to sarcolemme plaques

Function:

• exhibits spontaneous, wave – like activity
• ureters, uterine tubes, digestive organs: produces peristalsis
• a/v = regulate luminal diameters

connected w/ gap junctions – rapid ionic communications
regulated by SNS/PNS
influence the rate and force of contractility

Contraction:

1. Sarcoplasmic reticulum release Ca2+
2. Ca/calmodulin complex forms
3. which activates MLCK (Myosin light chain kinase)
4. this PO4’s myosin –> myosin attaches to actin = contraction

Skeletal muscles
long multinucleated cells w/ peripheral nuclei
very regular formation of myosin & actin in cytoplasm
contractile filaments form distinct cross striation patterns = dark A bands, light I bands

3 CT layers:
Skeletal musc surrounded by dense irregular CT = epimysium
less dense, irregular CT = perimysium – comes inside and divides interior of muscle into fascicles (bundles)
endomysium = CT fibers that go around individual fibers
w/in cell = 4-5 myofibrils
groups of 8-9 myocytes = fascicles

has neuromuscular spindles – CT capsule, contain musc fiber called intrafusal fibers, & n. endings, surrounding fluid filled space

Other features:

• No cell junctions
• well developed ER & T tubules
• voluntary innervation
• all or non contraction
• NO mitosis
• grows in response to demand
• limited regeneration
• made by myoblasts of para-axial mesoderm

Contraction:
Thick (A) = Myosin – tail region of globular head
Thin (I) = Actin – twisted chains
1. when myosin head attached to actin – no ATP present
2. ATP binds to head –> ATP becomes ADP + P, head moves away from actin
3. fibers slide past each other
4. length of sarcomere decreases
5. I & H band disappear

Embryology:The development of the pharyngeal gut.

The primitive gut forms during the 4th week of the development as a result of cephalocaudal and lateral folding of the embryo. This endoderm lined cavity is incorporated into the embryo, while the yolk sac and the allantois remain temporarily by outside the embryo. The endoderm of the primitive gut gives rise to the epithelium and glands of the digestive tract. The muscular and fibrous elements of the digestive tract are derived from the splanchnic mesoderm. The epithelium at the cranial and caudal extremities of the digestive tract is derived from the ectoderm of the stomodeum and the proctodeum (anal pit).
Formation of the gut tube Formation of the primitive gut Formation of the ventral abdominal wall Formation of the ventral abdominal wall	1. Foregut 2. Hindgut 3. Midgut 4. Central nervous system 5. Tracheobronchial diverticulum 6. Heart 7. Liver bud 8. Buccopharyngeal membrane 9. Vitelline duct 10. Allantois 11. Cloacal membrane 1. Yolk sac 2. Surface ectoderm 3. Amniotic cavity 4. Neural groove 5. Splanchnic mesoderm 6. Somatic mesoderm 1. Yolk sac 2. Surface ectoderm 3. Amniotic cavity 4. Neural tube 5. Splanchnic mesoderm 6. Somatic mesoderm 1. Gut endoderm 2. Intraembryonic coelomic cavity 3. Amniotic cavity 4. Dorsal mesentery 5. Splanchnic mesoderm 6. Somatic mesoderm 7. Neural tube

The primitive gut is divided into four parts: a) the pharyngeal gut which extends from the buccopharyngeal (oropharyngeal) membrane to the respiratory (tracheobronchial) diverticulum;

5. The anatomy of the oral cavity and salivary glands. The histology of the tongue and salivary glands. The development of the oral and nasal cavities.

Anatomy of the oral cavity and salivary glands.

General Info:

Borders:

• roof = palate (hard, soft)
• floor = tongue, mucosa, geniohyoid and mylohyoid m
• Lat/ant
  • Outer fleshy wall = cheeks, gums
  • Inner bony wall = teeth and inner aspect of gums
• communicates posteriorly with oropharynx

Divided into 2 areas: the oral vestibule, anterior to the teeth and buccal side of gingiva (gums) & oral cavity proper, which is the space behind the teeth and gums

Oral Vestibule = Cheeks, Lips, Gingivae

Lips

• Lips contain the orbicularis oris m, and sup/inf labial m, a/v/n.
• Covered externally by skin externally, and mucosa internally.
• Epithelium of skin transitions from normal skin –> red vermillion portion –> to inner mucosal layer. The border line b/w skin and red portion = transition zone.

Structures to identify in relation to the lips:

• upper lip = b/w nose & opening of oral cavity
• nasolabial grooves = seperate lips from cheeks, 1 cm lat to angle of mouth
• philtrum = a shallow depression below the nose, bordered by 2 lateral crests – not everyone has one
• lower lip = b/w opening of oral cavity and labiomental groove, separating lower lip from chin.
• labial frenula = a mucosal membrane fold that attaches the lips to the ant surface of the vestibular gingiva (gums facing the oral vestibule) — NOTE diff from lingual frenula, that attaches the tongue to the floor of the mouth

Blood supply = sup/inf labial a (facial a)

• upper lip = br of facial/ infraorbital = sup labial br
• lower lip = br of facial/mental a = inf labial br

Innervation

• upper lip = sup labial br of V2
• lower lip = inf labial br of mental n from V3 (mental n comes from inf alveloar n)

Lymph Drainage = submandibular/submental lymph nodes

Cheeks

over lie the zygomatic process
contain the buccinator m – that holds cheeks taught when exhaling forcefully
contains the buccal fat pad (of Bichat)
Blood Supply = buccal br of maxillary a (terminal br of ext carotid), n = buccal br of mandibular n (V3)

Gums

are fibrous tissue covered with mucosa
hold teeth in place
supplied by many a/v/n

Blood Supply

• upper (maxillary) lingual gingiva of incisors, canines = nasopalatine n,a/v – most ant, this makes sense because nasopalatine structures go through incisive foramen at most ant part of hard palate
• upper (maxillary) lingual gingiva of premolars, molars = gr. palatine n, a/v – post, makes sense b/c gr. palatine structures go through gr palatine foramen at post/lat part of hard palate
• lower(mandibular) labial buccal gingiva of incisors, canines, premolars = inf alveolar n/a/v
• lower(mandibular) labial buccal gingiva of molars = buccal n
• lower(mandibular) lingual gingiva = lingual n/a/v

*Teeth is another topic, please refer to that

Palate

Made up of hard and soft palate

Hard palate
is bony and makes up the ant 4/5 of the palate = palatine process of the maxilla, and horizontal plate of palatine bone
border b/w nasal and oral cavity
@ midline of hard palate, running back from incisive foramen = palatine raphe – where the 2 palatine shelves fused in embryonic life

3 foramina:
Incisive foramen (ant/med) = nasopalatine n/a/v

• In the netter, it looks like sphenopalatine a goes through there, but do not say this in a test, it will be considered incorrect.
• NOTE – makes the location of the fusion b/w primary/secondary palate in embryonic life

Greater and Lesser Palatine foramen (post/lat) – right next to 3rd molar (wisdom tooth) = the gr/lsr palatine n/a/v go through them.

• Gr palatine structures run ant and supply hard palate
• Lsr palatine stuctures run post and supply soft palate
• The a comes from desc palatine a, a br of maxillary a

Soft Palate

• is fibromuscular fold that makes up post 1/5 of palate
• moves agains the pharyngeal wall to close oropharynx while swallowing or speaking
• as mentioned earlier, supplied a/v/n by lesser palatine structures.
• Laterally, is continuous with palatoglossal and palato pharyngeal folds
  • These folds are form the lateral border to the exit of oral cavity = Isthmus of Fauces, that leads to Oropharynx (More on that in pharynx)
  • b/w them is the tonsillar bed = palatine tonsils
  • CLINCAL NOTE – are frequently inflamed and removed, along with pharyngeal tonsils (see pharyn) aka adenoids

• CLINCAL NOTE = Since lingual gingiva is connected to mucosa of soft palate, can inject anasthetic there to numb soft palate
• Has numerous palatine glands, that secrete mucus

Blood Supply: Gr and Lsr palatine a (more the 2nd one), Asc palatine a (Facial a), Palantine br of Asc Pharyngeal a

Innervation : SS = lsr palatine n, SM = CN X

Venous Drainage: hard and soft palate v drain in pterygoid venous plexus

NOTE that Hard palate has no SM innervation – no musc there.

Muscles of Palate: all innervated by CN X via pharyngeal plexus – except Tensor Veli Palatini (V3)

• Tensor Veli Palatini – tenses soft palate, has a large tendon that strengthens the soft palate = palatine aponeurosis
• Levator Veli Palatini – elevate soft palate
• Palatoglossus – elevates tongus (Just uses palate as an origin site, doesn’t do anything to palate itself)
• Palatopharyngeus – elevates pharynx, to help close off nasopharynx from oropharynx in swallowing
• Uvulus – @ termination of soft palate, no real function, but helps to identify issues with CN X, b/c if this doesn’t move when saying, “Ahhh”, then poss malfunction w. CN X

Tongue

• is almost purely made of muscle
• the ant 2/3 is called the oral part = originates from 1st pharyngeal arch
• post 1/3 = pharyngeal part, orginates from 3rd arch, behind terminal sulcus of tongue
• @ midline of terminal sulcus is foramen cecum, the remnant of thyroglossal duct
• root = from 4th arch
• Has midline sulcus on dosal surface = location of fusion of 1 lateral swellings of ant tongue over tuberculum impar.

Function: aid in speaking, allow for movement of food toward oropharynx and within oral cavity
Parts:
Body – most of the tongue
Apex – pointed ant part
root – part fixed to hyoid bone and mandible, is located behind palatoglossal fold, location of lingual tonsils.

Taste Buds: SEE HISTO

The inferior surface of tongue has a very thin mucus membrane, so can see many veins, and is attached to floor of mouth via another mucus membrane fold = lingual frenulum. – Basically keeps tongue in mouth while allowing apex to move about

Muscle of Tongue = all innervated by CN XII, except palatoglossus, which we already said is innervated by Pharyngeal plexus, via CN X

Intrinsic m – change the shape of tongue itself
Sup/Inf Longitudinal, Transverse, Vertical

Extrinsic m – change position of tongue

• Genioglossus – protrudes and depresses tongue
• Hyoglossus – depresses and retracts tongue
• Styloglossus – retracts and elevate tongue
• Palatoglossus – elevates tongue

How to remember them? Gay Hats STYLe Perfectly

Basic Taste sensations:
Sweetness = apex
Saltiness = lateral side
Sourness & bitterness = posterior part
Umami = used to taste the unusual tastes in cheese, meat, asparagus, & tomatoes

Blood Supply:

• Lingual a from Ext carotid a, emerges @ lever of gr. horn of hyoid bone in carotid triangle
• Pathway: runs deep to hyoglossis (lateral lingual groove), and lies on middle pharyngeal constrictorm
• Br = dorsal lingual, suprahyoid,sublingual a, terminates as deep lingual a ( on top of genioglossus m)

Lymph Drainage:

• Post 1/3 = deep cervical lymph nodes
• Medial ant 2/3 = inf deep cervical lymph nodes
• lat ant 2/3 = submandibular l.n
• apex = submental l.n

Innervation of Tongue:

• Ant 2/3:  SS = CN V3 via Lingual n, VS = CN VII via Chorda Tympani
• Post 1/3: SS/VS = CN IX
• Root: SS = CN X, no taste buds here, so no VS

Salivary Glands:

For contents of saliva and function = See HISTO

Parotid

Location: Retromandibular Space = Parotid Bed
Borders:

• ant = Masseter m, Ramus of mandible
• post = SCM, post digastric m
• sup = zygomatic arch
• inf = fascia b/w SCM and mandible
• Lat = open

General Info:
covered by dense fibrous capsule from investing fascia of neck
secretes serous saliva
largest of the glands

Duct Pathway:
From widest part of gland –> across masseter and deep to it –> lat/ant to Buccal fat pad –> peirces Buccinator m, and opens @ 2nd maxillary (upper) molar

Structures Passing through It:
Ext Carotid a – giving 2 terminal branches = Maxillary a, Superficial temporal a
Superficial Temporal v & Maxillary v combine to give Retromandibular v
Facial n peirces it and gives 5 terminal branches  – DOES NOT innervate the gland
Auriculo temporal n – carries PNS post synaptic fibers with it to increase secretion of gland

Blood supply:
from branches of external carotid and superficial temporal a = Transverse facial a
Veins follow a and drain into Retromandibular v

Lymph Drainage:
superficial and deep cervical lymph nodes

Innervation:

• Tympanic n arises from CN IX and emerges from jugular foramen
• n enters the middle ear via the tympanic canaliculus in petrous part of  temporal bone
• tympanic n forms the tympanic plexus — and lesser petrosal n emerges from this plexus
• lesser petrosal leaves skull via foramen ovale
  
• PNS fibers from it synapse in otic ganglion
• post ggl fibers from ggl RUN W/ auriculotemporal n (from V3) to supply parotid gland

*Parotid and Submandibular gland separated by stylomandibular lig b/w styloid process & angle of mandible

Submandibular Gland
Located:  below mylohyoid & mandible

General Info:
Has Superficial and Deep part (deep part located b/w mylohyoid and styloglossus)
secretes a mix of serous and mucus saliva

Duct Pathway:
ducts runs thru lat space of tongue w/ Hypoglossal n and lingual n = lateral lingual groove —> then eventually goes to and open lat to frenulum, b/w mylohyoid and styloglosses
lingual n loops under duct in the lateral lingual groove

Blood Supply: sunmental a (Facial a), V run with a.

Lymph Drainage: deep cervical l.n. –> jugulo-omohyoid nodes

Innervation:
Pre ggl PNS fibers from CN VII by chordatympani –> submandibular ggl –> post ggl fibers run w/ lingual n
SNS post ggl fibers come from sup cervical ggl

Sublingual Glands
Location: b/w mandible and genioglossus m

General info:
smallest of the 3 glands
secretes both mucus and serous, but more mucus

Duct Pathway: duct opens @ floor of oral cavity w/ submandibular duct, just below mucus membrane of tongue, lat to frenulum

Blood Supply : Submental and sublingual a (from facial and lingual a)

Innervation:
Pre ggl PNS fibers from CN VII by chordatympani –> submandibular ggl –> post ggl fibers run w/ lingual n

SNS post ggl fibers come from sup cervical ggl

Histology of the tongue and salivary glands.

Slide #38-39 Tongue * H&E

Structures to Identify:
#38

• circumvallate papillae
• serous gland (Von Ebner’s)
• CT
• Taste bud (also visible in palate, pharynx, esoph)
• ducts
• str. musc bodies
• lingual

#39

• lingual papillae
• fungiform papillae
• filliform papillae
• bundle of nerves
• sk m fibers
• adipose tissue

General info:
muscular organ in oral cavity
core = CT and bundles of sk musc fibers
distribution and random orientation of sk musc in tongue
allows inc movement during chewing, swallowing, speaking

Surface:
epith on ventral surface is smooth
epith on dorsal surface is irregular b/c of papillae – which are folds of mucosa pushed up by mounds of LP underneath
covered by str. squamous epith – partial keratinized – very fire-like

Filiform papillae

• most numerous & smallest papillae
• conical shaped
• cover entire dorsal surface of tongue
• NO taste buds

Fungiform papillae

• less in #
• larger & broader than the filiform papillae
• mushroom like shape
• ant region of tongue
• b/w filiform

Circumvallate papillae

• much larger than any of others
• about 8-12 located in post region of tongue, just next to sulcus terminalis
• have deep furrow’s next to each papillae = where von Ebner’s glands open
• Von Ebner’s glands = serous lingual glands

Foliate papillae

• not many, lateral side of tongue
• not picture on either slide

Taste buds
located in epith of foliate & fungiform papillae, lateral side of circumvallate papillae
have an apical opening = taste pore

3 types of cells:

1. have neuroepithelial taste cells w afferent n. fibers coming from them (VS)
   • VS innervation:
     • ant 2/3 = facial n (CN VII)
     • post 1/3 = CN IX
     • epiglottic region = CN X
   • most in #
   • elongated w/ light cytoplasm
   • oval and light nucleus
   • apical surface extended w/ microvilli that protrude thru taste pore
   • base forms synapses w/ processes off sensory neurons
2. also in taste bud = sustenacular (support) cells
   • elongated w/ darker cytoplasm
   • slender & darker nucleus
   • also have microvilli, but no synapse @ base
   • connected w/ tight jxns
3. base of taste bud = basal cells, thought to be stem cells for taste cells
   • small cells in basal portion of taste buds
   • near basal lamina

5 types of tastes :
sweet, bitter, umami  = G protein
salty, sour = ion channel

Core of Tongue: musc + CT
Extrinsic m: – changes position of tongue

• genioglossus m
• styloglossus m
• hyoglossus m
• palatoglossus m
• * all innervated by CN XII all except palatoglossus (pharyngeal br of CN X = pharyngeal plexus)

Intrinsic m: – changes shape of the tongue

• longitudinal
• transverse
• vertical

Connective Tissue Septa

• CT b/w musc = a/v , nerve fibers
• lower half of tongue & b/w musc fibers = seromucous lingual glands
• ant/ post seromucous glands exist – each have interlobular ducts
• interlobular ducts combine to form one lingual excretory duct

Histology of Salivary Glands:

Function of saliva:

• source of Ca2+ & PO4 for tooth development
• moisten oral mucosa
• moisten dry foods to aid swallowing
• release IgA
• controls bacterial flora by releasing lysozymes
• buffer contents of oral cavity – b/c of its inc HCO3 concentration
• digest carbs by releasing alpha amylase

Slide #40 Parotid gland *H&E

Structures to Identify:

• serous glands
• intercalated ducts
• striated ducts
• adipose cells
• excretory ducts
• CT
• n. bundles (br of Cn VII)

Easy to identify:
loads of adipose
only serous acini
looks like bubble bath

General Info:
located ant/inf to ext ear
largest of salivary glands
only serous

Lobules
entire gland surrounded by CT capsule
from CT capsule, comes CT septa that splits the gland into lobules
located w/in CT septa = arteriole, venule, interlobular excretory ducts, & adipose cells
occasional plasma cells may be seen in CT surrounding ducts = produce Igs taken up & resecreted by acinar cells

Serous acini = Secretory part

• made up of only serous acini = secretory cells
• pyramid shaped cells are arranged around a lumen
• spherical lumen located @ base of basophillic cytoplasm
• small lumen
• surrounded by thin, contractile myoepithelial cells – branches of CN VII found here
• secretory protein rich substance stored in zymogen granules
• stains in H&E better

Conducting system = Duct system

1. acini empty into intercalated duct
   • (squamous/ low cuboidal epith)
   • posses carbon anhydrase activity
   • secrete HCO3-
   • absorb Cl-
2. striated ducts
   • (larger lumina, lined by simple columnar epith w/ basal striations)
   • basal striations formed by deep infoldings of basal cell membranes
   • absorb Na+
   • secrete K+ HCO3-
3. interlobular excretory ducts
   • (pseudostratified epith)

Slide #41 Submandibular gland *H&E

Structures to Identify:

• mucus acini
• serous acini, demilunes
• adipose cells
• duct system = intercalated, striated, excretory ducts
• myoepith cells
• adipose
• a/v

General Info:

• compound tubuloacinar gland
• mixed gland = serous (2/3), mucus acini (1/3)
• duct opens lat to frenulum in oral cavity
• find adipose cells w/in lobule
• find a/v in CT septa

Conducting system:
same as parotid gland

Secretory portion:
Serous acini:

• pyramid shaped cells are arranged around a lumen
• spherical lumen located @ base of basophillic cytoplasm
• small lumen
• surrounded by thin, contractile myoepithelial cells – branches of CN VII found here
• secretory protein rich substance stored in zymogen granules
• stains in H&E better

Mucus acini:

• lightly stained w/ H&E, stained pink w/ PAS
• larger lumen
• cytoplasm is pale b/c loss of mucin during slide prep
• columnar cells, w/. flattened nuclei @ periphery
• may have serous semilunes
• surrounded by myoepithelial cells that help secretory units drain content

Slide #42 Sublingual gland *PAS w/ H background

Structures to identify:
mucus acini
ductal system

General info:
mixed tubuloacinar gland – more MUCUS (2/3) than serous (1/3)
b/c Mucin is made of carbs, stains well w/ PAS staining
cannot see serous very well

PAS reaction:
periodic acid = breaks carbs –> aldehydes
aldehydes react w/ Schiff base = magenta color

Ductal system a bit different:

• not very many intercalated and striated ducts, b/c the high amount of mucus can cause the ducts to be blocked
• and the saliva is modified minimally
• many more interlobular septa (and ducts) than in parotid or submandibular
• numerous lymphocytes & plasma cells

Embryology: Development of the oral and nasal cavities.

Nasal Cavities:

• On both sides of frontonasal prominences, there are forming 2 lateral thickenings of surface ectoderm = nasal placodes
• @ 5th wk = nasal cavity and nasal projection begins to form (nose)
  • nasal placodes fold inwards (”invaginate”) to form nasal pits
  • around nasal pit, there is a ridge of tissue = nasal prominences.
  • Picture a bowl – the actual bowl is nasal pit, and the rim of the bowl is the nasal prominences
  • The nasal prominences are split into lat & medial nasal prominences
• @ 6th wk = nasal pits deepen and penetrate into mesenchyme below
• Oronasal membrane – separate pits from oral cavity, via choanae,
  
• swelling on lat wall = sup/mid/lat conchae
• Paranasal sinuses = are pockets off nasal cavity, grow into neighboring bones – grow through puberty
• Ectoderm @ nasal placode = olfactory epith = make the sustenacular, basal, ciliated cells

Oral Cavity

• Lip formation  = see previous topic

Palate:

• Primary palate
  • formed from medial growth of maxillary prominences
  • the medial nasal prominences also merges deeper to form intermaxillary segment
  • forms philtrum of upper lip, 4 upper incisors, palate ant to foramen incisive
• Secondary palate
  • formed by 2 palatine shellves, a downward growth from maxillary segment
  • turns horizontal  @ 7th wk to fuse at midline, and then fuses ant with primary palate @ location of incisive foramen
• Primary & ant Secondary palate together form hard palate
• post secondary palate forms soft palate and uvula

Mouth:

• from surface depression called the stomodeum (ectoderm)
  
• meets foregut (endoderm)  post = oropharyngeal membrane

Tongue:

• Ant 2/3 = oral part of tongue
  • Originates from most 1st pharyngeal arch
  • there are 2 lat swelling, and 1 medial swelling (tuberculum impar)
  • lat swellings grow over the medial one and meet in midline = median sulcus
  • has the filiform, fungiform, circumvallate papillae
  • b/c from 1st arch – SS = CN V = mandibular n
• Ant 1/3 = pharyngeal part of tongue
  • behind foramen cecum & linea terminalis
  • from originally 2nd, 3rd arches – 3rd overgrows the 2nd.
  • from 2 medial swellings = copula (2nd arch), hypobranchial eminence (3rd/4th arch)
  • has lingual tonsil w/ it
  • b/c from 3rd arch – SS = CN IX
• Root of tongue
  • epiglottis & very back of the tongue
  • from post part of the hypobranchial eminence
  • from 4th arch, so SS = CN X
• Muscle of Tongue develop from occipital somites,  so innervating by CN XII, except palatoglossus (CN X)

4. The muscles and fasciae of the head and neck. The histology of the hypophysis. The development of the face.

4. The muscles and fasciae of the head and neck. The histology of the hypophysis. The development of the face.

Flash Cards:

Anatomy: The muscles and fasciae of the head and neck

Muscles of the Face:

These are mainly the muscles of facial expression. What are they? Look above at the flash cards, or at this one.

Sorry, I know it’s a bit unclear, but it’s the best I could find at the moment.

Muscles of Facial Expression:

General Info:

• are subcutaneous, and very close to the surface
• all innervated by CN VII = facial n.
• develop from mesenchyme of 2nd pharyngeal arch – (Hence why that CN VII innervation makes sense)

1. Occipito-frontalis (Epicranialis) – elevate eyebrow,wrinkles forehead (surprise)

• if you use just frontalis (frontal belly of epicranialis) = furrows eyebrows medially
• use both bellies = lift eyebrows, move scalp

2. Orbicularis Oculi

• has 3 parts: palpebral (just over the eyelid itself) = close eyes gently,
• orbital (around the whole eye) = close eyes tightly, or used to squint
• lacrimal (medially) = draws tears out, so capillaries can drain them

3. Auricularis m –

• ant, mid, post. – not all people have this muscle
• allows movement of the auricle, retract and elevate ear

4. Levator Labii Superioris m – elevate upper lip, dilate nares (disgust)

5. Zygomaticus Minor m – elevate upper lip

6. Zygomaticus Major m – draws angle of mouth up (smaller smile – like the fake one you give when you are in a bad mood)

7. Depressor Septi m – constricts nares

8. Risorius m – retracts angle of mouth more ( smile widely, a big cheesy grin)

9. Depresser Anguli Oris – depresses angle of mouth

10. Corrugater Supercili m – draws eyebrows down and medially (anger, frowning)

11. Procerus m – wrinkles skin over forehead (sadness)

12. Levator Labii superioris aleque nasi – elevate ala of nose, upper lip

13. Levator Anguli Oris m – elevate angle of mouth medially

14.Buccinator m – holds cheeks tight when blowing hard

• named after the word for trumpet, so when someone can blow into a trumpet, without inflating their cheeks, they are using their buccinator m.
• If you use only one, you can pull mouth to one side, like in a half-smile.

15. Orbicularis Oris – closes lips, and purses them (like for a kiss, or around a straw)

16. Depresser Labii inf m – pulls down lower lip

17. Mentalis m – elevates & protrudes lower lip, wrinkles chin

18. Nasalis m – pulls ala of nose towards septum, wrinkles nose (think the movie/show Bewitched)

• Dilator naris m – open nostrils
• Compresser naris m – constrict nostrils

19. Platysma – lowers mandible, can also help in frowning,  tenses skin of lower face and neck

To test yourself on m. of fascial expression: http://www.ivy-rose.co.uk/Topics/FacialMuscles.htm

For Muscles of Tongue, Palate, Pharynx, Larynx, etc – please refer to those topics in question. Those are technically muscles of the head & neck  too, but we doubt they are involved with this topic.

Fascia of Neck

• Superficial Cervical fascia
  • subcutaneous CT
  • cutaneous n, a/v/lymph, superficial lymph nodes
  • enlcose platysma
• Superficial (investing) layer of deep fascia
  • surround deeper parts of neck
  • encloses SCM & Trapezius m
  • also encloses the submandibular gland & makes fibrous sheat of parotid gland
  • has suprasternal space – ant jugular v, and arch of jugular v.
  • attached Sup = mandible, mastoid pr, ext occipital protuberance, sup nuchal line
  • Inf = acromion process, scapular spine, clavicle, manubrium
• Prevert fascia of deep fascia
  • cylindrical & encloses vert column & m. w/ it
  • covers Scalene m & deep m of back
  • extends laterally into axillary sheath – has axillary a/v and brachial plexus
  • attaches to ext occipital protuberance & basilar part of occipital bone & cont w/ endothoracic fascia & ant longitudinal lig of vert
• Carotid Sheath
  • Contents: Common & Int & Ext carotid a, Int jugular v, CN X, n to carotid sinus, deep cervical lymph nodes
    
  • DOES NOT contain SNS Trunk, which is post to Carotid sheath & ant to prevert fascia
  • blends w/ prevert, pretracheal investing layers & also attaches to base of skull
• Pretracheal Fascia of Deep Fascia
  
  • invests larynx & trachea, esoph
  • encloses thryoid gland & contributes to carotid sheath formation
  • has thin musc layer of infrahyoid m
  • connects w/ Buccopharyngeal fascia superiorly
  • Sup = Thyroid & Cricoid cart
  • Inf = Pericardium
• Buccopharyngeal fascia
  • covers buccinator m & pharynx
  • attached to pharyngeal tubercle & pterygomandibular raphe
• Pharyngobasilar fascia
  • fibrous coat in wall of pharynx
  • b/w mucus mem & pharyngeal constrictor m

Superficial & Lat M of the Neck

• Platysma – (CN  VII) – depress lower jaw, lip, and angle of mouth
• SCM – (CN XI) – 1 of them, turns face to opposite side, bringing chin to opposite shoulder, w/ BOTH = flex head, raise thorax

Muscles of Posterior Triangle (will discuss later)

• Splenius Capitis
  
• Levator Scapulae
  
• Scalenus m
  

Muscles of Anterior Triangle

Suprahyoid m:

• Mylohyoid (Mylohyoid n of V3) – elevate hyoid & floor of mouth, lowers mandible, makes up floor of mouth
• Geniohyoid (C1 via Hypoglossal n) – elevate hyoid and floor of mouth, rest above the mylohyoid
• Stylohyoid (CN VII ) – elevate hyoid
• Digastric (ant belly = Mylohyoid n of V3, post belly = CN VII) – elevate hyoid & floor of mouth, depresses mandible,

Remember that muscles that originate from 1st arch = CN V, and 2nd arch = CN VII

Infrahyoid M: all innervated by Ansa Cervicalis, except THYROHYOID (C1 via Hypoglossal n), together they anchor the hyoid bone, scapula, clavicle, and lower the hyoid bone and larynx for swallowing

Superficial muscles:

• Sternohyoid m – depresses hyoid & larynx
• Omohyoid m – depress and retracts hyoid & larynx

Deeper muscles:

• Sternothyroid m – depresses thryroid cartilage and larynx, is wider and just underneath sternohyoid
• Thyrohyoid m – depressed and retracts hyoid & larynx

Deep Neck Muscles:

Lat/Ant Vertebral muscles

Lateral Vertebral m

NOTE – Can mention Scalenus Tent, Hiatus, Subclavian a, Scaleno Tracheal Fossa here. See Flash Cards @ Beg of Topic.

• Ant Scalene m (C5-C8 ) – elevate 1st rib, bend neck
  • From transv. process of C3-6 –> scalene tubercle of 1st rib
• Mid Scalene m (C5-C8 ) – elevate 1st rib, bend neck
  • From transv. process of C2-7–> upper surface of 1st rib
• Post Scalene m (C6-C8 ) – elevate 2nd rib, bend neck
  • From transv. process of C4-6 –> outer surface of 2nd rib

Ant Vertebral m

• Longus Capitis (C1-4) – flex, rotate head
  • transv processes of C3-C6 –> inf surface of basilar part of occipital bone
• Longus Colli – (C2-6) – flex, rotate head – NOTE same as longus cervicis
  • ant tubercle of atlas –> Bodies of T3 and transv processes of C3-C6
• Rectus Capitis ant (C1-2) – flex, rotate head
• Rectus Capitis lat (C1-2) – flex head laterally

SubOccipital & Deep Neck M

• Suboccipital region flash card listed above, triangular region just below the occiput of the skull,
• all muscles innervated by suboccipital n (C1)
• Extend, rotate and flex head laterally.
• Rectus capitis posterior major – spinous process of C2 –> lat part of inf nuchal line
• Rectus capitis posterior minor – post tubercle of Atlas –> medial part of inf nuchal line
• Obliques capitis superioris- spinous process of C1 –> medial part of inf nuchal line
• Obliques capitis inferioris – transverse process of C1 –> occipital bone b/w nuchal lines

NOTE:  Layers in order in back m (That is, if you were to peel off the muscles layer by layer) – Trapezius, Semispinalis & Longissimus Capitis, Splenis Capitis, then these muscles, with the suboccipital triangle w.in them.

Suboccipital Triangle

Borders:

• med = rectus capitis post major
• lat = obliques capitis sup
• inf = obliques capitis inf
• roof = semispinalis m
• floor = post atlanto-occipital membrane, post arch of atlas

Contents: Vertebral a/v, Suboccipital n. NOTE – KNOW PATHWAY OF VERTEBRAL A!!

In Aqua is the location of the Suboccipital Triangle

Histology: Hypophysis.

Slide #31 Hypophysis *H&E

Structures to Identify:

• adenohypophysis
• neurohypophysis
• pars distalis
• pars intermedialis
• pars tuberalis
• pars nervosa
• CT capsule
• acidophils
• basophils
• chromophobes
• capillaries
• Herring bodies
• Dura mater (may not be able to see) – dense CT
• reticular fibers
• brown pigment

General Info:
Hypophysis has 2 major subdivisions: ant lobe = adenohypophysis, post lobe = neurohypophysis
is located in sella turcica of sphenoid bone
connected by stalk (tuber cinerum) to base of brain (hypothalamus)

Adenohypophysis – divided into 3 parts: pars distalis (most ant), pars tuberalis, pars intermedia
* Embryo: derived from invagination of ectoderm of oropharynx toward the brain = Rathke’s pouch, placode plate, becomes part of roof of oral cavity
Neural system in ant lobe:
since it does not develop from neural tissue, has rich a/v system that connects it w/ hypothalamus of brain via portal system
Neurons in hypothalamus synthesize hormones that have direct influence on cell functions of adenohypophysis
Axons of those neurons extend and terminate on 1st capillary bed of ant lobe – and then release hormones there

Pars distalis – bulk of ant lobe
have clusters of cells w/ layers of fiber between them

contains 2 types of cells:
Chromophobes – inactive cells, euchromatic nucleus, pale cytoplasm

Chromophils – active, hormone producing cells
2 types of them:

Acidophils (40%  of cells in ant lobe)
reddish pink = eosinophillic
2 types:

Somatotropes (GH cells) –

• oval w/ round nucleus + eosinophillic vesicles in cytoplasm
• (+) by Growth Hormone, (-) by somatostatin
• GH secreted while sleeping, important to keep healthy cells in order for them to go thru mitosis
• hypothalamus hormones regulate GH
• NOTE – Targets of acidophillic cells (secrete hormones w/ general effect), are not endocrine cells

Lactotropes (PRL cells) –

• large polygonal cells w/ eosinophillic vesicles of prolactin, oval central nuclei
• (+) by TRH + VIP (synthesis secretion)
• (-) by Dopamine – secretion

Basophils – bluish purple cytoplasm (all have round eccentric nucleus)

Corticotrophs (ACTH release)

• polygonal, produce precursors of ACTH
• (+) by CRH from hypothalamus

Gonadotropins (FSH + LH release)

• regulated by GnRH (Gonadotropin releasing hormone) from hypothalamus
• LH =
  • (+) production of corpus luteum
  • (+) testosterone secretion
• FSH = stimulates spermatogenesis, follicle release

Thyrotropins (TSH release) –

• large stimulate thyroid gland production of thyroid hormones (T3 + T4)
• regulated by TRH (Thyroid releasing hormone) from hypothalamus
• acts on follicular cells of thyroid

Pars Intermedialis

• surround small cystic cavities  representing residual lumen of Rathke’s pouch
• lined by epitheloid cells w/ a/v outside of them
• contain basophils + chromophobes in nests surrounding inner cavity = colloid
• fluid filled colloid contains pre-hormones stored there
• if need hormones, cells take back the pre-hormones , edit, then reject

Pars tuberalis

• ext of ant lobe along pituitary stalk, highly vascular region
• contains hypothalamus – hypophyseal portal system *talk about later*
• cells form cellular columns, not clusters, but parallel rows of cells and fibers
• To understand ant lobe:
  • need to know hormone regulation of hormone production
  • released by paracellular neurosecretory neurons in hypothalamus – regulates the hormone production of ant lobe
  • releasing factor – inc secretion
  • inhibiting factor – dec secretion
    

Posterior lobe = neurohypophysis

General Info:

Pituicytes

is downgrowth of CNS
CNS has 2 cell types: neurons, glial cells

• both are present in neurohypophysis
• but glial cells called pituicytes here

NO cell bodies of neurons here, but yes, axons of them are present
cell bodies of neurons located in nuclei of hypothalamus, axons are longer and terminate in walls of sinusoids in post lobe

NOTE – axons carry hormones continously, but these are only released sporadically
so hormones need to be stored = in Herring bodies
NO HORMONES PRODUCED IN POST LOBE

Appearence: homogenous appearence, pinkins lines = axons
post lobe has 3 parts: median eminence, infundibulum, parsa nervosa

1. Median eminence = @ base of hypothalamus
2. Infundibulum = part of post lobe that extends up to hypothalamus
3. Pars nervosa = largest part of post lobe

Pars Nervosa

• contains secretory vesicle = Herring bodies – difficult to distinguish these from a/v
  • contain oxytocin, vasopressin from hypothalamus,fibroblasts, mast cells, pituicytes
• Pituicytes = oval or round nuclei, and brown pigment in cytoplasmic vesicles
  • have processes to perivascular spaces = support
• GFAP = glial fibrillary acidic protein –> specific intermediate filaments
• Vasopressin (ADH)  – controls BP, contraction of smooth m in a./arterioles (VC = inc BP)
• Oxytocin = neural stimulation
  • contraction of uterine smooth m during orgasm, mestruation, birth
  • contraction of myoepith cells in mammary gland –> milk ejection in lactation

Hypophyseal Portal (circulatory) System:
a “portal” system is any system of arterial supply that makes 2 arterial capillary beds
Originates from superior/inferior hypophyseal a

Sup Hypophyseal a

• Superior hypophyseal a enters the hypophysis superiorly and supplies pars tuberalis, medial eminenece, conar skin
• In the median eminence, it makes the primary (1st) capillary bed, then reforms and then makes a second capillary bed in the ant lobe itself
  • primary capillary bed is where the axons from hypothalamus neurons synapse and release hormones – the releasing/inhibiting factors mentioned earlier
  • the secondary capillary bed carries secretions of hypothalamus from med eminence –> infundibulum –> pars distalis
• Once the releasing/inhibiting factors from hypothalamus are secreted into pars distalis, they will bind to specific receptors  on cells (chromophils) and cause them to either release or inhibit the release of the hormone they produce.

Inf Hypophyseal a

• Inf hypophyseal a enters hypophysis inferiorly and supplies pars nervosa, makes ONE capillary bed – therefore not part, technically, of the portal system
• unmyelinated axons from nuclei in hypothalamus release the oxytocin, ADH in the sinusoids of pars nervosa, and the hormones are then stored in nearby Herring bodies (@ axon terminals)

Sinusoids of pars nervosa  are fenestrated :

• meaning they have a discontinous endothelium = allows transport b/w cells and sinusoids more free
• they have NO BASEMENT MEMBRANE  – simply are resting on reticular fiber meshwork

Blood drains through hypophyseal v –> cavernous sinus –> systemic circulation
some thru short portal v from parts distalis –> pars nervosa –> hypothalamus

Slide #32 Hypophysis *AZAN (Azocarmine blue, anahiline red)

Structures to Identify:

• dura mater = bluish dense CT
• acidophils
• basophils
• reticular fibers
• Herring bodies
• brown pigmentation

Ant lobe
basophillic cells have complete blue cytoplasm
acidophillic cells are red
bluish line represent reticular fibers that belong to the CT stroma
v. homogenous look

Post lobe
bluish bodies and fibers are Herring bodies and their axons
brown pigmentation  = lipofusin – aging pigmentation in nerve tissue

Slide is designed to show Herring bodies (blue) + blood vessels (red) can be easily distinguished

Embryology:The development of the face.

• @ 4th wk = facial prominences form, formed by 1st pharyngeal arch from neural crest cells
  • Maxillary prominence – forms lat to stomodeum, the primordial mouth
  • Mandibular prominence – forms caudal (below) to stomodeum
  • Frontonasal prominence – is a growth of mesenchyme that makes the upper border of the stomodeum = forehead, orbital area
    
  • On both sides of frontonasal prominences, there are forming 2 lateral thickenings of surface ectoderm = nasal placodes
• @ 5th wk = nasal cavity and nasal projection begins to form (nose)
  • nasal placodes fold inwards (“invaginate”) to form nasal pits
  • around nasal pit, there is a ridge of tissue = nasal prominences.
    
  • *Picture a bowl – the actual bowl is nasal pit, and the rim of the bowl is the nasal prominences
  • The nasal prominences are split into lat & medial nasal prominences
• @ 6th-7th wk = Maxillary prominences grow
  • the future cheeks/zygomatic areas are growing
  • this pushes the medial nasal prominences towards each other
  • maxillary prominences & med. nasal prominences fuses
  • This forms the upper lip
• lower lip & jaw = mandibular prominences
• Nose is formed by 5 areas
  • frontal part of frontonasal prominence = bridge of nose
  • 2 medial nasal prominences = crest of nose, tip
  • 2 lateral nasal prominences = sides, ala of nose
• Nasolacrimal duct
  • starts off as groove b/w med/lat nasal prominences = nasolacrimal groove
  • the ectoderm in the floor of this groove – forms epithelial cord, that then detaches from the groove
  • this is the future duct – it will later open up into a canal
  • the upper part of it is widen up to form lacrimal sac
  • Deeper, med/lat nasal prominences fuse.

3. The viscerosensory and visceromotor innervation of the head and neck. The fibers of the connective tissue, the extracellular matrix. The development of the viscerocranium.

3. The viscerosensory and visceromotor innervation of the head and neck. The fibers of the connective tissue, the extracellular matrix. The development of the viscerocranium.

Flash Cards:

CN IX, XI - Glossopharyngeal, Accessory n

CN X Vagus n & branches

Autonomic n. and PNS ggl

SNS ganglia in Head & Neck

PNS ggl and SNS/PNS relations to them

Anatomy:The viscerosensory and visceromotor innervation of the head and neck.

This topic consists of mainly CN IX, X, and Autonomic innervation of Head & Neck. Yes, some of these cranial nerves also have SM/SS function, but they are very important inVS/VM function.  Other CN also add innervation of VS/VM in the body.  If you want to know all the branches of CNs, please refer to the cards above.

Viscerosensory of Head & Neck:

Viscerosensory innervation of the head and neck have to do with the special sensation function of the cranial nerves. There is a main sensory function we have to look at: taste

Taste:

CN VII – Facial n

covered mostly in last topic, but know that Chorda Tympani n provides VS innervation to ant 2/3 of tongue

• has motor and sensory roots,
• Pathway: IAM –> petrous part of temporal bone (through auditory canal) —> exit skull via stylomastoid foramen

Pathway of Chorda Tympani = in desc facial canal –> tympanic membrane –> b/w malleus & incus of middle ear –> thru Petrotympanic fissure –> joins lingual n —> submandibular ggl –> 3 places

• VM = submandibular, sublingual, lingual glands (discussed in more detail later)
• VS = ant 2/3 tongue, soft palate
• cxn w/ geniculate ggl & otic ggl

CN IX – Glossopharyngeal n

• exit = Jugular foramen,
• Pathway: from jugular foramen –> follow stylopharyngeus &  passes b/w sup/mid constrictor m. of pharynx –> oropharynx & tongue.
• Location = Find this n. in parapharyngeal space, behind int carotid, CN XII, CNX, on post surface of stylopharyngeus m
• innervates structures from 3rd branchial arch
• receives VS sensation  from parotid gland, carotid body, carotid sinus, pharynx, middle ear
  

Branches of CN IX that provide VS/VM:

• Tympanic n
  • forms tympanic plexus around wall of middle ear (w. SNS fibers from int carotid plexus, br from genu ggl of CN VII)
  • SM = tympanic cavity, mastoid antrum, mastoid air cells, auditory tubes, ext ear
  • VM = provides pre-ggl fibers to otic ggl
• Lingual branches
  • provides VS innervation to post 1/3 of tongue, & vallate papillae for taste sensation, as well as SS to same area

CN X – Vagus n

• exit = jugular foramen,
• Pathway: from foramen –> makes connections w. CN IX, CN XI, SNS sup cervical ggl –> goes thru carotid sheath –> thorax
• innervates structures from 4th & 6th branchial arches
• receives VS  from base of tongue, pharynx, larynx, trachea, bronchi, heart, esophagus, stomach, & intestine
  

Branches of CN X that provide VS/VM in head & neck:

• Mainly VM = will discuss soon

Visceromotor of Head & Neck:

Mainly comes from autonomic innervation. In the head & neck, visceromotor basically means the autonomic innervation of glands, as well as some muscle of the eye.  The four main glands we have to consider are: lacrimal, parotid, submandibular, sublingual, and as well we have to consider the glands of the nasal and oral mucosa & skin. The innervations are primarily run with PNS and SNS ganglia.

If you want to see the information sorted by ganglia, or by PNS v SNS, please refer to flash cards above.

NOTE: SNS fibers only GO THRU ggl (is not part of them, do not synaspe in PNS ggl) – their ggl are the cervical ggl, they are merely hitchhiking with the PNS nerves, and then they run w/ arteries to targets

Cranial Nerves VM innervation:

• CN III = PNS to sphincter pupillae m & ciliary m –> constrict pupil, help lens of eye
• CN VII = PNS to submandibular  & sublingual glands, lacrimal glands, glands of nose & palate
• CN IX = PNS to parotid gland
• CN X = PNS to smooth m of trachea,  bronchi, digestive tract,  & cardiac m of heart

Lacrimal gland

* Pterygopalatine ggl = in pterygopalatine fossa, where held in place by branches of V2, just ant to opening of pterygoid canal , and below V2

PNS pathway:

• Greater petrosal n comes from CN VII @ geniculate ggl, and exits out of petrous part of temporal bone
  • Gtr petrosal n has taste fibers that can go to the palate from ggl
• joins deep petrosal n. which carries SNS fibers @ foramen lacerum
• these two together become n of pterygoid canal –> pterygopalatine fossa
• PNS fibers synapse in pterygopalatine ggl
  
• post ggl fibers from ggl run to lacrimal gland via zygomatic br of V2 & lacrimal n of V1
• also supplies glands of nasal mucosa (via post nasal n) and palate ( Gr palatine n = hard palate, Lsr Palatine n = soft palate)
  

SNS pathway:

• SNS post ggl fibers are from the superior cervical ggl
• these fibers run with deep petrosal n.
  • deep petrosal n is from plexus on int. carotid ggl
    

Submandibular & Sublingual gland & glands of Oral Mucosa

*Submandibular ggl = lies on surface of Hyoglossus m inf to submandibular duct

PNS pathway:

• Chorda Tympani, comes from CN VII just above stylomastoid foramen
• the nerve cross medial to malleus and passes thru petrotympanic fissure
• joins lingual n of V3 in Infratemporal fossa
• PNS fibers synapse in submandibular ggl
• post ggl fibers from ggl run w/ arteries to supply Submandibular gland, Sublingual gland, & glands of Oral mucosa,

SNS pathway:

• SNS post ggl fibers are from superior cervical ggl
• these fibers run thru, BUT DO NOT SYNAPSE  in submandibular ggl,
• then run with PNS post ggl fibers

Parotid Gland

* Otic ggl = located b/w tensor veli palatini & V3, inf to foramen ovale

PNS pathway:

• Tympanic n arises from CN IX and emerges from jugular foramen
• n enters the middle ear via the tympanic canaliculus in petrous part of  temporal bone
• tympanic n forms the tympanic plexus — and lesser petrosal n emerges from this plexus
• lesser petrosal leaves skull via foramen ovale
  
• PNS fibers from it synapse in otic ganglion
• post ggl fibers from ggl RUN W/ auriculotemporal n (from V3) to supply parotid gland
  

SNS pathway:

• SNS post ggl fibers are from superior  cervical ggl via a plexus around middle meningeal a
• post ggl fibers run w/ PNS post ggl fibers on auriculotemporal n
• help supply a/v of parotid gland

Orbital region

*Ciliary ggl = b/w optic n and lateral rectus m.

PNS pathway:

• CN III and its divisions run to ciliary ggl
• post ggl fibers from ciliary ggl pass to ciliary m & sphincter pupillae m
• constrict pupil of eye, help with lens of eye

SNS pathway:

• post ggl fibers from sup cervical ggl  form a plexus around  int carotid a
• and then run with PNS post ggl fibers  to dilater pupillae and tarsal m.
• dilate pupil of eye & a/v of eye

Animation: PNS innervation of Head ===Check it out!!

Histology: The fibers of the connective tissue, the extracellular matrix.

Extracellular Matrix:

Ground Substance:

• transparent, shapeless, colorless extracellular matrix
• high water content
• supports and surrounds CT and its cells and fibers
• loads of Glycosaminoglycans,  glycoproteins, proteoglycans

Matrix glycoproteins:

• most molecule binding cells
• cells bind via integrin receptors: has Arg-Lys-Asp-R group
• regulate function of cells: proliferation, migration, etc
• interconnect cells & collegen fibers
  • ex/ Laminin – bound collagen IV in basal lamina (integrin)
  • hemidesmosomes in epithelial cells
• Ex/ fibronectin, tenasin, osteonectin, etc

Glycoaminoglycans (GAGs):

• polysaccharides, disaccharides, like hexosamine + hexuronic acid
• strong polyanions
  • bind lots of H2O
• Ex/ Hyaluronic acid, heparine, chondrolitine-sulfate, keratin-sulfate, dermatin-sulfate, heparin-sulfate

Proteoglycans (PGs):

• fibrular core proteins w/ 1 GAG side chains
• heparin found intracellularly
• Physiochemical properties = decided by GAG side chains
• Ex/ Syndecan: heparin-sulfacte side chains, membrane-intergrated, receptor function

Fibers of CT:

• Collagen Fibers
  
  • 3 tropocollagen helical units –> collagen fibrils
  • amino acids = Hydroxylated Proline (OH-Pro), Hydroxylated Lysine (OH-Lys), about 40% glycine
    
    • provide mechanical resistance due to OH-aa (Hydroxylate amino acids)
  • amount of glycosylation variable
  • look stratified in microscope
  • broken down by collagenases
  • >20 types, only 3 types  can form fibers themselves w/o aid of others = I,II,III
    • I = skin, bone, ligaments, tendons
    • II = cartilage
    • III = reticular
    • From Avi Sayag Biochem notes: One = Bone, 2 = CarTWOlage, 3 = ReThreecular
  • acidophillic, stain pink with eosin
  • stain well w/ AZAN (blue), H&E (red), Van Geison (spermatic cord)
• Reticular Fibers
  • glycosylated collagen fibers = III
  • made by reticular cells
    
  • low mech resistance
  • filled w/ CARBS
  • forms supporting meshwork of organs
  • stains well w/ Ag impregnation (black), PAS + (magenta, like in sublingual glands), AZAN (blue)
• Elastic fibers
  • made of tropoelastin & fibrillin
    
  • high amount of Gly, Val, Ala, & Pro
  • has hydroxylated-Pro, but not OH-Lys
  • have short amino acid side chains
  • can be extended due to presence of special cross bond –> higher mech resistance
  • broken down by elastases
  • stains well w/ Resorcin-Fuchsin, Orcein (brown)

Embryology: The development of the viscerocranium.

skeletal system develops from paraaxial, lateral plate mesoderm, & neural crest

Paraxial mesoderm forms somites,t hat split into somitomeres, dermatomes, & myotomes

@ 4th week -sclerotomes –> become mesenchyme (embryonic CT)

Mesenchyme can form many things, like osteoblasts = bone forming cells

Neural crest cells in head region can also become mesenschyme

2 types of bone formation:

• (Intra)membranous ossification – mesenchyme of dermis is converted right to bone
• Endochondral ossification – mesenchyme –> hyaline cartilage –> ossified by osteoblasts

Viscerocranium

• Viscerocranium = bones of the face, like nasal, lacrimal, etc
• formed mainly from the first 2 pharyngeal arches
• 1st arch =
  • dorsal portion that becomes maxillary process —> becomes maxilla, zygomatic bone, part of temporal bone
  • ventral portion that becomes mandibular process –> Meckel’s cartilage
• Mesenchyme around Meckel’s cartilage ossifies via membranous ossification *see previous topic for how this works* —> becomes mandible
• Meckel’s cartilage completely disappears except for sphenomandibular ligament
• Dorsal tip of mandibular process = becomes incus, malleus, stapes = bones of inner ear
• The rest of facial bones formed from neural crest cells
• Bones and paranasal sinuses continue to grow through puberty.
  

2. The somatosensory and somatomotor innervation of the head and neck. The cells of the connective tissue. The development of the neurocranium.

2. The somatosensory and somatomotor innervation of the head and neck. The cells of the connective tissue. The development of the neurocranium.

  Flash cards:

Trigeminal n. SS of Face and some SM

CN VII Facial N - SM for face

Cervical Plexus - SS/SM of Neck

 

Anatomy: The somatosensory and somatomotor innervation of the head and neck.

 This topic covers basically CN V (SS /SMof face), CN VII (SM of face), Cervical plexus (SS/SM of neck), and parts of CN IX, X, XI (flash cards of these on next topic, #2)

SS of Head & Neck

CN V = Trigeminal n

Remember = Feel the face w/ FIVE = 5th cranial nerve

• major sensory n for face, and is motor n for muscles of mastication, and some other m.

has 3 major divisions:

Ophthalmic n: V1

• exits skull via supraorbital fissure, w/ CN III, IV, VI, and ophthalmic v
• innervates structures that develop from the frontonasal prominences
• Nasociliary n
  • gives Ant ethmoid n –> gives ext nasal br = skin @ tip of nose
  • Post ethmoid n
  • Infratrochlear n = skin @ root of nose
• Frontal n
  • Supratrochlear n – skin @ medial forehead, exit via supratrochlear foramen
  • Supraorbital n – skin @ lat forehead, exit via supraorbital foramen
• Lacrimal n – lacrimal gland, lat upper eyelid

Maxillary n: V2

• exits skull via foramen rotundum, into pterygopalatine fossa
• innervates structures that develop from maxillary prominences
• below level of eyes & above upper lip
• Infraorbital n
  • thru infraorbital foramen, via inferior orbital fissure
  • lat side of nose, lower eyelid, upper lip
  • branches of it –> mucosa of maxillary sinus, upper inscisors, canines, and premolar teeth,  upper gingiva, hard palate
  • Ant, Mid, Post, Sup alveolar n forms maxillary dental plexus
• Zygomaticotemporal n
  • from foramen of same name
  • skin over ant temporal region
• Zygomaticofacial n
  • foramen of same name
  • skin over zygomatic region
  • carries post-ggl fibers from pterygopalatine ggl, via Gr palatine, Lsr palatine, & Nasopalatine n, to Lacrimal n

Mandibular n: V3

• exits skull via foramen ovale
• aff/eff branch of jaw jerk reflex
• innervates structures that develop from mandibular prominences
• level of lower lip and below
• Inf alveolar n
  • goes thru mandibular canal and emerges from mental foramen as mental n
  • supply lower teeth, chin, lower lip
• Auriculotemporal n
  • crosses root of zygomatic process –> temporal region deep to sup temporal a, encircles around middle meningeal a
  • supply ext acoustic meatus, tympanic mem, auricle
• Buccal n
  • only sensory br of motor div. of V3
  • deep to ramus of mandible –> runs ant and thru buccinator
  • supplies mucus membrane lining cheek, post part of buccal surface of gum
• Lingual n
  • SS to ant 2/3 of tongue
• SM = MOTOR branches –> m. of mastication, ant digastric, mylohyoid m, tensor veli palatini, tensor tympani

CN VII Facial n = SM of face

• has motor and sensory roots,
• SM = all muscles of facial expression, including platysma, auricularis m, post digastric m, stylohyoid m, stapedius m
• supplies structures developing from 2nd pharyngeal arch
• VS = taste to ant 2/3 of tongue – via Chorda Tympani (discussed in next topic)
• SS = w/ auricular branches from IX, X –> fibers to external ear, tympanic mem
• Pathway: IAM –> petrous part of temporal bone (through auditory canal) —> exit skull via stylomastoid foramen
• Once exits, gives off Post auricular n = m of auricle, occipitalis m, EAM, w/ branches from CN IX, X
• runs ant and through parotid gland, where it gives its 5 terminal branches
• NOTE DOES NOT INNERVATE PAROTID GLAND, merely runs through it

Terminal branches:

• Temporal – m of forehead, orbicularis oculi
• Zygomatic – m. over zygomatic bone, orbital and infraorbital m
• Buccal – Buccinator m, m of upper lip
• Mandibular (marginal)- m. of chin, lower lip
• Cervical – platysma, *w/transverse cervical n. of Cervical plexus

Cervical Plexus:

• from primary ventral rami of C1-C4, emerge next to ant scalene m
• ant branches = SM, post branches = SS to anterolat neck, sup part thorax

SS of Neck = cutaneous branches of Cervical plexus – see note card at start of this post

1. Lesser Occipital (C2,3) –  scalp behind ear
2. Greater Auricular (C2,3) – scalp around auricle, and parotid region
3. Transverse Cervical (C2,3) – skin of ant cervical triangle
4. Supraclavicular  n (C3,4) – ant, mid, post br to skin of clavicle and shoulder
5. NOTE = NOT A BRANCH OF CERVICAL PLEXUS, but does SS of head/neck – Greater Occipital n (dorsal rami of Cervical spinal n) – post part of scalp

SM of Neck =  2 major motor branches of cervical plexus, + many side motor branches

• Branches not from Cervical Plexus
  • ventral rami of cervical nodes – SM to rohomoids, serratus ant, prevertebral m
• Ansa Cervicalis
  • union of sup root (C1-2) + inf root (C2-3)
  • superior and w/in carotid sheath in ant cervical triangle
  • supplies infrahyoid m, except thyrohyoid (C1 via CNXII)
• Phrenic n – not technically part of neck, but part of plexus
  • arises C4, but rec branches from C3-4
  • has SM, SS, SNS n fibers
  • SM to lat diaphragm, SS to central tendon
  • desc on ant surface of ant scalene m under SCM
  • passes b/w subclavian a/v  –> thorax, joins pericardiophrenic br of int thoracic a
  • SS = mediastinal pleura
• SM br off plexus= longus capitis, longus cervicis, Levator scapulae, scalene m
• Acc phrenic n –  occasional br of plexus, from C5 and joins phrenic n below 1st rib

 SS/SM innervation from other CN:

• CN IX =
  •  SS to post 1/3 of tongue, palatine tonsil & soft palate, tympanic cavity, mastoid antrum, auditory tubes, ext ear
  • SM to stylopharyngeus m,
• CN IX, X, XI = give fibers to the common pharyngeal plexus
  • SM = m. of pharynx, larynx, palate except tensor veli palatini (V3)
• CN XI
  • SM = SCM, trapezius
  • as mentioned above, is part of pharyngeal plexus
  • spinal roots from ant horn of upper cervical segments, emerge from dorsal/ventral roots of spinal n – combine to form 1 trunk –> enter skull via foramen magnum
  • also exits via jugular foramen
• CN X
  • Superior Laryngeal n
    • Int laryngeal n – SS to larynx above vocal fold, lower pharynx, epiglottis
    • Ext laryngeal n – SM to cricothyroid, inf pharyngeal constrictor m.
  • Recurrent laryngeal n
    • hooks around subclavian a on R, and arch of aorta on L (lat to lig arteriosum)
    • asc in groove b/w trachea & esophagus
    • SS = larynx below vocal cord
  • SS from all mucus membranes = lower pharynx, larynx, and down to all thoracic/abdominal organs

 

•  

Histology:The cells of the connective tissue.

 There are two types of Connective Tissue cells:

1. Resident cells – have their own motility within tissue. ex/ histocyte, mast cell, adipocytes, smooth m cells, plasma cells, fibroblasts
2. Transient cells – move in and out of tissue, ex/ WBC – lymphocytes, granulocytes, monocytes

Cells of CT:

• fibroblasts –
  • elongated cell w/ cytoplasmic extensions
  •  ovoid nucleus, sparse chromatin, 1 or 2 nuclei
  • = synthesize  collagen, reticular, elastic fibers, and carbs of ECM
• fibrocyte –
  • more mature, smaller splindle shaped cells 
  •  no cytoplasmic extentions, smaller nucleus than fibroblast
  • = less active, but same function as fibrocyte
• plasma cell –
  • smaller, accentric nucleus, with condensed chromatin,
  • oval shape, cytoplasm mostly clear
  •  = secrete immunoglobulins & develop from B cells
• adipose cell –
  • narrow rim of cytoplasm, flat accentric nucleus
  • large and mostly empty cytoplasm
  • =  store fat
• lymphocyte – 
  • spherical shaped ells, dense chromatin in central nucleus,
  • no nucleoli
  • = mediate immune response, produce antibodies, defend body against infections, secrete proteins
• macrophages –
  • round, irregular cell outlines, small nucleus rich in chromatin,
  • cytoplasm filled w/ injested particles,
  • have feet like extensions called “pseudopodia”,
  • eosinophillic due to increased # of lysozymes
  • = phagocytes that injet bacteria, dead cells, cell debris, are Antigen presenting cells = APCs, also aid in immune response
  • * Look for fuzzy reddish ovoid structure with many spots in cytoplasm – can be found near a/v, but unlikely you would be asked to identify one
• eosinophil –
  • large WBC w/ bilobed nucleus *like headphones*,
  • large eosinophillic granules in cytoplasm – red color
  • = inc in # after parasitic infections or allergic reactions, phagocytose Antigen-antibody complexes after infection
• neutrophil –
  •  large WNC with many lobed nucleus, no granules in cytoplams,
  • cytoplasm more or less unstained
  • = engulf and destroy bacteria @ infection sites
• mast cell –
  • ovoid or circular, small central nucleus,
  • basophillic cytoplasm filled w/ fine closely packed, dense staining granules of histamine and heparin
  • = synthesize and release heparin and histamine.
    • Heparin = weak anticoagulant,
    • Histamine = used in inflammatory response, dilates a/v, increase a/v permiability to fluid, induces signs of allergic reaction
• monocytes –
  • largest  WBC, bean shaped nucleus
  • become macrophages
  • part of MPC = Mononuclear Phagocytotic System
  • = clean up tissue, antigen presentation = APCs

Embryology:The development of the neurocranium.

• skeletal system develops from paraaxial, lateral plate mesoderm, & neural crest
• Paraxial mesoderm forms somites,t hat split into somitomeres, dermatomes, & myotomes
• @ 4th week -sclerotomes –> become mesenchyme (embryonic CT)
• Mesenchyme can form many things, like osteoblasts = bone forming cells
• Neural crest cells in head region can also become mesenschyme
• 2 types of bone formation:
  • (Intra)membranous ossification –  mesenchyme of dermis is converted right to bone
  • Endochondral ossification – mesenchyme –> hyaline cartilage –> ossified by osteoblasts

Neurocranium = forms protective case around brain
Two parts:
1. Membranous part = flat bones, like Parietal, Frontal, Squamous part of temporal and occipital
2. Cartilaginous part = bones @ base of skull, like ethmoid, sphenoid, petrous part of temporal and occipital

Membranous Neurocranium

• from para-axial mesoderm and neural crest cells
• undergo membranous ossification
  • is the aggregation of mesenchyme cells in the area where bone is to be formed.
  • The tissue in this area becomes more vascularized, 
  •  mesenchyme cells begin to differentiate into osteoblasts,
  • osteoblasts secrete the collagen and ground substance (proteoglycans) of bone matrix (collectively called osteoid).
  • The osteoblasts maintain contact with one another via cell processes.
  •  The osteoid becomes calcified with time, and the processes of the cells (called osteocytes when they are surrounded with matrix) become enclosed in canaliculi.
  • Some of the mesenchymal cells surrounding the developing bone spicules proliferate and differentiate into osteoprogenitor cells.
  •  Osteoprogenitor cells in contact with the bone spicule become osteoblasts, and secrete matrix, resulting in appositional growth of the spicule.
  • Intramembranous ossification begins at about the eighth week in the human embryo.
• bone spicules  grow from primary ossification centers –>periphery
• bones grow by adding new membranous layers on the outside, and at the same time, resorption of inner layers by osteoclasts inside

On Newborn skull,  the flat bones of skull are not united. In fact, you don’t want them to be, as the movement of these bones against each other allow the head to be shaped in certain ways to make birth easier.

At this point, the flat bones are separated by CT sutures:

• sagittal suture – from neural crest cells, b/w two  parietal bones
• coronal suture – from paraaxial mesoderm, b/w frontal and parietal bones

Where more than 2 bones meet = fontanelle

• ant fontanelle – where 2 frontal/2 parietal meet, will close w/in 2 years (like mastoid fontanelle) to become bregma
• post fontanelle – where 2 pariteal/occipital meet, will close w/in 6 months (like sphenoid fontanelle) to become lambda
• some sutures remain open until adulthood

Chondrocranium & Cartilaginous Neurocranium

• formed by many cartilages
• prechordal chondrocranium
  • lie in front of rostral (front/ant) end of notochord (future spinal cord) — hence, prechordal
  • post border = sella turcica
  • neural crest origin
• chordal chondrocranium
  • lie behind  sella turcica
  • develop from occipital somites = para-axial mesoderm origin
  • is the area that will surround the future spinal code — hence, chordal.

 

 

1. Arteries, veins and lymphatic drainage of the head and neck. The epithelial tissue. The development of blood vessels.

1. Arteries, veins and lymphatic drainage of the head and neck. The epithelial tissue. The development of blood vessels.

Anatomy:  Arteries, veins and lymphatic drainage of the head and neck.

Arteries of Head & Neck

For this topic, you will need to discuss the branches of common carotid a, subclavian a, the veins that follow them, and superficial and deep lymph nodes of the head and neck.

In this topic, if you have time, you may want to review infratemporal fossa, carotid triangle, scalenotracheal fossa, scalenus hiatus & tent

Common Carotid a:

General Info:

• Emerges from brachiocephalic a on R side, and aortic arch on L side
• ascends in carotid sheath, w/ CN X, Int Jugular v and number of other structures (will discuss soon)
• divides into int/ext carotid at superior border of thyroic cartilage
• Has two receptors:
  • Carotid Body
    • located at the bifurcation of common carotid (Body = Bifurcation)
    • chemoreceptor = sensory receptor to detect levels of O2 & CO2
    • Or, remember that since it is located lower to the sinus, and closer to the lungs than the sinus – lungs = O2,CO2
  • Carotid Sinus
    • located at the beginning of the int carotid a (Sinus = Internal carotid)
    • baroreceptor = detects blood pressure
    • Remember that it is the one closest to the head, so need to keep track of blood pressure in the head.

Int carotid a:

• no branches in the neck,
• ascends in carotid sheath w/ CN X and IJV
• enters skull via carotid canal
• only major branch to head and neck region is ophthalmic a – exits skull via optic canal

Ext Carotid a

• emerges @ upper border of thyroid cartilage
• runs in carotid sheath, then to neck of mandible
• pierces the parotid glang, where it gives its 2 terminal branches = maxillary, and superficial temporal
• 8 main branches = Superior Thyroid, Lingual, Facial, Asc Pharyngeal, Greater Auricular, Occipital, Maxillary, Superficial Temporal.

NOTE: How to remember all the branches?

St. Louis FATSIS Apt to GO to Max Stein —- like fat people from St. Louis need to go to this famous weight loss instructor, Max Stein. Sounds stupid, but hang on – it works.

• Superior Thyroid a – St.
  • emerges at level of greater horn of hyoid bone
  • also in carotid sheath
  • branches = br. to infrahyoid m, br to SCM, sup laryngeal (which peirces the thyrohyoid membrane), br to cricthyroid m, glands
• Lingual a – Louis
  • emerges @ level of greater horn of hyoid bone
  • passes deep to hyoglossus m.
  • located w/in Pyrogov’s Triangle – Clinical note – by pushing at the location of triangle, can stop bleeding from branches of lingual a
    • Borders:
      • ant = mylohyoid m
      • post = post digastric m
      • sup = hypoglossal n (CN XII)
      • floor = hyoglossus m
    • part of the Submandibular triangle (see salivary gland topic)
  • branches = suprahyoid a, dorsal lingual a, sublingual a, deep lingual a
  • supplies most of blood supply of tongue
• Facial a  – Fatsis
  • emerges just above lingual a, goes forward, deep to post digastric m & stylohyoid m
  • hooks around lower border of angle of mandible @ ant border of masseter (jsut deep to platysma)
  • run diagonally to the medial corner of the eye, running deep to zygomatic major & levator labii superiorus
  • major blood supply to face, terminates with angular a.
  • branches = FATSIS – is an abbreviation for facial and all its branches
    • F = facial
    • A = asc palatine
    • T = tonsillar
    • SI = Sup/Inf labial
    • S = submental
• Asc Pharyngeal a – Apt
  • in carotid triangle
  • asc b/w int carotid & wall of pharynx
  • branches = pharyngeal, palatine, inf tympanic, meningeal branches
• Greater (Posterior) Auricular a – G
  • arises just above post digastric –> deep to parotid –> runs superficial to styloid process
  • branches = stylomastoid, auricular, and occipital branches
• Occipital a – O
  • emerges just above the hyoid bone –> passes deep to post digastric –> occipital groove –> on mastoid process
  • branches =
    • a to SCM – over CN XII, anatomosis w. SCM branch of sup thyroid a
    • decending br – has 2 branches
      • superficial – anatomosis w/ superficial br of transverse cervical a
      • deep – anatomosis w/ deep br of deep cervical a (from costocervical trunk of subclavian a
• Maxillary a – Max
  • lies in infratemporal fossa
  • many many branches  = How to remember them? DAAM I Bite SPAIDS.
  • divided into 3 parts by lat pterygoid m
    • Part 1 = Mandibular = DAAM I – 5 branches
      • Deep auricular a
      • Ant tympanic a
      • Acc meningeal a
      • Middle meningeal a – can be shown in practical exam
      • Inf alveolar a – can be shown in practical exam
    • Part 2 – Pterygoid = Bite (Bite = muscle of mastication) – 5 branches
      • lat & med pterygoid a
      • massteric a
      • buccal a
      • deep temporal
    • Part 3 – Pterygopalatine = SPAIDS – 7 branches
      • Sup (post/mid) alveolar a
      • Pharyngeal a
      • A. of pterygoid canal
      • Infraorbital a
      • Desc Palatine a
      • Sphenopalatine a
• Superficial Temporal a
  • terminal branch
  • emerges on face b/w TMJ and ear
  • runs w/ auriculotemporal n, sup temporal v
  • branches = transverse facial a (b/w zyg arch & parotid duct), frontal/parietal br
  • transv. facial a gives blood supply to parotid gland, duct, masseter and skin of face

Subclavian a

• br of Brachiocephalic trunk on R, arises from arch of aorta on L
• Pathway: enters neck behind the sternoclavicular joint –> runs towards the apex of pleura along the mediastinal surface –> over the apex –> turns forward and down along sternocostal surface of apex –> exits neck to enter thorax @ scalenus hiatus w/ brachial plexus
• has 3 divisions, separated by ant scalene m.
• NOTE = to remember the # of branches – its opposite of part # – i.e. Part 1 has 3 branches, Part 2 has 2 branches, and Part 3 has 1 branch (sometimes)
  • 123=321

Thoracic part = medial to ant scalene m – 3 branches, b/w trachea and ant scalene m

• Vertebral a – has a med/sup path –> goes thru transverse foramen of  C6-C1 –> thru post occipital membrane –> foramen magnum
• Int Thoracic a – runs along the inside of thoracic wall
  • 1st 6 ant intercostal a
  • sup epigastric – medistinal, thymic, sternal br
  • musculophrenic – gives the ant intercostal arteries 7-10
• Thyrocervical trunk – 3 branches again
  • Transverse cervical a – under  SCM –> occipital triangle –> runs below trapezius m
  • Suprascapular a – runs parallel to clavicle w/ a/v/n — anatomosis w/ circumflex scapular a
  • Inf thyroid a – asc along thyroid gland and anatomosis w/ asc cervical a

Muscular part = behind ant scalene m. – 2 branches, = Costocervical trunk

• Supreme IC a – gives 1st 2 post IC a
• Deep cervical a – blood supply to deep m of back, asc along levator scapulae m.

Cervial part = lat to ant scalene m – 1 branch, sometimes

• dorsal scapular a – only present if suprascapular a is missing
• usually no branches here

Veins of Head & Neck

Veins mostly follow the arteries, so there is no need to go into each branch. Also, veins have an extremely variable branching pattern, so your body may be different from what is laid out here. We’ve seen a body with 2 Ext Jugular v!

To learn veins of any area – just draw the picture a bunch of times. Hell, draw it on the exam.

Here’s an “in general” flow pattern of the veins:

• Supraorbital v + Supratrochlear v = angular v at the corner of the eye
• angular v + deep facial v = facial v
• Maxillary v + Superficial temporal v = Retromandibular v
• ant branches of Retromandibular v + Facial v —> flows into IJV, w/ a bunch of other v
• post branches of Retromandibular v + Post Auricular v = EJV
• Ant Jugular —> flows into EJV
• Subclavian v collect veins that follow the arteries that branch off subclavian a
• Subclavian v + IJV = Brachiocephalic v —- called angulus venosus, also where major lymph ducts of the the body drain into
• EJV can flow into Subclavian v OR IJV OR angulus venosus itself (the intersection of the 2 veins)

Other vein info, specifics: Doubt you have to know this, but rather give u extra info, than not at all.

• Supratrochlear v = begins as a collection of veins connected to the frontal branches of superficial temporal v
• Supraorbital v = begins also in the forehead, where it connects w/ branches from supratrochlear, superfical temporal v, and middle temporal v, a branch of it passes through supraorbital notch to anatomose w/ superior ophthalmic v
• Together, these 2 v. drain ant part of scalp and forehead
• Facial v = runs from medial angle of eye and inf border of orbit, starting from angular v, is much straighter than than facial a
  • receives pterygoid venous plexus (via deep facial v), sup/inf labial v
  • branch of it anatomose w/ superior ophthalmic v
  • drains ant scalp, forehead, eyelids, ext nose, ant cheek, lips, chin, submandibular gland
• Superficial temporal v = receives a number of v of scalp/zygomatic arch, runs thru parotid gland
  • drains side of scalp, superficial aspect of temporalis m, ext ear
• Retromandibular v = formed by union of superficial temporal & maxillary v
  • is post to ramus of mandible, goes thru parotid gland, has ext carotid a behind and facial n in front of it
  • drains masseter m, and parotid gland

Lymph Drainage of Head & Neck

The head and the neck, each have a set of superficial & deep lymph nodes and vessels. The superficial lymph nodes and vessels run with veins, deep lymph nodes and vessels run with arteries. All lymph from head and neck drains into deep cervical lymph nodes, that run w/ IJV.

Superficial lymph nodes of Head:

• In general, the face, scalp, and ear –> drains into occipital, retroauricular, parotid, buccal, submandibular, submental, superficial cervical l.n.
• lat face, including eyelids –> parotid l.n. –> deep cervical l.n
• upper lip, lat lower lip –> submandibular l.n.
• chin, central lower lip –> submental l.n.

Deep lymph nodes of Head:

• middle ear –> retropharyngeal & upper deep cervical l.n.
• nasal cavity/ pasanasal sinuses –> submandibular, retropharyngeal, upper deep cervical l.n.
• tongue –> submental, submandibular, upper/lower deep cervical l.n.
• larynx –> upper/lower deep cervical l.n.
• pharynx –> retropharyngeal, upper/lower deep cervical l.n.
• thyroid –> lower deep cervical, prelaryngeal l.n., pretracheal l.n., paratracheal l.n.

Superficial cervical lymph nodes:

• lie along the ext jugular v in posterior triangle & along ant jugular v in anterior triangle
• drain into deep cervical nodes

Deep cervical lymph nodes:

• Superior
  • lie along int jugular v, in carotid triangle of neck
  • receive: lymph from back of head and neck, tongue, palate, nasal cavity, larynx, pharynx, trachea, thryroid gland, & esophagus
  • efferent vessels that join those of the inf deep cervical nodes to from jugular trunk –> thoracic duct on L, and angulus venosus on R
• Inferior
  • lie on the IJV, near subclavian v
  • receive lymph from ant jugular, transverse cervical, axillary nodes

Histology:  The epithelial tissue.

Epithelium = sheets of cells that cover external surfaces of the body, line internal cavities, form various organs,glands and ducts. Remember that it is avascular – no blood vessels!

Epithelium can be classified in 3 ways: functionally, # of cell layers,  & structure of surface cells

Functional groups:

• Lining epith – formation of barrier on surface of body, ex/ skin, inner stomach
• Glandular epith – production/secretion of substances to extra cellular territory in high amt
• Sensory epith – for special sensations, ex/ taste buds, olfactory

Epithelium has what is called functional polarity = basically, this means that different sides of the cells have different functions.

• Basal side:
  • attached to basement membrane = basement lamina + reticular fibers
  • has hemidesmosomes
  • protein, polysaccharides rich layer
• Lateral side:
  • intracellular junctions = tight, adherent, desmosomes
• Apical side:
  • microvilli – inc surface absorption
  • kinocilia – move substances across apical surface
  • stereocilia – sensory function, absorption

Cell-Cell Junctions

• Occluding/Tight Jxns: impermeable and allow epithelia cells to functions as a barrier
  • form primary intercellular diffusion barriers b/w adjacent cells
  • located @ most apical part
  • Proteins:
    • occludins – maintain barrier b/w cells, @ apical/lateral domains, not in all tight jxns
    • claudins – form backbone of each strand, form extracellular H2O  channels for ions and small molecules
    • JAM (Junctional adhesions molecule) – immunoglobulin, w/ claudins, interactions b/w endothelium & monocytes
• Anchoring Junctions: mechanical  stability to epithelium, by linking cytoskeleton of 1 cell to adjacent cell.
  • interact w/ both actin & intermediate filaments
  • lateral cell surface, basal domain
  • signal transductions capability, cell-cell recognition, cell differentiation, morphogenesis
  • Zonula adherens – interact w/ network of actin filaments inside cell, lateral adhesion
  • Macula adherens (desmosomes) – interact w/ network of intermediate flaments
• Communication Junctions (Gap): direct communications b/w adjacent cells by diffusion of small molecules
  • epithelia, smooth m, cardiac m, and nerves
  • open communication – quicker exchange of ions, regulatory molecules, small metabolites
  • easier to coordinate activity
  • Proteins = connexons, in 6 subunits of 2 = connexin

Apical Modifications:

• Microvilli
  • small, non motile projections that cover all absorptive cells in SI and prox convoluted tubules in kidney
  • proteins = villin, actin filaments, fimbrin, fascin, myosin I in core, and spectrin & myosin II in base
  • sit on intermed filaments
• Kino cilia
  • motile structures that are found in uterin tubes, uterus, repiratory system
  • move substances across a surface
  • dark line @ apical surface

  • 2 microtubules in center, surrounded by 9 doublets of microtubles, w/ dynein, & nexin
• Sterocilia
  • long, non motile branched microvilli of sorts that cover cells in epididymis & vas deferens
  • absprption!
  • Proteins: actin filaments, erzin, fimbrin in core, and alpha -actinin in base

Classification by layers

• Simple – one layer of cells only, attached directly to basement membrane
• Stratified – multiple layers of cells
• Pseudostratified – one layer of cells, all attached to basement membrane, but have varying heights, so appear stratified

Classification by morphology

• squamous – flat cells
  • Simple squamous –
    • called mesothelium on the outside surfaces of lungs, heart, digestive organ == i.e. where-ever there is pleura, pericardium, or peritoneum, there is mesothelium anatomically – Histo wise, this is called a serosa covering.
    • called endothelium on the internal surface of arteries, lymph vessels, and internal surface of heart
  • Stratified squamous –
    • keratinized – top cells are dead & have no nuclei, are instead filled w/ keratin protein  – located in external areas of body ex/ skin
    • non-keratinized – live surfaces, all cells of epithelium alive – located in areas exposed to outside elements, but not on external areas of body ex/ oral mucosa, pharynx, vagina, anal canal, esophagus.
• Cuboidal – height = width
  • Simple cuboidal – excretory ducts, like prox convoluted tubules of kidney, very common in glands
  • Stratified cuboidal – not as common, ducts of salivary glands and pancreas
• Columnar – height > width
  • Simple columnar – characteristic of digestive organs, like in stomach and gallbladder, SI, LI – tend to have microvilli
  • Stratified columnar – limited in body, ducts again
• Transitional Epithelium = Urothelium
  • located in urinary system, like bladder and ureter, and minor/major calices – NOT IN URETHRA
  • Cell Types:
    • Umbrella cells – binucleated, is dome shaped when urinary structures are empty, flat when full
    • Piriform cells – in the middle
    • Basal cells – single layer on bottom , right above BM

Embryology:  The development of blood vessels

Blood vessels develop in two ways:

• vasculo genesis – vessels arise from the combination of blood islands aka angioblasts – mainly dorsal aorta, & cardinal veins
• angiogenesis – vessels arise from existing vessels

Development of arteries

• Aortic sac develops from distal part of truncus arteriosus
• sac gives a set of aortic arches, one to each pharyngeal arch
• arches terminate in two (R&L) dorsal aortas
• aorticopulmonary septum divides outflow part of truncus arterious into ventral aorta & pulmonary trunk
• dorsal aorta b/w 3rd and 4th arch disappears (carotid duct)
• R dorsal aorta disappears b/w 7th segmental aorta and L dorsal aorta
• heart is pushed into thoracic cavity by folding of embryo
• because of the heart movement – this is why recurrent laryngeal a is in diff location in R & L side

Aortic Arches:

• Arch I = part of maxillary a, by day 27
• Arch II = part of stapedial a & hyoid a
• Arch III = part of R &L common carotid a, R&L int carotid a
• Arch IV = part of R subclavian a, and part of aortic arch on L
• Arch V = disappears
• Arch VI = part of R &L pulmonary a, ductus arteriosus – connection b/w pul a & arch of aorta, is ligamentum arteriosum in non fetal life

Dorsal Aorta

• R & L dorsal aortae combines into dorsal aorta.
• from dorsal aorta, originates posterolateral a, lateral a, and ventral a
• Posterolateral a = a to upper and lower limb, IC, lumbar and lateral sacral arteries
• Lateral a = renal, suprarenal, and gonadal arteries *NOTE = paired visceral arteries of abdominal aorta
• Ventral a
  • Vitelline a = celiac, superior mesenteric, inf mesenteric a *NOTE = unpaired visceral arteries of abdominal aorta
  • Umbilical a = part of Int Iliac, superior vescical arteries, run in medial umbilical ligaments. = PELVIS

Coronary a – from 2 sources

• angioblasts formed elsewhere and sent over the heart surface
• from epicardium – some of its epithelial cells will become mesenchymal cells due to some reaction from underlying mesenchyme
  • new mesenchyme and neural crest cells create smooth m cells in these arteries
  • endothelial cells from these arteries push into aorta

Development of Veins

• develop mainly from three pairs of veins = vitelline v, umbilical v, and cardinal v —> empty blood into sinus venosus
• vitelline v = carry blood from yolk sac
  • become hepatocardiac part of IVC, hepatic v &sinusoids, ductus venosus, portal v, inf mesenteric v, sup mesenteric v, splenic v
  • form plexus around duodenum and pass thru septum transversum, pushing into liver to form sinusoids
  • the duodenal plexus becomes the portal v
• umbilical v = from chorionic villi and carries O2 blood to embryo
  • pass on each side of liver, some connect to sinusoids
  • only L umbilical v remains to carry blood from placenta to liver — becomes ligamentum teres of liver, and ductus venosus, to become ligamentum venosum in life.
• cardinal v = drains embryo itself
  • Ant =drain cephalic part of embryo intially–> SVC, int jugular v, L brachiocephalic v
  • Post = drain rest of embryo initially –> part of IVC, R common iliac v
  • Subcardinal v = drain kidneys –> renal v, part of IVC, gonadal v
  • Sacrocardinal = drain lower limb –> sacrocardinal part of IVC, L common iliac v
  • Supracardinal v = drain body wall via IC v (takes over fxn of post cardinal v) –>part of IVC, IC v, azygos system

Anim = Development of Aorta, Pulmonary Trunk, and Interventricular Septum

Anim = Aortic Arch Vessels