Tag Archives: urothelium

36. The anatomy, histology and development of the ureter, urinary vesicle and urethra.

6 Jan

36. The anatomy, histology and development of the ureter, urinary vesicle and urethra.

Anatomy of the ureter, urinary vesicle and urethra.


General Info:
musc tube that transmit urine via peristaltic waves, leads from kidney

is the most posterior structure that emerges from hilus of kidney
25-30 cm long
enter bladder @ anteromedially, superior to levator ani


  • crosses bifurcation of common iliac a @ pelvic brim
  • desc retroperitoneally on lat pelvic wall –> med to umbilical a & obturator a/v
  • post to ovary @ post surface of ovarian fossa
  • 1-2 cm lat to uterus, runs w/ uterine a, which runs above and ant to base of broad lig
  • passes post/inf to ductus deferens & lies in front of seminal vesicle before entering post/lat bladder (male)

2 parts – abdominal/pelvis


crossed by 3 structures: Topography
1. Gonadal a/v – in front
2. Psoas major – behind
3. Bifurcation of common iliac a w/ ureter in front of int iliac a

Male – ductus deferens crosses ureter in front


  • uterine a crosses in front
  • @ bifurcation of common iliac, forms post border of ovarian fossa
  • contacts lat fornix of vagina b4 entering bladder

Blood Supply:

  • rec blood from aorta, renal, gonadal, common & int iliac, umbilical, sup/inf vesicle a, middle rectal a
  • Vesicle venous plexus –> int iliac v (sometimes, prostatic vesicle plexus)

Lymph Drainage: lumbar, common iliac, ext iliac, int iliac l.n

Urinary Bladder

*Infraperitoneal – lower in female
located in pelvis minor when empty
located full, can enter major pelvis –> even up to umbilicus

General Info:

  • THICK muscular wall = detrusor m
  • holds urine, until ready to release it
  • mucus membrane attaches, except @ trigone
    • mucus membrane attaches to CT underlying, no mucosal folds
    • originates from mesonephric duct
    • marked by entrances of ureter & ejaculatory duct
    • has 2 ureteric openings and urethral openings (int urethral sphincter)
  • anchored by CT ligaments = paracysticum
  • held @ neck  to pubic bone, via puboprostatic (male), or pubovesical (female) ligaments

Structure of Bladder (Detail):

The bladder itself consists of 4 layers:-

(1) Serous – this outer layer being a partial layer derived from the peritoneum,
(2) Muscular – the detrusor muscle of the urinary bladder wall, which consists of 3 layers incl. both longitudinal and circularly arranged muscle fibres,
(3) Sub-mucous a thin layer of areolar tissue loosely connecting the muscular layer with the mucous layer
(4) Mucous – the innermost layer of the wall of the urinary bladder loosely attached to the (strong and substantial) muscular layer. The mucosa falls into many folds known as rugae when the bladder is empty or near empty.

  • The features observable on the inside of the bladder are the ureter orifices, the trigone, and the internal orifice of the urethra.
  • The trigone is a smooth triangular region between the openings of the two ureters and the urethra and never presents any rugae even when the bladder is empty – because this area is more tightly bound to its outer layer of bladder tissue.

Peritoneal relations of bladder:

Outer surfaces of the Bladder: The upper and side surfaces of the bladder are covered by peritoneum (also called “serosa”). This serous membrane of the abdominal cavity consists of mesthelium and elastic fibrous connective tissue. “Visceral peritoneum” covers the bladder and other abdominal organs, while “parietal peritoneum” lines the abdomen walls.

Topography of Bladder: Bladder Bed

  • ant = pubic bone, separated from ant ab wall & pelvis by rectopubic space
  • inf/lat = obturator int m, levator ani m
  • inf/post = rectum

B/w bladder & rectum:
Male – seminal vesicles & ejaculatory duct, ductus deferens
Female – uterus & upper vagina


Vesicouterine Pouch:
ant = bladder
post = uterus
lat = vesicouterine ligaments (folds)

Normally, pouch so small, there is nothing in it
If Rectoversion occurs, may contain SI loops
bladder connected to CT except @ neck where puboprostatic lig anchors it (male)

Rectovesicle Pouch:
ant = bladder, seminal vesicle, DD
post = rectum
lat = rectovesicular fold

In male, pertioneum covers fundus, reflecting from upper post wall, and covers tip of seminal vesicle


Parts of Bladder:

  1. Apex (ant end)
    • retro to symphysis
    • origin of median umbilical ligament – remnant of embryonic urachus (connection b/w urinary bladder and embryonic allantois)
  2. Fundus (post/inf)
    • contact w/ rectum in male, separated by rectovesicular septum
    • contacts w/ ant surface of vagina in female
  3. Neck (lat/post — converges here)
    • urethra originates from bladder here
    • just above = uvula – small eminence projects into urethra

Blood Supply:

  • Sup vesicle a (int iliac a)
  • Fundus of bladder
    • inf vesicle a (Male)
    • vaginal a (uterine a – Female)
  • veins = vesicle venous plexus –> int iliac v (prostatic venous plexus)

Lymph Drainage:

  • body = ext iliac lymph nodes
  • fundus = int iliac l.n
  • neck = sacral & common iliac l.n.


  • PNS from pelvic splanchnic n (S2-4)
    • VM for detrusor m
    • (-) for int urethral sphincter
  • SNS (T12-L2)
    • VM for int urethral sphincter
    • (-) detrusor m

From bladder –> opens @ perineum, urine emptied thru it

Male Urethra

Parts to it:
1. Prostatic urethra
3 cm long, and w/in prostate
widest part of urethra
covered w/ urothelium = transitional epithelium

The prostatic urethra begins at the neck of the bladder and includes all of the section that passes through the prostrate gland. It is the widest and most dilatable part of the male urethral canal.

Structures opening here:
1. Prostatic glands
2. Ejaculatory ducts
3. Prostatic utricle

long ridge = urethral crest

  • runs through out w/ 2 grooves beside it = prostatic sinuses
  • opening of submucosal ducts & prostatic glands
  • @ upper crest = seminal collicus

Seminal colliculus

  • small hill like structures protruding into urethra
  • lat to colliculus are prostatic sinuses, where prostate glands open
  • 3 small openings:
    • @ midline = utricle of prostate (remnant of paramesonephric duct – regresses in male)
    • inf to that = 2 ejaculatory ducts

secretions of prostate, seminal vesicle, and bulbourethral glands mixes w/ spermatozoa from testis = semen

2. Membranous urethra
1 cm long
passes thru UG diaphragm – here ext urethral sphincter seen

The membranous urethra is the shortest and narrowest part of the male urethra. This section measures approx. 0.5 – 0.75 inches (12 – 19 mm) in length and is the section of the urethra that passes through the male urogenital diaphragm.
The external urethral sphincter (muscle) is located in the urogenital diaphragm (as for the female urethra).
The passage of urine along the urethra through the urogenital diaphragm is controlled by the external urethral sphincter, which is a circular muscle under voluntary control (that is, it is innervated by the somatic nervous system, SNS).

3. Penile urethra
enters bulbous part of  penis
Pathway: turns up @ sharp angle (1st turn)  –> runs along bulb of penis –> to pubic symphysis –> bends down (2nd turn) –> corpus spongiosum –> runs down to tip of penis & opens @ navicular fossa

The spongy (penile) urethra is the longest of the three sections. It is approx. 6 inches (150 mm) in length and is contained in the corpus spongiosum that extends from the end of the membranous portion, passes through the penis, and terminates at the external orifice of the urethra – which is the point at which the urine leaves the body.

@ navicular fossa: str columnar –> str sq non keratinazing epith

CLINICAL NOTE: B/c of 2 sharp bends – makes it difficult to insert catheter

Blood supply: prostatic br of inf vesicle a & middle rectal a, v follow a

Lymph Drainage: int/ext iliac l.n

Nerve supply: pudendal n, prostatic plexus (inf hypogastric plexus)


Female urethra


At only about 1.5 inches (35 mm) long, the female adult urethra is shorter than the adult male urethra (approx. or 8 inches, or 200mm). The female urethra is located immediately behind (posterior to) the pubic symphysis and is embedded into the front wall of the vagina.

The urethra itself is a narrow membranous canal that consists of three layers:

  1. Muscular layer – continuous with the muscular layer of the bladder, this extends the full length of the urethra.
  2. Thin layer of spongy erectile tissue – including plexus of veins and bundles of smooth muscle fibres. Located immediately below the mucous layer.
  3. Mucous layer – internally continuous with the bladder and lined with laminated epithelium that is transitional near to the bladder.

After passing through the urogenital diaphragm (as shown in the diagram), the female urethra ends at the external orifice of urethra – which is the point at which the urine leaves the body. This is located between the clitoris and the vaginal opening.

The passage of urine along the urethra through the urogenital diaphragm is controlled by the external urethral sphincter, which is a circular muscle under voluntary control (that is, it is innervated by the somatic nervous system, SNS).

The female urethra is a much simpler structure than the male urethra because it carries only urine (whereas the male urethra also serves as a duct for the ejaculation of semen – as part of its reproductive function
upper 1/2 = prostatic urethra
lower 1/2 = “membranous”

@ upper part = Paraurethral glands –> ducts @ ext urethral orifice

@ lower part
goes through UG diaphragm
transverse perineal m wraps around to form = urethro vaginal sphincter
closely associated w/ ant wall of vagina

  • attached via strong CT sheath = urethrovaginal septum
  • b/w them = urethrovaginal space

Blood supply: int pudendal a, vaginal a, veins follow a

Lymph Drainage: sacral/int iliac l.n

Nerve supply: pudendal n

Process of Urination:
Initiated by (+) of stretch receptors in detrusor m in bladder in wall by inc volume of uring
innervated by S2-4 via pelvic splanchnic n
can be assisted by contraction of abdominal m = inc intra abdominal & pelvic pressures

1. SNS = (+) relaxation of bladder wall
contract inner sphincter –> (-) emptying
may stimulate detrusor m to prevent reflux of semen into bladder during ejaculation

2. PNS = preggl fibers in pelvis splanchnic n
synapse in pelvic (inf hypogastric plexus)
post ggl to bladder musc induc reflex = contraction of detrusor m
and relaxation of int sphincter
inc urge to urinate

3. SM fibers in pudendal n cause voluntary relaxation of ext urethral sphincter
bladder begins to release

4. @ end of urination
the ext urethral sphincter ( & bulbospongiosus m in male) contracts
expel the last few drops of urine from urethra

Histology  of the ureter, urinary vesicle and urethra.

Slide #63 Ureter * H&E

Structures to Identify:

  • 3 layers = mucosa, muscularis, adventia
  • transitional epith
  • umbrella cells
  • a/v
  • CT
  • piriform cells
  • basal cells

General Info

  • paired tubular structures that convey urine from kidney –> bladder
  • lined w/ transitional epith to adapt to changing environment (fluid v no fluid)


  • Epith = urothelium
    • thick, with cells that change shape
  • star shaped irregular lumen, made by mucosal folds, due to musc. contractions
  • Note that lumen is long , narrow and star shaped, not circular *like DD
  • 3 main cell types of Epith
    • umbrella cells – come in contact with urine, and adjust accordingly, can be bi-nucleated, shape change due to actin filaments
    • piriform cells – underneath umbrella cells and above basal cells, can also adjust morphologically
    • basal cells – located at lowest layer of stratified epith
  • LP = fibroelastic CT, denser near epith –> looser towards muscularis ext, with diffuse lymph tissue = MALT
  • No real muscularis mucosae
transitional epithelium or urothelium and cells of it

transitional epithelium or urothelium and cells of it

Muscularis Ext

  • 3 layers:
    • inner longitudinal layer
    • middle circular layer
    • outer longitudinal – but only in last 1/3 of ureter
  • smooth m responsible for creating peristaltic contractions to convey urine through ureter (30cm)


  • 3rd main layer
  • ureter = retroperitoneal, so covered w/ adventia
  • CT + a/v/n
  • adipose

Slide #64 Urinary Bladder * H&E

Contracted Bladder - Our slide doesnt look like this, but this shows layers well

Structures to Identify:

  • urothelium
  • muscularis
  • a/v
  • CT
  • mesothelium
  • PNS ggl

General Info

  • Receives urine from 2 ureters and under appropriate stimulation, will secrete it through urethra
  • lined by urothelium, which allows bladder to adjust to amount of urine


  • Epith = urothelium,  transitional epithelium
    • same cell types as ureter
    • up to 10 layers when bladder empty, # layers dec when bladder is full
  • when bladder is full, cells flatten and appear squamous, & when bladder was empty, cells became dome shaped
  • LP = CT tissue fibers, fibroblasts, a/v, many layers
    • Can either say LP has 2 layers = upper cell rich, and lower fibrous layer
    • Or can say there is a cell rich LP with a fibrous submucosa
    • fibrous layer not present in bladder trigone
  • changes in appearence and cells shapes in transitional epithelium are from thickened regions called plaques
    • interconnected via interplaque regions
    • allow  cell membrane to fold – which disappear when urine flows into bladder

Muscularis Mucosae

  • 3 muscular layers: – inner longitudinal, middle circular, outer longitudinal
  • not as organized as ureter
  • may be ggl cells wich are part of ANS
    • helps regulate urine secretion via relaxation & contraction of muscularis
    • controls detrusor m
  • Internal urethral sphincter = fromed @ site of entry of bladder –> Urethra
  • w/ CT in between, and a/v and capillaries, and occasional n. fibers


  • Infraperitoneal
  • fundus covered by peritoneum
  • serosa/ subserosa can be present where peritoneal pres – superiorly –> simple squamous = mesothelial cells
  • SNS n fibers maybe

Beyond the serosa/adventitia covering of the bladder is perivesical fat.  This is a layer of fat surrounding bladder.

Its upside down - sorry

It's upside down - sorry

Slide #71 Penile Urethra * H&E

Structures to Identify:

  • lumen
  • corpus spongiosum
  • smooth m
  • str columnar/ psuedo str columnar
  • tunica albuginea
  • urethral glands of Littre
  • paraurethral ducts
  • endo-epith glands


  • Epith = pseudostratified non keratinized epith
    • epith changes depend on part of urethra
    • Pars prostatica –  urothelium
    • Pars membranous – str columnar
    • Pars spongiosum –  str columnar – until navicular fossa – str squamous
  • LP = thin layer, merges with surrounding corpus spongiosum, cell rich
  • lumen is shaped like ureter, but does NOT have urothelium in our slide, so look for that, and the glands of Littre
  • mucosal folds makes small dips in lumen, and forms lacunae
  • lacunae attached to urethral ducts of urethral glands of Littre
    • mucus secretions
    • thin basophillic (blue) outer layer with pale interior (mucus)
    • duct is more basophillic, with small circular lumen

Corpus spongiosum

  • network  of cavities lined by simple squamous epith
  • a/v in b/w

Outer layer = Tunica albuginea

  • thick eosinophillic layer, with smooth m and elastic fibers
Ducts of Littre

Ducts of Littre

Development of the ureter, urinary vesicle and urethra.


  • intermediate mesoderm forms longitudinal ridge on post body wall = urogenital ridge
  • part of UG ridge becomes nephrogenic cord –> urinary system
  • nephrogenic cord develops into 3 structures: pronephros, mesonephros, metanephros
  • metanephros further develops from ureteric bud and from grouping of mesoderm w/in nephrogenic cord, metanephric mesoderm
  • further development of ureteric bud –> becomes ureters

Urinary bladder:

  • urinary bladder is formed from upper end of urogenital sinus, continuous w/ allantois
  • allantois becomes fibrous cord = urachus * stays in adult as median umbilical lig
  • lower end of mesonephric ducts –> post wall of bladder as trigone
  • mesonephric ducts open into urogenital sinus below bladder
  • transitional epith from endoderm


Female Urethra:

  • female urethra is formed from lower end of urogenital sinus
  • develops as endodermal outgrowths into surrounding mesoderm = urethral glands, paraurethral glands
  • end @ vestibule of vagina, also forms from urogenital sinus
  • vestibule of vagina – develop endoderm growths = greater vestibular glands
  • endoderm = epith

Male Urethra:

  • Prostatic urethra, membranous urethra, prox urethra
    • formed from lower end of urogenital sinus
    • endoderm = transitional epith, str columnar epith
    • prostatic urethra have endoderm outgrowth into mesoderm = prostate gland
    • membranous urethra have endoderm outgrowth into mesodem = bulbourethral glands
    • prox part of penile urethra have endoderm outgrowth into mesoderm = Littre’s glands
  • distal part of penile urethra
    • formed from ingrowth of surface ectoderm = glandular plate
    • glandular plate joins penile urethra and becomes tube = navicular fossa
    • ectodermal septa lat to navicular fossa –> becomes foreskin
    • str sq epith lines part of urethra = ectoderm
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1. Arteries, veins and lymphatic drainage of the head and neck. The epithelial tissue. The development of blood vessels.

1 Dec

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 arteriosusconnection 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