32. The anatomy, histology and development of the uterine tube and uterus.

Anatomy of Uterus/Uterine Tube

Uterus:

Location: b/w bladder (ant) and rectum (post), above and leads to vagina

Function: Major organ of gestation

General Info:
7-8 cm long, 5-7 cm wide, 2-3 cm wide
2 main parts = corpus (upper 2/3) and cervix (lower 1/3) , connected via isthmus

• Cervix protrudes into vagina @ angle of 60-70 degress = anteversion ( angle b/w vagina and cervical canal)
• Body inclines forward and bends over fundus of bladder, attached to cervix w/ angle of another 60 degrees = anteflexion ( angle b/w jxn of cervix and body)

Topography:

• ant = fundus of bladder
• post = coils of SI, and via pouch of Douglas, the rectum
• lat = cardinal ligament @ level of cervix (part of parametrium), that carries the uterine a/v
• sup = fundus of uterus touches SI coils
• inf = supported by pelvic diaphragm, UG diaphragm, round, broad, lateral cervical ligaments, pubovesical, sacrocervical, retro-uterine ligaments

Parts:

Cervical portion:
has 2 areas:
Vaginal portion – protrudes into vagina,surrounded by vaginal fornices

• has rounded end and ext os of uterine canal w/in it
• @ ext os, simple columnar epith –> str squamous
  
• If no kids (nulliparous) – opening is round, and small
• If kids (multiparous) – opening is slit like

Supravaginal portion – embedded into CT of visceral pelvic fascia (via parametrium), in direct contact w/ broad ligament (myometrium)

Cervical Canal:

• terminal portion of uterine cavity
• has impermeable plug of mucus,
  • helps prevent entrance of pathogens
    
  • that becomes permeable during ovulation –
  • does allow sperm to penetrate
• b/w cervix and isthmus of uterus = int histological os – where wall of cervix changes to uterus histologically

Epith of cervix isn’t shed in menstruation like the epith of rest of uterus = simple columnar, # of glands inc in this area – they secret the mucus to make mucus plug
keeps closed until few hours before birth – then begins to dilate to allow head thru – this is due to high amt of collagen and smooth M in cervix

Cervix doesn’t have real myometrium, called it, but really has less smooth m and more elastic fibers compared to rest of uterus

NOTE: (Please do not be confused by the 50 names out there for the same thing)

• Int opening of isthmic canal = anatomical int os (does not exist in pregnancy)
• Int opening of uterus = int os = histological int os = external opening of isthmus (isthmic canal)
• Ext opening of uterus = external os

Corpus

Biggest part of uterus
covered by broad ligament = called the mesometrium of uterus, attaches it to lateral body wall
bends over the bladder (ant)

Has two special parts : fundus & isthmus
Fundus

• area above the level of uterine tubes
• laterally, ends in uterine horns –> lead to uterine tube

Isthmus

• narrow part locared b/w cervix & corpus of uterus
• same histological structures as corpus of uterus
• incorporated into cavity of uterus during pregnancy – @ 2nd 1/2 of pregnancy, isthmus opens up, so anat int os ceases to exist, only histo os and ext os still there
  
• isthmic canal – canal w/in the isthmus
• Int anatomical os – b/w isthmic canal and uterine cavity

Wall of Uterus
Perimetrium = outer layer, peritoneum & underlying subserosa
Myometrium = middle musc layer, has sublayers
Endometrium = innermost layer, layer removed during menstruation

Ligaments of Female Pelvis

1. Broad ligament of uterus – 2 layers of peritoneal covering, from lat margin of uterus –> lat pelvic wall
   • holds uterus in position
   • contains: uterine tube, a/v, round ligament, ovarian ligament proper, urete, uterovaginal n. plexus, lymph vessels
2. Mesovarium – fold of peritoneum that connects ant surface of ovary w/ post layer of broad ligament
3. Mesosalpinx – fold of broad ligament that suspends the uterine tube
4. Mesometrium–  fold of broad lig below mesosalpinx, and meso-ovarium, lat wall of uterus –> pelvic wall
   
5. Proper Ovarian ligament – fibromusc cord from uterine end of ovary –> side of uterus below uterine tube w/in broad lig
6. Suspensory ligament of ovary – band of peritoneum that runs sup/lat from end of ovary –> pelvic wall, has ovarian a/v, lymph vessels
7. Lat/Transverse Cervical (Cardinal) Lig of Uterus (aka ligament of Mackenrodt’s) – fibromuscular condensations of pelvic fascia from cervix (hence, cervical) & lat fornix of vagina –> pelvic wall, run w/in parametrium of uterus
8. Parametrium – fibrous CT that runs w/in mesometrium, connects uterus to lat pelvic wall
9. Paracolpium – fibrous CT that connects the lat wall of vagina –> lat pelvic wall, fibers merge w/ those of para cysticum (for bladder)
10. Pubocervical ligament – firm bands of CT from post surface of pubis –> cervix of uterus
11. Sacrocervical(uterine) ligament – firm fibromuscular bands of pelvic fascia from lower end of sacrum –> to cervix, upper end of vagina *palpable in rectal exam
12. Pubovesical ligament – pelvic fascia bands from neck of bladder (or prostate in male) –> pelvic bone
13. Rectouterine ligament – holds cervis back and up and sometimes elevate a shelf-like fold of pertioneum (recto-uterine folds – called sacro-genital folds in male)
    • isthmus of uterus –> post wall of pelvis, lat to rectum

Ligament relations of Uterus & Uterine tube

Connective tissue ligaments of female pelvis

Also, peritoneal covering over pelvic organs in female create 2 pouches:
1. Vesicouterine Pouch

• ant = bladder
• post = uterus
• lat = vesicouterine folds

2. Rectouterine pouch – aka Douglas pouch

• ant = uterus
• post = rectum
• lat = rectouterine folds
• floor = post fornix of vagina, in direct contact w/ ampulla of rectum *can be felt there via rectal exam

CLINICAL NOTE: This is deepest point of peritoneal cavity in female, any excess peritoneal fluid will collect there
blood in pouch can indicate the presence of ectopic pregnancy

Pouces and ligaments/Topography of Female Pelvis

Blood Supply: primarily uterine a, secondarily ovarian a

• Uterine a enters parametrium via cardinal ligament of ovary
  • when it reaches isthmus, divides into large asc uterine br
  • small desc uterine br
  • also has ovarian and tubal br
  • @ cardinal lig  – uterine a/v crosses ureter and have vessels in fromt
• Ovarian a
  • has ovarian and tubal br that anastomose w/ same br of uterine a
• Veins = uterovaginal plexus of veins –> int/ext iliac v

Blood Supply of Uterus, Uterine tube

Lymph Drainage:
1. Fundic region = aortic nodes via ovarian lymph vessels
2. Corpus = ext iliac and sup inguinal nodes
3. Cervix = int iliac and sacral nodes

Nerve Supply = branches of hypogastric n plexus,

Uterine Tube:
non united part of Mullerian duct (embryo)
Location: from horn of uterus –> ends in ampulla @ uterine end of ovaries

Function:

• carries fertilized or unfertilized ovum from ovary to uterus, for Implantation
• via action of the cilia on its epithelium, and contraction of musc wall, also carries sperm towards the ovary
• Connects uterine cavity w/ peritoneal cavity
• Fertilization occurs in ampulla or infundibulum of uterine tube

Parts:
1. Infundibulum – funnel-shaped distal portion over end of ovary

• has 20-30 fimbriae, which attach to ovary
• move to guide oocyte in after ovulation
• communicates w/ peritoneal cavity via abdominal ostium

2. Ambulla – FERTILIZATION

• widest and longest part of uterine tube
• INTRAPERITONEAL
• attached w/in broad ligament via mesosalpinx

3. Isthmus – short 2.5 cm long area that leads to horn of uterus

4. Uterine part

• part that attaches to uterine wall
• opens into uterine cavity via  uterine ostium

Blood supply = tubal br of ovarian and uterine a, veins run w/ a

Lymph drainage = run to aortic/lumbar nodes

Nerve supply = pelvic/ovarian n. plexus, that run in mesosalpinx

Minimals related to this topic:

196.    Describe the relation of the ovary to the uterine tube!
The upper or tubal end of the ovary is closely related to the uterine tube. The infundibulum has irregular fringes called fimbriae that project from the margin of the infundibulum to the ovary.
197.    Define the term “broad ligament of the uterus” and list those structures that are located within its substance!
A double layered peritoneal ligament extending from the sides of the uterus to the lateral walls and the floor of the pelvis.
Structures: uterine tube, round lig. of uterus, ovarian lig., epoophoron, paroophoron, uterine vessels, uterovaginal venous plexus, nerves.

198.    Define the term “parametrium”!
The loose connective tissue found between the two diverging layers of the broad ligament of uterus, which connects the lateral part of the cervix with the pelvic wall.
199.    Define the position of the uterus under normal conditions?
In the axis of the true pelvic, in anteflexion (bends forward) and anterversion (inclines forward)

200.    Define the term anteflexion and anteversion of the uterus!
Anteversion: the cervix is inclined anteriorly at an acute angle (appr. 60°-70°) to the vagina.
Anteflexion: the body of the uterus is bent anteriorly at an acute angle (appr. 60’-70’) to the cervix.

201.    Describe visceral relations of the uterus!
anterior    : posterior wall of bladder,
posterior    : anterior surface of rectum, small intestines,
above    : small intestines,
lateral    : ureter, before its opening into the urinary bladder.

202.    What is the epithelium of the a.) cervical canal and b.) vaginal portion of the uterus?
simple columnar mucous producing epithelium, with scatterd ciliated cells,
stratified squamous non keratinizing epithelium.

203.    Describe the peritoneal relations of the uterus!
The body and the posterior aspect of the supravaginal portion of the cervix is enclosed between the two layers of the broad ligament. The peritoneum reflects from the uterus posteriorly to the rectum and anteriorly to the urinary bladder forming the rectouterine and vesicouterine pouches, respectively.

204.    Define the term “Douglas pouch”?
Rectouterine pouch. Reflection of the peritoneum from the rectum to the uterus. The deepest point of the peritoneal cavity.

205.    List those structures that help to fix the uterus in its original position!
Vagina, pelvic and urogenital diaphragms, round lig., ovarian lig., vesicouterine fold, rectouterine fold, thickenings of the visceral pelvic fascia, broad lig., parametrium.

206.    Which lymph nodes receive lymph from the a.) fundus, b.) body and c.) cervix of the uterus?
aortc, external iliac, superficial inguinal lymph nodes,
external iliac lymph nodes,
internal iliac and sacral lymph nodes.

Histology of Uterus/Uterine Tube

Slide #76 Uterus, Proliferative phase

Structures to Identify:

• all layers of wall
• simple columnar lining epithelium
• simple tubular glands
• a/v – arteries have a fused tunica mucosa
• LP w/ spinocellular CT

General Info:

• Endometrium (same as mucosa) changes with menstrual cycle
• Menstrual cycle
  • Day 1-5 = Menstruation
  • Day 5-6 Regeneration
  • Day 6-14 Proliferative/Estrogen phase
  • Day 14-28 Secretory/Progesterone/Luteal phase
• Uterus provides the site of implantation of fertilized embryo and formation for placenta
• Note that the embryo grows within the wall of the uterus, causing the lumen to narrow, and forms a separate amniotic sac – the embryo does not grow in uterus lumen per se.

Endometrium

• innermost layer, is equivalent to mucosa in other slides
• changes made in endometrium based on hormones produced by ovaries
• To tell that it is Uterus look for: v THICK mucosa, with loads of glands, and is very basophillic

Epith

• simple columnar epith (ciliated and non ciliated cells)
• epith is lower because this is the start of the cycle
• non-ciliated cells will secret hormones in second part of cycle

LP

• cell rich CT highly vascularized
• simple tubular glands – inactive in this  stage
• b/w glands, spinocellular CT & a/v
  • the endometrial stroma, which resembles mesenchyme
    
  • is highly cellular+ contains abundant intercellular ground substance.
  • cells  = stromal cells like in ovary
• thickness depends on stage in cycle
• Has two layers = Statum Functionalis superiorly, and Stratum Basalis inferiorly
• Blood Supply:
  • RADIAL ARTERIES, (branches from the arcuate arteries in myometrium), enter the basal layer of the endometrium, where it give off small straight arteries that supply this region of the endometrium.
  • The main branches of the radial artery continous upward, become highly coiled SPIRAL ARTERY
  • Spiral arteries give off numerous arterioles, that often anastomoses, as they supply a rich capillary bed.
  • Lacuna= dilated segmants, may also occur in the venous system, that drains the endometrium.
  • The straight arteries+ the proximal part of the spiral arteries do not change during the menstrual circle.
  • The distal portion of the spiral ateries undergoes degeneration+ regeneration, with each menstrual cycle, under the influence of estrogen+ progesteron.

Note the smooth and oval glands in the endothelium = def proliferative phase uterus

Stratum Functionalis

• the one that proliferate+ degenerate during menstrual cycle
• during this phase of the menstrual cycle, the endometrium varies from 1 to 6 mm in thickness.
• UTERINE GLANDS(simple tubular): surface epithelium invaginate into the underlying lamina propria, the endometrial stroma.
• containing fewer ciliated cells
• If the glands are oval and smooth in the section, then you know it is proliferative stage.
  
• Separated into upper Compact Layer, and inner Spongy layer
  

Stratum Basalis

• minimal changes in the is layer between stages in the uterus
• regeneration of epithelium starts from the stromal cells and glands in this layer
• large amount of cells int his layer – even more so than in basal layer

NO MUSC MUCOSA/ SUBMUCOSA separate the endometrium from the myometrium.

Myometrium

• is the thickest layer of the uterine wall

• composed of 3 undefined layers of smooth muscle bundles: you see cross, oblique, longitudinal sections.

• the smooth muscle bundles in the inner+ outer layers are predominantly oriented parallel to the long axis of the uterus.

• muscle separated by interstitial CT
• lots of a/v. —> tunica media of arteries merges with smooth m of the myometrium
• arcuate a in myometrium =  vascular zone
  • separates the uteine wall into three zones – Supra vascular, vascular, and perivascular below.

  • 6- 10 arcuate arteries coming from the uterine artery that anastomose in the myometrium

Perimetrium

• adventia/serosa
• on sup surface of uterus, covered with peritoneum –> serosa
• In other surfaces of uterus, is infraperitoneal –> covered with  adventia
• If adventia, can possibly see ggl cells and nerve cells
  

PROLIEFERATING PHASE REGULATED BY  ESTROGEN:

• at the end of the menstrual phase, the endometrium consits of a thin band of CT(about 1 mm) thick, containing the basal portion of the uterine gland+lower portion of the spiral arteries. = stratum basale the layer, that was sloughed off was the stratum functionale.
• Stromal, endothelial+ epithelial cells in the stratum basale proliferate rapidly, following changes can be seen:
• Epithelial cells in the basal portion of the glands reconstitute the glands &  migrate to cover the denuded endometrial surface.
• Stromal cells:  proliferate, secrete collagen, & ground substance
• Spiral arteries lenghten, as the endometrium is reestablished, these arteries are only slightly coiled+ do not extend into the upper third of the endometrium.
• Continous until 1 day after ovulation, which occurs at about day 14, of a 28- day cycle.
• At the end of this phase, the endometrium has reached a thickness of about 3 mm.
• The glands have narrow lumina+ relatively straight, but have a slightly wavy appearance.
• Accumulation of glycogen are present in the basal portion of the epithelial cells.

Slide #77 Uterus, Secretory phase

See the white space between the cells of stroma? And the twisted glands? = Secretory Phase Uterus

Structures are the same as listed above, with some key differences

Endometrium

• Stratum functionalis –
  
  • MUCH thicker,
    
  • uterine glands are now larger and wavy, not oval shaped –> increase size due to secretion within
    
    • inside of glands are pale because secretions are mostly carbs
      
  • arteries are also more coiled , and become more prominent in this layer
    • increase in volume, to prepare for menstruation, the next phase
      
• Stratum basalis –
  
  • less cells in interstitial tissue, more white space between cell
  • the increased interstitial fluid between the cells is called Interstitial EDEMA
  • more WBC, monocytes, neutrophils, granulocytes
  • straight a in this layer —> coiled arteries in fuctional layer
• Stromal cells become decidual cells –> preperation for formation of placenta
  

Myometrium

• more smooth m fibers

SECRETORY PHASE IS REGULATED BY PROGESTERON

• The stimulation for transformation is the implantation of the blastocyst.
• Large, pale cells rich in glygogen result from this transformation,
• they create a specialized layer that facilitates the seperation of the placenta from the uterine wall at the termination of pregnancy.

Menstrual phase *Dont need to know for test, just theory to understand *

• results from a decline in the ovariation secretion of progesterone+ estrogen

• CORPUS LUTEUM produces hormones for about 10 days if fertilization does not occur.
• As hormone levels rapidly decline, changes occur in the blood supply to the stratum functionale.
• Periodic contractions of the walls of the spiral arteries, lasting for several hours, cause the stratum functionale.

Periodic conctraction of the walls of the spiral arteries, lasting for several hours stratum functionale to become ischemic.

• Glands stop secreting+ the endometrium shrinks in heigh as the stroma becomes less edematous.
• After about 2 days, extended periods of arterial contraction, with only brief periods of blood flow, cause disruption of the surface epithelium+ rupture of the blood vessels.
• When spiral arteries close off, blood flows into the stratum basale, but not in the stratum functionale.
• Blood, uterine fluid+ sloughing stromal+ epithelial cells from the stratum functionale constitute the vaginal discharge.
• As patches of tissue separate from the endometrium, the torn ends of veins, arteries+ glands are exposed.
• In the absence of fertilization, cessation of bleeding would accompany the growth+ maturation of new ovarian follicels.
• The epithelial cells would rapidly proliferate+ migrate to restore the surface epithelium as the proliferative phase of the next cycle begins.
• In the absence of ovulation( a cycle refered to as an anovulatory cycle), a corpus luteum does not form, and progesterone is not produced.
• In the absence of progesterone, the endometrium does not enter the secretory phase until menstruation.

Slide #76 Uterus, Pregnant * H&E

Structures to Identify

• endometrium with glands = decidua basalis
• myometrium
• chroion frondosum (primary villi)
• embryonic cavity
• primary, secondary, tertiary villi
• chorion leave
• decidua capsularis, marginalis, parietalis
• a/v

General Info:

This slide is not as difficult as it may seem.  Look at the picture to the right to first familairize yourself with the layers listed.

First look for a long white tube with a thick wavy over covering –> this is the embryonic (amniotic) cavity.

• On one side of it is chorion frondosum, with all the villi inside
• Villi contain fetal blood
  • between the villi is the intervillus space that houses maternal blood
• lateral to the chorion frondosum, is decidua basalis
• on the other side of the amniotic cavity, is the chorion laeve, with the decidua capsularis lateral to that.

Villi

• Villi are projections from the decidua that house branches of the uterine a/v, and contain fetal blood
• they project into the space between the decidual layers.
• maternal blood surrounds them in intervillous space
• Free gas exchange occurs between the villi and intervillous space
• 2 types of villi: anchoring villi (attached to chorion), floating villi (free floating)
• made from trophoblast cells – which makes two layers of cells – syncytiotrophoblast (outer) & cytotrophoblast (inner)
  
• Primary villus
  • 2 layers of trophoblast cells only
• Secondary villus
  • 2 layers with extra embryonic mesoderm in w/in
  • light center – look for white space in center
  • may have small a/b near the center
• Tertiary villus
  • the largest ones
  • only syncytiotrophoblast layer, much bigger, with a/v near periphery

Slide #74 Uterine Tube * H&E

Labyrinth like lumen of Uterine tube

Structures to Identify:

• simple columnar epithelium
• peg cells (right ovulation, might not be there)
• LP
• muscular layer
• a/v
• mesothelium (cells of perimetrium)
• adipocytes

Lumen: very labyrinth like – looks like a fern

• protrusion into lumens from mucosa
• amt of labyrinth depends  on location where section was taken –> less in infudibulum, more closer to uterus
• Do NOT confuse with Prostate. The folds look similar, but there are no prostatic calcifications, and there is only one lumen here, not a bunch of small fuzzy tubules
• 
• Epith and LP of Uterine Tube, with ciliated and peg cells shown

Epith

• simple columnar epithelium – do NOT say psuedo stratified
• some cells ciliated
  • these are shorter and have less cilia at times,
  • After ovulation , are taller with more cilia,
  • depending on hormones released in ovarian cycle (estrogen)
• thickness changes w/ menstrual cycle
• the non ciliated cells = peg cells
  • secrete mucin = carbs for sperm
    
  • expelled from epith when dead (die after excreting their mucin)
  • project into lumen
  • look like nails
  • look for long cells in a bump on top of epith
• During proliferative phase of uterus, with increase amount of estrogen, the cilated cells become larger and have more ciliae – peg cells secret more mucin

L.P.

• loose CT, with a/v
• numerous fibroblasts with collagen and reticular fiber
• supports the CT papilla projections into the mucosa

No Musc. mucosae or Submucosa

Muscular coat (Musc ext)

• inner ciruclar, outer longitudinal layers
• more developed closer to uterus
• has PNS ggl/nfibers – may be able to find them

Outer coat = serosa

• made of double layer of broad ligament with a/v inside
• made of mesothelial cells
• has a/v + adipocytes
  

Embrology of Uterus/Uterine Tube

• PARAMESONEPHRIC DUCTS  develop into the MAIN GENITAL DUCTS OF THE FEMALE.

• 3 parts can be recognized in each duct:

  • a cranial vertical portion that opens into the abdominal cavity

  • a horizontal part that crosses the mesonephric duct

  • a caudal vertical part that fuses with its partner from the opposite side.

• With descent of the ovary, the first 2 parts develop into the uterine tube+ the caudal parts fuse, to form the uterine canal.

• When the second part of the paramesonephric ducts moves mediocaudally, the urogenital ridges gradually come to lie in a transverse plane.

• DUCTS fuse in the midline, a broad transverse pelvic fold is established.

• BROAD LIGAMENT OF THE UTERUS: fold, which extends from the lateral sides of the fused paramesonephric ducts toward the wall of the pelvis.

• The uterine tube lies in its upper border, and the ovary lies on its post. Surface.

• UTERORECTAL POUCH+ UTEROVESICAL POUCH are devided by the uterus+ broad ligaments

• CORPUS+ CERVIX of the uterus coming from the fused paramesonephric ducts.

• MYOMETRIUM(= muscular coat of the uterus)+ Peritoneal covering(perimetrium) = layer of mesenchyme

16. Lymphatic dranaige of thoracic organs. The diaphragm. The histology of the skin. Implantation. Formation and differentiation of the trophoblast. Early phases of placentation.

16. Lymphatic dranaige of thoracic organs. The diaphragm. The histology of the skin. Implantation. Formation and differentiation of the trophoblast. Early phases of placentation.

Flash Cards:

Diaphragm 1

Anatomy: Lymphatic dranaige of thoracic organs. The diaphragm.

Lymph Drainage of Thoracic Organs:

Lung:

• superficial (subpleural) lymphatic plexus –  deep to visceral pleura, drain tissue of lung itself and visceral pleura –> bronchopulmonary l.n
• Deep lymph plexus (submucosal) – in submucosa of bronchi, and in peribronchial CT, drain structures that will go into root of lung  –> pulmonary l.n along bronchi –> broncho pulmonary l. n
• From bronchopulmonary l.n. –> sup/inf tracheobronchiol lymph nodes ( above/below bifurcation of trachea) –> R & L bronchomediastinal l.n. @ angulus venosus
• R bronchomediastinal l.n. –> R lymphatic duct
• L bronchomediastinal l.n. –> thoracic duct
• Lymph from parietal pleura –> nodes of thoracic wall ( IC, parasternal, mediastinal, phrenic l.n.), some near cupula pleura go to axillary l.n.

Lymph Drainage of heart:

• Lymph vessels in myocardium and subendocardial CT –> subepicardial lymph plexus –> coronary  groove & follow coronary a
• some will flow to inf tracheobronchial l.n. on R side

Thymus:
lymph vessels of thymus –> parasternal, brachiocephalic and tracheobronchial l.n

Posterior mediastinum:
Posterior mediastinal l.n. rec lymph from esophagus, post side of diaphragm and pericardium, middle/post IC spaces –> thoracic duct

Diaphragm:

• ant/post diaphragmatic l.n. on thoracic surface of diaphragm –> parasternal, post mediastinal, phrenic l.n
• diaphragmatic l.n. on abdominal surface of diaphragm –> ant diaphragmatic, phrenic, superior lumbar l.n
  
  • absorb peritoneal fluid
    

Thoracic Duct:

• in posterior mediastinum
• lies of ant side of T5-T12
• receives lymph from:
  • lower limbs,pelvis, abdomen, and left upper quadrant of body
  • and middle/upper IC spaces, post mediastinal structures
  • jugular, subclavian, bronchomediastinal lymph trunks
• originates from cisterna chyli in abdomen
• comes thru aortic hiatus
• empties eventually into L angulus venosus

Topography:
ant = esophagus
post = vertebral column
left = aorta
right = azygos v

Right Lymphatic duct:

• also in post mediastinum
• receives lymph from R upper quadrant of body: R half of head & thorax, and R upper limb
• empties into R angulus venosus

Diaphragm:

Parts of Diaphragm:
Central fibrous tendon – clover leaf shaped, no bony attachment
Peripheral musc fibers:

• sternal part – attach to post side of xyphoid process
• costal part – attach to inf six costal cartilages, and ribs – form R & L domes of diaphragm
• lumbar part – from med/lat arcuate ligaments, L1-3, form R & L crura

Med arch: made of the crura of diaphragm : musc/tendon bundles from ant surfaces of L1-L3, ant longitudinal ligament, IV discs

• R crus – L1-3/4,
• Lcrus – L1-2

Lat arch:

• Med arcuate lig – L1 body –> transv process of L1, rib 12, passes over psoas major and SNS trunk
• Lat arcuate lig – transverse process of L2 –> rib 12, passes over quadratus lumborum
  

Topography:

• central tendon attaches to pericardium via pericardiophrenic ligaments
  

Origin:

• xyphoid process (sternum)
• lower 6 costal cartilages and ant costal margin
• med/lat lumbosacral arches (lumbar arches)
• tip of 12th rib

Insertion:

• insert into central tendon of diaphragm
• b/w 12th rib and lumbar vert, diaphragm will attach to fascia over quadratus lumborum, psoas major

Function: major musc of inspiration/expiration

Actions:
1. Contraction = diaphram desc, causing inc thoracic volume, by inc vert diameter of thoracic cavity –> dec intrathoracic pressure –> Lungs EXPAND

2. Relaxation = diaphram asc, causing dec thoracic volume, by dec vert diameter of thoracic cavity –> inc intrathoracic pressure –> Lungs DEFLATE

Openings of Diaphragm:
A. Outside diaphragm
1. Sternocostal triangle – b/w rib cage & sternal and lumbar part of diaphragm – contains int thoracic a/v or sup epigastric a/v
2. Aortic hiatus – behind diaphragm, space b/w L and R crus  – contain Aorta, thoracic duct, gr. splanchnic n, azygos v (called asc lumbar v below diaphragm)

B. W/in Diaphragm
1. Caval hiatus – lies in central tendon, @ T8, to the R and post – contains IVC, R phrenic n, lymph vessels
2. Esophageal hiatus – T12 behind crossing of L & R crus – contains Esophagus, ant/post trunks of vagus

C. Structures that pierce diaphragm w/o specific opening

• SNS trunk
• Splanchnic n

Surface Projection of Diaphragm:
R = upper border of 5th rib @ midinguinal line – higher b/c of liver underneath it, attaches to liver via coronary ligament, R & L triangular ligament
L = lower border of 5th rib @ midinguinal line

Blood supply:

• Musculophrenic (int thoracic a)
• Pericardiophrenic (int thoracic a)
• Sup/inf phrenic (aorta)

Nerve supply:

• SM = phrenic n
• Central tendon SS = phrenic n
• Peripheral musc SS = IC n

Develops from:

• septum transversum
• pleuro-peritoneal folds
• mesoderm of adjacent bodywalls
• esophageal mesoderm

Ignore the developmental errors, just see where it develops from

Histology: The histology of the skin.

Embryology: Implantation. Formation and differentiation of the trophoblast. Early phases of placentation.

Implantation

• occurs w/in ant/post sup wall of uterus on day 7 after fertilization w/in functional layer of endometrium during secretory phase of menstrual cycle
• this is when the trophoblast splits into cytotrophoblast & syncytiotrophoblast
• the Uterine glands and arteries become coiled b/w opening of glands

Trophoblast

• Syncytiotrophoblast – outer multinucleated cells of trophoblast
  • no mitosis
  • invasion of endometrial stroma, eroding the endometrium a/v & glands
  • lacunae formed w/in – filled w/ nutrient material from maternal blood & glandular secretions – comes in via diffusion
  • NOTE Fetal and maternal blood never mix!!
  • Endometrial stromal cells = filled w/ glycogen + lipids =to feed to embryoblast
• Cytotrophoblast = inner mononucleated layer of trophoblast, mitotically active
  • makes cells that migrate to syncytiotrophoblast
  • from cells into mounds called primary villi (chorionic villi)

Placenta

• @ 3rd wk = Primary villi form = cytotrophoblastic core covered by syncytioblast
• mesodermal cells –> core of primary villi, grow toward decidua = secondary villi
  
• @ end of 3rd wk = mesodermal cells in the core –> differentiate into RBCs + small a/v = form villous capillary system = tertiary villi
• Tertiary villi – connect w/ a/v of mesoderm of chorionic plate and in connecting stalk
  • connect w/ intraembryonic circulation  = connect placenta w/ embryo
• Cytotrophoblastic cells in villi –> syncytioblast –> endoderm form a  thin outer cytotrophoblastic shells = attaches chorionic sac firmly to maternal endoderm
• Anchoring villi = villi from chorionic plate that extend to decidua basalis
• Free villi = villi that branch from anchoring villi, into intervillous spaces
• @ 24th day, embryo attached to trophoblastic shell by connecting stalk

14. The pleura and pericardium. Bone formation. Formation of the blastocyst and the bilaminar germ disc.

14. The pleura and pericardium. Bone formation. Formation of the blastocyst and the bilaminar germ disc.

Flash cards:

Pleura 1

Pleura 2 - reflections

Pericardium 1

Pericardial reflections

Anatomy:  The pleura and pericardium.

Pleura:

• serous membrane covering the Lung
• Double layer:
  • Inner visceral – covers lung itself
  • Outer parietal -covers inner surface of thoracic wall
• B/w 2 layers = Pleural cavity – 4 ml of serous fluid
• Function:
  • lubricates the 2 pleural surfaces
  • allows layers of pleura to slide smoothly over each over during respiration
  • surface tension allows lung surface to stay touching thoracic wall
  • Creates a seal b/w 2 pleural surfaces
• The two layers combine around the root of of the lung – so the root of lung has no pleural coverage, the layers combine to form the pulmonary ligament, which runs inf and attaches the root of the lung to the diaphragm
  
• CLINICAL NOTE: When parietal pleura is punctured, lungs collapse due to air rushing (air pressure higher outside than in) = pneumothorax

Pleural surfaces and recesses

Parietal Pleura – senses PAIN, lines inner surface of thoracic wall
4 parts:

1. Cupula pleura (aka cervical pleura) – part of pleura which project above clavicle
   • located w/in scalenus tent
   • strengthened by a layer of endothoracic fascia call the suprapleural membrane = Sibson’s fascia
2. Diaphragmatic pleura – faces domes of diaphragm inf
   • , also separated from diaphragm via endothoracic fascia,
   • only attached to lateral sides of diaphragm
   • as central tendon of diaphragm attaches to pericardium
3. Sternocostal pleura – attaches to rib and sternum
   • separated from ribs via a part of endothoracic facsia called phrenicopleural fascia
4. Mediastinal pleura – faces vert column and midline space b/w two areas of pleura = mediastinum

3 Pleural reflections: Lines where the surfaces of parietal pleura meet each other

• Sternal line = costal –> mediastinal (ant)
• Costal line = costal –> diaphragmatic (inf)
• Vertebral line = costal –> mediastinal (post)

* first 2 have a sharp,defined border, the last is a gradual rounded border

Nerve supply:

• IC n (sternocostal pleura, and peripheral part of diaphragmatic pleura)
• Phrenic n (central diaphragmatic pleura, and mediastinal pleura)

Blood supply = Int thoracic a, post IC, sup phrenic a, sup IC a

Visceral Pleura – sensitive to STRETCH, lines lung ext and dips into all fissures
Nerve supply = contains vasomotor fibers and sensory ending of CN X for respiratory reflexes

Blood Supply = bronchiol a, pulmonary v

Surface Projection:

1. Lat –  lat wall thorax = lat wall of pleura
2. Sup = Cupula Pleura= dome of pleura,
   • projects into neck
   • above neck of 1st rib
   • 2 cm above clavicle @ med end
   • middle 1/3 clavicle b/w midclavicular line and midline
3. Med border:
   • R – R sternoclavicular joint –> desc to lower border of R 6th rib
   • L – goes toward midline from apex, but never reaches it, follows the lung and desc down to 4th rib, runs a bit laterally and then comes back towards midline @ 6th rib, to form the pleural cardiac notch
4. Inf border
   • @ parasternal line – inf border crosses border of 6th/7th rib
   • @ midclavicular line – inf border crosses 8th rib
   • @ mid axillary line – 10th rib
   • @ paravertebral line – T12, 11th rib

Surface Projection of Pleura

Pleural recesses:
If you notice, the surface projection of pleura is larger than the surface projection of the lung itself.

In between parietal pleura, are a series of recesses:

1. Costo-mediastinal recesses – vertical in direction, costal & mediastinal pleura meet
2. Phrenico-mediastinal recess – ant-post direction, b/w mediastinal & diaphragmatic pleura
3. Costo-diaphragmatic recess – b/w costal & diaphragmatic pleura
   • largest of the 3, horseshoe shaped,
   • accumulates fluid when standing
   • potential space that allow lung to expand into them when inhaling
   • can collect sample of pleural fluid from here
   • deepest point of sinus is @ mid-ax line where space b/w lung and pleura = 12 cm, or 4 fingers

Pleural Recesses

Pericardium.
strong fibrous layer, double walled sac w/ heart w/in
originates from intraembryonic somato and splanchno pleura

Layers of Heart itself: (sup –> deep)

1. Fibrous pericardium –
   • bound to central tendon of diaphragm for deep inspiration,heart follows diaphragm, so heart is more vertical,
   • in deep expiration, heart rises due to upward movement of diaphram – heart is more horizontal
2. Serous pericardium
   • Has a parietal layer – stong dense reg CT, prevent heart from over dilating
   • Visceral layer – simple squamous epithelium (mesothelium), that lines the heart itself aka Epicardium
   • B/w 2 layers = Pericardial cavity
3. Subepicardial CT
4. Myocardium – muscular wall – striated cardiac m
5. Subendocardial CT
6. Endocardium – simple squamous epithelium (endothelium), same epith as blood vessels

Layers of Pericardium

Pericardium moves along w. movements of structures around it b/c:

• fused w/ tunica adventia of great vessesl entering/leaving heart
• attached to post surface of sternum by sternopericardial ligaments
• fused w. central tendon of diaphragm

Blood supply = mostly from pericardiophrenic a (int thoracic a) musculophrenic a (int thoracic a), bronchiol, esophageal, sup phrenic a (thoracic aorta), coronary arteries

Innervation = phrenic n (C3-C5), vagus n (CN X), SNS trunk

Reflections of pericardium: where 2 layers of pericardium meet each other

1. @ arterial end – Transverse sinus
   • where pul a and aorta leave heart,
     
   • when doing surgery on aorta or pulmonary a, can stop circulation to this area by making a stitch through this sinus,
   • reach by reaching under pulmonary trunk and ant to SVC
2. @ venous end – Oblique sinus =
   
   • where SVC,IVC pulmonary v enter heart,
     
   • reach via inserting finger under apex of heart and pushing up and right towards root of R lung

Development of Sinuses:

• Form during embryonic life due to folding of embryonic heart tube
• As heart tube folds, venous end moves posterior and up, so venous end then is up by arterial end, separated by transverse sinus
• As veins of heart grow and expand, oblique sinus is formed, a recess, a blind sac behind post side of the heart,

Development of pericardium

Histology: Bone formation.

Embryology: Formation of the blastocyst and the bilaminar germ disc.

Blastocyst

Image via Wikipedia

• fluid is secreted within the morula (16 cell) = blastocyst cavity
• now called blastocyst, and has 2 distinct cell layers
  
• inner cell mass = embryoblast –> is the future embryo
• outer cell mass = trophoblast –> will form the placenta

Bilaminar Germ Disk

Bilaminar Disc Formation:

• In the 8th day, the blastocyst has the inner cell mass & outer cell mass
• Each cell mass  differentiated into 2 different cell layers
• Trophoblast = outer cell mass – splits into:
  • Cytotrophoblast – inner layer of mononucleated cells – distinct cell barriers
  • Syncytiotrophoblast – outer layer of mutlinucleated cells – no  obvious cell boundaries
  • cells are probably created in cytotrophoblast, and then migrate into syncytiotrophoblast
• Embryoblast = inner cell mass – splits into:
  • Epiblast – layer of high columnar cells, next to amniotic cavity
  • Hypoblast – layer of small cuboidal cells, next to blastocyst cavity
  • small cavity forms in epiblast – is amniotic cavity , epiblast cells next to the cytotrophoblast = amnioblasts
  • Cells at periphery of hypoblast migrate over inner surface of cytotrophoblast – forming thin layer extraembryonic endoderm = Heuser’s membrane
  • Blastocyst cavity = is then called primitive yolk sac
• Uterus endometrium has interstitial edema (increased interstitial fluid b/w cells), and increased # of a/v