Anatomy Flashcards
Parietal layers of serous cavity are innervated by what? The visceral layer is innervated by what?
parietal - spinal innervation
visceral - autonomic nerves
when the diaphragm contracts, what happens to the thorax and abdomen?
diaphragm contracts, thorax increases in size, decreasing abdominal volume
what are the abdominal wall layers, starting with the skin and going to the peritoneum?
skin superficial fascia - Campers - Scarpas deep fascia muscles/aponeurosis transversalis fascia extraperitoneal fat peritoneum
what is scarpa’s fascia continuous with?
dartos fascia (deep to scrotal skin/fascia labia majora), superficial penile fasacia, and Colle’s fascia (perineum)
what muscles aponeurosis helps form the inguinal ligament, rectus sheath and linea alba?
external oblique
What direction do EO muscle fibers run? IO?
EO run inferior and medial; IO runs superior and medial (perpendicular to each other)
What is the lateral border of the rectus abdominis called?
semilunar line
What denotes the transition of aponeurotic layers between the umbilicus and pubis?
arcuate line
What muscles make up the anterior and posterior rectus sheath superior to the arcuate line? Inferior to the line?
superior anterior: EO and IO
superior posterior: IO and TA
inferior anterior: EO, IO, TA
inferior posterior: transversalis fascia
What muscle is responsible for posterior pelvic tilt?
rectus abdominis
If the R EO and L IO contract simultaneously, what movement is caused?
L rotation of the torso
All muscles of the abdomen do what two things?
protection above the arcuate line, and increase intra-abdominal pressure
What two arteries feed the anterolateral abd wall and go between the IO and TA?
posterior intercostal arteries (10 and 11) with subcostal artery
Superior epigastric artery is a branch from what? Where is it and what does it supply?
Terminal branch of internal thoracic artery on posterior surface of RA, supplying upper RA
Inferior epigastric artery is a branch from what? Where will it be found and what does it supply?
branch of external iliac on posterior surface of RA against transversalis fascia, within rectus sheath at arcuate line, supplying lower RA
Veins of the abdominal wall drain to what?
azygos system, internal throacic, external iliac, femoral, and great saphenous veins
What forms a communication between the axillary and femoral veins?
thoracoepigastric vein
Superficial superior lymphatics of the abdomen drain where? superficial inferior to where? deep abdomen to where?
superficial superior lymphatics to axillary lymph nodes;
superficial inferior lymphatics to superficial inguinal lymph nodes;
deep abdomen lymphatics drain to external/common iliac veins and abdominal aorta
What levels of spinal nerves innervate the abdominal muscles?
T7 to L1
What two nerves come from L1 level?
iliohypogastric nerve (to skin above pubis) and ilioinguinal nerve (skin in inguinal region)
On the interior anterior abdominal wall, what folds are there? What are they remnants of ?
median umbilical fold - remnant of urachus/allantois; goes bladder to umbilicus
medial umbilical fold - remnant of umbilical arteries
lateral umbilical fold - contains inferior epigastric artery and is used for hernia classification
ligamentum teres - remnant of umblicial vein within free edge of falciform ligament, passing from umbilicus to liver
is a direct hernia medial or lateral to the lateral umbilical fold? A direct hernia would then be considered in what area?
direct hernia is medial to lateral umbilical fold, putting the hernia in the inguinal (Hesselbach’s) triangle
Testes and ovaries develop in the ________ space and descend toward the labioscrotal swelling by the _________.
retroperitoneal; gubernaculum
the labioscrotal swelling is the precursor to what?
labia majora
as testes descend, an outpocket of peritoneum is pulled into the LS swelling called what?
processus vaginalis
after testes with their BV, nerves and connecting duct go inside the processus vaginalis, what happens?
processus vaginalis gets pinched off and becomes tunica vaginalis
how many layers does the tunica vaginalis have? What layer is missing?
has a parietal and visceral layer with a cavity in between; dorsal layer is missing, so it only covers 3/4
Within the vaginalis, the fibrous outer layer of testes is called what? What does it do?
tunica albuginea, septates testis into lobules
what is the pathway/connections after the seminiferous tubules collect sperm?
to rete testis - efferent ductile - head of epididymis confluence - body - tail - ductus deferens
Is the pathway from tubules to ductus deferens inside or outside of tunica vaginalis?
pathway is outside of tunica vaginalis
spermatic cord attaches the testis back to the abdominal wall. What is in this cord?
ductus deferens, a of dd, pampiniform venous plexus, autonomic nerves and genitofemoral n, testicular a, lymph vessels
what nerve supplies the anterior part of scrotum, or labia majora? it also supplies the TA and IO
ilioinguinal nerve (L1)
What does the inguinal canal primarily do? What ligament does it give off?
inguinal canal conducts the spermatic cord from retroperitoneal position to the scrotum; gives off lacunar ligament
What nerves innervates posterior scrotum?
perineal nerve (S2-S4)
The IO and TA arch over the inguinal canal and join together to form what?
conjoint tendon
the opening of the deep inguinal ring goes through what?
transversalis fascia
what is the iliopubic tract?
thickening of transversalis fascia that covers the inguinal ligament posteriorly
What two nerves go through the inguinal canal? What is their relationship to the spermatic cord?
ilioinguinal n (L1) goes on the surface of the spermatic cord; genitofemoral n stays inside the spermatic cord
What nerve innervates the cremaster muscle? What is the origin of the cremaster muscle?
genitofemoral n. ;
derived from the IO
What are the layers covering the spermatic cord?
external spermatic fascia (from EOA), cremaster muscle, internal spermatic fascia (transversalis fascia)
What is a way to classify hernias?
based off location in relation to inferior epigastric vessels - medial is direct, lateral is indirect
Does the spermatic cord pass medial or lateral to the inferior epigastric vessels?
lateral
the ovaries do not descend into LS swelling, instead, what happens?
gubernaculum partially gets attached to the lateral side of the uterus, stopping the descent
In female development, some of the gubernaculum continues to descend through the deep ring, canal, and superficial ring to attach to what? What is this then called?
attaches to deep surface of the labia majora; round ligament of the uterus
Women are more prone to get what kind of hernia?
direct hernia
A femoral hernia passes where?
inferior to the inguinal ligament
How does the esophagus attach to the diaphragm?
phrenico-esophageal ligaments
When the esophagus goes through the diaphragm, it is encricled by what?
muscles of the R crus of diaphragm
What are the arterial supplies for the esophagus?
small branches of thoracic aorta to thoracic region;
L gastric artery from celiac trunk to abd/thoracic regions
Blood above the diaphragm drains to wear?
azygos venous system then to superior vena cava
blood below the diaphragm drains to wear?
L gastric vein to portal venous system
The overlap of two venous systems in the esophagus is an example of what?
portal-caval anastomoses
innervation of the esophagus is by what nerve?
branches off vagus for both sensory and motor
lymphatic drainage of the abdominal portion of esophagus goes where?
to L gastric lymph nodes to celiac lymph nodes
Where is the hepatogastric ligament?
part of lesser omentum, attaches stomach to liver
What lines the interior of the stomach, arranged in thick mucosal folds, longitudinally?
gastric rugae
What layer of smooth muscle does the stomach have that the SI and LI do not have?
oblique layer of smooth muscle
The omental bursa lies where and opens to the greater sac through what?
lies posterior to stomach and opens to greater sac through epiploic foramen (of Winslow)
Where is the epiploic foramen of Winslow?
posterior to the hepatoduodenal ligament
Transverse colon is attached to greater omentum and greater curvature of stomach by what?
its mesentery - transverse mesocolon
What direct branch of the celiac artery goes to the lesser curvature of the stomach?
L gastric a
What arteries supply the fundus of the stomach? Where does this come from?
short gastric arteries from the terminal part of splenic a
What pair of arteries go to greater curvature and what are they branches from?
gastroepiploic arteries - R is terminal continuation of gastroduodenal a - L is branch of splenic artery
R gastric a is a branch of what? Where does it go and anastomose with?
branch of hepatic proper a going to lesser curvature to anastomose with L gastric a
Most all venous drainage in this region around the stomach goes to where?
portal vein
lymph drainage from the region around the stomach ends in a single large duct called what? What does this duct connect to?
cisterna chyli, connecting to thoracic duct
What two segments of duodenum are considered intraperitoneal?
first (2 cm) and fourth segments
What is the proximal part of the first segment of duodenum called?
ampulla, or duodenal cap
What is the second segment of duodenum described as? What happens here? What is this area called?
descending segment, bile duct and main pancreatic duct empty into the second part at the major duodenal papillae (of Vater)
The initial section of duodenum is anterior to what?
portal vein and IVC
second part of duodenum is where?
to the R of the IVC and anterior to the hilum of R kidney
What crosses anterior to the third duodenal segment?
SMA and SMV
arterial supply to the duodenum is from what?>
celiac trunk and SMA; inferior pancreaticoduodenal a branch of SMA
lymph from around duodenum goes where?
to nodes and channels adjacent to aorta and IVC
What suspends the junction between the duodenum and jejunum to the posterior abdominal wall?
ligament of treitz (fibromuscular)
Jejunum and ileum are suspended from the posterior abdominal wall by what?
THE mesentery
Which section of the SI has a larger diameter and more muscular wall?
jejunum
Which section of the SI has smoother internal walls?
ileum
What are peyers patches and where are they found?
groups of lymphoid follicles in the ileum
What is the arterial supply to jejunum and ileum like?
both supplied by SMA, terminal branches make arcades, perpendicular to which are vasa recta that pass to bowel
Where does venous blood drain to? What two veins converge to make this?
portal vein from SMV and splenic vein
How is the cecum attached to the posterior abdominal wall?
it is not attached, it lacks mesentery
What is attached to the inferior margin of the cecum and where is it located 2/3 of the time?
vermiform appendix, retrocecal
What converges at the distal end of the cecum?
taniae coli
Describe the position of the ascending colon .
secondarily retroperitoneal, superior to R lobe of liver, but R hepatic flexure is posterior to liver; anterior to R kidney
Liver and GB are enterior to what?
R part of transverse colon
Are the ascending and descending colon intraperitoneal or retroperitoneal?
retroperitoneal
What is the most mobile part of the large intestine?
transverse colon
The junction from transverse to descending colon is attached to the diaphragm by what?
an extension of transverse mesocolon - phrenicocolic ligament
The root of the sigmoid colon crosses what vessels and structure?
L common iliac vessels and L ureter
What are the lobules of fat attached along the colon called?
epiploic appendices
Enlargement of cicrcular muscle throughout the colon causes sacculations called what? what is between this?
haustra, with semilunar folds in between
What artery supplies the R half of the colon? L half?
SMA gets R half; IMA gets L half
What is the name of the anastomotic supply between the SMA and IMA
marginal artery of drummond
Venous drainage from the colon can go to what two main sites?
IVC or portal vein
lymph drains superiorly from what, to accumulate where, to drain ultimately to what?f
from aortic nodes to accumulate in cisterna chyli and then to thoracic duct
lymph from organs with retroperitoneal surface can drain where?
adjacent body wall
What are four functions of the liver?
- secrete bile and hormones
- synthesize serum proteins and lipids
- process products/toxins/drugs
- eliminate particles and senescent cells from blood stream
What ligament contains the portal triad?
hepatoduodenal ligament
What are the parts of the portal triad? Where are they in relationship to one another?
common bile duct on R, proper heaptic a on L, hepatic portal vein posterior
What is the coronary ligament?
reflection of peritoneum from liver to diaphragm, encircles the bare area of the liver, direct contact with the diaphragm
What is on the R and L of the coronary ligament?
triangular ligaments
What does the falciform ligament enclose?
ligamentum teres hepatis (round ligament of the liver)
What is the falciform ligament continuous with?
coronary ligament on superior surface and lesser omentum at porta hepatis
What recess is between the anterior liver and diaphragm?
supphrenic recess
What is the hepatorenal recess called? Why is this area important?
Morrison’s pouch, will show fluid accumulation on FAST exam s/p trauma
When supine, fluid from where will flow into the hepatorenal recess? What communicates with the hepatorenal recess?
omental bursa (posterior to stomach); R subphrenic recess
What recess is between the L lobe of the liver and diaphragm while below the posterior layer of coronary ligament?
superior recess of omental bursa
Vessels and ducts enter and leave the liver through what structure?
porta hepatis
What are four structures of the visceral surface of the liver leading to the porta hepatis?
fossa for GB (ant/R)
groove for IVC (posterior aspect near midline)
fissure for ligamentum teres hepatis (ant/L)
fissure for ligamentum venosum (posterior aspect)
anatomical R and L lobes of liver are separated by what? (not surgical)
falciform ligament
What is between the GB and ligamentum teres on the anterior part of the liver?
quadrate lobe
What is between the ligamentum venosum and IVC, posterior to the porta hepatis?
cuadate lobe with possible inferior projection called papillary process
How are functional/morphological lobes of the liver identified?
established by intrahepatic branching of vasculature - 8 hepatic segments
What two vessels supply blood to the liver? which has more nutrients?
portal vein (more nutrients) and hepatic artery (more oxygen)
What forms the hepatic portal vein?
SMV and splenic vein
What are four tributaries of the splenic vein?
Short gastric veins
L gastro-omental vein
pancreatic veins
IMV which drains distal part of LI
SMV runs with the mesentery of SI to ultimately terminate posterior to the neck of pancreas into what?
portal vein
What are four tributaries of the portal vein?
R and L gastric veins
posterior pancreaticoduodenal veins
cystic veins
paraumbilical veins
Portal vein ascends to the liver ________ to first part duodenum, in free margin of ________, and posterior to _________ and _________
posterior; lesser omentum; bile duct and proper hepatic artery
Common hepatic artery divides into what?
gastroduodenal a and proper hepatic a
Primary lymphatic drainage of the liver goes to what two places?
phrenic nodes near and above the diaphragm and hepatic nodes near porta hepatis
Where does the sympathetic innervation of the liver and GB come from?
T6-T9: pre-g in greater splanchnic nerves to post-g in celiac ganglion
Where does the parasympathetic innervation of the liver come from?
pre-g from vagus, post-g in ganglia within or near organ wall
What nerve provides afferent fibers related to diaphragmatic parietal peritoneum?
R phrenic nerve
What are three functions of the GB/bile?
- stores and concentrates bile
- bile emulsifies lipids and aids in digestion
- excretion pathway
What plane is the GB fossa in? Where is the fundus of the GB located?
transpyloric plane;
at the tip of the 9th costal cartilage
What does the neck of the GB have that allows it to join to the cystic duct?
spiral valves/folds
The bile duct merges with what, passing through the posterior medial wall of the second part of duodenum?
pancreatic duct
What three things make up the border of the cystohepatic triangle of Calot?
cystic duct, common hepatic duct, and liver
What is within the cystohepatic triangle?
R hepatic artery and cystic artery with possible accessory bile ducts
What is the location of the pancreas?
secondarily retroperitoneal, to the R side of L1-3, abutting the hilum of spleen
What part of the pancreas enters the splenorenal ligament?
tail
What does the pancreas produce?
exocrine and endocrine products
What is posterior to the pancreas?
aorta, renal arteries to L kidney, renal veins, IVC and portal vein
What is anterior to the pancreas?
omental bursa then stomach
What runs the entire length of the pancreas, from L to R, midway between the superior and inferior borders, nearer the posterior surface of the gland?
main pancreatic duct (of Wirsung)
Where do the bile duct and main pancreatic duct end?
major duodenal papillae
What is the dilation of the lumen of bile duct and pancreatic duct within the major duodenal papillae called?
hepatopancreatic ampulla of Vater
What encloses and constricts the ampulla, causing bile movement?
hepatopancreatic sphincter of oddi
Accessory pancreatic duct drains the anterior superior part of pancreatic head and opens onto what?
minor duodenal papillae
What is the arterial supply to the pancreas?
celiac trunk > splenic a > dorsal pancreat a and great pancreatic a
OR
celiac trunk > common hepatic a > gastroduodenal a > sup. PD arteries
OR
SMA . > inf. PD arteries
What is the venous drainage of the pancreas?
pancreas to splenic v or SMV both to portal vein
Lymphatic drainage of nodes superior to attachemnt site of transverse mesocolon go where? Inferior to attachement go where?
above go to celiac nodes and below goes to SM nodes
Where is sympathetic innervation from? parasympathetic from?
symp from greater splanchnic nerves; parasymp from vagus
Inferior pancreas receives innervation from what ganglion?
superior mesenteric ganglion
What are three functions of the spleen?
Filters blood for immune system, recycles RBCs, stores platelets and WBCs
What ribs are the spleen under?
9-11 ribs
Lower pole of the spleen contacts what ligament?
phrenicocolic ligament
What ligament contains the splenic a and v?
splenorenal ligament
Splenic a is the largest branch of what? This artery enters what ligament on the way to the hilum of the spleen?
celiac trunk, enters splenorenal ligament
Lymphatics of the spleen drain to what nodes?
celiac nodes
What is Kehr’s sign?
When spleen irritates the diaphragm, referred pain to L shoulder
What are the hilar structures of the kidney from anterior to posterior?
renal vein, renal artery, renal pelvis
renal papillae project into what? These join to form what? then those join to form what?
renal papillae into minor calyx, minor calices join to form major calices, which join to form expansive pelvis
At hilum of kindey, pelvis narrows to a tube and forms what? Where does it go?
ureter, going to the urinary bladder
What is the sympathetic innervation for renal and suprarenal areas?
T10-L1 utilize renal plexus, from lesser thoracic/splanchnic nerves, celiac ganglion, and aorticorenal ganglion
The medulla is stimulated by what, causing it to be considered what type of ganglion?
stimulated by pre-g fibers, considering it a sympathetic ganglion
Is parasympathetic innervation from the vagus nerve going to both kidneys and suprarenal glands?
no, vagus only goes to kidney, not suprarenal glands
What are the muscular boundaries of the posterior abdominal wall?
psoas (medial)
quadratus lomborum (lateral)
iliacus (inferior)
diaphragm (superior)
What two muscles in the posterior abd wall join together at their insertion point on the greater trochanter of the femur?
psoas major and iliacus
Where does the psoas minor insert?
pectineal line and iliopubic eminence
Where is quadratus lumborum located?
deep and lateral to psoas major, between rib 12 and iliac crest
What muscle depresses and stabilizes rib 12 and is a weak lateral flexor of torso?
quadratus lumborum
What muscle does the femoral nerve innervate in post. abd wall?
iliacus
The diaphragm is lower (ant/post) and is higher on the (R/L)
lower posterior and higher on the R
Contraction of the diaphragm does what?
depresses the diaphragm, increasing negative pressure in the pleural cavity
L and R crura join to form what? what passes through here?
median arcuate ligament (aortic hiatus); aorta and thoracic duct go through
What is and what is within the T8 aperature of the diaphragm?
caval foramen; IVC, terminal branch of R phrenic nerve, lymphatics
What is and what is within the T10 aperature of the diaphragm?
esophageal hiatus; esophagus, anterior and posterior vagal trunks, lymphatics, esophageal branch of L gastric artery
What is the arterial supply to the superior surface of the diaphragm?
internal thoracic artery branches: musculophrenic a and pericardiophrenic a. along with superior phrenic aa off of the aorta
What is the arterial supply to the inferior surface of the diaphragm?
inferior phrenic arteries
What is the pattern of venous drainage from the superior surface of the diaphragm?
surface> pericardiophrenic v and musculophrenic v> internal thoracic v
OR
surface> superior phrenic vein> IVC or L suprarenal
How is the diaphragm innervated?
motor- phrenic n (central rami C3-C5); sensory - phrenic n (T7-T11 and T12)
What two fascias make up transversalis fascia of the posterior abdominal wall?
thoracolumbar fascia (wrapping around muscles and getting different names) and iliac fascia
What are the three visceral unpaired branches of the abdominal aorta?
celiac trunk (T12), SMA(L1), and IMA (L3)
What are the three visceral paired branches off the abdominal aorta?
middle suprarenal arteries(L1), renal arteries (L1-L2), and gonadal arteries(L2)
What are the parietal branches off the abdominal aorta?
inferior phrenic a (paired), lumbar artery (4 pairs), median sacral a (unpaired)
What spinal level is the IVC formed at and where does it ascend?
L5, ascend to the R of the aorta, piercing the diaphragm at T8, going posterior to liver in caval groove
What veins drain to the IVC around post. abd wall?
R gondal, R suprarenal, and both renal veins
Where do lumbar veins drain to?
1 and 2 go to azygos system, 3 and 4 go to IVC
What is nutcracker syndrome?
compression of L renal vein by the SMA and AA. causes hematuria, flank pain, L testicular pain and varicocele
Where do pre-aortic lymph nodes drain?
para-aortic lymph nodes
What is the saccular dilation of the joining of L and R lymphatic trunks?
cisterna chyli
Where is the subcostal nerve from and what does it innervate?
ventral ramus of T12, to motor EO and sensory ant/lat abdominal wall
Where does the lumbar plexus form?
in psoas major muscle
What nerve pierces the psoas major muscle and goes posterior to ureter?
genitofemoral n
What nerve pierces the TA and IO anteriorly to enter the inguinal canal?
ilioinguinal n
What nerve is on the medial side of the psoas major and articulates the hip joint?
obturator nerve
What are the layers from the inside to the outside of the kidney?
fibrous capsule, perirenal fat, renal fascia, pararenal fat
Where do renal arteries arise from?
just inferior the SMA on AA
Are ureters intraperitoneal or retroperitoneal?
retroperitoneal
Do ureters cross anterior or posterior to bifurcation of common iliac a?
anterior
What are the three points along a ureter for potential sites of obstruction?
ureteropelvic junction, crossing over pelvic brim (and bifurcation), passage through wall or urinary bladder
Where is the superior suprarenal a from?
inferior phrenic a
Where does the venous drainage of suprarenal glands go?
L side goes to suprarenal vein> L renal vein
R side goes to R suprarenal vein to IVC
Where are sympathetic pre-g neurons within the spinal cord for T1-L2/3
lateral column of spinal cord
What connects the paravertebral sympathetic trunk with the prevertebral sympathetic trunk?
splanchnic nerves - all descend and all cross diaphragm (greater, lesser, and least splanchnic) to converge and forme pre-g prevertebral chain
What are the prevertebral sympathetic chain ganglia and what splanchnic nerves do they associate with?
celiac ganglion - greater splanchnic nerve
SM ganglion - lesser splanchnic nerve
IM ganglion - lumbar splanchnic nerve
aorticorenal ganglion
Splanchnic nerves are formed from what?
pre- g nerves that cross without synapsing on sympathetic trunk
What two plexi are ENS and receive pre-gs
myenteric and submucosal plexuses
Trace from the visceral receptor to segmentor part of PNS
visceral afferents goes with sympathetic nerves so -
receptor> pre vertebral> paravertebral chain > white communicating ramus> segmentor part of PNS
What kind of neurons are found in the dorsal root of spinal cord?
pseudounipolar neurons
Where do lumbar splanchnic nerves travel?
through sympathetic trunk to posterior abd wall to synapse on IM ganglion or post-g sympathetic neurons in pelvis
Where do anterior and posterior vagal trunks synapse?
on or near organs, not in ganglia, even if passing through
When the primitive gut tube forms, what two things are left out?
yolk sac and allantois
What are the two membranes that close off the primitive gut tube?
buccopharyngeal membrane and cloacal membrane
What are the cut off areas of foregut, midgut, and hindgut?
foregut - pharyngeal gut from BP membrane to respiratory diverticulum part of foregut, remainder of foregut lies caudal to pharyngeal and goes to liver bud
midgut - liver to adult TC
hindgut - from distal 1/3 TC to cloacal membrane
What artery supplies foregut, midgut, and hindgut respectively?
celiac a, SMA, IMA
endodermal lining of primitive gut tube is lined by what?
splanchnic mesoderm
What does the dorsal mesentery suspend?
caudal ends of foregut, midgut and large part of hindgut (from lower esophagus to cloacal region)
What is ventral mesentery derived from? What does it suspend
septum transversum; suspends terminal esophagus, stomach, and upper doudoenum from ventral abdominal wall
What are subdivisions of ventral mesentery?
falciform ligament and lesser omentum
Describe the development of the stomach starting in week 4
dilation of tube, then 2 rotations
- ro in transverse plane (ant becomes R side, posterior becomes L side) L side grows faster - becomes greater curvature, R side slower - becomes lesser curvature
- displaces dorsal mesentery, creating omental bursa between posterior stomach and post abd wall
- also causes formation of greater omentum and fusion with transverse mesocolon
- causes ventral mesentery to go R, causing lesser omentum to go from stomach/duodenum to liver - ro in frontal plane (pyloric part moves superior and R, cardiac part moves inf and L)
How is the duodenum formed? Arteries involved?
duodenum gets both celiac and SMA arteries
as stomach rotates, duodenum forms C shaped loop and rotates R, goes retroperitoneal except for duodenal bulb, initial segment
Hepatic diverticulum formation at level of duodenum during third week is induced by what?
cardiac mesoderm
What does the hepatic diverticulum make?
GB, liver, biliary duct system
What is the septum transversum?
site where vitelline veins form sinusoids, Kupffer cells, connective tissue of liver develop
How is the bile duct formed?
hepatic cells penetrate septum transversum, connection between duodenum and hepatic diverticulum narrows, becoming bile duct (ventral outgrowth is cystic duct and GB)
What direction does the bile duct enter the duodenum?
initially is anterior, but with rotation, is posterior
The ventral bud of the pancreas makes up what part of the mature pancreas?
lower part of head of pancreas and uncinate process
How and when is the spleen formed?
in the fifth week, a block of mesenchyme develops, dorsall mesentery gets pushed against posterior abdominal wall and degenerates, allowing spleen attachment to posterior body wall (intraperitoneal)
How is the Primary intestinal loop formed and what makes it up?
- suspended dorsally by mesentery and anteriorly communicating with yolk sac via vitelline duct
- SMA and vitelline duct act as axis, midgut forms primary intestinal loop (PIL) with a cephalic and caudal limb
- cephalic limb is distal duodenum, jejunum, and prox ileum
- caudal limb is distal ileum, cecum, appendix, AC and 2/3 TC
How does the PIL rotate and displace?
in 6th week, midgut undergoes physiological herniation, entering the extraembryonic cavity in the umbilical cord - during which - 90 degree rotation occurs, counterclockwise
- limbs of PIL elongate and cephalic involves coiling
- by week 10, it returns to abdominal cavity with another 180 degrees of rotation counterclockwise
What is the cavity lined by endoderm and ventrally covered by ectoderm?
cloaca
How is the anorectal canal and the urogenital sinus formed?
hingut enters the cloaca posteriorly to make anorectal canal
allantois enters the cloaca anteriorly to make urogenital sinus
the urorectal septum of mesoderm separates
end of week 7 cloacal membrane ruptures making 2 openings.
ectoderm closes anal canal but is recanalized in week 9
