Part II. Anatomy Of Midgut/hindgut Derivatives Pg 60-72 Flashcards
Where does the jejunum begin?
Begins at at duodenojejunal flexure (left side of L2 vertebra)
Is the jejunum and ileum retroperitoneal or intraperitoneal?
Intraperitoneal because they are suspended by mesentary
Where does the ilium end?
Ends at ileocecal junction
The jejunum is located primarily in what abdominal quadrant?
Upper left
The ileum is located primarily in what abdominal quadrant?
Lower right abdomen and some pelvis
What is the primary function of the ileum and jejunum?
absorption of foodstuffs (large surface area present)
Fold of peritoneum attaching jejunum/ileum to posterior abdominal wall
Mesentary
The mesentary extends from what two landmarks on the small intestine?
Extends obliquely and inferiorly from duodenojejunal junction to ileocecal junction
What is located between the two layers of mesentary?
BVs, nerves, lymph nodes and fat
The superior mesenteric artery (SMA) branches from Abdominal Aorta at what vertebral level?
L1, between the 2 layers of mesentery
The 15-18 arteries branching from left side of Superior Mesenteric Artery that unite to form arterial arcades and supply the jejunum and ileum?
Jejunum and ileal arteries
The short, straight vessels that pass from the arterial arcades to the jejunal and ileal wall?
Vasa recta
Which arterial arcades are longer and fewer in number?
Jejunal arcades
Which arterial arcades are shorter and greater in number?
Ileal arcades
Venous drainage for the jejunum and ileum is via what?
Superior mesenteric vein
Where in relation to the superior mesenteric artery is the superior mesenteric vein usually found?
Anterior and right of the superior mesenteric artery
The superior mesenteric vein usually merges with what other vein to drain to the hepatic portal vein?
Splenic vein
The primary nodes for lymphatic drainage of the jejunum and ileum?
Mesenteric nodes
The secondary nodes for lymphatic drainage of the jejunum and ileum?
Superior mesenteric nodes
Lymphatic drainage of the jejunum, ileum, appendix, cecum and colon ultimately goes to the thoracic duct via what?
Chyle cistern
The jejunum and ileum are innervated by what plexus?
Perivascular plexus
Sympathetic innervation to the jejunum and ileum is via what nerve and which spinal nerve levels contribute?
Greater and Lesser Splanchnic N (T8-T10)
Preganglionic sympathetic neurons that supply the jejunum and ileum will synapse where?
Celiac and Superior Mesenteric ganglia
Sympathetic innervation to the jejunum and ileum will stimulate what?
reduce motility and secretion, vasoconstriction
Parasympathetic innervation to the ileum and jejunum is via what?
Vagal trunks
The preganglionic parasympathetic fibers that supply the jejunum and ileum will synapse where?
myenteric and submucosal plexuses
Parasympathetic innervation to the jejunum and ileum with stimulate what?
increase motility and secretion, vasodilation occurs secondarily
Visceral afferents from the jejunum, ileum will accompany sympathetics and refer pain to what dermatomes?
T8-T10
What are the functions of the large intestines?
- Responsible for completing absorption (primarily water)
- Compacts and temporarily stores indigestable materials as feces
What are the general regions of the large intestines?
- Cecum (with appendix)
- Ascending, Transverse, Descending and Sigmoid colon
- Rectum
- Anal canal
What are the 3 longitudinal strips of smooth muscle in outer layer of muscularis externa of the large intestines?
Tenia coli
The presence of the tenia coli on the large intestines causes sacculation in the wall of the colon between the tenia coli. What are these sacculations called?
Haustra
What are the small fatty projections on the outside of the large intestine?
Epiploic appendages
The cecum is located in which abdominal quadrant?
Right lower
The blind pouch at inferior portion of ascending colon that can become distended by gas or feces?
Cecum
Is the cecum intraperitoneal or retroperitoneal?
Intraperitoneal although it has no mesentary and is therefore fairly mobile
What prevents reflux from cecum to ileum?
Ileocecal valve
The blind intestinal diverticulum at posteromedial aspect of cecum?
Appendix
The appendix used to be considered vestigial but now is know to contain a large amount of what kind of tissue?
mucosal GALT, a type of lymphatic tissue of the gut
The short triangular mesentary that spans between the cecum and proximal appendix?
Mesoappendix
What is the arterial supply to the cecum?
Ileocolic artery which is a terminal branch of superior mesenteric artery
What is the arterial supply to the appendix?
Appendicular artery which is a branch of ileocolic artery (off superior mesenteric artery)
What is the path of venous drainage from the cecum and appendix?
Ileocolic vein -> superior mesenteric vein -> hepatic portal vein
The primary nodes for lymphatic drainage of the cecum and appendix?
Ileocolic nodes
Secondary nodes for lymphatic drainage of the cecum and appendix?
Superior mesenteric nodes
Sympathetic innervation to the cecum, appendix and ascending colon is via what nerve and what spinal nerve levels contribute?
Lesser Splanchnic N (T10)
The preganglionic sympathetic neurons that supply the cecum, appendix and ascending colon will synapse where?
Superior mesenteric ganglion
Parasympathetic innervation to the cecum, appendix and ascending colon is via what?
Vagal trunk
The preganglionic parasympathetic neurons that supply the cecum, appendix and ascending colon will synapse where?
Myenteric and submucosal plexus
Visceral afferents from the cecum, appendix and ascending colon will accompany sympathetics to what dermatome?
T10 dermatome (level of umbilicus)
The leftward bend of the ascending colon at the liver?
R Colic (hepatic) Flexure - where the transition to transverse colon occurs
Is the ascending colon intraperitoneal or retroperitoneal?
Retroperitoneal and lies on the right side of the posterior abdominal wall with the right paracolic gutter present laterally
The anterior surface of the ascending colon is covered by what?
Parietal peritoneum
What are the three arteries that contribute blood supply to the ascending colon?
- right colic artery off of the ride side of the superior mesenteric artery
- marginal artery which parallels inner aspect of the entire colon
- ileocolic artery which is a terminal branch of the superior mesenteric artery
What is the path of venous drainage from the ascending colon?
Ileocolic vein and Right colic vein -> superior mesentary vein -> hepatic portal vein
Primary nodes for lymphatic drainage of the ascending colon?
Paracolic, ileocolic and right colic nodes
Secondary nodes for lymphatic drainage of the ascending colon?
superior mesenteric nodes
The transverse colon is the largest and most mobile portion of the large intestine that crosses abdomen from what landmark on the right to what landmark of the left?
from R Colic Flexure (hepatic) to L Colic Flexure (splenic)
What suspends the transverse colon?
Transverse mesocolon
The transverse colon is suspended and usually hangs at the level of what?
Umbilicus
Arterial supply to the transverse colon
Meddle colic artery which is a branch of the superior mesenteric artery
The middle colic artery, which supplies the transverse colon pass through what structure where it divides into right and left branches.
Transverse mesocolon
The left and right branches of the middle colic artery contribute to the formation of what artery around the inner edge of the transverse colon?
Marginal artery
What is the path of venous drainage of the transverse colon?
Middle colic vein -> superior mesenteric vein -> hepatic portal vein
Primary nodes for lymphatic drainage of the transverse colon?
Middle colic nodes
Secondary nodes for lymphatic drainage of the transverse colon?
Superior mesenteric nodes
Sympathetic innervation to the transverse colon is via what nerve and what spinal level contributes?
Lesser splanchnic N (T11) and superior mesenteric plexus
Parasympathetic innervation to the transverse colon is via what?
Vagal Trunks and superior mesenteric plexus
Is the descending colon retroperitoneal or intraperitoneal?
Retroperitoneal (i.e., parietal peritoneum only anteriorly, adventitia posteriorly) with left paracolic gutter present laterally
The descending colon extends from where to where?
from L Colic Flexure to left iliac fossa where it transitions to sigmoid colon
S-shaped segment of the colon that connects the descending colon to the rectum?
Sigmoid colon
Where do the tenia coli stop?
At the end of the sigmoid colon about 15cm from anus
Is the sigmoid colon retroperitoneal or intraperitoneal?
Intraperitoneal and usually has long mesentary
Arterial supply to the descending colon and sigmoid colon?
- Left colic artery (branch of inferior mesenteric artery
- marginal artery creates an anastomoses between middle colic artery and left colic artery (branches of superior and inferior mesenteric arteries, respectively)
- sigmoidal arteries which are 2-4 branches from the inferior mesenteric artery
What is the path of venous drainage fro descending and sigmoid colon?
Inferior mesenteric vein -> splenic vein -> hepatic portal vein
Primary nodes for lymphatic drainage of the descending and sigmoid colon?
Paracolic or left colic nodes
Secondary nodes for lymphatic drainage of the descending and sigmoid colon?
Inferior and superior mesenteric nodes
Sympathetic innervation to the descending and sigmoid colon is via what nerve? What spinal cord levels contribute?
Least and Lumbar Splanchnic N (T12-L3)
Preganglionic sympathetic neurons that supply the descending and sigmoid colon will synapse on which ganglia?
Least splanchnic nerve synapses on Superior Mesenteric and lumbar splanchnic nerve synapses on Inferior Mesenteric ganglia
Parasympathetic innervation to the descending and sigmoid colon is via what nerve
Pelvic Splanchnic N (S2-S4) - Pass through Inferior Hypogastric Plexus
The artery to the midgut is what?
Superior mesenteric artery
There are 5 main branches from superior mesenteric artery. What are they and what do they supply?
- Inferior Pancreaticoduodenal A – pancreas and duodenum
- Jejunal/Ileal A – jejunum and ileum
- Middle Colic A – transverse colon
- R Colic A – ascending colon
- Ileocolic A – distal ileum and cecum
The middle colic artery (off of superior mesenteric artery) gives off a branch that will anastomose and connect to the left colic artery. What is this branch?
Marginal artery
The ileocolic artery (a branch off superior mesenteric artery) gives off a branch that supplies the appendix. What is that branch?
Appendicular A
The vascular structures that form a loop to connect two jejunal arteries is called?
Jejunal arcades
The vascular structures that form a loop to connect two ileal arteries is called?
Ileal arcades
The straight vessels that branch off of jejunal arcades?
Jejunal vasa recta
The straight vessels that branch off of ileal arcades?
Ileal vasa recta
The inferior mesenteric artery has 3 main branches. What are they and what do they supply?
- L Colic A – descending colon
- Sigmoid A – sigmoid colon
- Superior Rectal A – terminal branch to superior portion of rectum
Are the kidneys retroperitoneal or intraperitoneal?
Retroperitoneal
What vertebral level on the posterior abdominal wall are the kidneys found?
T12-L3 (in supine)
Which kidney is displaced slightly lower and why?
The right is displaced lower by the liver
What structures associate with the right kidney?
Liver, duodenum, ascending colon
What structures associate with the left kidney?
Stomach, spleen, pancreas, descending colon
There are three nerves that pass posterior to the kidney. What are they?
Subcostal N, Iliohypogastric N and Ilioinguinal N
What are the main functions of the kidneys?
- Remove salts and metabolic wastes from blood while preserving nutrients
- Maintain appropriate water balances in body
- Secrete substances into blood that regulate blood pressure and erythropoiesis
Urine that is produced in the kidneys pass through ______ to the urinary bladder.
Ureter
The kidneys are surrounded by what kind of tissue that is located INSIDE the renal fascia?
Perirenal fat
What gland sits superomedially to each kidney in the perirenal fat?
Suprarenal gland
What is the function of the Suprarenal gland?
Produce corticosteroids, androgens, epinephrine and norepinephrine
The kidneys are surrounded by what kind of tissue that is located OUTSIDE the renal fascia?
Pararenal fat
What is the purpose of the perirenal and pararenal fat surrounding the kidneys?
Hold the kidneys in place and cushion them
What is the vertical, concave cleft on the medial surface of the kidney?
Hilum
The hilum of the kidney is the point of passage for what?
Renal artery and vein
Nerves
Lymphatics
Ureter
What is the anterior to posterior order of structures inside the renal hilum?
Renal vein -> renal artery -> ureter
What is the fat filled space within the kidneys that houses the renal pelvis and calicoes?
Renal sinus
What is the flattened, funnel-shaped origin of the ureter called?
Renal pelvis
The renal pelvis collects urine from _______ directly and _______ indirectly.
Major calyces : minor calyces
Arterial supply to the kidney is via what?
Renal artery which is a branch of the abdominal aorta
The renal artery branches from the abdominal aorta at approximately what vertebral level?
L1-L2 IVD
Which renal artery is longer, right or left?
Right because it branches off of the abdominal aorta which is on the left side of the abdomen
Which renal artery passes posterior to the IVC, right or left?
right
At the renal hilum, the renal artery will divide into what?
Anterior and posterior rami
The anterior ramus of the renal artery will further divide into what?
Anterior, superior and inferior segmental arteries
The posterior ramus of the renal artery will further divide into what?
Posterior and inferior segmental arteries
Do the segmental arteries of the kidneys anastomose or are they end arteries?
End arteries which means that obstruction leads to cessation of function and death of segment
The left renal vein receives what tributaries?
- left inferior phrenic vein
- left suprarenal vein
- left gonadal vein (testicular vein in males, ovarian vein in females)
NOTE: the right renal vein does not receive the corresponding tributaries due to the presence of the IVC on the right
The inferior vena cava receives what tributaries around the area of the right kidney?
- right inferior phrenic vein
- right suprarenal vein
- right gonadal vein (testicular vein in males, ovarian vein in females)
Are the venous tributaries from the kidneys to the renal vein segmentally restricted like the segmental arteries of the kidneys?
No
Where do the renal arteries drain to?
IVC
Primary lymphatic drainage from the kidneys is via what?
Lumbar lymph nodes
Efferent lymphatic drainage of the kidneys is ultimately through what?
Thoracic duct
Sympathetic innervation of the kidneys is via the renal plexus which is supplied by what nerves?
Lesser and least splanchnic nerves
The presynaptic sympathetic fibers that supply the kidneys will synapse on what ganglion?
Aorticorenal ganglion
What is the effect of sympathetic stimulation to the kidneys?
Vasoconstriction (which leads to lower urine output)
Parasympathetic innervation to the kidney is via the renal plexus and supplied by what?
Posterior vagal trunk
Parasympathetic stimulation of the kidneys produces what?
Vasodilation (which leads to higher urine output)
visceral afferent pain from the kidneys refers through the sympathetics to what cord segment dermatomes?
T10-T12, usually as back pain
The muscular duct spanning from the kidney to urinary bladder
Ureter
Is the ureter intraperitoneal or retroperitoneal?
Retroperitoneal
The ureter has 3 points of constricted. Where are they?
- Junction between renal pelvis and ureter
- Point where ureter crosses brim of pelvic inlet
- Point where ureter passes through wall of urinary bladder
What is the arterial supply to the abdominal part of the ureter?
Renal artery
Gonadal artery
Abdominal aorta
What is the venous drainage of abdominal part of ureter?
Renal vein
Gonadal vein
Primary nodes for the lymphatic drainage of abdominal part of ureter
Lumbar or common iliac lymph nodes
Efferent lymphatic drainage of the abdominal part of ureter is ultimately to where?
Thoracic duct
Sympathetic innervation to the abdominal part of the ureter is from what spinal levels? Via what plexi?
T11-L2 via renal, aortic and hypogastric plexuses
Sympathetic innervation to het abdominal part of the ureter has what effect?
Leads to increased peristaltic activity
Where is the suprarenal (adrenal) gland located?
Between the superomedial kidney and thoracic diaphragm. It is enclosed in perirenal fat but in a separate fascial compartment from the kidney
What shape is the right suprarenal gland?
Triangular or pyramidal shape
The right suprarenal gland contacts what 4 structures?
Right kidney
Thoracic diaphragm
IVC
Liver
What shape is the left suprarenal gland?
Crescent or semilunar in shape
What 5 structures does the left suprarenal gland contact?
Left kidney Thoracic diaphragm spleen stomach Pancreas
From right to left, what structures are located between the 2 Suprarenal glands?
IVC -> R Crus of Thoracic Diaphragm -> Celiac Ganglion -> Celiac Trunk -> Superior Mesenteric A -> L Crus of Thoracic Diaphragm
What does the suprarenal cortex secrete?
Corticosteroids and androgens
Embryologically, what is the suprarenal cortex derived from?
Mesoderm
Embryologically, suprarenal medulla is derived form what?
Neural crest (i.e. ectoderm)
What does the suprarenal medulla secrete?
Epinephrine and norepinephrine
The secretions of the suprarenal medulla activate sympathetic activities such as:
- Increases heart rate and blood pressure
- Dilates bronchioles
- Increases blood flow to brain and skeletal muscle
Secretion from the suprarenal medulla is regulated by sympathetic innervation where presynaptic neurons will synapse on _________.
Medullary cells
What is the arterial supply to the suprarenal glands?
- Superior Suprarenal A branching from Inferior Phrenic A
- Middle Suprarenal A branching from Abdominal Aorta
- Inferior Suprarenal A branching from Renal A
NOTE: These branch to produce up to 50 or more arteries which enter gland
What is the path of venous drainage from the right suprarenal gland?
Right suprarenal vein -> IVC
What is the path of venous drainage from the left suprarenal gland?
Left suprarenal vein -> left renal vein
Efferent lymphatic drainage from the suprarenal glands is to what nodes?
lumbar lymph nodes and then to Thoracic Duct
Sympathetic innervation of suprarenal glands is via what?
Lesser and Least Splanchnic N and Celiac Plexus
What is the effect of sympathetic stimulation to the suprarenal glands?
Increase epinephrine secretion
Parasympathetic innervation of the suprarenal glands is via what?
Posterior vagal trunk and celiac plexus
What is the effect of parasympathetic stimulation to the suprarenal glands?
Action is unknown
The primary muscle of inspiration?
Thoracic diaphragm
What happens when the thoracic diaphragm contacts?
It descends to increase the volume of the pulmonary cavities
What structure attaches the parietal pericardium to the central part of the diaphragm?
Pericardiophrenic ligament
The muscle fibers of the thoracic diaphragm converge radially on what structure?
Central tendon
The opening for what passes through the central tendon of the thoracic diaphragm?
IVC
The muscular region of the diaphragm has 3 parts:
Sternal part
Costal part
Lumbar part
The sternal part of the diaphragm is attached where?
2 slips of muscle attaching to posterior aspect of xiphoid process
NOTE: Not always present or obvious
The costal part of the diaphragm is attached where?
Wide muscular slips attaching to internal surfaces of inferior 6 costal cartilages - forms left/right domes of diaphragm
The lumbar part of the diaphragm is attached where?
Muscular crura that ascend to central tendon from 3 upper lumbar vertebrae
Where does the crura of the thoracic diaphragm arise from?
- Anterior surface of superior lumbar vertebral bodies and associated IVDs
- Anterior Longitudinal L
Where does the right crus of the diaphragm arise from?
from L1-L3 or L4 vertebrae
The fibers of the right crus of the diaphragm pass _______ (right/left) of the aortic hiatus.
Right
The fibers of the left crus of the diaphragm pass _______ (right/left) of the aortic hiatus.
Left
Where does the left crus of the diaphragm arise from?
from L1-L2 or L3 vertebrae
The fibers of the right crus encircle what landmark?
Esophageal hiatus
The thoracic diaphragm has 3 arcuate ligaments. What are they?
- median arcuate ligament
- medial arcuate ligament
- lateral arcuate ligament
What ligament arches over anterior aspect of abdominal aorta at aortic hiatus and unites R/L crura at aortic hiatus?
Median arcuate ligament
What is the thickened fascia superior to Psoas Major Muscle that spans from L1 vertebral body to L1 transverse process and blends with ipsilateral crus?
Medial arcuate ligament
What is the thickened fascia superior to Quadratus Lumborum Muscle that spans from L1 transverse process to 12th rib?
Lateral arcuate ligament
What is the caval opening?
The opening in the central tendon of the thoracic diaphragm for IVC and right phrenic nerve and lymphatics
Where (vertebral level) is the caval opening located?
right of median plane (level with T8/T9 IVD)
How does the caval opening in the thoracic diaphragm affect venous return?
Diaphragm contraction widens the lumen of the IVC and facilitates venous return
What is the vertebral level of the esophageal hiatus?
T10
What is the oval opening in the right crus of the diaphragm?
Esophageal hiatus
What passes through the esophageal hiatus?
- Esophagus
- Anterior/Posterior Vagal Trunks
- Esophageal Branch of L Gastric A
What attaches the esophagus to the diaphragm?
Phrenicoesophageal ligament
What is the function of the lower esophageal sphincter?
Diaphragm contraction causes constriction as esophagus passes Right Crus to seal off thoracic and abdominal cavities
Where is the aortic hiatus located?
posterior to diaphragm (level with T12) between R/L crura and posterior to Median Arcuate L
NOTE: this means that aortic blood flow is unaffected by diaphragm contraction
What structure pass through the aortic hiatus?
- aorta
- thoracic duct
- azygos/hemazygos vein
What passes through the sternocostal foramen in the diaphragm?
Superior epigastric artery and vein
When the diaphragm contracts and increases volume of the thoracic cavity while decreasing the volume of the abdominal cavity what happens to the intrathoracic and intraobdominal pressure?
- Intrathoracic pressure decreases
- intraabdominal pressure increases
The diaphragm is most superior in location when in what body position?
Supine
The diaphragm is most inferior in location when in what body position?
Sitting or standing
What is the arterial supply to the superior surface of the thoracic diaphragm?
- Pericardiacophrenic A centrally from Internal Thoracic A
- Musculophrenic A anteriorly from Internal Thoracic A
- Superior Phrenic A posteriorly from Thoracic Aorta
What is the arterial supply to the inferior surface of the thoracic diaphragm?
- Inferior Phrenic A from Abdominal Aorta (Branch just superior to celiac trunk or may arise from it)
NOTE : this is the Primary blood supply to diaphragm
What is the venous drainage from the superior surface of the thoracic diaphragm?
- Pericardiacophrenic V and Musculophrenic V drain to Internal Thoracic V
- Superior Phrenic V drains to IVC
- Some posterior venous drainage is to azygos system of veins
What is the venous drainage from the inferior surface of the thoracic diaphragm?
Inferior Phrenic V
- On right side usually drains to IVC
- On left side usually drains to L Suprarenal V
NOTE: Inferior venous drainage is primary for diaphragm
What are the primary nodes for lymphatic drainage form the thoracic diaphragm?
Anterior and posterior diaphragmatic nodes
What are the secondary nodes for lymphatic drainage from the thoracic diaphragm?
Parasternal and posterior mediastinal notes
Efferent lymphatic drainage from the thoracic diaphragm ultimately continues to where?
Thoracic duct
Motor innervation of the thoracic diaphragm is from what?
Phrenic N (C3-C5 ventral rami)
Phat is the path of the phrenic nerve through the thoracic cavity?
Passes between parietal pericardium and mediastinal pleura as it descends to the diaphragm
Central sensory innervation (pain/proprioception) for the diaphragm is via what nerve?
Phrenic
Where is the referred pain from diaphragmatic pleura or diaphragmatic peritoneum?
base of neck and shoulder region via C3-C5
Peripheral sensory innervation to the thoracic diaphragm is via what nerves?
Intercostal Ns (T5-T11) and Subcostal N
Referred pain from peripheral regions of the diaphragm will go to what dermatomes?
Overlying dermatomes of intercostal nerves (T5-T11) and subcostal nerve (T12)