Abdomen Flashcards
what are the 9 regions of the abdomen?
1) right hypochondriac
2) epigastric
3) left hypochondriac
4) right lumbar
5) umbilical
6) left lumbar
7) right inguinal
8) hypogastric
9) left inguinal
what are the layers of the abdominal wall?
1) skin
2) superficial fascia
3) investing fascia
4) external oblique
5) internal oblique
6) transversus abdominis
7) transversalis fascia
8) extraperitoneal fat
9) parietal peritoneum
rectus sheath
- layer of fascia that envelopes the rectus abdominis muscle
- internal oblique, external oblique and transversus abdominis become aponeurotic anteriorly (flat sheet of tendon-like material that anchors a muscle)
Arterial supply of anterior abdominal wall
superior epigastric artery and inferior epigastric artery
superior epigastric artery
- a terminal branch of the internal thoracic artery
- enters rectus sheath posteriorly and anastomoses with inferior epigastric artery
the inferior epigastric artery arises from where?
- branch of external iliac artery
superficial lymphatic drainage of the anterior abdominal wall
- drains to axillary nodes from above umbilicus
- drains to superficial inguinal nodes from below umbilicus
deep lymphatic drainage of the anterior abdominal wall
- drains to external iliac, common iliac and lumbar nodes
what are the 2 ends of the inguinal canal?
superficial inguinal ring and deep inguinal ring
superficial inguinal ring
- opening into external oblique aponeurosis
- lies superior to pubic tubercle
deep inguinal ring
- invagination of transversalis fascia
- lies superior to midpoint of inguinal ligament
main structure in inguinal canal in females
round ligament of uterus
main structure in inguinal canal in males
spermatic cord
ilioinguinal nerve
passes through canal exiting through superficial inguinal ring
- in females, innervates skin of upper labia majora and mons pubis
- in males, innervates upper scrotum and root of penis
- innervates adjacent upper thigh
psoas major
- long cylindrical muscle
- origin: lumbar vertebrae
- insertion: merges with iliacus to form iliopsoas (attaching to lesser trochanter of femur)
superior portion of the posterior abdominal wall
- muscular extensions of diaphragm (right and left crus) insert into lumbar vertebrae
- larger right crus originates from bodies of L1-3
- smaller left crus originates from bodies of L1-2
Quadratus lumbordum
- thin, flat muscle
- origin: iliac crest and lumbar vertebrae
- insertion: rib 12
lumbar plexus
- network of nerve fibres that supply skin and musculature of the lower limb
- formed in psoas major muscle from the ventral rami of the lumbar spinal nerves 1-4
branches of the lumbar plexus emerge from the psoas major and further divide into which nerves?
1) iliohypogastric nerve
2) ilioinguinal nerve
3) genitofemoral nerve
4) lateral femoral cutaneous nerve
5) femoral nerve
6) obturator nerve
7) lumbosacral trunk
iliohypogastric nerve
- spinal nerve L1
- supplies skin and muscles of lower anterior abdominal wall
ilioinguinal nerve
- spinal nerve L1
- runs through inguinal canal, exits at superficial inguinal ring supplying upper medial thigh, root of penis, anterior scrotum/mons pubis and labium majus
genitofemoral nerve
- spinal nerve L1&2
- divides into 2 branches:
- genital branch enters inguinal canal
- femoral branch supplies skin on upper anterior thigh
lateral femoral cutaneous nerve
- spinal nerves L2&3
- supplies skin of anterolateral thigh
femoral nerve
- spinal nerve L2-4
- supplies muscles of anterior compartment of thigh, hip, knee joints and skin of anterior thigh
obturator nerve
- spinal nerves L2-4
- supplies muscles of medial compartment of thigh, hip, knee and skin of medial thigh
lumbosacral trunk
- part of L4 joins with L5
- joins S1-4 ventral rami to form sacral plexus
sympathetic autonomic nerves of the abdomen
lumbar sympathetic trunk runs down the posterior abdominal wall lateral to the vertebral column
parasympathetic autonomic nerves of the abdomen
- branches of the left and right vagus nerves (vagal trunks) carry parasympathetic fibres to the aortic plexus
- spinal nerves S2-4 (pelvic splanchnic nerves) carry parasympathetic fibres to superior hypogastric plexus
what is a nerve plexus
a network of intersecting nerves
how many autonomic plexuses are there in the body?
5 (we only cover 2)
aortic (prevertebral) plexus
- prevertebral ganglia are associated with aortic plexus (celiac, superior mesenteric, inferior mesenteric, aorticorenal ganglia)
- aortic plexus innervates organs of abdomen
superior hypogastric plexus
- aortic plexus continues inferiorly until it reaches bifurcation of descending aorta, here nerve fibres form superior hypogastric plexus
- innervates organs of pelvis
abdominal aorta
- called abdominal aorta after passing through aortic hiatus at T12
- bifurcates at L4/5 into left and right common iliac arteries
- largest and thickest blood vessel
left and right common iliac arteries
bifurcate into external and internal iliac arteries
IVC
- formed by union of R & L common iliac veins at L5
- ascends through caval opening of diaphragm to return blood to heart
unpaired visceral branches
celiac artery, SMA and IMA
celiac artery
- forms at level of T12
- supplies foregut structures (distal esophagus to proximal duodenum, pancreas, liver, gallbladder)
what are the 3 branches of the celiac artery?
left gastric, common hepatic and splenic arteries
superior mesenteric artery
- forms at level of L1
- supplies midgut structures (distal duodenum to proximal 1/2 of transverse colon)
what are the branches of the SMA?
inferior pancreatic duodenal artery, jejunal and ileal arteries, middle and right colic arteries
inferior mesenteric artery
- forms at vertebral level L3
- supplies hindgut structures (distal 1/3 of transverse colon to rectum)
what are the 3 branches of the IMA?
left colic artery, sigmoidal artery and superior rectal (hemorrhoidal) artery
lateral paired visceral branches
suprarenal arteries, renal arteries and gonadal arteries
at what level do the suprarenal arteries form?
R & L formed at L1
at what level do the renal arteries form?
R & L formed between L1 and L2
at what level do the gonadal arteries form?
R & L (testicular/ovarian) arteries formed at L2
posterior parietal branches
- supply musculoskeletal structures of posterior abdominal wall
- R and L inferior phrenic arteries
- lumbar arteries
R and L inferior phrenic arteries
- arise just below aortic hiatus near beginning of abdominal aorta
- supply inferior surface of diaphragm
lumbar arteries
- 4 pairs run in series with intercostal arteries
- supply posterior abdominal wall
parietal peritoneum
- lines inferior surface of diaphragm, abdominal and pelvic walls
- forms roof over pelvic viscera
visceral peritoneum
- covers organs so their visceral surfaces are in contact with each other or with parietal peritoneum
- serous fluid between the peritoneal surfaces allows free movement
the peritoneum forms a sac that encloses the peritoneal cavity - what is the difference in females
females have an incomplete closure of the cavity due to communication with exterior by opening of fallopian tubes
- can lead to spread of infection from external environment to peritoneal cavity via vagina (ex. yeast infections)
peritoneal folds
- 2 structures formed by tissues of peritoneum (omenta and mesenteries)
- double folds of peritoneum suspend abdominal organs from abdominal walls or each other
omenta
- large double folds of peritoneum
- greater omenta hangs below the stomach
- lesser omenta lies between the stomach and liver
- helps cushion intestines, act as protective barrier for infection and trauma of underlying organs
mesenteries
- double folds of peritoneum that anchors abdominal organs to posterior abdominal wall
pre-aortic lymph nodes
- anterior surface of aorta
- close to major unpaired branches of aorta
- drains foregut, midgut and hindgut
para-aortic lymph nodes
- along length of aorta
- drains posterior abdominal wall, kidneys, suprarenal glands, ureters, gonads (ovaries and testes), uterus and uterine tubes
intraperitoneal organs
- almost completely covered by peritoneum
- these organs require mobility
- anchored to posterior wall by mesentery
retroperitoneal organs
- found behind peritoneum
- only covered anteriorly
- ex. kidneys
peritoneal cavity
- space between parietal and visceral layers of peritoneum
- analogous to pericardial and pleural spaces of heart and lungs
lesser sac (omental bursa)
lies behind stomach extending upward to diaphragm (superior recess), downward between layers of greater omentum (inferior recess) and as far as spleen to right where it communicates with greater sac through epiploic (omental) foramen (of Winslow)
Greater sac
extends from diaphragm to pelvis
innervation of parietal peritoneum
innervated by network of nerves including the phrenic nerves, lower intercostal nerves and others
innervation of the visceral peritoneum
supplied by visceral sensory nerves that accompany autonomic nerves
where does well localized, sensitive pain originate from?
parietal peritoneum – more sensitive to pain because it receives same somatic nerve supply as region of abdominal wall that it lines
wheres does poorly localized pain originate from?
visceral peritoneum
esophagus
- one continuous muscular tube extending from pharynx to stomach
- 3 parts: cervical (head and neck), thoracic and abdominal
abdominal esophagus
begins at esophageal hiatus (T10) and ends at stomach (1-2.5 cm long)
lower esophageal sphincter
- between abdominal esophagus and stomach
- smooth muscle
- prevents reflux of gastric contents into esophagus
- under involuntary control
stomach
- rugae (gastric folds) of stomach allow expansion
- at distal end, stomach narrows to form pyloric orifice
- intraperitoneal structure
pyloric sphincter
- controls movement of chyme into duodenum
- under autonomic control
arterial supply of the stomach
- supplied by celiac trunk
- receives blood from left and right gastric arteries which anastomose at the lesser curvature
- left and right gastro-epiploic arteries anastomose at the greater curvature
- large vascular network ensures stomach receives sufficient blood without depriving other organs
small intestine
- extends from pyloric orifice to ileocecal junction
- divided into 3 parts: duodenum, jejunum, ileum
- intraperitoneal except for proximal portion of duodenum which is retroperitoneal
what is the relationship between the superior part of duodenum (duodenal cap), the bile duct and the gastroduodenal artery
- bile duct and gastroduodenal artery pass posterior to the duodenal cap
describe the pathway of the descending part of duodenum
- descending part runs vertically passing anterior to hilum of right kidney (this region contains major duodenal papilla – site where hepatopancreatic ampulla of Vater drains into duodenum)
describe the pathway of the horizontal part of duodenum
- passes transversely across IVC and abdominal aorta just inferior to origin of SMA and vein
- compression of duodenum between aorta and SMA is a rare condition called superior mesenteric artery syndrome
describe the pathway of the anterior part of duodenum
- passes upward to left of aorta forming duodenojejunal flexure
- flexure is anchored to wall by fibromuscular suspensory ligaments of duodenum (ligament of Treitz)
arterial supply of the foregut portion of the small intestine (1st and 2nd parts of the duodenum)
gastroduodenal artery and its branch, pancreaticoduodenal artery
arterial supply of midgut portion of small intestine (3rd and 4th parts of the duodenum)
inferior pancreaticoduodenal artery (branch of SMA)
arterial supply of jejunum and ileum
jejunal and ileal arteries (branches of SMA)
- both arteries form series of anastomotic loops (arterial arcades) from which terminal straight branches (vasa recta) reach intestinal wall
- networks that supply jejunum have fewer arcades with long vasa recta whereas networks that supply ileum have many arcades with shorter vasa recta
tenae coli
3 thickened bands of longitudinal muscle in the large intestine
haustra
segmented pouches or folds in the large intestine
epiploic (omental) appendages
fatty tags enclosed by peritoneum in the large intestine
iileocecal valve
controls point where ileum joins large intestine at cecum in right inguinal region
intraperitoneal structures of large intestine
cecum, transverse colon and sigmoid colon
retroperitoneal structure of large intestine
ascending colon, descending colon and rectum
blood supply of hindgut portion of large intestine
branches of IMA
blood supply to descending colon
left colic artery
blood supply to sigmoid colon
sigmoidal arteries
blood supply to rectum and upper anal canal
superior rectal artery
blood supply of midgut portion of large intestine
3 branches of SMA: ileocolic artery, right colic artery and middle colic artery
blood supply to cecum and appendix
ileocolic artery
blood supply to ascending colon
right colic artery
blood supply to transverse colon
middle colic artery
why is the anastomoses between the right, middle and left colic arteries continuous
anastomoses between the right, middle and left colic arteries form continuous marginal artery along border of colon, allows for collateral circulation
venous drainage of GI viscera
splenic vein
superior mesenteric vein
inferior mesenteric vein
hepatic portal vein
splenic vein
- leaves spleen and passes posterior to pancreas to join superior mesenteric vein
- drains spleen, lower esophagus, part of stomach and pancreas
- various pancreatic conditions can compress the vein leading to formation of thrombosis
superior mesenteric vein
- ascends through mesentery of small intestine to join splenic vein, posterior to pancreas
- names of superior mesenteric vein tributaries correspond to branches of the superior mesenteric artery
- mesenteric ischemia = occlusion of superior or inferior mesenteric vein
inferior mesenteric vein
- ascends on left to join splenic vein
- tributaries correspond to branches of inferior mesenteric artery
hepatic portal vein
- carries nutrient-rich deoxygenated blood from digestive tract to liver
- formed posterior to pancreas by union of splenic and superior mesenteric veins
- portal vein ascends before entering porta hepatis of liver
- assessment of pulsatility in hepatic portal vein useful for detecting cirrhosis
liver
- largest organ in the body
- right and central upper abdomen
- inferior to diaphragm, right dome of diaphragm higher than left dome to accommodate size of liver
- inferior surface adjacent to abdominal viscera
- lobes of liver divided by attachment of fold of peritoneum (falciform ligament)
why is it clinically important that the peritoneal cavity incompletely divides the spaces and recesses/fossae of the liver
allows passage for infectious fluids from different compartments of the abdomen
subphrenic recess of the liver
- superior extensions of peritoneal cavity between liver and diaphragm
- left and right subphrenic recess separated by falciform ligament of liver
hepatorenal recess
- pouch of Morrison
- deep recess in peritoneal cavity on right side between liver and right kidney
blood supply of liver
- 1/3 of cardiac output passes through liver
- 80% delivered via portal vein
- 20% delivered via hepatic artery proper
gallbladder
- receives, stores and concentrates bile
- fundus of gallbladder projects anteriorly from inferior border of liver, body projects posteriorly and narrows to neck which is continuous with cystic duct
- gallstones = hardened deposits of bile
- biliary colic is spasmodic pain caused by attempt to expel gallstone
- affects liver, gallbladder and pancreas
where is the common bile duct in relation to the pancreas
the common bile duct passes through the duodenum, proximal to the pancreas
pancreas
- lies transversely on posterior abdominal wall, posterior to stomach
- head of pancreas sits on concavity of duodenum
- medial projection (unicate process) lies deep to superior mesenteric vessels and origin of portal vein
- body extends towards left passing behind stomach and tapering to become tail
- tail abuts medial side of spleen
spleen
- largest lymphatic organ
- left upper quadrant of abdomen
- under left dome of diaphragm, behind stomach, anterior to ribs 9, 10, 11
- unique notches on anterior border and hilum on medial surface
- splenic artery (branch of celiac trunk) and splenic vein enter and exit at hilum
kidneys
- retroperitoneal structures located on posterior abdominal wall
- right kidney slightly lower due to position of liver which lies superior to it
- posterior to both kidneys is diaphragm as well as costodiaphragmatic recesses of pleural cavities
- with contraction of diaphragm, kidneys move downwards
blood supply to kidneys
- receive blood from left and right renal arteries that arise from the lateral side of the abdominal aorta at L2
venous drainage of kidneys
- right and left renal veins travel anterior to renal arteries
- unlike right renal vein, left renal vein passes under SMA to drain into IVC
- left renal vein is longer b/c it has to cross aorta to reach IVC
accessory renal arteries
arise from aorta above/below main renal artery and enter kidney above/below hilum
ureters
- muscular tubes that transport urine from kidneys to bladder
- ureters leave hilum and descend vertically towards pelvic
- during descent, passes anterior to psoas muscle and bifurcation of common iliac artery and vein
adrenal glands
- lie on upper poles of kidneys
- right adrenal gland is pyramidal
- left adrenal gland is semilunar
- supplied by suprarenal artery and branches from inferior phrenic and renal arteries
