Anatomy Exam 3

Intraperitoneal

Organ suspended in mesentery (stomach, spleen, transverse colon)

Primarily retroperitoneal

Organ develops behind the peritoneum and stays there throughout development (esophagus, last 2/3 of rectum, anal canal, kidneys)

Secondarily retroperitoneal

Organ develops within the mesentery (intraperitoneal) and is now posterior to the mesentery due to rotation and mesenteric fusing (duodenum parts 2-4, ascending and descending colon, pancreas)

Foregut

Esophagus through the first part of the duodenum; also includes pancreas, spleen, liver, and gallbladder; supplied by the celiac trunk; outpocketings include pharyngeal pouches, lower respiratory system, pancreas, liver, and gallbladder

Midgut

Duodenum through 2/3 of the transverse colon; supplied by the superior mesenteric artery

Hindgut

Last 1/3 of the transverse colon through the anus; supplied by the inferior mesenteric artery; outgrowths are urinary bladder and urethra

Celiac trunk

Supplies the foregut; branches are the left gastric, splenic, common hepatic

Left gastric artery

Branch of the celiac trunk that goes to the lesser curvature of the stomach; anastomoses with the right gastric artery

Splenic artery

Branch of the celiac trunk that passes behind the stomach and pancreas to serve the spleen; branches include dorsal and greater pancreatic, short gastric, and left gastro-omental

Pancreatic arteries

Branches of the splenic artery of the celiac trunk; dorsal branch supplies the body of the pancreas and the greater branch supplies the tail

Short gastric arteries

Branches of the splenic artery of the celiac trunk that supply the stomach closest to the spleen

Left gastro-omental artery

Branch of the splenic artery of the celiac trunk that supplies the left side of the greater curvature of the stomach

Common hepatic artery

Major branch of the celiac trunk that goes toward the right side (liver); branches include gastroduodenal, right gastric, and proper hepatic

Gastroduodenal artery

Branch of the common hepatic artery of the celiac trunk; gives rise to right gastro-omental, superior pancreaticoduodenal, and supraduodenal arteries

Right gastro-omental artery

Branch of the gastroduodenal artery of the common hepatic artery of the celiac trunk; goes to the right side of the greater curvature of the stomach

Superior pancreaticoduodenal artery

Branch of the gastroduodenal artery of the common hepatic artery of the celiac trunk; goes to the stomach, pancreas, and head of duodenum

Supraduodenal artery

Branch of the gastroduodenal artery of the common hepatic artery of the celiac trunk; goes to the superior duodenum; is sometimes absent

Right gastric artery

Branch of the common hepatic artery of the celiac trunk; goes to the right lesser curvature of the stomach; anastomoses with the left gastric artery

Proper hepatic artery

Branch of the common hepatic artery of the celiac trunk; branches include right hepatic and left hepatic arteries

Right hepatic artery

Branch of the proper hepatic artery of the common hepatic artery of the celiac trunk; goes to the liver; gives off the cystic artery to the gallbladder

Superior mesenteric artery

Supplies the midgut (and collaterally the pancreas); branches include inferior pancreaticoduodenal, intestinals, ileocolic, right colic, middle colic, and marginal arteries

Inferior pancreaticoduodenal artery

Branch of the superior mesenteric artery; goes to the head of the pancreas and the duodenum

Intestinal arteries

Branches of the superior mesenteric artery; go to the jejunum and ileum; branch off into arcades which loop in the mesentery and vasa rectae which come off the arcades

Ileocolic artery

Branch of the superior mesenteric artery that goes to the distal ileum and cecum

Right colic artery

Branch of the superior mesenteric artery that foes to the ascending colon

Middle colic artery

Branch of the superior mesenteric artery that goes to the transverse colon

Marginal artery

Anastomotic branch of the superior mesenteric artery that circles the colon; formed by branches of the ileocolic, right colic, middle colic, and left colic (IMA); gives rise to vasa rectae

Inferior mesenteric artery

Supplies the hindgut; branches include left colic, sigmoid, and superior rectal arteries

Left colic artery

Branch of the inferior mesenteric artery that goes to the descending colon; anastomoses with the ileocolic, right colic, and middle colic arteries to form the marginal artery

Sigmoid arteries

Branches of the inferior mesenteric artery that goes to the sigmoid colon

Superior rectal arteries

Branches of the inferior mesenteric artery that go to the proximal rectum

Important anastomoses

Right and left gastro-omentals, right and left gastrics, superior and inferior pancreaticoduodenals, inferior pancreaticoduodenal and jejunal arteries, ileocolic/right colic/middle colic/left colic, superior rectals with middle and inferior rectals

Portal system

Goes through two capillary beds before returning to the heart; deoxygenated blood from the abdomen passes through the hepatic system before returning to the heart via the inferior vena cava

Hepatic portal system

Major portal system in the human body; main branches include splenic vein from the foregut, superior mesenteric vein of the midgut, and inferior mesenteric vein of the hindgut; veins converge to form the hepatic portal vein which goes to the liver to get filtered; hepatic vein brings filtered blood back to the heart; has esophageal, rectal, umbilical, and colonic anastomoses

Liver enlargement

Can be caused by cirrhosis, valvular cardiac disease, hepatitis, hepatic tumors, and more; can cause portal hypertension

Portal hypertension

Blood pressure raises due to resistance of the diseased liver; blood finds alternate routes around the hepatic portal vein; can cause esophageal varices, external hemorrhoids, opening of umbilical vessels

Sympathetics of celiac plexus

Innervate the foregut; rise from T5-T9 spinal nerve levels; presynaptics pass through the sympathetic chain; pass through the greater splanchnic nerve; synapse in the celiac ganglia; postsynaptics follow branches of celiac trunk to target organs

Parasympathetics of celiac plexus

Innervate the foregut; arise from the brain and pass through vagus nerve; pre-synaptics pass through celiac plexus; follow branches of celiac trunk to targets; synapse in ganglia in the gut plexuses; postsynaptics reach targets via short postsynaptics fibers

Sympathetics of superior mesenteric plexus

Innervate the midgut; arise from T10-T12 spinal nerve levels; presynaptics pass through sympathetic trunk; pass through lesser or least splanchnic nerve; synapse in superior mesenteric ganglion; postsynaptics follow branches of superior mesenteric artery to target organs

Parasympathetics of superior mesenteric plexus

Innervate the midgut; arise from the brain and pass through vagus nerve; pass through superior mesenteric plexus without synapsing; follow branches of superior mesenteric artery to targets; synapse in ganglia in gut plexuses; postsynaptics reach targets via short postsynaptic fibers

Sympathetics of inferior mesenteric and hypogastric plexuses

Innervate hindgut; arise from L1-L2 spinal levels; presynaptics pass through sympathetic trunk; pass through lumbar splanchnic nerves; synapse in inferior mesenteric ganglion; postsynaptics follow branches of inferior mesenteric artery to target organs

Parasympathetics of inferior mesenteric and hypogastric plexuses

Innervate hindgut; arise from S2-S4 spinal levels; pass through sacral spinal nerves; pass through pelvic splanchnic nerve; branches to colon pass cranially through hypogastric plexus and inferior mesenteric plexus; follow branches of inferior mesenteric artery to targets; synapse in ganglia in gut plexuses; postsynaptics reach targets via short postsynaptic fibers

Referred pain in abdomen

Visceral afferents share rami communicans coming back from somatic nerves, so brain perceives signals as coming from somatics themselves

Cranial-caudal folding

Occurs 4 weeks into development; embryo forms a primitive endodermal gut tube connected to the yolk sac via the yolk stalk; provides nutrients for 2 weeks; functions as the primordial gut and its endoderm forms the gut tube and respiratory tract; these germ cells also give rise to gonads and blood develops here until liver is functional

Recanalization

During weeks 5-6 gut tube lumen becomes narrow due to epithelial cell development; vacuoles form and hollow out the gut tube; failure most commonly occurs at the duodenum

Ventral mesentery

Connected the ventral body wall to the gut tube; by birth, it is not connected to the body wall except for the falciform ligament; remnants can also be found in the lesser omentum

Dorsal mesentery

Connects the dorsal body wall to the gut tube; provides mesentery for most abdominal organs

Polyhydramnios

Too much amniotic fluid in the cavity; means the fetus is unable to drink fluid and indicates a blockage due to recanalization failure

Non-rotation

Intestines grow but do not rotate

Subhepatic cecum and appendix

Cecum and appendix do not descend and stay in the top right quadrant; may present as gallbladder issues

Stomach development

Dorsal border grows faster than ventral border, producing greater and lesser curvatures; rotates 90 degrees clockwise bringing the vagus nerves with it; lesser curvature moves to the right and greater curvature moves to the left

Foregut duodenum development

Ends just distal to the common bile duct; solid ventral outgrowths form ducts for the liver, pancreas, and gallbladder

Pancreatic development

Forms a ventral and dorsal bud; if two ventral buds form and go opposite directions, can wrap around duodenum and cause a blockage

Splenic development

Not an endodermal derivative; outpocketing of mesoderm in dorsal mesentery

Median umbilical fold

Remnant of urachus, which drained the fetal bladder, and paraumbilical veins, which can become enlarged and patent during portal hypertension

Medial umbilical folds

Bilateral remnants of umbilical arteries

Lateral umbilical folds

Bilateral ridges of parietal peritoneum covering the inferior epigastric vessels

Midgut development

Small and large intestines herniate out of the umbilicus, then rotate 90 degrees counter-clockwise; grows and forms a loop with the superior mesenteric artery as its axis; small intestine returns to gut cavity while large intestine rotates another 180 degrees counter-clockwise; cecum and appendix descend to lower right

Cloaca

Forms the caudal hindgut; common outlet for fetal waste; gets divided by urorectal septum into urogenital membrane and anal membrane

Urorectal septum

Divides allantois and yolk stalk, separating cloaca into urogenital membrane and anal membrane

Pectinate line

Line of the anus where endoderm and ectoderm meet

Non-perforate anus

Anal opening does not develop properly; thin layer of tissue usually separates the anus from the outside

Anoperineal fistula

Anal opening is misplaced in the perineum; no anal sphincter

Rectourethral fistula

Tunnel connecting urethra to rectum; anus is usually absent or vestigial; feces exits penis

Rectovaginal fistula

Tunnel connecting rectum to vagina; anus is usually absent or vestigial; feces exits vagina

Kidneys

Positioned on the posterior body wall between T12 and L3; remove excess water/salts/wastes of protein metabolism; return nutrients to blood; regulate blood pressure and production of red blood cells; have pararenal and perirenal fat; consist of cortex and medulla; pyramids drain into minor calices which drain into major calices which drain into the pelvis

Kidneys blood supply

Renal artery, segmental arteries, interlobar arteries, arcuate arteries, renal vein

Kidneys innervation

Sympathetic from T10-L1; probably no parasympathetic

Hilum

Area of the kidney where all contents enter and exit; contains renal arteries, veins, and renal pelvis which becomes the ureter

Suprarenal glands

Cortex produces corticosteroids and androgens; medulla produces norepinephrine and epinephrine; blood supply from superior suprarenal (from inferior phrenic), middle suprarenal (from aorta), and inferior suprarenal (from renal) arteries

Suprarenal glands innervation

Medulla has presynaptic sympathetics penetrating directly and synapsing on chromaffin cells (sympathetic ganglion cells); cortex has autonomic fibers associated with blood cells controlling vasodilation and vasoconstriction

Diaphragm

Major muscle of respiration; motor and sensory innervation from phrenic nerve; intercostal nerves provide sensory innervation to periphery; right crus muscle wraps around esophagus; superior surface is supplied by superior phrenic arteries and inferior surface is supplied by inferior phrenic arteries

Hiatal openings

Holes in diaphragm where other structures pass through; vena cava at T8, esophagus at T10, aorta at T12

Psoas major origins

Transverse processes of lumbar vertebrae, side of vertebral bodies T12-S1

Psoas major insertions

Lesser trochanter of femur

Psoas major innervation

Lumbar plexus via anterior branches of nerves L1-L3

Psoas major actions

Flexes thigh, flexes vertebral column laterally, flexes trunk

Psoas minor origins

Sides of vertebral bodies T12-L1

Psoas minor insertions

Pectineal line and iliopubic eminence

Psoas minor innervation

L1

Psoas minor actions

Weak trunk flexor

Iliacus origins

Superior 2/3 of iliac fossa, ala of sacrum, anterior sacro-iliac ligaments

Iliacus insertions

Lesser trochanter of femur and shaft inferior to it

Iliacus innervation

Femoral nerve (L2-L4)

Iliacus actions

Flexes thigh and stabilizes hip joint

Quadratus lumborum origins

Medial half of inferior border of rib 12, tips of lumbar transverse processes

Quadratus lumborum insertions

Iliolumbar ligament and internal lip of iliac crest

Quadratus lumborum innervation

Anterior branches of T12 and L1-L4 nerves

Quadratus lumborum actions

Extends and laterally flexes vertebral column; fixes 12th rib during inspiration

Subcostal nerves

From ventral rami of T12; innervate external obliques and skin of anterolateral abdominal wall

Lumbar plexus

Arises from L1-L4; gives rise to iliohypogastric, ilioinguinal, genitofemoral, lateral femoral cutaneous, femoral, obturator, and accessory obturator nerves

Lumbosacral trunk

L4-L5; joins sacral plexus to form sciatic nerve

Iliohypogastric nerve

L1 of lumbar plexus; motor innervation to abdominal muscles and sensory innervation to overlying skin

Ilioinguinal nerve

L1 of lumbar plexus; sensory innervation to skin of inguinal and pubic regions (scrotum, labia majora, skin of medial thigh)

Genitofemoral nerve

L1-L2 of lumbar plexus; sensory innervation to skin below inguinal ligament; motor innervation to cremaster muscle

Lateral femoral cutaneous nerve

L2-L3 of lumbar plexus; sensory innervation to anterolateral skin of thigh

Femoral nerve

L2-L4 of lumbar plexus; motor innervation to iliacus, hip flexors, quadriceps; sensory innervation to skin of anterior leg

Obturator nerve

L2-L4 of lumbar plexus; sensory innervation to skin of medial thigh; motor innervation to thigh adductors

Accessory obturator nerve

May not be present; L3-L4 of lumbar plexus; motor innervation to pectineus muscle and hip joint

Subcostal arteries

Bring blood from the abdominal aorta to the posterior body wall inferior to the 12th rib