Posterior Abdominal Wall

Make your own free website on Tripod.com

Vasculature

arteries consist of the paired branches of the abdominal aorta

inferior phrenics: arise from posterolateral aorta just below the diaphragm; supply diaphragm

suprarenal arteries: arise from lateral aorta; supply suprarenal glands

superior: inferior phrenics
middle: suprarenals
inferior: renal artery branches

renal arteries: arise at L1/L2; branch into superior; anterior superior; anterior inferior; posterior; inferior segmental arteries

gonadal arteries: testicular, ovarian; run along psoas major; testicular enters inguinal canal; ovarian enters the pelvis minor

lumbar arteries: four arteries; analagous to intercostal arteries of thorax

veins run alongside the arteries into the IVC with two exceptions:

left suprarenal vein and left gonadal vein dump into the left renal vein not directly into the IVC
renal veins are anterior to renal arteries

lymphatics

superior to the umbilicus: drainage to the axillary lymph nodes

inferior to the umbilicus: drainage to the inguinal nodes Þ preaortic nodes Þ cisterna chyli Þ thoracic duct

Nerves

Autonomic

sympathetic trunk enters abdomen posterior to the medial arcuate ligament

usually composed of five lumbar sympathetic ganglia

celiac plexus: on either side of the celiac trunk (solar plexus)

greater splanchnic nerve: arises from ganglia at T5 – T9

lesser splanchnic nerve: arises from ganglia at T10 – T11

least splanchnic nerve: arises from ganglia at T12
kidneys are innervated by lesser and least splanchnics (T10 - L1)
suprarenal glands are innervated by greater, lesser, least splanchnic, lumbar nerves (T6 - L2)
foregut: greater splanchnic nerve
midgut: lesser and least splanchic nerve
hindgut: lumbar nerves

Somatic

subcostal nerve (12^th thoracic nerve): supplies anterior abdominal wall between the umbilicus and pubic symphysis

iliohypogastric nerve: supplies skin of suprapubic and inguinal regions

ilioinguinal nerve: supplies skin of the inner thigh and scrotum

iliohypogastric and ilioinguinal nerves arise from a common branch of L1

genitofemoral nerve: arises L1, L2; has femoral branch; genital branch enters inguinal canal, supplies cremaster muscle

lateral femoral cutaneous nerve of the thigh: arises L2, L3; supplies skin on anteriolateral thigh

femoral nerve: arises L2, L3; supplies psoas and iliacus muscles, extensor muscles of the thigh

obturator nerve: arises L2, L3, L4; supplies adductor muscles of the thigh

Diaphragm

blood supply through inferior phrenic arteries

innervation: phrenic nerves (C3, 4, and 5 keep the diaphragm alive)

origins: sternal: at xiphoid process

costal: at the lower six ribs

vertebral:

lateral arcuate ligament Þ runs from L1 transverse process to rib 12

medial arcuate ligament Þ runs from L1 transverse process to L1 vertebral body (crura of diaphragm)

median arcuate ligament Þ unites left and right crura of diaphragm

insertion: central tendon

vena caval foramen at T8 and is a hole in the central tendon

hiatus for esopahgus at T10; usually in the muscles of the right crus

aortic hiatus: posterior to the diaphragm at T12; posterior to the median arcuate ligament, between left and right crura

Suprarenal glands

venous drainage: IVC on right, renal vein on left

right gland is more triangular

glands are surrounded by fat

outer cortex is of gut origin and secretes corticosteroids

inner medulla is of neural crest origin and secretes epinephrine and norepinephrine

innervation from T6 - L2

Kidneys

right kidney is slightly lower than the left

right kidney may be palpable; left is usually not

covered by renal capsule (Glisson’s capsule) Þ perirenal fat Þ renal fascia (around kidney and suprarenal gland) Þ pararenal fascia

renal pyramids (18-20) drain to renal papillae Þ minor calyxes Þ major calyxes Þ renal pelvis Þ ureter

bifid ureter is fairly common: two ureters leave kidney and then coalesce

gonadal vessels originate medial to the ureter then cross laterally

stones most likely originate at pelvis or major calyx; pain can anywhere from ilius to the medial aspect of the leg

innervation by T10 - L1

Structures

Vessels

Gonadal (Ovarian or Testicular)

Arteries: arise from aorta, run along psoas muscle; supply testicles or ovaries

Veins: right drains to IVC; left drains to left renal vein

Renal Veins: lie anterior to arteries; left longer than right

Renal Arteries

Abdominal Aorta

Suprarenal Arteries: suprarenal blood supply from three sources

Superior from Inferior Phrenic; Middle from Aorta; Inferior from Renal

Inferior Phrenic Arteries: supply diaphragm

Lumbar Arteries: small branches off of the aorta; analagous to the intercostal arteries

Common Iliac Arteries: bifrucation of the aorta at L4

Muscles

Psoas Major

Origin: transverse process of T12 thru L5

Insertion: lesser trochanter of the femur

Innervation: branches of L2 - L5

Action: leg flexion (with iliacus), torso flexion

Psoas Minor (50% of people)

Origin: T12 and L1

Insertion: iliopubic eminence

Innervation: ventral ramus of L1

Action: torso flexion

Iliacus

Origin: superior iliac crest and fossa

Insertion: lesser trochanter of the femur

Innervation: femoral nerve L2 - L4

Action: leg flexion (with psoas)

Quadratus Lumborum

Origin: inferior border to 12^th rib; tips of lumbar transverse processes

Insertion: iliolumbar ligament and iliac crest

Innervation: branches of T12 - L4

Action: stabilizes 12^th rib; lateral flexion

Kidney

Perirenal Fat: lies between kidney and renal fascia; also surrounds suprarenal glands

Ureters: drain renal pelvis to the urinary bladder
Sections

Cortex

Medulla

Renal Pyramid: contains collecting ducts; empties into renal papillae

Renal Columns: portions between renal pyramids

Renal Papillae: apex of renal pyramid; site where collecting ducts empty to minor calyx

Minor Calyces: usually 7 - 14; dump into major calyces

Major Calyces: usually two or three; dump into renal pelvis

Renal Pelvis: funnel shaped

Suprarenal Gland: right gland is triangular in shape; left is semilunar in shape

Cortex: lighter region; secretes steriod hormones

Medulla: darker; secretes norepinephrine and epinephrine

Diaphragm

right and left crura: musculotendinous structures arising from L1 - L3 vertabrae; joined superiorly and anteriorly by the median arcuate ligament forming the aortic hiatus

medial arcuate ligament: runs from transverse process of L1 to crus of the diaphragm

lateral arcuate ligament: runs from transverse process of L1 to the 12^th rib

central tendon: insertion of all the muscle fibers of the diaphragm; hole just off right center forms vena caval foramen

esophageal hiatus: formed by splitting of the fibers of the lumbar part of the diaphragm

Nerves

subcostal nerve (12^th thoracic nerve): supplies anterior abdominal wall between the umbilicus and pubic symphysis

iliohypogastric nerve: supplies skin of suprapubic and inguinal regions

ilioinguinal nerve: supplies skin of the inner thigh and scrotum

iliohypogastric and ilioinguinal nerves arise from a common branch of L1

genitalfemoral nerve: arises L1, L2; has femoral branch; genital branch enters inguinal canal, supplies cremaster

lateral femoral cutaneous nerve of the thigh: arises L2, L3; supplies skin on anteriolateral thigh

femoral nerve: arises L2, L3; supplies psoas and iliacus muscles, extensor muscles of the thigh

obturator nerve: arises L3, L4; supplies adductor muscles of the thigh

Phrenic Nerve: from C3 - C5; keeps the diaphragm alive

Lumbosacral Trunk: large flat nerve; from L4, L5; forms part of the sacral plexus; is not a branch of the lumbar plexus

sympathetic trunk enters abdomen posterior to the medial arcuate ligament

usually composed of five lumbar sympathetic ganglia

celiac plexus: on either side of the celiac trunk (solar plexus); contains celiac ganglia

greater splanchnic nerve: arises from ganglia at T6 - T 10