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