Abdomen 4 - Posterior Abdominal Wall Flashcards
what is the sacral promontory?
landmark where lumbar spine transitions to sacrum
what type of curvature is the sacral region?
primary curvature/kyphosis - develops during foetal development
origin of the psoas major?
transverse processes of T12-L4
origin of the iliacus muscle?
iliac fossa
describe the insertion of the iliacus & psoas major
iliacus & psoas major fibres join - form the iliopsoas muscle
insert on the lesser trochanter of the femur
actions of the iliacus?
flexes thigh at hip joint
flexes trunk
actions of the psoas major?
flexes thigh at hip joint
flexes trunk
action of the iliopsoas?
primary hip flexor
origin & insertion of the psoas minor?
origin: vertebral bodies of T12-L1
insertion: pectinate line & inguinal ligament
(variable presentation - not everyone has this muscle)
action of the psoas minor?
assists trunk flexion - minimal involvement
what nerve plexus is embedded within the psoas major?
lumbar plexus (T12-L4)
origin, insertion & action of psoas major?
origin: transverse processes of T12-L4
insertion: fibres pass inguinal ligament & join with iliacus - forms iliopsoas & inserts on *lesser trochanter of femur&
actions: flexes thigh at hip joint & flexes trunk
origin & insertion of quadratus lumborum?
origin: iliac crest
insertion: 12th rib & transverse processes of L1-4
what happens with bilateral contraction of the quadratus lumborum?
extends vertebral column
what happens with unilateral contraction of the quadratus lumborum?
lateral flexion of trunk (ipsilateral/ same side as contraction)
the quadratus lumborum is a posterior continuation of WHAT MUSCLE
transversus abdominis
what is the central tendon of the diaphragm?
an aponeurosis that serves as the main insertion site for diaphragm muscle fibres
why is the right dome of the diaphragm higher than the left?
presence of liver makes right dome higher
stomach & spleen makes left dome lower
what is the function of the arcuate ligaments?
provide fascial attachments to posterior abdominal wall muscles - form a continuous structural layer
what are the three arcuate ligaments (from medial to lateral)? what do they attach to?
median arcuate ligament - no attachments; aorta passes posteriorly
medial arcuate ligament - attaches to psoas major
lateral arcuate ligament - attaches to quadratus lumborum
what attaches to the lateral arcuate ligament?
quadratus lumborum
what attaches to the medial arcuate ligament?
psoas major
what part of the diaphragm secures the oesophagus at the midline? how?
right & left crura of the diaphragm - encircle the oesophageal hiatus to secure the oesophagus
what is the difference between the right and left crura of the diaphragm?
right crus is longer - attaches to L1-3
left crus is shorter - attaches to L1-2
which diaphragm crus attaches at L1-2?
left crus (shorter than the right)
what contents pass through the caval opening?
(at T8) - IVC & right phrenic nerve
what passes through the diaphragm at T10?
oesophagus
anterior & posterior vagal trunks
what passes with the aorta through the aortic hiatus?
thoracic duct
azygos vein
at what thoracic level does the right phrenic nerve pass through the diaphragm
T8 - passes through caval opening with IVC
does the aorta pass through the diaphragm?
NO - aorta travels posterior to the diaphragm between the crura (at the level of T12)
how does the left phrenic nerve pass through the diaphragm?
perforates the diaphragm rather than passing through a hiatus
which phrenic nerve passes with the IVC through the diaphragm?
right phrenic nerve
what muscle compartments/subsets does the thoracolumbar fascia separate?
separates deep back muscles from posterior abdominal wall muscles
(then converges into lumbar fascia)
what fascia serves as an attachment point for muscles like the internal & external obliques?
lumbar fascia - attachment point for anterolateral abdominal muscles
at what vertebral level does the abdominal aorta begin and end?
begins at T12 (aortic hiatus)
ends at L4 (bifurcation into common iliac arteries)
which branches of the abdominal aorta are unpaired and supply the GI tract?
midline unpaired branches
- coeliac trunk (T12) = foregut
- superior mesenteric artery (L1) = midgut
- inferior mesenteric artery (L3) = hindgut
at what vertebral level does the IMA come off the aorta?
L3
at what vertebral level does the SMA come off the aorta?
L1
at what vertebral level does the coeliac trunk come off the aorta?
T12
which paired visceral branches of the abdominal aorta supply organs?
renal arteries
gonadal arteries - testicular/ovarian
suprarenal arteries (to adrenals)
what are the paired posterolateral branches of the abdominal aorta?
lumbar arteries - one from each lumbar vertebral level; supply the posterior abdominal wall and vertebrae
what do the lumbar arteries supply?
supply the posterior abdominal wall and vertebrae
what are the three vascular planes of the abdominal aorta?
unpaired midline arteries
paired visceral arteries
paired posterolateral arteries
what vertebral levels does the lumbar plexus originate from?
T12-L4
where is the lumbar plexus located?
within the psoas major muscle, with most nerves running behind or in front of it
which nerve of the lumbar plexus is considered an intercostal nerve?
subcostal nerve (T12) - called “subcostal” because it arises below the last rib
which two nerves of the lumbar plexus wrap around the top of psoas major?
iliohypogastric (L1)
ilioinguinal (L1)
what are are the branches of the genitofemoral nerve (L1-2)?
genital branch
femoral branch
which nerve of the lumbar plexus is vulnerable to compression under the inguinal ligament?
lateral femoral cutaneous nerve (L2-3)
