Short Notes: Anatomy of the Posterior Abdominal Wall

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ANATOMY
Medicine Made Simple

, POSTERIOR ABDOMINAL WALL
 Made up of 3 bony & 4 muscular structures
 Bones- Bodies of lumbar vertebrae
Sacrum
Wings of ilium
(11th & 12th ribs)
 Muscles - Diaphragm
Quadratus lumborum
Psoas major & minor
Iliacus

Psoas major
 Origin - transverse process of all lumbar vertebrae
Side of the bodies (T12-L5 )
Intervening discs (T12-L5 )
 Insertion - lesser trochanter of femur
 Action – flexion of the hip joint
 Roots of lumbar plexus lie within the substance of the muscle.
 Genitofemoral nerve - front of psoas
 Femoral, Iliohypogastric, ilioinguinal, lateral femoral cutaneous
nerves, femoral nerve - lateral border
 Obturator & lumbosacral trunk - medial border
 Nerve supply - first 3 lumbar nerves

 Psoas fascia - invests the surface of psoas major
- Attached to vertebral bodies, fibrous arches & transverse processes
- Thickening, curving from body of L1
(or L2) to transverse process of L2 - medial arcuate ligament
Clinical
 Psoas abscess
 enclosed in sheath
 pus from tubercular infection may tract down through the sheath in to the thigh
 soft swelling in the femoral triangle
Iliacus
 Origin - Upper 2/3 of iliac fossa, anterior sacroiliac and iliolumbar ligament.
 Insertion - lesser trochanter of femur along with the psoas tendon
 Nerve supply - femoral nerve (L2-L4)

 Iliac fascia - covers iliacus muscle
Attached to the margins of the muscle & to the inguinal ligament

Quadratus lumborum
 Origin - transverse process of vertebra LV, the iliolumbar ligament, and the adjoining
part of the iliac crest
 Insertion - attach superiorly to the transverse processes of the first four lumbar
vertebrae and the medial half of the inferior border of rib XII.

 Nerve supply - anterior rami of T12 and L1 to L4 spinal nerves.

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