Posterior Abdominal Wall Muscles

Question 1

Origin of Psoas Major (Deep Layer)

Answer 1

L1-L5 (costal processes)

Question 2

Insertion of Psoas Major

Answer 2

Femur (lesser trochanter), joint insertion as iliopsoas muscle

Question 3

Innervation of Psoas Major

Answer 3

Direct branches from lumbar plexus (L2-L4)

Question 4

Action of Psoas Major

Answer 4

Hip Joint: Flexion and external rotation

Lumbar spine (with femur fixed):
     Unilateral: bends trunk laterally
     Bilaterally: raises trunk from supine position

Question 5

Origin of Psoas Minor

Answer 5

T12, L1 vertebrae and intervertebral disk (lateral surfaces)

Question 6

Insertion of Psoas Minor

Answer 6

Femur (lesser trochanter), joint insertion as iliopsoas muscle

Question 7

Innervation of Psoas Minor

Answer 7

Direct branches from lumbar plexus (L2-L4)

Question 8

Action of Psoas Minor

Answer 8

Weak flexor of the trunk

Question 9

Origin of Iliacus

Answer 9

Iliac fossa

Question 10

Insertion of Iliacus

Answer 10

Femur (lesser trochanter), joint insertion as iliopsoas muscle

Question 11

Innervation of Iliacus

Answer 11

Femoral n. (L2-L4)

Question 12

Origin of Quadrates lumborum

Answer 12

Iliac crest and iliolumbar ligament

Question 13

Insertion of Quadrates Lumborum

Answer 13

12th rib, L1-L4 vertebrae (transverse processes)

Question 14

Innervation of Quadrates lumborum

Answer 14

T12, L1-L4 spinal nn.

Question 15

Action of Quadrates lumborum

Answer 15

Unilateral: Bends trunk to same side

Bilateral: Bearing down and expiration, stabilizes 12th rib

Question 16

Origin of Psoas Major (Superficial Layer)

Answer 16

T12-L4 vertebral bodies and associated intervertebral disks (lateral surfaces)