Unit 3 - Thorax, Abdomen, Pelvis, and Perineum: Posterior Abdominal Wall Muscles (Ex. III)

Question 1

superficial psoas major

Answer 1

O: L surfaces of vertebral bodies and associated IV disks of T12-L4
I: lesser trochanter of femur; joint insertion as iliopsoas muscle
Inn: direct branches from L plexus (L2-L4)
A: hip joint - flexion and external (L) rotation; contraction ipsilaterally laterally flexes/bends trunk @ L spine w/ femur fixed; bilateral contraction raises spine from supine position @ L spine w/ femur fixed

Question 2

deep psoas major

Answer 2

O: transverse processes of L1-L5
I: lesser trochanter of femur; joint insertion as iliopsoas muscle
Inn: direct branches from L plexus (L2-L4)
A: hip joint - flexion and external (L) rotation; contraction ipsilaterally laterally flexes/bends trunk @ L spine w/ femur fixed; bilateral contraction raises trunk from supine position @ L spine w/ femur fixed

Question 3

psoas minor

Answer 3

O: vertebrae and L surface of IV disk of T12-L1
I: lesser trochanter; joint insertion of iliopsoas muscle
Inn: direct branches from L plexus (L2-L4)
A: weak trunk flexor

Question 4

iliacus

Answer 4

O: iliac fossa
I: lesser trochanter; joint insertion of iliopsoas muscle
Inn: femoral n. (L2-L4)
A: flexes thigh; stabilizes hip joint; acts w/ psoas major

Question 5

quadratus lumborum

Answer 5

O: iliac crest; iliolumbar ligament
I: rib 12; transverse processes of L1-L4
Inn: spinal nn. (T12, L1-L4)
A: ipsilaterally laterally flexes/bends trunk; bilaterally bears down - expiration stabilizes rib 12