Muscles of the Posterior Abdominal Wall

Question 1

Name the muscles of the posterior abdominal wall

Answer 1

Psoas Major
Iliacus
Quadratus lumborum

Question 2

Psoas Major - Origin

Answer 2

Transverse processes of Lumbar vertebrae

Sides of the bodies and IV discs of T12-S1

Question 3

Psoas Major - Insertion

Answer 3

strong tendon to lesser trochanter of femur

Question 4

Psoas Major - Innervation

Answer 4

lumbar plexus via anterior branches of nerves L2-L4

Question 5

Psoas Major - Action

Answer 5

inferiorly - flexes thigh
superiorly - flexes vertebral column laterally to balance trunk
sitting - flex trunk

Question 6

Illiacus - Origin

Answer 6

Superior 2/3rds of iliac fossa
ala of sacrum
anterior sacro-iliac ligaments

Question 7

Illiacus - Insertion

Answer 7

lesser trochanter of femur and shaft inferior to is and to psoas major tendon

Question 8

Illiacus - Innervation

Answer 8

femoral nerve (L2-L4)

Question 9

Illiacus - Action

Answer 9

Anterior branches of T12 and L1-L4 nerves

Question 10

Quadratus Lumborum - Origin

Answer 10

Medial half of inferior border of 12th rib and tips of lumbar transverse processes

Question 11

Quadratus Lumborum - Insertion

Answer 11

Iliolumbar ligament and internal lip of iliac crest

Question 12

Quadratus Lumborum - Innervation

Answer 12

Anterior branches of T12 and L1-L4 nerves

Question 13

Quadratus Lumborum - Action

Answer 13

Extends and laterally flexes vertebral column

fixes 12th rib during inspiration