posterior abdominal wall muscles

Question 1

Psoas Major

Answer 1

Origin: Vertebral bodies of T12-L4, Intervertebral discs between T12-L4, Transverse processes of L1-L5 vertebrae
* Insertion: Lesser trochanter of femur
* Innervation: Anterior rami of spinal nerves L1-L3
* Function:
* Hip joint: Thigh/trunk flexion
* Thigh: external rotation
* Trunk: lateral flexion

Question 2

Psoas Minor - not present in most

Answer 2

• Origin: Vertebral bodies of T12 & L1 vertebrae
• Insertion: Iliopubic eminence, Pectineal line of pubis
• Innervation: Anterior rami of spinal nerves L1-L3
• Function:
• Hip joint: Thigh/trunk flexion
• Thigh: external rotation
• Trunk: lateral flexion

Question 3

Illiacus

Answer 3

• Origin: Iliac fossa
• Insertion: Lesser trochanter of femur * Innervation: Femoral nerve (L2-L4)
• Function:
• Hip joint: Thigh/trunk flexion
• Thigh: external rotation
• Trunk: lateral flexion

Question 4

Quadratus Lumborum

Answer 4

• Origin: Iliac crest, Iliolumbar ligament
• Insertion: Inferior border of rib 12, Transverse processes of vertebrae L1-L4
• Innervation: Subcostal nerve (T12), Anterior rami of spinal nerves L1-L4
• Function:
• Bilateral contraction - Fixes Ribs 12
  during inspiration, Trunk extension
• Unilateral contraction - Lateral flexion of trunk (ipsilateral)