Second Order for Unit 4

Psoas Major M: Origin

Transverse processes and bodies of T₁₂–L₅ vertebrae

Psoas Major M: Insertion

Lesser trochanter of femur with iliacus

Psoas Major M: Action

Flexes thigh

Psoas Major M: Innervation

Branches of lumbar plexus (L2–L3)

Quadratus lumborum M: Origin

Iliac crest

Quadratus lumborum: Insertion

12th rib; transverse processes of lumbar vertebrae

Quadratus lumborum M: Action

• Bilateral action: Extends vertebral column

• Unilateral action: Laterally flexes vertebral column

Quadratus lumborum M: Innervation

Thoracic and lumbar spinal nerves

Coccygeus M: Origin

Ischial spine

Coccygeus M: Insertion

Lateral and inferior borders of sacrum

Coccygeus M: Action

Forms pelvic floor and supports pelvic viscera

Coccygeus M: Innervation

Spinal nerves (S4–S5)