Lumbar Muscles

Question 1

Rectus Abdominis

Answer 1

Origin: pubic crest & pubic symphysis
Insertion: ribs 5-7
Function: Flexion & lateral flexion of the trunk
Innervation: Intercostal nerves

Question 2

External Abdominal Oblique

Answer 2

Origin: Anterior Iliac crest, inguinal ligament
Insertion: ribs 5-12
Function: Flexion & lateral flexion & rotation of the trunk
Innervation: Intercostal nerves

Question 3

Internal Abdominal Oblique

Answer 3

Origin: Iliac crest, inguinal ligament
Insertion: rib 10-12 & rectus sheath
Function: Flexion, lateral flexion, rotation of the trunk
Innervation: Intercostal nerves

Question 4

Transversus Abdominis

Answer 4

Origin: Iliac crest, inguinal ligament, rib 7-12
Insertion: Midline abdominal aponeurosis
Function: compression/stabilization of the abdomen
Innervation: Intercostal nerves

Question 5

Rotatores

Answer 5

Origin: TP of C4-L5
Insertion: SP of vertebrae above
Action: Extension & lateral flexion & extension of the trunk
Innervation: Dorsal Rami Spinal nerve

Question 6

Quadratus Lumborum

Answer 6

Origin: Posterior Iliac crest, iliolumbar ligament
Insertion: rib 12 & TPs L1-L4
Function: Elevation of pelvis, lateral flexion of trunk, depression of rib 12, extension of L-spine
Innervation: Lumbar plexus (T12-L3)