Muscles for Exam 3

Question 1

Rectus Abdominis

Answer 1

Origin: Public symphysis and pubic crest
Insertion: Xiphoid process and 5th-7th costal cartilages
Innervation: Thoraco-abdominal nerves (T6-T12 spinal nerves)
Action: Flexes trunk and compresses abdominal viscera. Stabilizes and controls tilt of pelvis.

Question 2

External Oblique

Answer 2

Origin: External surface of ribs 5-12.
Insertion: Linea alba, pubic tubercle, anterior half of iliac crest
Innervation:Thoraco-abdominal nerves (T7-T12 spinal nerves) and subcostal nerve
Action: Compresses and supports abdominal viscera. Flexes and rotates trunk.

Question 3

Internal Oblique

Answer 3

Origin: Inguinal ligament, Iliac crest and the thoracolumbar fascia.
Insertion: Linea alba, Pectineal Line of Pubis (via Conjoint tendon) and ribs 10-12.
Innervation: Thoraco-abdominal nerves (anterior rami or T6-T12 spinal nerves) first lumbar nerve
Action: Compresses and supports abdominal viscera. Flexes and rotates trunk.