ANTERIOR ABDOMINAL WALL MUSCLES

Question 1

External oblique muscle

Answer 1

• Origin: lower 8 ribs
• Insertion: Xiphoid process, linea alba, symphysis
  pubis, pubic tubercle, anterior half of iliac crest

N:lower six thoracic nerves

A:(unilateral contraction of) do lateral rotation and flexion of the trunk

Question 2

Internal oblique muscle

Answer 2

Origin: Lumbar fascia, anterior 2/3 of iliac crest, lateral 2/3 of inguinal ligament.

• Insertion: Lower 3 ribs & their costal cartilages, xiphoid process, linea alba, symphysis pubis, through conjoint tendon to body of pubis.

N:lower six thoracic nerves,iliohypogastric & ilioinguinal nerves

A:(unilateral contraction of) do lateral rotation and flexion of the trunk

Question 3

Transversus abdominis muscle

Answer 3

• Origin: Lower 6 costal cartilages, lumbar fascia, anterior 2/3 of iliac crest and lateral 1/3 of inguinal ligament.
• Insertion: Xiphoid process, linea alba & symphysis pubis, through conjoint tendon to body of pubis.

N:lower six thoracic nerves,iliohypogastric & ilioinguinal nerves

A: Compresses and supports abdominal viscera

Question 4

Rectus abdominis muscle

Answer 4

• Origin: body of pubis
• Insertion: Xiphoid process, 5 – 7costal cartilages

N:lower six thoracic nerves

A:When the thoracic cage is fixed in supine position, rectus abdominis causes tilting upwards of the pelvis.
-flexes the trunk anteriorly against resistance or against gravity from supine position.

Question 5

Pyramidalis muscle

Answer 5

• Usually absent
• Origin: Anterior surface of pubis
• Insertion: Linea alba
  N: Subcostal nerve
  A: Tenses linea alba

Question 6

ACTION OF ALL MUSCLES

Answer 6

Contraction assists diaphragm to increase the intra-abdominal pressure, by keeping the wall in a fixed position.