Muscles of the Abdominal Wall

Question 1

Rectus Abdominis

Answer 1

Origin: Pubis crest and smphysis
Insertion: xiphoid process and costal cartilages of ribes 5-7
Action: flexes and rotates lumbar region of vertebral column; fixes and depresses ribs, stabilizes pelvis during walking, increase intra-abdominal pressure; used in sit-ups, curls
Innervated by the intercostal nerves T7-T12

Question 2

External Oblique

Answer 2

Origin: Fleshy strips from outer surfaces of lower 8 ribs
Insertion: Most insert into the linea alba, some into the pubic crest and tubercle and iliac crest
Action: Flex vertebral column and compresses abdominal wall, aids rectus abdominis in flexing and rotating spine
Innervated by the intercostal nerves T7-T12

Question 3

Internal Oblique

Answer 3

Origin: lumbodorsal fascia, iliac crest, and inguinal ligament
Insertion: Linea alba, pubic crest, last 3 ribs, and costal margin
Action: Flex vertebral column and compresses abdominal wall, aids rectus abdominis in flexing and rotating spine
Innervated by the intercostal nerves T7-T12 & L1

Question 4

Transverse Abdominal

Answer 4

Origin: Inguinal ligament, lumbodorsal fascia, cartilages of last 6 ribs, iliac crest
Insertion: linea alba, pubic crest
Action: Compresses abdominal contests
Innervated by the intercostal nerves T7-T12 & L1