Muscles of the Abdomen

Question 1

External Abdominal Oblique

Answer 1

Origin - Lower 8 ribs
Insertion - Linea alba, pubic crest & tubercle, ASIS, & ½ of iliac crest
Action - Flexes and laterally bends the trunk
Innervation - lntercostal nerves 7-11, subcostal, iliohypogastric and ilioinguinal nerves
Artery - Musculophrenic a., superior epigastric a., intercostal aa. 7-11, subcostal
a. , lumbar aa., superficial circumflex iliac a., deep circumflex iliac a.,
superficial epigastric a., inferior epigastric a., superficial external
pudendal a.

Question 2

Internal Abdominal Oblique

Answer 2

Origin - Thoracolumbar fascia, anterior ½ of iliac crest, lateral ½ of inguinal ligament
Insertion - Lower 3 or 4 ribs, linea alba, pubic crest
Action - Flexes and laterally bends the trunk
Innervation - lntercostal nerves 7-11, subcostal, iliohypogastric and ilioinguinal nerves
Artery - Musculophrenic a., superior epigastric a. , intercostal aa. 7-11, subcostal
a., lumbar aa. , superficial circumflex iliac a. , deep circumflex iliac a.,
superficial epigastric a., inferior epigastric a., superficial external
pudendal a.

Question 3

Psoas Major

Answer 3

Origin - Bodies and TVPs of lumbar vertebrae
Insertion - Lesser trochanter of femur (with iliacus) via iliopsoas tendon
Action - Flexes thigh; flexes & laterally bends the lumbar vertebral column
Innervation - Branches of the ventral primary rami of L2-L4 spinal nerves
Artery Subcostal a., lumbar aa.

Question 4

Psoas Minor

Answer 4

Origin- Bodies of the T12 & L 1 vertebrae
Insertion - lliopubic eminence at the line of junction of the ilium and the superior pubic ramus
Action - Flexes & laterally bends the lumbar vertebral column
Innervation - Branches of the ventral primary rami of L 1-L2 spinal nerves
Artery Lumbar aa.

Question 5

Pyramidalis

Answer 5

Origin - Pubis, anterior to the rectus abdominis
Insertion - Linea alba
Action- Draws the linea alba inferiorly
Innervation - Subcostal nerve
Artery - Subcostal a., inferior epigastric a.

Question 6

Quadratus Lumborum

Answer 6

Origin - Posterior part of the iliac crest and the iliolumbar ligament
Insertion - TVPs of L 1-L4 and 12th rib
Action - Laterally bends the trunk, fixes the 12th rib
Innervation - Subcostal nerve and ventral primary rami of L 1-L4 spinal nerves
Artery - Subcostal a. , lumbar aa.

Question 7

Rectus Abdominis

Answer 7

Origin - Pubis and the pubic symphysis
Insertion - Xiphoid process of the sternum and costal cartilages 5-7
Action - Flexes the trunk
Innervation - lntercostal nerves 7-11 and subcostal nerve
Artery - Superior epigastric a., intercostal aa., subcostal a., inferior epigastric a.

Question 8

Transverse Abdominis

Answer 8

Origin - Lower 6 ribs, thoracolumbar fascia, anterior ¾ of the iliac crest, lateral ½ of inguinal ligament
Insertion - Linea alba, pubic crest and pecten pubis
Action - Flexes and laterally bends the trunk
Innervation - lntercostal nerves 7-11, subcostal, iliohypogastric and ilioinguinal nerves
Artery - Musculophrenic a. , superior epigastric a., intercostal aa. 7-11, subcostal
a., lumbar aa., superficial circumflex iliac a., deep circumflex iliac a.,
superficial epigastric a. , inferior epigastric a. , superficial external
pudenda! a.

Question 9

Coccygeus

Answer 9

Origin - lschial spine
Insertion - Side of coccyx and lower sacrum
Action - Elevates the pelvic floor
Innervation - Branches of the ventral primary rami of S3-S4 spinal nerves
Artery - Inferior gluteal a.

Question 10

lliococcygeus

Answer 10

Origin- Arcus tendineus levator ani and the ischial spine
Insertion - Anococcygeal raphe and the coccyx
Action - Elevates the pelvic floor
Innervation - Branches of the ventral primary rami of S3-S4 spinal nerves
Artery - Inferior gluteal a.

Question 11

Levator Ani

Answer 11

Origin - Posterior surface of the body of the pubis, fascia of the obturator internus m. (arcus tendineus levator ani), ischial spine
Insertion - Anococcygeal raphe and the coccyx
Action - Elevates the pelvic floor
Innervation - Branches of the ventral primary rami of S3-S4 spinal nerves
Artery - Inferior gluteal a.

Question 12

Pubococcygeus

Answer 12

Origin - Posterior aspect of the superior pubic ramus
Insertion - Coccyx
Action - Elevates the pelvic floor
Innervation - Branches of the ventral primary rami of S3-S4 spinal nerves
Artery - Inferior gluteal a.

Question 13

Puborectalis

Answer 13

Origin - Posterior aspect of the body of the pubis
Insertion - Unites with the puborectalis m. of other side posterior to the rectum
Action - Draws the distal rectum forward and superiorly; aids in voluntary retention
of feces
Innervation - Branches of the ventral primary rami of S3-S4 spinal nerves
Artery - Inferior gluteal a