Muscles of abdomen

Question 1

Cremaster (G. kremaster, a suspender)

Answer 1

Attachments: from the medial edge of the internal oblique to spermatic cord

Actions: elevation of testis

Innervation: genitofemoral n.

Blood supply: cremasteric a.

Question 2

Diaphragm

Answer 2

Attachments: from the xiphoid process, inner surface of the lower ribs & costal cartilages, medial & lateral arcuate ligaments & lumbar vertebrae via the crura to the central tendon

Actions: inspiration (negative thoracic pressure by inferior displacement)

Innervation: phrenic n.

Blood supply: musculophrenic, inferior phrenic, subcostal & lower posterior intercostal aa.

Question 3

External oblique

Answer 3

Attachments: from lower 8 ribs to iliac crest & rectus sheath

Actions: flexion & rotation of the trunk, & compression of the abdominal cavity

Innervation: ventral rami T7-12

Blood supply: superior & inferior epigastric, subcostal, lower posterior intercostal, lumbar, superficial & deep circumflex iliac aa.

Question 4

Internal oblique

Answer 4

Attachments: from thoracolumbar fascia to inguinal ligament, iliac crest & rectus sheath

Actions: flexion & rotation of the trunk, & compression of the abdominal cavity

Innervation: lower thoracic & L1 ventral rami

Blood supply: superior & inferior epigastric, subcostal, lower posterior intercostal, lumbar, superficial & deep circumflex iliac aa.

Question 5

Quadratus lumborum

Answer 5

Attachments: from 12^th rib to iliolumbar ligament & iliac crest

Actions: extension & lateral flexion of the trunk, and fixes 12^th rib during respiration

Innervation: ventral rami T12-L3

Blood supply: subcostal, lumbar & iliolumbar aa.

Question 6

Rectus abdominis

Answer 6

Attachments: from xiphoid process & adjacent costal cartilages to pubic crest & tubercle

Actions: flexion of trunk & compression of abdominal cavity

Innervation: lower thoracic ventral rami

Blood supply: superior & inferior epigastric aa.

Question 7

Transversus abdominis

Answer 7

Attachments: from lower six costal cartilages & thoracolumbar fascia to inguinal ligament, iliac crest & rectus sheath

Actions: compression of the abdominal cavity

Innervation: lower thoracic & L1 ventral rami

Blood supply: superior & inferior epigastric, subcostal, lower posterior intercostal, lumbar, & superficial & deep circumflex iliac aa.