6.1 Muscles of the Posterior Abdominal Wall

Question 1

Identify the psoas major, its attachments, function, and innervation.

Answer 1

• Attaches to lesser trochanter and transverse processes of lumbar vertebrae.
• Functions in flexion of the thigh, or lateral flexion (one sided contraction)
• Innervated by Lumbar plexus (ventral rami of L1-L4).

Question 2

Identify the medial abdominal hiatus and median arcuate ligament as well as the median and lateral arcuate ligaments.

Answer 2

Median arcuate ligament arches over abdominal aorta to form abdominal hiatus.
Medial arcuate ligament

Question 3

Identify the iliolumbar ligament.

Answer 3

a strong ligament passing from the tip of the transverse process of the fifth lumbar vertebra to the posterior part of the inner lip of the iliac crest

Question 4

Identify the left and right crura of the diaphragm.

Answer 4

The esophageal hiatus is found within the arching fibers of the right crus.

Question 5

Identify the caval foramen

Answer 5

IVC passageway

Question 6

Identify the central tendon of the diaphragm

Answer 6

Top of right and left crus which connect to top of diaphragm.

Question 7

Identify the psoas minor, its attachments, function, and innervation.

Answer 7

• Attaches and functions along with psoas major.

- Innervated by branch of L1

Question 8

identify the Quadratrus lumborum, its attachments, function, and innervation.

Answer 8

• Attaches from 12th rib and lumbar transverse processes.

- Functions in Extension (or lateral flexion if unilateral contraction).

Question 9

Identify the Iliacus, its attachments, function, and innervation.

Answer 9

• Ataches to Iliac fossa and lesser trochanter.
• Functions in flexion of the thigh or lateral flexion with bilateral contraction. Also hip stability.
• Innervated by Femoral nerve (L2-L4).