Muscles of the Anterior & Laterl Abdominal Wall

Question 1

What are the rectus abdominis?

Answer 1

Medial superficial muscles originating at pubic crest and symphysis inserting in xiphoid process and costal cartilage of ribs 5-7.
Ensheathed by aponeuroses of lateral muscles w/ 3 segmented, tendinous intersections.
Action: flex and rotate lumbar region if vertebral column.

Question 2

What is the external oblique?

Answer 2

Largest and most superficial lateral abdominal, fibers run inferiorly and medially, aponeurosis turns under inferiorly and forms inguinal ligament.
O- direct from outer surface of lower 8 ribs.
I- linea alba via broad aponeurosis, pubic crest, tubercule, and illiac crest.
Action: flex vertebral column and compress abdominal wall, aid back muscles in trunk rotation and lateral flexion.

Question 3

What is the internal oblique?

Answer 3

Deep to external oblique, fibers run in a fan following the illiac crest.
O- lumbar fascia, illiac crest, and inguinal ligament.
I- linea alba, pubic crest, last 3-4 ribs, and costal margin.
Action: flex certebral column and compress abdominal wall. Aids back muscles in trunk rotation and lateral flexion.

Question 4

What is the transverse abdominis?

Answer 4

Deepest abdominal muscle w/ horizontal fibers.
O- inguinal ligament, lumbar fascia, cartilages of last 6 ribs, and iliac crest.
I- linea alba and pubic crest.
Action: compresses abdominal contents.