Muscles of Abdominal Wall

Question 0

Pyramidalis

Answer 0

Small triangular muscle that lies in the rectus sheath anterior to the inferior part of the rectus abdominis - absent in 20% of people

Question 1

Linea alba

Answer 1

Extends from the xiphoid process to the pubic symphysis

Question 2

Rectus sheath

Answer 2

Encloses the rectus abdominis muscles and is formed by the interlaced aponeuroses of the flat abdominal muscles

Question 3

What are the three flat abdominal muscles?

Answer 3

External oblique, internal oblique, and transverse abdominis

Question 4

What are the two vertical muscles?

Answer 4

Rectus abdominis and the pyramidalis

Question 5

Arcuate line

Answer 5

Demarcates the transition between the posterior rectus sheath covering the superior three quarters of the rectus abdominis proximally and the tranversalis fascia covering the inferior quarter - and sits posterior to rectus abdominis

Question 6

Cremaster muscle

Answer 6

Formed by the lowest fascicles of the internal oblique muscle arising from the inguinal ligament - draws the testis superiorly in the scrotum when it is cold and relaxes to descend the testis deeply in the scrotum when it is warm - innervated by the genital branch of the genitofemoral nerve (L1,L2)

Question 7

Rectus sheath superior to umbilicus (arcuate line)

Answer 7

• External oblique - front and back fascia go anterior to the rectus abdominis
• Internal oblique - front fascia goes to the anterior side and back fascia goes to the posterior side of the rectus abdominis
• Transverses abdominis - front and back fascia go posterior to the rectus abdominis

Question 8

Rectus sheath inferior to umbilicus (arcuate line)

Answer 8

All abdominal muscle fascias run anterior to rectus abdominis and transversalis fascia stays posterior

Question 10

Transversalis fascia

Answer 10

Lines the transverse abdominis

Question 11

What are the nerves of the anterior abdominal wall?

Answer 11

Thoracoabdominal nerve (anterior rami of T7-T11) which branch into the anterior and lateral cutaneous branches, subcostal nerve (anterior rami of T12), and iliohypogastric and ilioguinal nerves (anterior rami of L1) and spinal nerve T11

Question 12

Dartos muscle

Answer 12

Assists in testicular elevation as it produces contraction of the skin of the scrotum