Session 1: Additional Resources

Question 1

Action, innervation, origin and insertion of external oblique.

Answer 1

Origin: External surfaces of 5th to 12th ribs.
Insertion: Linea alba, pubic tubercle and anterior half of iliac crest.

Innervated by inferior six thoracic nerves and subcostal nerve.

Compresses and supports abdominal viscera, flexes and rotates the trunk.

Question 2

Action, innervation, origin and insertion of internal oblique.

Answer 2

Origin: Thoracolumbar fascia anterior two thirds of iliac crest, and lateral half of inguinal ligament.
Insertion: Inferior borders of the 10th to 12th ribs, linea alba and pubis via conjoint tendon.

Innervated by anterior rami of inferior six thoracic nerves and 1st lumbar nerve.

Compresses and supports abdominal viscera; flexes and rotates the trunk.

Question 3

Action, innervation, origin and insertion of tranversus abdominis.

Answer 3

Origin: Internal surfaces of costal cartilages 7-12, thoracolumbar fascia, iliac crest, and lateral third of inguinal ligament.
Insertion: Linea alba with aponeurosis of internal oblique, pubic crest and pecten pubis via conjoint tendon.

Innervated by the anterior rami of inferior six thoracic nerves and 1st lumbar nerve (similar to internal oblique).

Compresses and supports the abdominal viscera.

Question 4

Action, innervation, origin and insertion of rectus abdominis.

Answer 4

Origin: Pubic symphysis and pubic crest.
Insertion: Xiphoid process and costal cartilages 5-7.

Innervated by the anterior rami of inferior six thoracic nerves.

Compresses abdominal viscera and flexes trunk.

Question 5

Difference between the rectus sheath above the arcuate line and below it. (in regards to rectus abdominis)

Answer 5

Above: Aponeurosis of external oblique passes anterior
Aponeurosis of internal oblique passes anterior and posterior
Aponeurosis of transverse abdominis passes posterior.

Below: Rectus abdominis is only supported posteriorly by transveralis fascia, extraperitoneal fat and peritoneum. The anterior is supported by all the aponeuroses of the muscles.

Question 6

What does the myenteric plexuses mainly control?

Answer 6

Motility of the gut

Question 7

What does the Meissner’s plexuses mainly control?

Answer 7

GI secretions and blood flow.

Question 8

How do the retroperitoneal viscera relate to the peritoneum?

Answer 8

They are only attached to the parietal peritoneum anteriorly.