A case of appedicitis

[Suvash]

A 45- year old man was admitted to the emergency department complaining of severe pain in the right lower quadrant of the anterior abdominal wall. He had repeatedly vomited, and his temperature and pulse rate were elevated. His history indicated that he had acute appendicitis and that the pain had suddenly increased. On examination, the muscles of the lower part of the anterior abdominal wall in the right lower quadrant showed rigidity. The diagnosis of peritonitis after perforation of the appendix was made.
The symptoms and signs displayed by this patient can be explained by the following facts except:

1. The perforation of the appendix had resulted in the spread of the infection from the appendix to involve the parietal peritoneum.
2. The parietal peritoneum in the right iliac region, the muscles of the anterior abdominal wall and the overlying skin are all supplied by the segmental nerves of T12 and L1.
3. Irritation of the parietal peritoneum reflexly increases the tone of the abdominal muscles causing rigidity.
4. The greater omentum tends to become stuck down to the appendix and restricts the spread of infection.
5. The pain was intensified after perforation of the appendix because of stimulation of the autonomic pain endings in the parietal peritoneum.

[Suvash]

The answer is
5. In the parietal peritoneum lining the anterior abdominal wall in the right iliac fossa, the sensation of pain originates in the nerve endings of somatic spinal nerves (T12 and L1).