The muscles that form much of the structure of the posterosuperior abdominal wall are as follows (Figure 11-1):
is in close relationship with the parietal peritoneum, including that covering the right psoas muscle
. When the appendix is inflamed, the inflammation irritates the parietal peritoneum. The parietal peritoneum is innervated by somatic nerves, including pain fibers, and thus inflammation of the parietal peritoneum results in a “shooting” abdominal pain. To diagnose acute appendicitis, the physician will push on McBurney's point when the patient is in a supine position. If the patient suffers from acute appendicitis, the pain reflex will flex the hip joint.