At the lateral side of the abdomen there is a dotted line passing through the abdominal wall. Note the layers must pass through to get to the peritoneal cavity:
1. skin
2. superficial fascia (this may be as thin as or less than a half inch or as thick as 6 inches or more)
3. deep fascia (all skeletal muscle is surrounded within its own deep fascia). The deep fascia of the abdominal wall is different than that found around muscles of the extremities, however. It is of the loose connective tissue variety. It is necessary in the abdominal wall because it offers more flexibility for a variety of functions of the abdomen. At certain points, this fascia may become aponeurotic and serve as attachments for the muscle to bone or to each other, as is the case at the linea alba.
4. subserous fascia also known at extraperitoneal fascia (a layer of loose connective tissue that serves as a glue to hold the peritoneum to the deep fascia of the abdominal wall or to the outer lining of the GI tract. It may receive different names depending on its location (i.e. transversalis fascia when it is deep to that muscle, psoas fascia when it is next to that muscles, iliac fascia, etc.)
5. peritoneum (a thin one cell thick membrane that lines the abdominal cavity and in certain places reflects inward to form a double layer of peritoneum) Double layers of peritoneum are called mesenteries, omenta, falciform ligaments, lienorenal ligament, etc.)
--At the anterior wall of the abdomen, in the midline there is no muscle.
--If we look at the wall inferior to the level of the belly button (umbilicus), you will see that the superficial fascia has become divided into 2 parts:
* a superficial fatty part that is continuous with the same layer over the rest of the body (Camper's fascia)
* a deep membranous layer that is continuous down into the perineum to surround the penis and to form a layer of the scrotum. (Scarpa's fascia)