Dissection of anterior abdominal wall – posterior view
This specimen shows the muscles and the blood vessels of the anterior abdominal wall from the inner aspect.
The anterior abdominal wall is made up of flat muscles, namely the external oblique muscle, the internal oblique muscle and the transversus abdominis muscles. These muscles insert medially in the form of aponeurosis. The aponeurosis forms the rectus sheath which encloses a muscle known as the rectus abdominis. The arcuate line represents the lower limit of the rectus sheath. The inferior epigastric blood vessels are also seen in this specimen.
External oblique muscle:
The external oblique muscle is the superficial muscle of the anterior abdominal wall. Its fibres are directed downwards, forwards and medially. Its aponeurosis presents a few modifications, namely, the superficial inguinal ring, the inguinal canal and the rectus sheath.
Internal oblique muscle:
The internal oblique muscle is the intermediate muscle of the anterior abdominal wall. Its fibres are directed upwards, forwards and medially. Its aponeurosis forms the rectus sheath.
The transversus abdominis is the innermost muscle of the anterior abdominal wall. The fibres are directed transversely. Its aponeurosis forms the rectus sheath and also presents the deep inguinal ring for the passage of the spermatic cord.
The rectus sheath is a sheath which covers the rectus abdominis muscle. It consists of anterior and posterior layers. The layers are formed by the aponeurosis of the external oblique, internal oblique and transversus abdominis muscles.
The arcuate line represents the lower limit of the rectus sheath along its inner aspect.
Median umbilical fold:
The median umbilical fold is formed by the median umbilical ligament which is a remnant of the developing urinary bladder.
The rectus abdominis is a longitudinal muscle of the anterior abdominal wall. It is placed on either sides of the midline of the abdomen. It extends from the pubic bone to the lower ribs. It is made up of smaller units separated by the tendinous intersections. These units increase the strength of the anterior abdominal wall. It is supplied by the lower thoracic and the lumbar nerves.