Five muscles form the anterolateral group of the abdominal wall muscles, and they can be divided into two main groups - flat and vertical muscles.

There are three flat muscles with fibers beginning posterolaterally, passing anteriorly, and being replaced by an aponeurosis as the muscles continue toward the midline. These are the:

• External abdominal oblique muscle (read more)
• Internal abdominal oblique muscle (read more)
• Transversus abdominis muscle (read more)

There are two vertical muscles located near the midline and enclosed within a tendinous sheath formed by the aponeuroses of the flat muscles (known as the rectus sheath). These muscles are the:

• Rectus abdominis (read more)
• Pyramidalis (read more)
  

The linea alba is the fusion site of three pairs of abdominal anterolateral muscle aponeuroses. It is formed by the aponeuroses of the external and internal abdominal oblique muscles and transversus abdominis muscle. The linea alba stretches between the xiphoid process of the sternum and the pubic symphysis.