The abdominal muscles are a group of muscles that form the abdominal wall. The abdominal wall is divided into the anterolateral and posterior wall.
There are five sets of anterolateral abdominal muscles. From superficial to deep, they are:
- Rectus abdominis muscle
- External abdominal oblique muscle
- Internal abdominal oblique muscle
- Transverse abdominis muscle
- Pyramidalis muscle (present only in 80% of individuals)
The posterior abdominal wall consists of just three components:
- Quadratus lumborum muscle
- Iliopsoas muscles (composed of iliacus and psoas major muscles)
- Psoas minor muscle
The rest of the posterior abdominal wall is reinforced by the muscles of the back.
All of these muscles are paired, meaning that they can contract only from the one side of the body (unilateral contraction) or both (bilateral contraction). Bilateral contraction supports the trunk and increases the internal abdominal pressure, whereas unilateral movement bends and rotates the trunk. They are also involved in breathing, balance, supporting overall physical integrity of the body, as well as bowel and bladder control.
Read the articles in this section to learn about the topic with interactive diagrams of the abdominal wall muscles functions.