Abdominal muscles
Abdominal muscles cover the anterior and lateral abdominal region and meet at the anterior midline. These muscles of the anterolateral abdominal wall can be divided into four groups: the
Anterior abdominal wall
![](http://upload.wikimedia.org/wikipedia/commons/thumb/7/7c/1112_Muscles_of_the_Abdomen_Anterolateral.png/400px-1112_Muscles_of_the_Abdomen_Anterolateral.png)
There are three flat skeletal muscles in the antero-lateral wall of the abdomen. The external oblique, closest to the surface, extend inferiorly and medially, in the direction of sliding one’s four fingers into pants pockets. Perpendicular to it is the intermediate internal oblique, extending superiorly and medially, the direction the thumbs usually go when the other fingers are in the pants pocket. The deep muscle, the transversus abdominis, is arranged transversely around the abdomen, similar to the front of a belt on a pair of pants. This arrangement of three bands of muscles in different orientations allows various movements and rotations of the trunk. The three layers of muscle also help to protect the internal abdominal organs in an area where there is no bone.
Linea alba
The
Posterior abdominal wall
![](http://upload.wikimedia.org/wikipedia/commons/thumb/0/08/1112_Muscles_of_the_Abdomen_Posterior.png/300px-1112_Muscles_of_the_Abdomen_Posterior.png)
The posterior abdominal wall is formed by the
Functions
Movement | Target | Target motion direction | Prime mover | Origin | Insertion |
---|---|---|---|---|---|
Twisting at waist; also bending to the side | Vertebral column | Supination; lateral flexion | External obliques; internal obliques | Ribs 5–12; ilium | Ribs 7–10; linea alba; ilium |
Squeezing abdomen during forceful exhalations, defecation, urination, and childbirth | Abdominal cavity | Compression | Transversus abdominis | Ilium; ribs 5–10 | Sternum; linea alba; pubis |
Sitting up | Vertebral column | Flexion | Rectus abdominis | Pubis | Sternum; ribs 5 and 7 |
Bending to the side | Vertebral column | Lateral flexion | Quadratus lumborum | Ilium; ribs 5–10 | Rib 12; vertebrae L1–L4 |
Source text
This article incorporates text from a free content work. Licensed under CC BY 4.0. Text taken from Anatomy and Physiology, J. Gordon Betts et al, Openstax.