Front and posterior abdominal wall muscles
General information
The anterior and posterior abdominal wall muscles are composed of the anterior, straight (M. rectus abdominis and M. pyramidalis) and the posterior, deep (M. quadratus lumborum and M. psoas major) abdominal wall muscles. The M. psoas major forms together with the M. iliacus the M. iliopsoas. Only the M. psoas major belongs topographically to the posterior abdominal wall muscles. Functionally, the M. psoas major belongs to the hip muscles.
The most important functions of the abdominal wall muscles are the movement of the trunk, the stabilization of the spine and the tension of the abdominal wall. They belong to the expiratory auxiliary breathing muscles and support breathing by pulling the thorax downwards through their movement. By increasing the intraabdominal pressure, they enable the so-called abdominal press.
A schematic drawing of the muscles (M. rectus abdominis, M. pyramidalis, M. quadratus lumborum and M. iliopsoas) can be displayed by clicking on the respective name in the "WebViewer".
Front, straight abdominal wall muscles
| M. rectus abdominis | M. pyramidalis | |
| origin | cartilage of the 5th-7th rib; processus xiphoideus of the sternum | pubic bone (ventral at the insertion of the M. rectus abdominis) |
| insertion | pubic bone (between tuberculum pubicum and symphysis) | Linea alba (runs inside the rectus sheath) |
| function | Ventral flexion, straightening of the pelvis, abdominal pressure, exhalation | Tensioning the Linea alba |
| innervation | Nervi intercostales (Th5-12) | Nervus subcostalis (Nervus intercostalis 12) |
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Back, deep abdominal wall muscles
| M. quadratus lumborum | M. iliopsoas: M. psoas major and M. iliacus | |
| origin | Crista iliaca | M. psoas major: surface layer: Lateral surfaces of the 12th thoracic vertebral body, the 1st-4th thoracic vertebral body. Lumbar vertebral body and the corresponding disci intervertbrales deep layer: processi costarii of the 1st-5th lumbar vertebra M. iliacus: fossa iliaca |
| insertion | 12th rib, rib extensions of the 1st-4th lumbar vertebra | together as M. iliopsoas on trochanter minor of Os femoris |
| function | in the case of one-sided contraction, lateral flexion of the trunk to the same side occurs in the case of bilateral contraction, it serves the abdominal press and exhalation |
flexion and external rotation of the hip joint in case of one-sided contraction (punctum fixum at the femur): lateral flexion of the lumbar spine to the same side in case of bilateral contraction: enables the trunk to be straightened from the supine position |
| innervation | Nervus subcostalis and branches of Plexus lumbalis | direct branches from the Plexus lumbalis and Nervus femoralis (Th12-L4) |
Further links
