Muscles of the Abdominal Wall

There are five pairs of muscles that form the abdominal wall.

The main function of these paired muscles is to form the strong muscular anterior wall of the abdominal cavity.

Other major anterior trunk muscles include the following:

Muscle	Origin	Insertion	Action
Rectus Abdominis	Pubis and the Pubic Symphysis	Xiphoid process of the sternum Costal cartilages 5-7	Flexes the trunk

Muscle	Origin	Insertion	Action
External Abdominal Oblique	Lower 8 ribs	Linea alba Pubic crest & tubercle Anterior superior iliac spine Anterior half of iliac crest	Flexes and laterally bends the trunk

Muscle	Origin	Insertion	Action
Internal Abdominal Oblique	Thoracolumbar fascia Anterior 2/3 of the iliac crest Lateral 2/3 of the inguinal ligament	Lower 3 or 4 ribs Linea alba Pubic crest	Flexes and laterally bends the trunk

Muscle	Origin	Insertion	Action
Transversus Abdominis	Lower 6 ribs Thoracolumbar fascia Anterior 3/4 of the iliac crest Lateral 1/3 of inguinal ligament	Linea alba Pubic crest Pecten of the pubis	Flexes and laterally bends trunk

Muscle	Origin	Insertion	Action
Quadratus Lumborum	Posterior part of the iliac crest Iliolumbar ligamen	Transverse processes of lumbar vertebrae 1-4 12th rib	Laterally bends the trunk Fixes the 12th rib