Anterior Muscles Of The Abdomen

Front 1

External Oblique

Back 1

Origin: Inferior eight ribs

Insertion: Linea alba; iliac crest

Unilateral action: lateral rotation and flexion of spine; Bilateral action: flexion of trunk; forced exhalation

Front 2

Internal Oblique

Back 2

Origin: Inguinal ligament, iliac crest, thoracolumbar fascia

Insertion: Cartilage of last 4 ribs, linea alba

Unilateral action: rotation and flexion of abdomen and spine; Bilateral action: flexion of spine; forced exhalation

Front 3

Rectus Abdominis

Back 3

Origin: Pubic crest and pubic symphysis

Insertion: Cartilage of ribs 5, 6 and 7; xiphoid process

Function: Flexion and lateral rotation of vertebral column; depresses ribs-forced exhalatoin; compresses abdomen

Front 4

Transversus Abdominis

Back 4

Origin: Iliac crest; inguinal ligament thoracolumbar fascia; cartilage ribs 7-12

Insertion: Xiphoid process, linea alba; crest of pubis

Function: Compresses abdomen; forced exhalation

Front 5

Erector Spinae

Spinalis (medial), longissimus (intermediate) and iliocostalis (lateral)

Back 5

Origin: Spinous processes, transverse processes, and ribs from the occiput to the sacrum and ilium

Insertion: Spinous processes, transverse processes, and ribs from the occiput to the sacrum and ilium

Action: Bilaterally - Extend. Unilaterally - Lateral bend.