Transversus abdominis muscle

Transversus abdominis muscle (or transverse abdominal muscle), is a muscle layer of the anterior and lateral (front and side) abdominal wall which is deep to (layered below) the internal oblique muscle. It is thought by most fitness instructors to be a significant component of the core.

Structure

The transversus abdominis muscle is located deep within the abdomen, underneath the oblique muscles. It is the deepest of the abdominal muscles and wraps around the abdomen between the lower ribs and the pelvis, functioning like a corset.

Origin and insertion

The muscle originates from the lateral third of the inguinal ligament, the anterior three-quarters of the inner lip of the iliac crest, the thoracolumbar fascia and the inner surfaces of the lower six costal cartilages. It inserts into the xiphoid process, the linea alba, and the pubic crest and pecten pubis via the conjoint tendon.

Nerve supply

The transversus abdominis is innervated by the lower six thoracic spinal nerves (T7-T12), the iliohypogastric nerve and the ilioinguinal nerve.

Function

The transversus abdominis helps to compress the ribs and viscera, providing thoracic and pelvic stability. The muscle has been shown to activate before any movement of the limbs occurs, suggesting a role in stabilization.

Clinical significance

A weak transversus abdominis has been linked to lower back pain, and strengthening exercises for this muscle may help alleviate it.

See also

• Abdominal exercise
• Rectus abdominis muscle
• Internal oblique muscle
• External oblique muscle

External links

• Diagram at ntu.edu.tw
• Diagram at dartmouth.edu