External abdominal oblique muscle

External abdominal oblique muscle

The External Abdominal Oblique Muscle is a large, thin, muscular layer forming part of the lateral walls of the abdomen. It is one of the outermost abdominal muscles, extending from the lower ribs to the pelvis. Its primary function is to assist in the rotation and lateral flexion of the trunk and to help maintain abdominal pressure.

Anatomy

The External Abdominal Oblique Muscle originates from the outer surfaces of the 5th to the 12th ribs. Its fibers run diagonally downward and medially, inserting into the linea alba, pubic tubercle, and the anterior half of the iliac crest. The lower fibers interdigitate with the Internal Abdominal Oblique Muscle, forming the conjoint tendon, which attaches to the pubic bone.

Function

The main functions of the External Abdominal Oblique Muscle include:

• Rotation of the trunk: When the muscle on one side contracts, the trunk rotates to the opposite side.
• Lateral flexion of the trunk: It aids in bending the trunk to the same side when the muscles on one side contract.
• Support and compression of abdominal viscera: It helps in increasing intra-abdominal pressure, which is essential for functions such as defecation, urination, and childbirth.

Clinical Significance

Injuries to the External Abdominal Oblique Muscle can occur due to overuse, sudden twists, or direct impacts. Symptoms may include pain, swelling, and a decrease in the strength of trunk rotation or lateral flexion. Treatment typically involves rest, ice, compression, and physical therapy.

Hernias, particularly inguinal hernias, can also involve the External Abdominal Oblique Muscle. A weakness in the muscle wall can allow abdominal contents to protrude, requiring surgical intervention for repair.

See Also

• Abdominal muscles
• Internal Abdominal Oblique Muscle
• Transversus Abdominis Muscle
• Rectus Abdominis Muscle