The external oblique muscle refers to a paired muscle found on each side of the abdomen, which plays a crucial role in the musculoskeletal system. It is part of the larger group of abdominal muscles and is considered one of the superficial muscles located closest to the surface.
The external oblique muscle originates from the external surfaces of the lower eight ribs and extends diagonally downward towards the midline. At the midline, the muscle forms a broad, flat tendon called the linea alba, which runs vertically along the abdomen. The muscle then attaches to the iliac crest, a curved ridge on the pelvis, as well as to the pubic bone.
The primary function of the external oblique muscle is to assist in various movements of the trunk. When both sides contract simultaneously, they flex and compress the abdomen, offering support to the viscera and helping to stabilize the spine. Furthermore, when only one side contracts, it allows for lateral flexion and rotation of the trunk. This muscle also aids in forced expiration, alongside the internal oblique and transversus abdominis muscles.
The external oblique muscle is innervated by the lower intercostal nerves and the subcostal nerve, which are branches of the thoracic spinal nerves. Its blood supply is derived from the lower intercostal arteries and the lumbar arteries.
Overall, the external oblique muscle is essential for a range of movements and contributes to maintaining abdominal stability, protecting internal organs, and promoting efficient respiration.
