The serratus anterior is a ridge-shaped muscle that originates on the upper eight or nine ribs and is inserted on the medial and anterior border of the scapula. The serratus anterior gets its name from its appearance and location: It has jagged edges, like the serrations of a knife, and is located on the front (anterior) of the body. Because of its shape, the muscle is often confused for the ribs, and is most visible on bodybuilders. The muscle is innervated by the long thoracic nerve, which travels inferiorly on the surface of the muscle.
Action
The primary action of the serratus anterior is protraction and upward rotation of the scapula. The muscle is nicknamed "the boxer's muscle" because it moves the scapula in the same motion that occurs when throwing a punch. The serratus anterior also holds the scapula close to the rib cage to assist in abduction of the arm and acts as an accessory muscle of respiration.
Winged Scapula
With a "winged scapula," the scapula no longer lies flat against the back. Instead, the medial (pointy) side sticks out from the body, like a chicken wing. The winged scapula is not in itself a condition, but the symptom of another problem. One of the most common causes of a winged scapula is damage to the long thoracic nerve that innervates the serratus anterior. When determining the cause of a winged scapula, doctors use the wall test to diagnose long thoracic nerve injury. With the wall test, the patient stands, facing a wall, about two feet away, and pushes against the wall with flat palms at waist level. If one of the scapulas pops out, it means the serratus anterior is no longer able to hold the scapula flat--a possible sign of long thoracic nerve damage.
Symptoms of Serratus Anterior Dysfunction
Symptoms of serratus anterior dysfunction usually present as pain just below the axillary (armpit) area. There may also be pain in the side and mid back at the lower end of the shoulder blade. Because the serratus anterior acts as an auxillary breathing muscle, many patients also experience pain while taking both normal and deep breaths. Serratus anterior dysfunction also affects the muscles in the neck, like the scalene and sternocleidomastoid, resulting in dizziness, jaw pain, headaches and other myofacial symptoms.
Self-Treatment for Serratus Anterior Dysfunction
Trigger point therapy is an effective self-treatment for serratus anterior dysfunction. The trigger point is located on the most prominent rib, approximately three finger widths down from the armpit. In most cases, the trigger point will be the area of most tenderness on the muscle and will be unpleasant to touch. However, it is possible for trigger points to appear on all nine of the ribs to which the muscle attaches. If pressing one point does not relieve the pain, you may need to try a different point. It doesn't take a lot of pressure to relieve a trigger point, but it may require several minutes. The best option is to lean against a tennis ball, against a wall, or hold the ball in your hands. Self-massage of the serratus anterior muscles will also relieve pain from serratus anterior dysfunction.
Strengthening the Serratus Anterior
Motions that mimic the action of the serratus anterior will also strengthen the muscle. Dumbbell exercises like the incline shoulder press and incline shoulder raise both strengthen the muscle through its full range of motion. Yoga hand stands also condition the serratus anterior in addition to the other muscles that stabilize the scapula.
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