Scapular winging is a rare condition sometimes caused by nerve injury or another disorder affecting the shoulder. Any overhead arm movement requires scapular motion so that the socket can move along with the ball of the shoulder joint, facilitating the smooth rhythm of normal shoulder movement. The coordinated contraction of the muscles that move the scapula pull it along the chest wall so that it tilts up and away from the chest when the arm is raised from the side to above shoulder level. This unconscious rhythmic movement is analogous to the motion of a seal’s nose beneath a ball, keeping it balanced in the air.
What does the inside of the shoulder look like?
The scapula is a triangular shaped bone on the upper back that forms the socket of the ball and socket joint of the shoulder. It is also the attachment for all the rotator cuff muscles.
What is winging of the shoulder?
When the muscles that move the scapula, do not work together correctly, raising the arm moves the scapula in an abnormal direction, resulting in scapular winging. The weight of the arm pushing back on the scapula causes this winging effect. Usually paralysis of the long thoracic nerve (which goes to the serratus anterior muscle) is responsible for this disorder.
Although there is no clear cause of shoulder winging in approximately half of all cases, some recognized causes of this condition include:
trauma
viral infection
stretch injury from lifting
malfunction of the trapezius muscle, which extends from the base of the neck to the shoulder, involving paralysis of the spinal accessory nerve. This can occur as the result of compression by a seat belt shoulder harness in an automobile accident. Surgery to remove a lymph node from the neck can also sometimes injure the spinal accessory nerve.
