The above photograph shows the subject's inability to raise the arm overhead when both the serratus and trapez-ius are paralyzed. The winging of the medial border of the scapula makes it appear that the rhomboids were weak even though, in fact, they were not. (See photo at right.)
The above photograph shows the abnormal position of the right scapula that results from a paralysis of both the trapezius and serratus anterior. The acromial end is abducted and depressed. The inferior angle is rotated medially and elevated. The rhomboids were strong.
PARALYZED RIGHT TRAPEZIUS AND NORMAL SERRATUS
Raising the arm sideways (in the coronal plane) requires abduction of the shoulder joint, accompanied by upward rotation of the scapula in an adducted position. With paralysis of the trapezius, the scapulae cannot be rotated in the adducted position. Hence, the movement of shoulder abduction is limited, as seen in the photograph at left above.
Raising the arm forward (in the sagittal plane) requires that the scapula upwardly rotate in the abducted position. With an intact serratus, the arm could be raised higher in flexion than in abduction, as seen in the photograph at right above.
With a weak serratus and strong trapezius, the arm could be raised higher in abduction than in flexion.
During a time of hospital affiliation, the Kendalls examined and treated numerous cases of serratus anterior paralysis. Depending on the etiology, some patients had pain associated with the paralysis, but not in the area of the muscle itself. Additionally, some patients did not complain of pain before, during, or for a while after the onset of paralysis. Early complaints were about the inability to use the arm normally. In some cases, when the onset was gradual, patients made no complaints until weakness became more and more pronounced. When the effects of serratus weakness created secondary problems involving other structures, patients complained of pain or discomfort in areas other than that of the serratus muscle, such as the neck or shoulder. Significant to such history is the fact that the long thoracic nerve to the serratus is purely motor. (See p. 252; see also Appendix B)
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