Patients who present with complaints of neck and/or shoulder pain often state that one of their most pain provoking activities is raising their arm overhead. The shoulder abduction test helps us to determine if the patient has a normal or abnormal scapulo-humeral rhythm and to determine if their scapular stability is compromised when they raise their arm overhead. This test, if abnormal, may also indicate that the patient has abnormal neurobiomechanics with involvement of the brachial plexus. If this is the case the patient may hold their shoulder in an elevated position even when at rest and side bend their head to the ipsilateral side during the shoulder abduction test in an attempt to diminish tension on the plexus.

Anatomy and Biomechanical Considerations:

Normally during shoulder abduction the scapula upwardly rotates around an AP axis, posteriorly tilts around a horizontal axis running along the spine of the scapula and externally rotates around a vertical axis (Ludewig et al., 1996). This three-dimensional movement of the scapula occurs as a result of a force couple between the lower trapezius muscle working in tandem with the serratus anterior. If either of these muscles should become inhibited/weak then normal scapular mobility and stability is compromised.

According to Janda (1990) shoulder abduction also requires activation of the contralateral quadratus lumborum as part of the shoulder abduction muscle firing sequence. This would appear to be especially important at approximately 120 degrees of abduction, when the weight of the movement arm must be counterbalanced. Palpation of the quadratus lumborum during unilateral shoulder abduction is used to assess the appropriate firing of this muscle as part of the shoulder abduction test. In a dysfunctional test we often find that the ipsilateral rather than the contralateral QL will fire making it difficult for the patient to elongate that side of the trunk during abduction of the arm and result in compensatory superior translation of the scapula. Excessive superior translation of the scapula has been found in subjects with shoulder impingement (Lukasiewicz et al., 1999). Ipsilateral FRS dysfunctions at T12,L1 are most often the cause of hypertonicity in the quadratus lumborum and therefore must be looked for and treated, when present, before considering to stretch this muscle. A muscle energy technique to address the FRS dysfunction will often result in normalizing the tone of the ipsilateral quadratus and restore the ability of the contralateral quadratus to fire normally during shoulder abduction.

Considering the effect that dysfunction of the postural muscles, as described by Janda in the Upper Crossed Syndrome, can have upon scapular mechanics during shoulder abduction, we look for and most often treat the following:

1. Hypertonicity of the levator scapula and pectoralis minor that restricts posterior tilt of the scapula.
2. Hypertonicty of the levator scapula and upper trapezius that restricts upward rotation of the scapula.
3. Hypertonicity of the pectoralis minor that restricts external rotation of the scapula.
4. Hypertonicity of the ipsilateral quadratus lumborum that forces substitution by the upper trapezius and levator scapula resulting in excessive superior translation of the scapula.