Behrsin and Maguire studied the levator scapulae muscle with electromyography and x-rays to determine it's activity and length during shoulder motion. They found that the levator scapulae contracts concentrically (shortens) during the first 90 degrees( of shoulder abduction and eccentrically (lengthens) during the second 90 degrees( of abduction. Eccentric activity, creates a greater force than concentric activity so that more force is exerted by the levator scapulae on the spine during the second 90 degrees( of shoulder abduction. The authors determined that at the higher ranges of abduction (over 90 degrees), there was increased compressive load on the cervical joints and discs with the tendency to laterally flex and rotate the spine ipsilaterally. They felt that stress on the cervical spine by the levator scapulae might create referred pain in the shoulder.
Fig. 1.Testing of the right levator scapulae for shortening. With permission from: Hammer W. Functional Soft Tissue Examination & Treatment by Manual Methods: New Perspectives, 2nd. ed., Gaithersburg, MD; Aspen Publishers, 1999.
It is very important in both shoulder and cervical spine problems to evaluate the upper trapezius and levator scapulae muscles, which have a tendency to shorten. Figure 1 depicts evaluation of the levator scapula for shortness.
If the levator scapulae was involved, it would probably contain trigger points and fascial barriers. The transverse processes of the upper four cervical vertebrae might be tender, as would the superior medial angle of the scapula.
I wonder if a functional test to determine this problem could be performed by having a seated patient abduct their shoulder 130 degrees( while they resist their head in an ipsilateral laterally-flexed, rotated position to contract the levator scapula.
- Behrsin JF, Maguire K. Levator scapulae action during shoulder movement: a possible mechanism for shoulder pain of cervical origin. Australian J of Physio 1986;32(2);101-106.
- Kahle W. Leonhardt H, Platzer W. Color Atlas/Text of Human Anatomy, Vol I: Locomotor System. New York: G.T. Verlag, 1991:142.
Click here for more information about Warren Hammer, MS, DC, DABCO.