The scalene reflex: relationship between increased median or ulnar nerve pressure and scalene muscle activity.

Neck pain, headaches, upper thoracic pain, and dystonic scalene muscles are common findings in patients who have severe entrapment neuropathies of the upper extremities. This problem was taken to the laboratory in an attempt to discover the correlation between distal entrapment neuropathies, brachial plexus entrapments, and prominent scalenus muscles. When increased pressure (over 40 mmHg) was applied to the median and ulnar nerves in the forelimbs of eight goats, increased electromyographic activity was noted in the ipsilateral scalenus muscle.