The deep cervical extensors and the deep cervical flexors can in partnership control segmental movements in the cervical spine. Little knowledge has however been gained of the extensor muscles in patients with neck disorders.
Structural changes are found in the extensor muscles, include fatty tissue infiltration in whip-lash patients, however not in patients with insidious-onset neck pain. A transformation of type 1 to type II fibres has been observed, independent of neck pathology. These factors are attributed to disuse, chronic denervation (nerve irritation or compression), functional adaption to altered activity (from pain or fear of movement), facet joint (spinal joints) trauma and involvement of the sympathetic nervous system (flight, fright , fight nervous system).
Superficial cervical extensors show increased activation and delayed relaxation after activity, however deep extensor muscles have displayed reduced activation and less activity in multidirectional isometric (where there is no movement of the body) contractions, thereby less defined activation. Magnitude of pain and muscle activation seems to be related. Higher pain levels are associated with reduced strength.
Other factors that may have an influence include psychological distress, fear avoidance behaviour and general disuse. Activation of the deep cervical extensors should be emphasized at selected spinal levels for the management of such dysfunction.
From: Schomacher & Falla, Manual Therapy 18 (2013) pg 360-366.
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