Splenius Capitis Muscle Syndrome
by Edwin A. Ernest III, DMD, FAANaOS and Mark W. Ernest, BA.
 This article describes a very painful and commonly occurring pain
syndrome associated with the splenius capitis muscle insertion. This syndrome was first
described in the 1980’s by this author. The onset of pain is often caused by motor
vehicular trauma, blunt trauma, falls, and, in particular, postural situations where
superior and inferior lateral oblique movements of the head on the neck occur. This type
of excessive repetitive movement can cause an overuse injury where small focal,
degenerative changes in the insertion fibers can occur. This is, in practical terms,
similar to the histopathologic process of insertion tendinosis seen at other narrow bony
processes. Bony processes include the mandibular coronoid process tip,1 and the
greater cornu of the hyoid bone,2 as described by this author in other articles
demonstrating photomicroscopic evidence of degenerative change in insertion fibers.
Anatomy
Gray3 describes the origin of the splenius capitis muscle to begin on the spinous
processes of vertebrae from C-7 to T-3 and the ligamentum nuchae. The insertion extends
from the medial edge of the mastoid process and the lateral part of the superior nuchal
line. Dissection of the insertion area shows the splenius capitis lying under the triangle
formed by the trapezius and sternocleidomastoid muscles (see Figure 1). The nerve supply
to the splenius capitis is provided by lateral branches of the posterior rami of the
middle and lower cervical spinal nerves.
Function
Bilaterally, the splenius capitis muscles extend and hyper-extend the head and neck.
However, acting unilaterally, the muscle flexes and rotates the head and neck to the same
side; particularly in the superior and inferior lateral oblique movements. The muscle can
be felt to tighten in the mandibular protrusive movement and in the wide opening movement
of the lower jaw. The dynamic relationship of the cranio-cervico-mandibular-hyoid
musculature is perhaps one of the most complex inter-relationships of muscle groups in the
human body.
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— Jul/Aug 2006
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