• Jon Cornwall and Ewan Kennedy.
• Departments of Anatomy and Physiology, University of Otago, PO Box 913, Dunedin, New Zealand, jon.cornwall@otago.ac.nz.
• Eur Spine J. 2015 Sep 1;24(9):1986-91.

PurposeThe anterior and lateral cervical muscles (ALCM) are generally considered to be postural, yet few studies have investigated ALCM fiber types to help clarify the function of these muscles. This study aimed to systematically investigate ALCM fiber types in cadavers.MethodsAnterior and lateral cervical muscles (four scalenus anterior, medius, posterior muscles; five longus colli, five longus capitis taken bilaterally from one cadaver) were removed from four male embalmed cadavers (mean age 87.25 years). Paraffin-embedded specimens were sectioned then stained immunohistochemically to identify type I and II skeletal muscle fibers. Proportional fiber type numbers and cross-sectional area (CSA) occupied by fiber types were determined using stereology (random systematic sampling). Results were analyzed using ANOVA (P < 0.05) and descriptive statistics.ResultsScalenus anterior had the greatest average number and CSA of type I fibers (71.9 and 83.7%, respectively); longus capitis had the lowest number (48.5%) and CSA (61.4%). All scalene muscles had significantly greater type I CSA than longus capitis and longus colli; scalenus anterior and medius had significantly greater type I numbers than longus capitis and longus colli. Some significant differences were observed between individual cadavers in longus colli for CSA, and longus capitis for number.ConclusionThe ALCM do not share a common functional fiber type distribution, although similar fiber type distributions are shared by longus colli and longus capitis, and by the scalene muscles. Contrary to conventional descriptions, longus colli and longus capitis have type I fiber proportions indicative of postural as well as phasic muscle function.

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