Size and shape of the posterior neck muscles measured by ultrasound imaging: normal values in males and females of different ages

Significant gender differences were found (P<0.001) but muscle size did not alter significantly with age. Between-side symmetry can be used to assess abnormality of the deep neck muscle group but not semispinalis capitis. A regression equation is provided for predicting the cross-sectional area (CSA) of the deep neck muscles from spinous process length in males. Clinically, linear measurements can be used to predict the neck muscle CSAs (r=0.66-0.84, P<0.001). The method described for assessing the neck muscles is a potentially valuable tool in clinical practice.