LONGUS-COLLI HAS A POSTURAL FUNCTION ON CERVICAL CURVATURE

To determine the postural role of longus colli (LC) and dorsal neck mu scles, we have studied the relationship between their cross-sectional areas related to their force of contraction and the lordosis and the l ength of the cervical spine. This study was carried out in 36 healthy subjects. Muscle cross-sectional areas were measured by computerized t omography. The index of lordosis and the length of the cervical spine were measured on an X-ray profile. The cross-sectional area of LC was correlated to the lordosis index (R = -0.432, p < 0.02) whereas all th e other parameters were not correlated. The authors conclude that LC c ounteracts the lordosis increment related to the weight of the head an d to the concentration of the dorsal neck muscles. Postural functions of LC and postcervical muscles are complementary. They form a sleeve w hich encloses and stabilizes the cervical spine in all positions of th e head.