OBJECTIVE: The aim of the study was to compare the dimensions of cervical multifidus muscle (CMM) in different conditions.

METHODS: Twenty five women with neck pain and 25 healthy subjects participated in this study. The dimensions of the CMM were measured at rest, 50% and 100% maximum isometric voluntary contraction (MIVC) at six directions of neck movements, using ultrasonography.

RESULTS: The size of multifidus was smaller in patients than healthy individuals at rest state (P < 0.05). A significant smaller CMM dimension was found in the affected side compared with unaffected side in patients group (P < 0.05). The result of ANOVA for MLD showed a significant difference for contraction levels (P < 0.001) and neck movements (P < 0.001) in both groups. The MLD of the CMM was significantly different between CMM at rest and 50%, and 100% MIVC (P < 0.001). No significant differences were found between the groups at 50% and 100% MIVC (P > 0.05 in both instances). The most prominent CMM size change was observed during neck extension, flexion, ipsilateral lateral-flexion, and ipsilateral rotation, respectively (P < 0.05).

CONCLUSIONS: Results of the present study indicate that the size of CMM was decreased in patients with neck pain in rest state. The size of CMM changes in all directions of neck movements, although the most prominent was during neck extension. This points out CMM stabilization role's in different directions of neck movements.