Cervical flexion, extension, protrusion, and retraction - A radiographic segmental analysis

Study Design. A lateral radiographic analysis of the cervical spine was per formed on 20 asymptomatic volunteers. Objectives. To quantify the contribution of each cervical segment to each o f four sagittal cervical end-range positions: full-length flexion, full-len gth extension, protrusion, and retraction. Summary of Background Data. Recent clinical research supports the relevance of cervical protrusion and retraction in symptomatic patients. Currently, few quantitative studies are available regarding cervical protrusion and re traction. Methods. Lateral cervical radiographs of 20 asymptomatic volunteers for fou r test positions and a neutral position were collected. Mean angular measur ements and available ranges of motion were calculated from the occiput to C f. Results. Retraction consists of lower cervical extension and upper cervical flexion, whereas protrusion consists of lower cervical flexion and upper c ervical extension. Full-length cervical flexion produced more flexion at lo wer segments than did protrusion, and full-length cervical extension produc ed more extension at lower segments than did retraction. With both full-len gth flexion and retraction, upper cervical segments are positioned in the f lexion portion of their total range, bur only retraction takes Occ-C1 and C 1-C2 to their full end-range of flexion. Similarly, with both full-length e xtension and protrusion, upper cervical segments are positioned in the exte nsion portion of their total range, but only protrusion takes Occ-C1 and C1 -C2 to their end-range of extension, Conclusion. A greater range of motion at Occ-C1 and C1-C2 was found for the protruded and retracted positions compared with the full-length flexion an d full-length extension positions. Effects on cervical symptoms reported to occur in response to flexion, extension, protrusion, and retraction lest m ovements may correspond with the position of lower cervical segments.