EFFECTS OF FLEXION-EXTENSION MOVEMENTS OF THE HEAD AND SPINE UPON THE SPINAL CORD AND NERVE ROOTS

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Abstract
In a study using 18 necropsy cases maximum movement during flexion of head and neck from normal erect position appeared to occur from C-7 to T-3. Greatest stretch, averaging 10%, was found in approximately the same region. Movements were minimal at the root of C-5 and greatest at roots C-8 to T-5. The lower cervical and upper thoracic regions show maximum flexion kyphosis. Stretch is greatest between the roots of C-2 and T-1. Stretch may be an important factor in increasing pathological damage by disrupting relationships between nerve cells and fibers and their blood supply. Over a 3 mm projection into the canal the cord and dura exerted an anterior pressure of about 2 lb. per square inch in normal posture and 30 and 40 lb. per square inch in flexion. These mechanisms are of particular interest in cervical spondylosis. Movements and pressure do not only cause direct trauma to the cord but can produce indirect damage by interfering with the blood supply.