An anatomical study of the role of the detate ligaments in the cervical spinal canal.

C ERVICAL spondylosis has been increasingly recognized as a cause of spinal cord myelopathy and nerve root irritation in elderly patients. 2,3,1~ The pathology seen in the spinal cord has been well described by Wilkinson 14 and Mair and Druckman. s I n their specimens the cords were flatter than normal from compression in their anteroposterior diameter. Swelling of the myelin and of the axons and demyelination were noted in the posterolateral columns and in the anterior parts of the cuneate fasciculi. In many of thc specimens the anterior and posterior grey horns showed neural loss. Brain et al. 2 described "saucershaped and oval indentat ions" of the anterior aspect of the spinal cord corresponding to the bosses and transverse bars found on the vertebral bodies. There is continuing debate as to what mechanisms are responsible for the myclopathy found in the spinal cord. Kahn 7 and Bedford et at. 1 stressed the role of the dentate ligaments which, they believed, anchored the spinal cord in the cervical spinal canal. These ligaments prevented posterior migration of the spinal cord when pressure was exerted on its ventral surface by extradural masses. Mair and Druckman s implicated pressure on the anterior spinal artery and its distal ramifications as the cause of the pathological changes seen in their specimens. Taylor la believed tha t the lesions found in the spinal cord were ischelnic and due to compression, by osteophytcs, of the cervical radicular arteries, in their passage through the cervical foramina. Stol tmann and Blackwood H emphasized tha t mechanical compression of the spinal cord in the cervical spinal canal was "one of the main mechanisms responsible for the myelopa thy found in cervical spondylosis."