Anatomy and physiology of the cervical spine.

Although the lumbar spine was extensively studied from 1934 to the present, the cervical spine has received far less attention. Anatomic, physiological, biochemical, and biomechanical characteristics of the lumbar spine are often presumed to apply to the cervical spine. The differences are far too extensive to warrant such an assumed correlation. Beginning in 1955, the authors have collected 171 whole human spines and studied them anatomically, physiologically, and histologically. Reported in this article are clinically important anatomic characteristics of the nucleus pulposus, the uncinate process, nerve root exit sites, position of the motor (anterior) nerve root, relation of spinal cord volume to size and shape of the spinal canal, anatomy of the anterior and posterior spinal canal, menisci of the zygapophyseal joints, and the anatomy and clinical significance of the autonomic nervous system in the cervical spine.