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Critical Reviews™ in Physical and Rehabilitation Medicine

ISSN Print: 0896-2960
ISSN Online: 2162-6553

Critical Reviews™ in Physical and Rehabilitation Medicine

DOI: 10.1615/CritRevPhysRehabilMed.v12.i4.40
28 pages

Contrasts between Cervical and Lumbar Motion Segments

James Taylor
Curtin University of Technology, Perth, Western Australia 6845
Lance Twomey
Curtin University of Technology, Perth, Western Australia 6845
Bo Levander
Ryhov Hospital Jonkoping, Sweden

ABSTRACT

Cervical discs are not small replicas of lumbar discs. Lumbar discs have a nucleus pulposus enclosed in an envelope formed by the anulus fibrosus and cartilage plates, this basic structure persisting into old age. Adult cervical discs show extensive transverse fissuring through the nucleus and posterior anulus, from one uncovertebral cleft to the other. The fissuring begins in the uncovertebral regions at puberty and by 35 years of age, only the anterior anulus remains intact. These regional contrasts develop due to the growth of cervical uncinate processes and greater cervical mobility, from the different facet orientation. In middle and later life, lower cervical discs lose height, and cervical uncovertebral osteophytes appear with potential compressive effects on nerves, vertebral arteries, and the spinal cord. The contrasting regional course of the nerve roots exposes cervical nerves to greater risk in the intervertebral foramina from uncovertebral osteophytes; lumbar nerves are at risk in the lateral recesses of the spinal canal from disc protrusions and facet hypertrophy. The greater loadbearing function of the lumbar spine results in degenerative changes in discs and facet joints with different pain syndromes compared to the cervical region. Cervical disc fissures are painless but lumbar radial fissures are painful when internal disc disruption extends to the outer anulus and lumbar pain may result from segmental instability. The protection afforded to lumbar discs by the facets is less effective when the spine is loaded in a flexed rotated posture and there is an increased risk of injury. Lumbar axial or flexion compression injuries cause vertebral endplate fractures, bone bruising, or vertebral wedging. High axial loading of the cervical spine is less common but the neck is vulnerable to extension injury in whiplash, due to the relative weakness of anterior muscles. The intervertebral joints are at greater risk than the vertebrae with anterior distraction tears in the anulus and posterior compression injuries to the soft tissues of the facet joints.