The vertebral foramina are smaller and more rounded than those in the cervical region, and so conform to the reduced size and more circular shape of the spinal cord in…

The pedicles are short and strong and arise from the upper and posterolateral aspects of the bodies; the superior vertebral notches are therefore less deep than the inferior notches. The…

The cervical vertebral bodies are smaller than those of the other movable vertebrae and increase in size from above downward; they are broader in the transverse diameter than anteroposteriorly. The…

The anterior atlanto-occipital membrane is a wide, dense, fibroelastic band extending between the anterior margin of the foramen magnum and the upper border of the anterior arch of the atlas….

The broad, strong tectorial membrane lies within the vertebral canal. It prolongs the posterior longitudinal ligament upward from the posterior surface of the body of the axis to the anterior…

The atlas (named after the mythical giant who carried the earth on his shoulders) supports the globe of the skull. It lacks a body and forms a ring consisting of…

All vertebrae conform to a basic plan, but individual variations occur in the different regions. A typical vertebra consists of an anterior, more-or-less cylindric body and a posterior arch composed…

Human T-cell Lymphocytic Virus-1 (HTLV-1) Myelopathy. This disorder, also known as tropical spastic paraparesis/HTLV-1–associated myelopathy (TSP/HAM), may be acquired as a sexually transmitted disease, particularly in the Caribbean, eastern South…

With age, the nucleus pulposus of the disk dehydrates, placing more stress on the annulus fibrosus (outer lining). Tears in the annulus may permit a sudden herniation of the nucleus—a…

Symptoms typically develop gradually after age 40 and progress slowly. They consist of some combination of back or radicular pain, weakness, sensory disturbances, and impaired sphincter function. Neurogenic claudication may…