Spinal Cord and Ascending, Descending, and Intersegmental Tracts

Spinal Cord and Ascending, Descending, and Intersegmental Tracts

CHAPTER OBJECTIVES

. To learn how injuries to the spinal cord can occur

. To understand the position of the main nervous pathways and nerve cell groups in the spinal cord as well as be able to correlate radiologic evidence of bone injury with segmental levels of the spinal cord and neurologic deficits

A thirty-five-year-old man is galloping his horse when he attempts to jump over a farm gate. The horse refuses to jump, and he is thrown to the ground. His head strikes a log, and his head and neck are excessively flexed. On initial evaluation in the emergency department after he regains consciousness, he is found to have signs and symptoms of severe neurologic deficits in the upper and lower extremities. A lateral radiograph of the cervical region of the spine shows fragmentation of the body of the fourth cervical vertebra with backward displacement of a large bony fragment on the left side.

After stabilization of the vertebral column by using skeletal traction to prevent further neurologic damage, a complete examination reveals that the patient has signs

Spinal cord injuries are common and can occur as a result of automobile and motorcycle accidents, falls, sports injuries, and gunshot wounds. Spinal cord and spinal nerve damage may also be associated with vertebral fractures; vertebral infections; vertebral tumors, both primary and secondary; and herniated intervertebral discs. The student must learn the course and connections of the various tracts within the spinal cord in order to be able to diagnose and understand the treatment of cord injuries. Particular attention should be paid as to whether a specific tract crosses the midline to the opposite side of the central nervous system or remains on the same side. If the tract does cross the midline, the level of the crossover is important.

The assessment of neurologic damage requires not only an understanding of the main nervous pathways within the spinal cord but an ability to correlate

. To review the basic structure of the delicate spinal cord and the positions and functions of the various ascending and descending tracts that lie within it

. To make simple line drawings of each of the ascending and descending tracts, showing their cells of origin, their course through the central nervous system, and their destination and symptoms indicating incomplete hemisection of the spinal cord on the left side.

Any medical personnel involved in the evaluation and treatment of a patient with spinal cord injuries must know the structure of the spinal cord and the arrangement and functions of the various nerve tracts passing up and down this vital conduit in the central nervous system.

Because of the devastating nature of spinal cord injuries and the prolonged disability that results, all concerned with the care of such patients must be trained to prevent any additional cord injury and provide the best chance for recovery. All medical personnel must have a clear picture of the extent of the cord lesion and the possible expectations for the return of function.

radiologic evidence of bone injury with segmental levels of the spinal cord. The close relationship of the spinal cord to the bony vertebral column necessitates a brief review of the vertebral column before the spinal cord is considered.

BRIEF REVIEW OF THE VERTEBRAL COLUMN

The vertebral column is the central bony pillar of the body. It supports the skull, pectoral girdle, upper limbs, and thoracic cage and, by way of the pelvic girdle, transmits body weight to the lower limbs. Within its cavity lie the spinal cord, spinal nerve roots, and the covering meninges, to which the vertebral column gives great protection.