[Illustration: FIG. 204.--Destruction of Bones of Left Orbit, caused by Rodent Cancer. The patient died of septic meningitis. (Mr. D. M. Greig's case.)] CHAPTER XVI THE VERTEBRAL COLUMN AND SPINAL CORD Surgical Anatomy--Injuries of the spinal cord: _Concussion_; _Traumatic hæmatorrachis_; _Traumatic hæmatomyelia_; _Total transverse lesions at different levels_; _Partial lesions_; "_Railway spine_"--Injuries of the vertebral column: _Sprain_; _Isolated dislocation of articular processes_; _Isolated fracture of arches and spinous processes_; _Compression fracture of bodies_--Traumatic spondylitis--Fracture-dislocation--Penetrating wounds. #Surgical Anatomy.#--The veretebral column is the central axis of the skeleton, and affords a protecting casement for the spinal cord. The spine is movable in all directions--flexion, extension, lateral flexion, and rotation around the long axis of the column. Flexion is accompanied by compression of the intervertebral discs, and by a slight forward movement of each vertebra on the one below it. This forward movement is checked by the tension of the ligamenta flava which stretch between the laminæ. In the infant, the spine is either straight or presents one long antero-posterior curve with its convexity backwards. With the assumption of the erect posture the normal S-shaped curve is developed, the cervical and lumbar segments arching forward, while the thoracic and sacral segments arch backward. Through the skin it is often difficult to identify with certainty the individual spinous processes. The spine of the seventh cervical vertebra,--vertebra prominens--and that of the first thoracic, are those most readily felt. While the arm hangs by the side, the root of the spine of the scapula is opposite the third thoracic spine, and the lower angle of the scapula is on the same level as the seventh. The twelfth thoracic vertebra may be recognised by tracing back to it the last rib. A line joining the highest points of the iliac crests crosses the fourth lumbar spine; and the second sacral spine is on the same level as the posterior superior iliac spine. The bodies of the upper cervical vertebræ may be felt through the posterior wall of the pharynx. The cricoid cartilage corresponds in level to that of the lower border of the sixth cervical vertebræ and its transverse process. It is important for surgical purposes to bear in mind that most of the spinous processes do not lie on the same level as their corresponding bodies. The tips of the spines of the cervical and first two or three thoracic vertebræ lie, roughly speaking, opposite the lower edge of their respective bodies; those of the remaining thoracic vertebræ lie opposite the body of the vertebræ below; while the spines of the lumbar vertebræ lie opposite the middle of their corresponding bodies.