XI. Accessory or Spinal Accessory Nerve.—This nerve is seldom damaged within the skull. It supplies the sterno-mastoid and trapezius; but as these muscles usually have an additional nerve supply from the cervical plexus, the accessory may be divided, or a considerable portion of it resected, as, for example, in the treatment of spasmodic torticollis, without any serious disablement resulting. It is liable to be accidentally divided in excising malignant or tuberculous glands in the neck. When, however, the accessory is the only source of supply to these muscles, its division is followed by considerable disablement, which appears to depend almost entirely on the paralysis of the trapezius. The head is inclined slightly forward, the shoulder is depressed, the arm hangs heavily by the side and is slightly rotated forward, the scapula is drawn away from the spine and rotated on its horizontal axis, and there is slight cervical scoliosis with the concavity towards the affected side. The trapezius is markedly wasted, and is, therefore, less prominent in the neck than normally, and the functions of the arm and shoulder are impaired, especially in making overhead movements. In time other muscles compensate in part for the loss of the trapezius.
When divided accidentally, the nerve should be immediately sutured. Even when the paralysis has lasted for some time, secondary suture should be attempted; if this is impossible, the peripheral end should be anastomosed with the anterior primary divisions of the third and fourth cervical nerves (Tubby). Massage, electricity, and the administration of tonics are also indicated.
XII. Hypoglossal Nerve.—This nerve has been ruptured in fractures passing through the canalis hypoglossi (anterior condylar foramen). It is also liable to be divided in wounds of the submaxillary region—for example, in cut throat, or during the operation for ligation of the lingual artery, or the removal of diseased lymph glands.
The paralysed half of the tongue undergoes atrophy. When the tongue is protruded, it deviates towards the paralysed side, being pushed over by the active muscles of the opposite side. Speech and mastication are interfered with, the tongue feeling too large for the mouth; in time this disability is to a large extent overcome.
The Cervical Sympathetic.—The cervical sympathetic cord and its ganglia may be injured in the neck by stabs or gun-shot wounds, or in the course of deep dissections in the neck; and in injuries of the lower part of the cervical enlargement of the spinal cord ([p. 417]) or of the first dorsal nerve root.
Paralysis of the cervical sympathetic is characterised by diminution in the size of the pupil on the affected side. The pupil does not dilate when shaded, nor when the skin of the neck is pinched—“loss of the cilio-spinal reflex.” The palpebral fissure is smaller than its fellow, and the eyeball sinks into the orbit. There is anidrosis or loss of sweating on the side of the face, neck, and upper part of the thorax, and on the whole upper extremity of the affected side.
CHAPTER XV
DISEASES OF THE CRANIAL BONES
Suppurative Periostitis and Osteomyelitis.—These conditions may be the result of infection through the blood stream, but as a rule they follow upon a breach of the surface caused by a wound, a severe burn as in epileptics, a tertiary syphilitic ulcer, or a compound fracture that has become infected. Sometimes they follow suppuration in the middle ear and mastoid or in the frontal sinus, and epithelioma and rodent cancer that has ulcerated and become infected after spreading from the face towards the vertex. They are occasionally associated with acute cellulitis of the scalp. When the infection is blood-borne suppuration occurs on both aspects of the bone—a point of importance in treatment.
The illness is usually ushered in by a rigor, and this is soon followed by other signs of suppuration—high temperature, pain and tenderness, and the formation of a fluctuating swelling in relation to the bone. When pus forms between the bone and the dura, there is a characteristic œdema of the overlying area of the scalp—spoken of as Pott's puffy tumour—which is of value as indicating the extent of the disease in the bone, and of the collection of pus between it and the dura. When suppuration occurs under the pericranium, an incision gives exit to a quantity of pus, and exposes an area of bare bone. If the incision is made early, this bone may soon be covered by granulations and recover its vitality; but if operation is delayed, it usually undergoes necrosis. The sequestrum that forms includes, as a rule, only the outer table, but in some cases the whole thickness of the bone undergoes necrosis. In either case the separation of the sequestrum is an exceedingly slow process, and is not accompanied by the formation of new bone. When the whole thickness of the skull is lost, there may be a protrusion of the contents of the skull—hernia cerebri; should the patient survive, the gap becomes filled in by a dense fibrous membrane which is fused with the dura mater.