The acquired causes include:
1. Traumatisms, either direct, as by injury to the muscles, such as may happen from gunshot wounds, etc., or follow operations by which the spinal accessory has been injured, or by burns, and other lesions which cause much cicatricial contraction.
2. Reflex activity in connection with disease of the lymph nodes, deep cervical abscesses, parotid phlegmons or tumors, etc. Whitman states that tuberculous disease of the cervical nodes caused the condition in 50 per cent. of over 100 cases analyzed by him.
3. Reflexes from the eyes, as Bradford and Lovett have described from the orthopedist’s standpoint, and Gould from that of the oculist, refractive errors causing the head to be held in unnatural positions in order to improve vision.
4. Compensation in high degrees of rotary lateral curvature, the effort being to keep the head facing to the front.
5. Myositis, usually rheumatic, but sometimes a sequel of the infectious fevers, or even of gonorrhea.
6. Habitual deformity, the result of occupation or sheer bad habit.
7. Tonic or intermittent spasm leading to spastic contractures whose causes are difficult to seek, but appear to inhere in the central nervous system.
8. Paralyses of certain muscles, permitting lack of opposition and consequent deformity.