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 been weakened by the use of alcohol. Many surgeons dislike to operate on an old drunkard.

Posterior Curvature of the Spine.—The spine (see Figs. 28, 31) has two backward curves (opposite chest and hips) and two forward curves (at loins and neck). The deformity called posterior curvature is chiefly an exaggeration of the upper posterior curve. Round shoulders is the slightest, and hunchback the most marked, degree of this deformity. Causes: 1, bending over the work while either standing or sitting; 2, slipping down in the seat, as in Figure 51; 3, working habitually with the work low in front, as reading and writing at too low a desk (Fig. 49), or bending over while hoeing, sitting on the floor (Japanese and Chinese); 4, weak muscles in the back; 5, wearing shoes with high heels; 6, binding the ribs down with tight clothing; 7, walking with the head drooped forward or the chest flat; 8, wearing suspenders without a pulley, or lever, at the back; 9, carrying the hands in the pockets. (Swing the arms to keep the hands out of the pockets and break the habit); 10, wearing a coat or vest that is tight at the back of the neck. This deformity is brought about by stretching the ligaments at the back side of the spine, and by compressing the cartilages until they become wedge-shaped, with the thin part of the wedge in front. The flexibility of the spine is a great advantage, but it increases the risk of deformity. One of the most serious evils of posterior curvature is a flat chest and restricted breathing.

Lateral Curvature of the Spine.—A perfect spine curves to neither side (Fig. 47), but is perfectly erect. The least habitual lateral curvature is deformity. Causes: 1, writing at a desk that is too high; 2, habitually carrying a book, satchel, or other weight in the same hand; 3, carrying the head on one side (Fig. 46); 4, habitually standing with the weight on the same foot; 5, a certain defect of vision (astigmatism, Chap. IX).

, but strained and stiff.

To overcome Spinal Deformities.—The work, or the manner of doing the work, should be so changed as to give extra labor to the neglected muscles. Avoid the habits mentioned above as causing deformity. Sit and stand in the manner described in the next paragraph. Sleeping on the back upon a hard mattress without a pillow tends to cure posterior curvature and flat chest.