=Morbid Anatomy.=—The vertebræ in the region involved are rotated so that their spinous processes point toward the concavity of the lateral curve. The bodies of the vertebræ on the side next to the concavity are thinner, due to absorption; the intervertebral discs are made thin on the same side by pressure and absorption. The ribs are considerably distorted, depressed on the concave side and prominent on the convex side. The ligaments on the concave side are contracted, and stretched on the convex side. The muscles on the concave side are more or less contracted, and on the convex side they are stretched, causing atrophy and fatty infiltration of their tissues. =Kyphosis.=—This may be a slight posterior curve really amounting to nothing, or it may be a very grave pathological condition as in Pott’s disease. Therefore it is very necessary that one should make a most careful diagnosis (see Pott’s disease). The most common =causes= of kyphosis are Pott’s disease, rachitis, occupation, general weakness, rheumatism and old age. In Pott’s disease, the posterior curve is characterized by a sharp angle, and by the spine being very rigid. This, taken in conjunction with the history and other symptoms should be sufficient to enable one to make a diagnosis. Radiographic examination should be made. The condition of round shoulders, which in time produces marked kyphosis, is rarely a habit as it is usually termed. In nearly every case it indicates either a weakness of the back muscles or, what is more apt to be the cause, a strained posterior condition of the dorsal vertebræ, commonly of the lower dorsal region. =Morbid Anatomy.=—In mild cases there is simply a relaxation of the ligaments of the vertebræ and a separation of the laminæ and spinous processes. In severe forms there may be absorption of the anterior portion of the intervertebral discs and the bodies of the vertebræ (Pott’s disease). =Lordosis.=—This may be a congenital condition, especially when occurring in the lumbar region. Anterior curves of the spine are generally found in the lumbar or cervical regions, but occasionally occur in the dorsal region, causing the spinal column to be more or less straight, and thus weakening the individual. This curve is commonly compensatory to kyphosis, hip-joint disease and congenital dislocations of the hip.