By scoliosis we mean a deformity characterized by lateral deviation of the spinal column, associated with a rotation of the bodies of the vertebrae around a vertical axis. In this position of rotation the bodies face toward the resulting convexity, while the spines of the vertebrae point in the opposite direction; a slight deviation of the spines does not always indicate an equally slight degree of aberration of the vertebral bodies.
Further, as a result of the rotation, the transverse processes on the side of the convexity are directed backward, and carry with them, in the dorsal region, the ribs, whose angles become more or less prominent according to the degree of deformity.
In scoliosis of slight degree the angulation itself may not be marked; instead, a costal bulging or boss is formed, which becomes more noticeable when compared with the flattened area of the opposite side of the chest.
GRAY EA. CERTAIN PHYSICAL SIGNS IN SCOLIOSIS OF LESSER DEGREE. JAMA. 1912;LIX(25):2249-2251. doi:10.1001/jama.1912.04270140053019