The skin of the chest is freely movable on the underlying structures, owing to the lax nature of the subcutaneous tissues, which are particularly abundant over the posterior and lateral regions. While the skin over the front and sides of the chest is thin and fine, that over the shoulders is thick (nearly ¼ inch) and coarse, and contains many sebaceous glands, acne frequently occurring in this region. The shoulders are also a favourite site for lipomas, which frequently develop in the subcutaneous tissues. As a rule, the two sides of the thorax are not symmetrical, the right being the larger. In the female the general capacity is less, and the sternum is shorter than in the male. In a transverse section of the chest the vertebrae are seen to project far forward toward the sternum, the shape resembling the Greek omega. The sternal notch corresponds with the disc between the second and third dorsal vertebrae, and at this point there is a space of only slightly over 2 inches between the sternum and vertebrae.
The chest overlaps the neck in front and the abdomen below. In the neck the apex of the lung rises about ½ inch above the clavicle, while, owing to the dome-like obliquity of the diaphragm, which is attached to the xiphoid in front, and the crurae and lumbar vertebrae behind, there is a region common to both thorax and abdomen, which is thoracic posteriorly, and abdominal anteriorly.
Deformities of the chest are seen in association with various diseases. Thus, in emphysema it is described as being barrelshaped. In pigeon-breast the sternum and cartilages are prominent, while a sulcus exists along the costo-chondral line, due, it is supposed, to yielding of this, the weakest part, where there is some impediment to respiration. Deformities of the spine often have a marked effect upon the thorax. In Pott's disease, with angular curvature of the spine, the sternum may project forwards, increasing the antero-posterior diameter, and the ribs may be crowded together, so as even in very severe cases to overlap the iliac crests. In scoliosis, or lateral curvature of the spine, in which the vertebrae rotate so that their bodies point to the convexity of the curve, the ribs, being firmly attached to the vertebrae by the costovertebral and transverse ligaments, move with them, rendering the angles very prominent and the front of the chest flattened on the convex side, while on the. concave side the angles are flat and the front of the chest prominent. Further, on the convex side the ribs are wide apart, while they are crowded together on the concave.