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8. Sternum or Breast Bone.—This bone is small and short in the horse and is situated on the lower surface of the chest cavity. The principle points to be noted in this bone are that of its softness, and that the first eight pairs of ribs are attached to it on either side. This bone, in the horse resembles the keel and cut-water of a boat.

9. Ribs.—In the horse the ribs usually number eighteen on each side. They extend in a series of arches of varying curvature from the dorsal vertebrae above, towards the sternum and sides of the abdomen below. Their shape, in a great measure, determines the conformation or shape of the thorax or chest cavity; they protect its contents, and materially aid in its contraction and expansion. They are continued downward and forward by a small piece of cartilage or gristle, and are just slightly attached to the breast bone or sternum; these are called the false ribs. Note that, starting with the first rib, they get longer until the ninth rib is reached; they then get shorter, the last rib being only a few inches long.