e. Median Plane. The vertical plane that passes through the vertebral column
thus dividing the body into two equal halves.
f. Medial. Directed toward the median plane; it is inward or internal.
g. Lateral. Directed away from the median plane; it is external or outward.
h. Proximal. Area nearest the long axis of the body (referring to the area of the
limbs). For example, the round bone (femur) is proximal to the hind shank (tibia).
i. Distal. Area farthest from the long axis of the body (referring to the area of
the limbs). For example, the foreshank is distal to the elbow.
Bone is a dense, hard tissue that forms the framework of the body. All of the
bones collectively make up the skeleton. The skeleton supports and protects such soft
tissues as the brain, lungs, and heart. Bones serve also as attachment points for
skeletal muscles and act as levers for the muscles. The skeletal muscles give
movement to the body. See figure 1-2.
a. Classes. Bones are divided into classes according to their shape.
(1) Long bones. Long bones are elongated and cylindrical in form, with
enlarged extremities. The femur and humerus are examples of long bones.
(2) Flat bones. Flat bones are relatively thin and are expanded in length
and breadth to provide a large surface area for attachment of the major muscles,
primarily those of locomotion. The scapula and pubis are examples of flat bones.
(3) Short bones. Short bones are somewhat similar in dimensions in regard
to length, width, and thickness. The carpus (knee) in the foreleg and the tarsus (hock)
in the hind leg are examples of short bones.
(4) Irregular bones. Irregular bones are bones that have the continuity of
their surfaces broken by the presence of projections (spines) or prominences. The
vertebrae are examples of irregular bones.