Fig. 32 shows a =vertebra=, or one of the bones that compose the column. The three _projecting points or processes_ are for the attachment of ligaments and muscles. The _main body_ of each vertebra is for supporting the weight transmitted by the column above. Just behind this thick body is a _half ring_ (Fig. 32), which with the half rings on the other vertebrae form the channel for the spinal cord. Between the vertebrae are thick pads of gristle, or cartilage, which act as cushions to prevent jars, and by compression allow bending of the spinal column in all directions. [Illustration: FIG. 32.--SIDE AND UNDER VIEW OF A VERTEBRA.] =The Chest= (see Fig. 75).--The twelve pairs of ribs are attached to the spinal column behind, and extend around toward the front of the body, somewhat like hoops. The first seven pairs, called _true ribs_, are attached directly to the flat breastbone, or _sternum_. Each of the next three pairs, called _false ribs_, is attached to the pair above it. The last two pairs, called _floating ribs_, are free in front. =The Shoulder Girdle.=--_The collar bones_ (Fig. 28) can be traced from the shoulders until they nearly meet on the breastbone at the top of the chest. The collar bone is shaped like the italic letter _f_; it helps to form the shoulder joint and holds the shoulder blade out from the chest that the motions of the arm may be free. The flat, triangular _shoulder blade_ (Fig. 75) can be felt by reaching with the right hand over the left shoulder. It spreads over the ribs like a fan. Its edges can be made out, especially if the shoulder is moved while it is being felt. The high ridge which runs across the bone can be felt extending to the top of the shoulder. =The Pelvic Girdle.=--The edges of the _hip bones_ can be felt at the sides of the hips (Fig. 28). The hip bones, with the base of the spine, form a kind of basin called the _pelvis_. The =skull= (Fig. 33) rocks, or nods, on the top vertebra. It consists of the cranium, or brain case, and the bones of the face. The shapes and names of the bones of the skull are shown in Fig. 33. [Illustration: FIG. 33.--HUMAN SKULL, disjointed.] =Adaptations of the Skull for Protection.=--Its arched form is best for resisting pressure and turning aside blows. Like all flat bones, the skull has a spongy layer of bone between the layers of compact bone forming the outer and inner surfaces; hence it is elastic and not easily cracked. The nose, brow, and cheek bones project around the eye for its protection. The delicate portions of the ear are embedded in the strongest portion of the skull. The branches of the nerves of smell end in the lining of the bony nasal chambers. The spinal cord rests securely in the spinal canal.