The bones of the fore-limbs do not articulate directly with the bones of the trunk, but are attached to the body by means of the skin and muscles. From above to below we distinguish the following bones:
1. The scapula, or shoulder-blade (10), a flat, triangular bone, prolonged at its upper border by a flat, very elastic cartilage, called the scapular cartilage. At its lower end the scapula articulates with—
2. The upper end of the humerus (11), forming the shoulder-joint (scapulo-humeral articulation). The humerus articulates at its lower end with—
3. The radius (12) and the ulna (13), to form the elbow joint. These two bones are the basis of the forearm. The ulna, smaller and weaker than the radius, lies behind and projects above it to form the point of the elbow. The lower end of the radius articulates with—
4. The carpus, or knee (14), which comprises seven small, cubical bones disposed in two horizontal rows, one above the other. The upper row comprises four bones and the lower row three. The lower row rests upon—
5. The large metacarpal or cannon bone, and the two rudimentary metacarpal or splint-bones. The lower end of the radius, the upper ends of the metacarpal bones, and the small carpal bones together form the carpal or knee-joint (wrist of man). Of the metacarpals, the middle one is the largest, longest, strongest, and most important, and is called the large metacarpal, cannon, or shin-bone (15). It articulates at its lower end with the os suffraginis, or long pastern (17), and with the two small sesamoid bones (20). On each side of the upper part of its posterior surface lie the two long, slender splint-bones (16). The inner splint-bone is sometimes affected with bony thickenings (exostoses) called “splints.”
6. The bones of the phalanges (all bones below the cannon) will be fully described in another place.
The bones of the hind limbs articulate directly with the pelvis at the hip-joint. They are stronger than the bones of the anterior limbs. We distinguish the following bones in the hind legs:
1. The highest bone in the hind limb is the femur (21). It is the strongest bone in the entire body. It lies in an oblique direction downward and forward, and at its lower end articulates with—
2. The patella (22), the tibia (23), and the fibula (24), to form the stifle-joint (knee of man). The patella plays over the anterior surface of the lower end of the femur. The fibula is small, and lies against the upper and outer side of the tibia. The latter at its lower end articulates with—