1.Skull, or skeleton of the head.15.Os Melacarpi Magnus, metacarpal, or cannon bone.
2.Cervical vertebræ or neck bones.16.Ossa Melacarpi Parva, or splint bones.
3.Dorsal vertebræ or back bones.17.Proximal Phalanx, os suffraginis, or large pastern bone.
4.Lumbar vertebræ or loin bones.18.Great Sesamoid Bones.
5.Sacral vertebræ or rump bones.19.Medium Phalanx, os coronæ, or small pastern bone.
6.Coccygeal vertebræ or tail bones.20.Distal Phalanx, os pedis, or coffin bone.
7.Pelvic or hip bones.21.Os Naviculare, small sesamoid, or shuttle bone. (This bone can be plainly seen Plate [VII]).
8.Sternum or breast bone.22.Femur, or thigh bone.
9.Ribs.23.Patella, or stifle bone.
10.Scapula or shoulder blade.24.Tibia, or leg bone.
11.Humerus or shoulder bone.25.Fibula. (This bone is little developed in the horse.)
12.Radius or bone of the fore-arm.26.Tarsus or hock bones.
13.Ulna or bone of the fore-arm.27.Metatarsus, or os metatarsi magnus.
14.Carpus or bones of the knee.28.Ossa Metatarsi Parva, or splint bones of the hind leg.
Names of joints placed according to numbers.

I.

Shoulder Joint.

VI.

Coffin Joint.

II.

Elbow Joint.

VII.

Hip Joint.

III.

Carpus or knee joint.

VIII.

Stifle Joint.

IV.

Fetlock Joint.

IX.

Tarsus or hock joint.

V.

Pastern Joint.

CHAPTER I.

OSTEOLOGY.

Structure of the Bones—Bones are hard, yellow-white, insensitive objects, which form the skeleton and give attachment to soft structures (muscles, tendons and ligaments); they are of various sizes, forms and densities. In the limbs the bones are ordinarily more or less long, circular bodies, with expanded ends, effectually supporting the body, supplying leverage and attachment for soft structures, and forming the basis of all joints. Where cavities, such as the cranium, chest, and pelvic, enclosing the organs requiring protection and support, the bones tend to assume a flat, expanded form.

Living bone is bluish pink, insensitive, and elastic; on exposure to air it becomes diseased and blackened, very sensitive and painful; (the teeth excepted) which are harder and of a higher specific gravity than any other bone formation.

Bones are composed of two kinds of substance—animal, which makes the bone tough and flexible; earthy, which makes it hard and fragile. In young animals the animal matter forms about one-half of the bone substance; in the adult, it diminishes to about a third, while in old animals it is still less; hence the bones of very old animals are brittle, more liable to fracture and harder to mend.

Bones in a six-year-old horse contained, Phosphate of Lime, 54.37 per cent; Carbonate of Lime, 12.00 per cent; Phosphate of Magnesia, 1.83 per cent; Soluble Salts, 0.70 per cent, or mineral matter, 68.90 per cent. While they contain Cartilage, 27.99 per cent; Fat, etc., 3.11 per cent, or animal matter 31.10 per cent.

In bone tissue there are two modifications of texture, the compact and the cancellated. The former—hard, dense, and ivory-like, is always situated externally; the latter porous and spongy lies within.