. Principles of veterinary science; a text-book for use in agricultural schools. Veterinary medicine. THE SKELETAL SYSTEM 51. elbow; and ball-and-socket joint, as that between the pelvis and the femur at the hip. The freely movable joints are the only true joints (Fig. 9). They are composed of the following structures: 1. Two or more bones with joint surfaces that are usually somewhat expanded. 2. Articular cartilages, which cover the articular surfaces of the bones. These are exceedingly smooth and are thickest on the central part of a convex surface, while on a concave surface the marginal c
. Principles of veterinary science; a text-book for use in agricultural schools. Veterinary medicine. THE SKELETAL SYSTEM 51. elbow; and ball-and-socket joint, as that between the pelvis and the femur at the hip. The freely movable joints are the only true joints (Fig. 9). They are composed of the following structures: 1. Two or more bones with joint surfaces that are usually somewhat expanded. 2. Articular cartilages, which cover the articular surfaces of the bones. These are exceedingly smooth and are thickest on the central part of a convex surface, while on a concave surface the marginal cartilage is thickest. They diminish the effects of con- cussion and greatly reduce friction. 3. A joint capsule, which re- sembles a sac open at both ends, is attached around the articulating surfaces. It is composed of two layers—an external, strong fibrous layer, and an internal, velvety synovial layer. 4. Ligaments, strong fibrous bands which bind the bones firmly together. They are pliable, but inelastic, and maintain the articular surfaces in more or less close contact and thus greatly strengthen the joint. In most joints the ligaments lie external to the joint capsule. In others, such as the hip and stifle, they lie within the joint-capsule. Synovia is a viscid, straw-colored fluid which gives an alkaline reaction. It is not secreted by glands but is a tissue fluid that exudes into the joint. It contains proteins, salts, and mucin. Synovia reduces friction by lubricating the joints. The amount of synovia increases and diminishes to a certain extent under normal conditions. When an excessive quantity is present a puffy swelling occurs in the region of the joint. Bog spavin is a good example of an excess in the hock-joint. All joint movements are due to muscle contraction and relaxa- tion. True joints are found to vary greatly in their possibilities for movement depending upon the location and extent of their ligaments. The se^nYjgg^^jp^^^g^ joint movements are: Fig. 9.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectveterin, bookyear1920
