3. What is conjunctivitis? Give causes and treatment.
4. What is "moonblindness"? Give the symptoms.
5. Describe the symptoms of infectious ophthalmia of ruminants and the treatment.
CHAPTER XIII
GENERAL DISEASES OF THE LOCOMOTORY APPARATUS
GENERAL DISCUSSION.—The movements of the different parts of the animal body depend on the union of the bones that form the skeleton (Fig. 28), and mode of insertion of the muscles. The bones meet and form joints or articulations. These are divided into three classes: movable, mixed and immovable. Nearly all of the articulations in the extremities belong to the movable class. The articulations between the bodies of the vertebrae belong to the mixed, and those between the flat bones of the head to the immovable class.
[Illustration: FIG. 28.—Skeleton of horse.]
The bony surfaces that meet and form the different types of articulations are held together by ligaments (Fig. 29). Sometimes the ligament is placed between the bony surfaces, but usually it is attached to the margins of the articular surfaces that it unites. The immovable class possesses fibrous-like ligaments that are placed between the margins of the flat bones that form the articulation. The mixed articulations are united by a fibro-cartilaginous pad that is firmly attached to the articular faces of the bones, and by peripheral ligaments that may be flat or formed by scattered fibres. All movable articulations are formed by bony surfaces encrusted with a thin cartilaginous layer that makes them perfectly smooth, ligaments and complimentary cartilages. Sometimes the bony surfaces do not fit each other, and we find between them fibro-cartilages that complete the articulation by adapting the articular surfaces to each other. Round or flat ligaments may extend from one articular surface to the other, and attached to the margins of the articulation are membranous, flat or round ligaments. Muscles and tendons that cross the articulations should be included among the structures binding them together.
[Illustration: FIG. 29.—Photograph of model of stifle joint, showing: ligaments; complementary cartilages; femur; and tibia.]
Movable joints possess a synovial membrane. This membrane lines the structures that enclose the articulation and secretes a fluid, the synovia, that lubricates the surfaces.