THE SKELETON AND MUSCLES 337 



Fractures. — A fracture is a break in a bone, and usually 

 injures the periosteum and other tissues connected with the 

 bone. In an accident of this kind the physician brings 

 the two ends of the bones together and binds them between 

 splints until new bone is formed and the fracture healed. 



Sprains. — The tearing, or pulling out of place, of a liga- 

 ment and muscles in the region of a joint results in a sprain. 

 The physician must bandage a sprain tightly and the patient 

 must rest the injured parts for many weeks. Relief from 

 pain before the physician comes is afforded by hot appHca- 

 tions and by arnica or other liniment. 



Comparison and composition of skeleton of child 

 and adult. — In very early life many of the bones are formed 

 of cartilage. Later the real bone tissue is formed that sup- 

 plants the cartilage except in the region of the joints. In 

 youth, when bone tissue is first formed it is comparatively 

 soft and flexible, the living or organic part far exceeding 

 the mineral matter. It is for this reason that bones are less 

 easily broken and more quickly repaired in youth than in 

 age. It is for this reason also that young people must 

 exercise much care in standing, walking and sitting correct- 

 ly, for in youth the skeleton is sometimes permanently de- 

 formed by incorrect usage. 



THE MUSCLES 



Arrangement and structure. — The muscles in the human 

 body, as in all animals, are the active organs of motion and 

 locomotion. Each muscle constitutes a separate organ, 

 composed of a mass of fibers collected in bundles and im- 

 bedded in connective tissue. The biceps muscle is a mass 

 of muscle fibers on the front part of the upper arm. When 

 the arm is hanging by the side at rest the muscle feels soft. 

 It is then relaxed and at its greatest length. When the arm 

 is bent at the elbow, the muscle is harder, shorter and bulges 



