=Sprains.=--_Immerse the part in hot water_ for half an hour, then _bandage_ to keep the part at rest. _Use the limb as little as possible._ It may be necessary for a physician to apply a plaster dressing to a very bad sprain where the ligament is torn from the bone. =Broken Bones.=--To prevent bone from cutting flesh and skin, do not move the person until a temporary splint has been provided by tying sticks or umbrellas around the limb with handkerchiefs. PRACTICAL QUESTIONS. =The Skeleton.=--=1.= What kind of a chair back causes one to slide forward in the seat? =2.= What fault in sitting is made necessary by using a chair with so large a seat that the front edge strikes the occupant behind the knee? =3.= Why is the shoulder more often dislocated than the hip? =4.= High pillows may cause what deformity? =5.= Find three bones in the body not attached to other bones. Find twenty-five bones attached to other bones by one end only (Figs. 28 and 39). =6.= What deformities may result from urging a young child to stand or walk? =7.= Which bone is most often broken by falling upon the shoulder? =8.= Where in bones is fat stored for future use? =9.= Ligaments grow very slowly. Why is recovery from a sprain often tedious? [Illustration: FIG. 39.--THE HUMAN SKELETON IN ACTION.] CHAPTER IV THE MUSCLES It has already been stated that there are at least two muscles attached to a bone to move it in opposite directions. Since there are two hundred and six bones, you are not surprised to learn that to move the bones and accomplish the various purposes just stated, there are five hundred and twenty-six (526) skeletal muscles. =Two Kinds of Muscles.=--All muscles are controlled by means of the nervous system. Some of them are directed by parts of the brain that work consciously; others are controlled by the spinal cord and the parts of the brain that work unconsciously. Those of the first kind are _usually controlled by the will_, but they sometimes act involuntarily. _They are called voluntary muscles._ They move the bones and are located in the limbs and near the surface of the trunk (Fig. 44). The other kind of muscles are _never controlled by the will, and are called involuntary muscles_. We cannot cause them to act, nor can we prevent them from acting. They contract more slowly than the voluntary muscles. Most of them are tubular and found in the cavity of the trunk. The involuntary muscles _belong to the internal organs_, and relieve the will of the responsibility and trouble of the activity of these organs; otherwise, the mind would have no time for voluntary actions.