*Relation of Anatomy and Physiology to the Study of Hygiene.*—If the chief object in studying the body is that of learning how to manage or care for it, and hygiene supplies this information, why must we also study anatomy and physiology? The answer to this question has already been in part suggested. In order to determine what things and conditions are in harmony with the plan of the body, we must know what that plan is. This knowledge is obtained through a study of anatomy and physiology. The knowledge gained through these subjects also renders the study of hygiene more interesting and valuable. One is enabled to see _why_ and _how_ obedience to hygienic laws benefits, and disobedience to them injures, the body. This causes the teachings of hygiene to be taken more seriously and renders them more practical. In short, anatomy and physiology supply a necessary basis for the study of hygiene. *Advantages of Properly Managing the Body.*—One result following the mismanagement of the body is loss of health. But attending the loss of health are other results which are equally serious and far-reaching. Without good health, people fail to accomplish their aims and ambitions in life; they miss the joy of living; they lose their ability to work and become burdens on their friends or society. The proper management of the body means health, and it also means the capacity for work and for enjoyment. Not only should one seek to preserve his health from day to day, but he should so manage his body as to use his powers to the best advantage and prolong as far as possible the period during which he may be a capable and useful citizen. CHAPTER II - GENERAL VIEW OF THE BODY *External Divisions.*—Examined from the outside, the body presents certain parts, or divisions, familiar to all. The main, or central, portion is known as the _trunk_, and to this are attached the _head_, the _upper extremities_, and the _lower extremities_. These in turn present smaller divisions which are also familiar. The upper part of the trunk is known as the _thorax_, or chest, and the lower part as the _abdomen_. The portions of the trunk to which the arms are attached are the _shoulders_, and those to which the legs are joined are the _hips_, while the central rear portion between the neck and the hips is the _back_. The fingers, the hand, the wrist, the forearm, the elbow, and the upper arm are the main divisions of each of the upper extremities. The toes, the foot, the ankle, the lower leg, the knee, and the thigh are the chief divisions of each of the lower extremities. The head, which is joined to the trunk by the neck, has such interesting parts as the eyes, the ears, the nose, the jaws, the cheeks, and the mouth. The entire body is inclosed in a double covering, called the _skin_, which protects it in various ways.