The Pedestrian's Record

the pedestrian's record. 59 enlarging the chest comeinto play. Thus, the arms and shoulders being fixed, the serratus magnus passing from the scapulae to the middle of the first eight or nine ribs, the pectoralis minor passing from the coracoid to the front parts of the third, fourth, and fifth ribs, the pectoralis major from the humerus to the costal cartilages, from the second to the sixth and that portion of the latissimus dorsi which passes from the humerus to the last three ribs, all serve to elevate the ribs, and thus to enlarge the chest ; and other muscles passing from the neck to the sternum are also called into action. In fact, every muscle, which by its contraction can either elevate the ribs or contribute to the fixed support of muscles which do elevate them, such as the trapesius levator anguli scapulae and rhomboidei, by fixing the scapula, may, in the inspiratory effort, be brought into action. In easy expiration the effort is the simple effect of elastic reaction. As the inspiratory muscles relax their power, the elasticity of the lungs exerts its in­ fluence, and the air is driven out, and in a similar manner the muscles just previously engaged return to their normal position, and thus depress the ribs and diminish the dimensions of the chest. During laboured expiration the abdominal muscles become important adjuvants by pressing on the contents of the abdomen, and thus forcing them and the dia­ phragm into the chest as breathing becomes more forced. Every muscle in the body which can either by contracting depress the ribs or press on the ab-