OF Tua RESPIRATORY MOVESIENTS.—The breathing volumes have been divided into three kinds ; so likewise the breathing move ments admit of a similar division,—one ordi nary and two extraordinary movements.
By the independent action of the intercostal muscles, every intercostal lamella can act sepa rately, therefore we have the thorax furnished with 22 spaces by which it can enlarge ; and the diaphragm acting as one muscle, makes 23 mobile regions for respiration.
The respiratory movements of health may be classed as costal and abdominal. The cha racter should be established by the order in which they follow each other. In health the walls of the thorax and the floor do not dilate simultaneously but consecutively. The character of "the breathing" cannot always be told by the eye, but it can always be deter mined by the touch. If we stand behind a patient, when seated and leaning against the back of the chair or against our person, and pass the right arm over the shoulder, extending it over the anterior part of the chest, until the hand rests upon the abdomen over the mnbilical region, we command a delicate index of the breathing movements. It will then be found, that in ordinary male breathing the ab domen first bulges outwards ; the ribs and sternum nearest the abdomen gently follow this movement, until the motion, like a wave, is lost over the thoracic region. The undu lation commences at the abdomen. This is aoaomina, or diaphragmatic respiration. We here have costal motion, but as the ribs moved second it is not called costal breathing.
In costal breathing the upper ribs movefirst, and the abdomen second. This is the ordinary breathing in women.
All difficult, sudden, and extraordinary breathing is costal ; we at such times direct all our power towards the apex of the thorax, first expanding that region, and gradually those below it.
When we determine the order of breathing by the sight, we must be careful to take the position of the body into account. If the pa tient be recumbent (supine), we may notice extensive costal motion, and, indeed, it may be true costal breathing ; but place the pa tient erect, and the breathing may be diaphrag matic. When recumbent, all the motion is
thrown forwards, the natural backward and lateral motion of the ribs being prevented ; and so sensitive are the breathing movements to impediments, that they may either take a reverse action, or all the motion being thrown forwards, will give a preternatural movement of the ribs, which may be mistaken for costal respiration.
Profile view of the breathing movements— (a) Ordinary breathing (Male).—Fig. 711 was obtained by tracing the shadow of a man on paper. The back was fixed, so as to throw all the movement forwards. The anterior black, continuous line represents the ordinary breathing. This line is thicker over the ab domen than elsewhere. The anterior margin of this line indicates the boundary of the ordi nary inspiration, and the posterior margin the boundary of the ordinary expiration.
(Female). — This is represented by the anterior continuous line in fig. 712., in the same manner as shown in the male. This line in the female is broadest over the sternum, and narrow over the abdomen. The movement over the abdomen of the female is so small, that the number of the respirations cannot be counted by the hand resting on that region as it can be on the male. The question of why women breathe costal, and men abdo minal, we cannot pretend to answer. We doubt its being caused by any tight costume, for we found the same to exist in twenty-four girls between the ages of eleven and four teen, none of whom had ever worn any tight dress. This peculiarity may be a reservation against the period of gestation, when the ab domen cannot allow of so free a descent of the diaphragm.
The lateral movement of ordinary breathing is too limited to be represented by a line of varying thickness : the position is given by the continuous line, figs. 713. and 714.
(b) Deep inspiratory.— In fig. 711. the dotted line shows this position, as when a man is just ready to displace his vital ca pacity-volume. The sternum is protruded and the abdomen is drawn in. This is the same in the female (fig. 712.), the dotted line is most advanced over the sternum, while over the abdomen it is drawn inwards.