172 



THE BODY AT WORK 



During expiration the space between the muscle of the 

 diaphragm and the chest-wall closes up, and the lower border 

 of the lung slips out of it. 



There is a marked difference in the relative extent of the 

 costal and diaphragmatic movements in men and women. In 

 women respiration is chiefly costal ; in men it is chiefly 

 diaphragmatic. In men the abdomen moves forwards, as the 

 diaphragm descends in tranquil breathing ; in women the chest 

 rises. Men who wish, for the purposes of athletics, or singing, 



B 



Right Auride Right Ventricle 



Ribv 

 Pleura 



Diaphra 



FIG. 8. THE DIAPHRAGM AND ORGANS IN CONTACT WITH IT A, IN EXPIRATION ; B, AT THE 

 END OP A DEEP INSPIRATION. TRANSVERSE VERTICAL SECTIONS IN THE LINE OF THE 

 ARMPIT. 



A, At the end of an ordinary expiration the lung does not extend below the upper border of 

 the eighth rib. From this level to the middle or lower border of the tenth rib the two 

 layers of the pleura covering respectively the inner wall of the chest and the upper surface 

 of the diaphragm are in contact. B, When the lung is distended with air it occupies the 

 whole of the pleural cavity. 



or public speaking, to retain the power of making the most of 

 their chest-capacity are wise in not allowing themselves to fall 

 into the habit of lazy, abdominal breathing. 



When additional pressure is required, when respiration is 

 forced, various external muscles attached to the spinal column, 

 the shoulder-blades, and the clavicles, as well as the muscles of 

 the abdomen, come into play. 



The chest is lined and the lungs covered by a serous mem- 

 brane the pleura. Normally there is only just sufficient 

 lymph in the space between the visceral layer of the pleura 



