MANUAL 



OF 



PRACTICAL ANATOMY. 



THORAX. 



r T*HE dissection of the thorax is commenced on the thirteenth 

 * day 1 after the subject has been placed in the dissecting- 

 room. By that time the upper limbs have been detached 

 from the trunk. 



In form, the thorax resembles a truncated cone. Anteriorly 

 and posteriorly it is flattened ; laterally it is full and rounded. 



The cavity of the thorax is bounded (i) anteriorly, by 

 the sternum and costal cartilages ; (2) posteriorly, by the twelve 

 thoracic vertebrae and the intervening fibre-cartilages, together 

 with the portions of the ribs which extend laterally from the 

 vertebral column as far as the angles of the ribs ; (3) on each 

 side by the bodies of the twelve corresponding ribs, from 

 their angles posteriorly to their anterior extremities anteriorly. 

 The boundaries mentioned constitute the framework of the 

 thorax, and can be studied on the skeleton, as well as upon 

 the part, before the dissection is commenced. 



The anterior wall of the thorax is so much shorter than the 

 posterior wall that, during expiration, the upper margin of the 

 sternum lies opposite the nbro-cartilage between the second 

 and third thoracic vertebrae, and the lower end of the body 

 of the sternum corresponds in level with the middle of the 



1 Saturdays and Sundays are not counted. 

 VOL. II 1 



