404 THE MECHANICAL FUNCTIONS. 



The two bones by which the anterior extremity 

 is connected with the trunk are the blade-bone, 

 or Scapula (B), which sends out a process called 

 the coracoid bone; and the collar-bone, or the 

 Clavicle* which extends from the scapula to the 

 sternum. The corresponding connecting bones 

 of the posterior extremity are three in number, 

 and constitute, together with the part of the 

 spine to which they are attached, what is called 

 the Pelvis (p). The part of the spine which is 

 thus included in the pelvis, is termed the Sacrum* 

 In its complete state of ossification it is a single 

 bone ; but it was originally composed of a 

 number of separate vertebrae, which have after- 

 wards become consolidated into a single bone, 

 and which bear the marks of having been com- 

 pressed from behind forwards during their growth, 

 so that they could only expand laterally. The 

 vertebrae which succeed to these, and which are 

 not consolidated with the sacrum, compose what 

 is called the os coccygis, (Q), or more properly the 

 coccygeal vertebrae: when they are sufficiently 

 numerous to compose a tail, they come under the 

 denomination of caudal vertebra. The three 



* This bone does not exist in the skeleton of the hog ; but its 

 form and connexions with the sternum and scapula in the 

 human skeleton are shown in Fig. 182, where s is the sternum; 

 c, the clavicle ; B, the scapula ; a, the acromion ; k, the cora- 

 coid process ; and g, the glenoid cavity for the articulation of 

 the humerus. 



