THE SKELETON. 99 



36. 5th. The caudal or cnccyqian region, which in man i-s com- 

 posed of four very small vertebrae, concealed beneath the skin, in 

 many animals, is very long, constituting the tail, (Fig. 38. co.) 



37. The vertebral column seen in profile, presents four curves, 

 which correspond to the neck, the back, the loins, and the ;>*'/r/>, 

 or basin, and which serve to augment its solidity. On its sides, 

 we find, between all the vertebrae, a hole which gives passage to 

 a nerve, coming from the spinal marrow. 



38. The rib*) which are attached to the dorsal vertebra?, are 

 long, flat bones, which enclose the thorax: on each side : they are 

 curved and bear considerable resemblance to a half hoop. In 

 man there are twelve pairs. The seven first, called true ribs, 

 articulate in front with the sternum, through the medium of a 

 cartilage ; the five last pairs, called false ribs, terminate anteriorly 

 by a cartilage which joins that of the preceeding rib, or they are 

 entirely without cartilage. 



39. The aU'rnnm. is a flat bone placed in front of the thorax; it 

 articulates with the ribs and with the clavicles. 



40. The superior or anterior eytremiiie* are composed of the 

 shoulder, the arm, the fore-arm and the hand. 



41. The .\iionLier is the basis of the whole limb attached to it. 

 It consists of two bones; the scapula or shoulder blade, and the 

 clavicle, or collar-bone. 



42. The scapula is a large bone nearly triangular in shape, 

 which is applied against the ribs at the superior and lateral part oi 

 the back. At its superior external angle, it presents an enlarged 

 articular surface, slightly hollowed, which receives the bone of 

 the arm and is called the ylenoni carity of t/ic scapula. On the 

 posterior face of this bone there is a projecting comb or riJge 

 which extends over the articulation of the shoulder, and arti- 

 culates with the clavicle. This prolongation is named the 

 acroiaion. 



43. The dariclf is a long thin bone situated at the base of the 

 neck ; it extends like a buttress between the scapula and sternum; 



36. What are those vertehrae called which form the skeleton of the tail in 

 animals ? 



37 For what use ar the several holes found between the vertebra on (he 

 liijes of the spinal column 1 



38. VVhat are the ribs? Whatnumbei of ribs belong to man? How many 

 tre true and how many are false ribs ? 



33. What is the sternum? 



40. How are the superior extremities divided ? 



4 I. What is the shoulder ? ^ hat bones c >mpose the shoulder? 



42. Wl ere is the scapula placed ? VVhat is the glenoid cavity ? WL&t iff 

 4ie acromion? 



43. What is the use of the clavicle ? 



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