ANATOMY. 



these, the first, that immediately supports 

 the head, is called the atlas ; and the 

 second, from a remarkable bony process 

 which it possesses, the vertebra; dentata. 

 The twelve next are called dorsal verte- 

 bra;, and are distinguished by having the 

 ribs articulated to them. The five last 

 are called lumbar. These all differ from 

 each other in some circumstances. The 

 most obvious distinction arises from the 

 size : the upper ones are the smallest, and 

 there is a gradual increase as we descend. 

 The column of the spine, when viewed 

 altogether, is not perpendicular; it stands 

 forward in the neck, recedes in the up- 

 per part, of the back, and projects again 

 in the loins. Holes are left between the 

 hone.-), for the transmission of the nerves 

 which arise from the spinal marrow. 



The sacrum forms the back of the pel- 

 vis, and is followed out in front. In form 

 it is triangular, and the base is joined to 

 the last vertebra. It is perforated by a 

 canal, in which the termination of the me- 

 dulla spinalis is lodged. Its apex has 

 connected to it the os coccygis. 



The thorax is formed by the twelve 

 dorsal vertebra, the ribs, and sternum. 

 The ribs are long, curved, flattened, and 

 narrow bones, attached behind to the 

 dorsal vertebra:, both in their bodies and 

 transverse processes, and joined in front 

 tc a piece of cartilage. They are twelve 

 in number, and the seven upper ones, 

 whose cartilages are affixed to the sides 

 of the sternum, are called true ribs ; the 

 live lowerones, the cartilages of which do 

 not reach so far, are called the false ribs. 

 The sternum is a broad and flat bone, 

 placed in the front of the chest. It con- 

 Si.sts of two pieces of bone, and of a carti- 

 . lied the ensiform. The clavicles 

 :uv articulated towards its upper parts, 

 and the cartilages of the ribs are joined 

 to its sides. 



The pelvis is formed by the two ossa 

 innouiinata, or haunch bones, the sacrum, 

 and os coccygis. The former are very 

 large and Hut bones, expanded into a 

 broad surface above for the support of 

 the abdominal viscera, and the attachment 

 of the abdominal muscles, and furnished 

 : ;<e tuberosities below, for the sup- 

 ; lie body in the sitting position. 

 Each os innoniinatum is divided into the 

 ilium, isciiium, and puhes. It is firmly 

 joined to the sacrum behind, and to the 

 opposite Lone in front, by The bymphisis 

 pubis. The conjoined portions form an 

 arch, called the arch of the pubcs. The 

 cavity of the pelvis is much larger in the 

 female than in the male, as ii. holds the 



uterus and vagina, in addition to what it 

 contains in the male, and as the fetus 

 passes through it in parturition. 



The bones of the upper extremity are 

 distributed into those of the shoulder, 

 arm, fore-arm, and hand. 



The shoulder contains two; the scapula 

 and clavicle. The former is situated at 

 the upper and outer part of the chest, and 

 is joined to the end of the clavicle. 



The humerus is a long and nearly cy- 

 lindrical bone, joined by a round head to 

 the scapula above, and articulated with 

 the radius and ulna below. 



The fore-arm has two bones ; the ulna, 

 which is joined by a hinge or ginglymus 

 to the humerus ; and the radius, which 

 has a cavity playing upon a rounded head 

 of that bone. The prominent extremity 

 of the ulna, which forms the elbow, is 

 called the olecranon. The hand is di- 

 ded into the carpus, 'or wrist, the meta- 

 carpus, and the fingers and thumb. 



The carpus contains eight bones, dis- 

 posed in two phalanges, of which the first 

 forms, with the radius, the joint of the 

 wrist, and the second is articulated to the 

 metacarpus. 



The bones of the first phalanx are the 

 os scaphoides, lunare, cuneiforme, and 

 pisiforme : those of the second, os tra- 

 pezium, trapezioides magnum, and unci- 

 forme. 



The metacarpus lias five bones, and 

 each of the fingers three ; the thumb only 

 two. 



In the lower extremity we have the fe- 

 mur, the largest of the cylindrical bones 

 in the body. This has a round head, con- 

 tained in a socket of the os innominatum : 

 tlie great trochanter forms a conspicuous 

 process at the upper and outer pail of the 

 bone. Below it has two condyles, which 

 form part of the knee. 



The leg has two bones; the tibia and 

 fibula. A large flat portion of the former, 

 covered only by skin, is called the shin. 

 The foot is composed of the tarsus, meta- 

 tarsus, and toes. The tarsus has seven 

 bones : 1. Astragalus, composing the 

 ankle, with the lower portion of the tibia 

 and fibula. 2. Os calcis. 3. Os navicu- 

 lare. 4. Os cuboides. 5, 6, 7. Ossa cu- 

 neiforijiia. The metatarsal bones are five 

 in number, and the bones of each toe an: 

 three, except the great toe, which has 

 only two. 



SY.VJJtSMOLOKT, On DOCTRIXE OF THK 

 JOISTS. 



Construction of a joint. The opposed 

 surfaces of bones, which form joints, aiv 



