16 



BONES OF THE TRUNK. 



24 of which are classified as true vcrtebrce, on account of their mo- 

 bility, and the 5 remaining are caWed false vertebrce. The true 

 vertebrse are divided into 7 cervical, 12 dorsal, and 5 lumbar ; the 

 false vertebrog consist of the sacrum, and 3 or 4 coccygeal bones. 



A vertebra consists of a body, 7 processes, and a spinal foramen. 

 The body is in front and is the thickest part ; its upper and lower 

 surfaces articulate with a contiguous vertebra by means of a carti- 

 lage ; it is convex anteriorly from side to side. The j^i'ocesses are, 

 one spmous, of a triangular shape, and situated behind for the at- 

 tachment of muscles ; two transverse, one projecting horizontally on 

 either side for the attachment of muscles and ligaments ; and four 

 oblique processes, two of which are superior and two inferior, which 

 are for the purpose of articulation. The spinal foramen is in the 

 middle, and constitutes a portion of the spinal canal. The interver- 

 tebral foramen is formed on each side by a groove upon the upper 

 and lower surface of each vertebra, and transmits a spinal nerve. 



Fig. 1. 



CERVICAL VERTEBRJE. 



The bodies are small and flattened in 

 front; the superior surfaces^ are con- 

 cave laterally, the inferior, are concave 

 antero-superiorly ; they gradually in- 

 crease in size. The spinous processes'*' 

 are short, thick, horizontal, and bifid. 

 The oblique jjrocesses are flat, oval, and 

 short; the sujwrior'' look upwards and 

 backwards, and the inferior^ down- 

 wards and forwards at an angleof forty- 

 five degrees. The transverse processes^ 

 arc broad, perforated at their base by a 

 foramen^ for the transmission of the vertebral artery. The spinal 

 foramen" is very large. 



The first cervical vertebra is called the atlas ; it has no body, 

 and resembles a ring. Tn place of a body, there is an arch which 

 has a tubercle in the middle of its anterior surface ; in the correspond- 

 ing part of its posterior surface is an articular fossa for the processus 

 dentatus of the second vertebra. The posterior arch has a tubercle 

 instead of the spinous process. The superior oblique processes are 

 large, oblong, and concave, adapted to the. condyloid processes of 

 the occiput ; and admit of flexion and extension. The inferior ob- 

 liq}ie processes are round, flat, and horizontal, adapted to the rotatory 

 motion of the head. The transverse process is extremely long. On 

 the inner side of thQ oblique processes is a tubercle for the attachment 

 of the transverse ligament. The spinal foramen is the largest. 

 The second is called dentata, from its tooth-like process projecting 

 from the upper surface of the body ; the tip of which is rough for 



