8 VERTEBRAL COLUMN. 



wards. Its superior surface is rendered transversely concave by the upward 

 projection of its lateral margins, and is sloped down anteriorly. The under 

 surface, on the contrary, is rounded oif at the sides, while its anterior margin 

 forms a marked projection downwards. 



The lamina are remarkable for their length and flatness. The superior 

 notches are deeper than the iufeiior. 



The spinous process is short, projects horizontally backwards, or is only 

 slightly depressed, and is bifid at its extremity. That of the seventh, 

 however, terminates in a tubercle, and is so long as to be readily felt below 

 the skin, while the others lie more deeply, and are covered with muscles : 

 hence the name vertebra prominens, applied to the seventh. 



The transverse processes are short, and bifid at the extremity. They pre- 

 sent a deep groove superiorly, in which the spinal nerves lie ; and at the 

 base are perforated vertically by a round foramen of considerable size. They 

 have two roots or points of connection with the vertebra, one in front and 

 one behind the foramen. The posterior root springs from the place of 

 junction of the pedicle and lamiua, and in so far corresponds with the 

 dorsal transverse processes ; the anterior root is attached to the body of the 

 vertebra and ranges in the same line with the ribs. The foramen corresponds 

 with the space left between the root of a dorsal transverse process and the 

 neck of the attached rib : it gives passage usually in the upper six ver- 

 tebrae to the vertebral artery and vein, but in the seventh, though the 

 foramen likewise exists, those vessels rarely pass through it. The trans- 

 verse process of the seventh cervical vertebra 

 presents only a slight appearance of a groove on 

 its upper surface, and is widened rather than 

 bifid at its extremity. 



Fig. 5. THIRD CERVICAL VERTEBRA. 4 



A, from above and slightly from behind ; B, from 

 the side. 1, the body ; 2 (omitted), the pedicle and 

 intervertebral notch ; 3, lamina ; 4, vertebral ring, of 

 a triangular form ; 5, bifid spinous process ; 6, 6*, 

 transverse process 6, posterior, 6*, anterior tubercle ; 

 a, foramen in the root of the transverse process trans- 

 mitting the vertebral artery; 7, 7', articulating processes 

 7, the superior, 7', the inferior. 



B ytriWE^ni^^hT "-^ke articulating processes are large and flat. 



Their articular surfaces are situated obliquely, 

 the superior pair looking backwards, upwards, 

 and in most of them blightly inwards ; the 



inferior pair forwards, downwards, aud in most of them slightly outwards. 



The portion of bone between the superior and the inferior articular surface 



on each side forms a short vertical pillar. 



The ring is of a triangular form, and larger than in either the dorsal or 



lumbar vertebrae. 



THE FIRST AND SECOND CERVICAL VERTEBRAE. 



THE FIRST VERTEBRA, or Atlas, so called from supporting the. head, is 

 remarkable for the smallness of the parts occupying the position of the 

 body and spinous process. 



The ring, which is large from before backwards, is wider in the posterior 

 than in the anterior part of its extent. The wide posterior part corresponds 



