, 
, 
] 
THE CERVICAL VERTEBR. 75 
The inferior surface, which is more or less saddle-shaped, is directed downwards 
and backwards. It is convex from side to side, and concave from before backwards, 
with a slight rounding off of the projecting anterior lip. The vertical diameter of 
the body is small in proportion to its width. The anterior surface is flat in the 
middle line, but furrowed laterally. The posterior surface, which is rough and 
pierced by many small foramina, is flat from side to side and above downwards; it 
forms in its entire extent the anterior wall of the spinal foramen. The lateral 
aspects of the body, particularly in their upper parts, are fused with the costal 
parts of the transverse processes, and form the inner wall of the vertebrarterial 
foramen (foramen: transversarium). 
The pedicles which spring from the posterior half of the lateral aspects of the 
body, about equi-distant from their upper and lower margins, are directed hori- 
zontally backwards and outwards. The superior and inferior notches are nearly 
equal in depth. 
The laminez are long, and about as wide as the body of the bone is thick. 
The spinal foramen is larger than in the thoracic and lumbar regions; its shape 
is triangular, or more nearly semi-lunar. 
The transverse processes, so called, are pierced by the vertebrarterial foramen 
Bifid spine 
Superior articular process Superior notch 
Inferior F 
articular - Anterior 
process tubercle 
Superior Groove for 
articular ate 
process : : 
Posterior 
Pedicle : 7 tubercle 
Piaed Inferior notch 
osterior 
tubercle Inferior articular process 
Transverse 
process 
Spinous process 
Anterior tubercle 
Fic. 56.—FourtH CERVICAL VERTEBRA FROM ABOVE AND FROM THE RIGHT SIDE. 
(foramen transversarium). They consist of two parts—the part behind the foramen, 
which springs from the neural arch and is the true transverse process, and the 
part in front, which is homologous with the ribs in the thoracic part of the column. 
These two processes, united externally by a bridge of bone, which thus converts the 
interval between them into a foramen, terminate in two tubercles, known respec- 
tively as the anterior and posterior tubercles. The general direction of these pro- 
cesses is outwards, slightly forwards, and a little downwards, the anterior tubercles 
lying internal to the posterior. The two tubercles are separated above by a groove 
directed outwards, downwards, and forwards; along this the spinal nerve trunk 
passes. The vertebrarterial foramen (foramen transversarium), often subdivided by 
a spicule of bone, is traversed by the vertebral artery and vein in the upper six 
vertebrae. The spinous processes, which are directed downwards, are short, com- 
pressed vertically, and bifid. The articular processes are supported on cylindrical 
masses of bone fused with the arch where the pedicles and laminee join. These 
cylinders are sliced away obliquely above and below, so that the superior articular 
facets, more or less circular in form, are directed upwards and backwards, whilst 
the corresponding inferior surfaces are turned downwards and forwards. 
First Cervical Vertebra or Atlas.—This bone may be readily recognised 
by the absence of the body and spinous process. It consists of two lateral masses, 
which support the articular and transverse processes. The lateral masses are 
themselves united by two curved bars of bone, the anterior and posterior arches, of 
which the former is the stouter and shorter. Each lateral mass is irregularly six- 
sided, and so placed that it lies closer to its fellow of the opposite side in front than 
behind. Its upper surface is excavated to form an elongated oval facet, concave 
from before backwards, and inclined obliquely inwards; not infrequently this 
