852 SKELETON 
The Second Cervical, known as the Axis or Epistropheus, as being 
the pivot on which the Atlas and Head turn, is composed of seven 
separate elements, the first of which is really the centrum of the 
Atlas, but fused with the second, the centrum of the Axis, so as to 
form the “odontoid process.” The third and fourth are the pair of 
pieces which form the neural arch, and generally bear a prominent 
spinous process. The fifth and sixth are a pair of rib-elements, each 
of which is perforated by a transverse arterial foramen, and fuses with 
the antero-lateral portion of the centrum and neural arch. The 
seventh element is a single median piece wedged ventrally between 
the anterior end of the axial centrum and the Odontoid process, 
and is really equivalent to the second pair of basiventral elements, 
having formed in the embryo the intervertebral pad connecting the 
Odontoid with the body of the Axis, which last frequently carries on 
its ventral side a single hypapophysis. The neural arch of the Axis 
DIAGRAM OF First THREE CERVICAL VERTEBR/& DIAGRAM OF ATLAS FROM 
FROM THE LEFT SIDE. THE FRONT. 
Cc. Centrum ; C.3, Odontoid process; B. Basiventral element ; B.,, the ventral half of the Atlas 
ying ; B.o, the first so-called Intercentrum ; B.3, the meniscus of Vertebra 3; Ch. Chorda 
dorsalis; M. spinal canal; Lt. Ligamentuin transversum ; N. Neural arch. 
possesses a pair of postzygapophyses to articulate with the pre- 
zygapophyses of the Third Vertebra, but owing to the reduced con- 
dition of the Atlas the preezygapophyses of the Axis are insignificant 
or aborted, and in most of the Bucerotide the Atlas is fused with 
the Axis. In general the Axis, which owing to the Odontoid 
process is really the compound of a vertebra and a half, is consider- 
ably longer and larger than any one of 
The next succeeding Cervical Vertebre, which have many features 
in common. Each of them consists of a centrum, a right and left 
basidorsal piece, forming a neural arch above the spinal cord and 
frequently sending out a long single or short bifurcated spinous 
process, a pair of ribs and an intervertebral pad ; but the ribs have 
mostly lost their shaft and are fused by their head and tubercle 
with corresponding short knobs of the centrum or with larger 
processes of the neural arch. A transverse foramen is always 
present, and is a rather characteristic feature. The centra frequently 
