: 
7 
; 
7 
THE VERTEBRAL COLUMN. 73 
For descriptive purposes, the vertebral column is subdivided according to the 
regions through which it passes. Thus the vertebrie are described as cervical 
(vertebre cervicales), dorsal or thoracic (vertebrie thoracales), lumbar (vertebra: 
lumbales), sacral (vertebrie sacrales), and coccygeal (vertebrie caudales), according , 
as they lie in the regions of the neck, back, loins, pelvis, and tail. The number of 
vertebree met with in these regions is fairly constant, though, as will be hereafter 
pointed out, variations may occur in the number of the members of the different 
series. The vertebre in man are thus apportioned—7 cervical, 12 dorsal, 5 lumbar, 
5 sacral, and 4 or 5 coccygeal; the three former groups comprise the true or mov- 
able vertebrae, the two latter the false or fixed vertebra. The vertebral formula 
may be thus expressed :— 
Movable or True Vertebre. Fixed or False Vertebre. 
Cervical. Dorsal. = Lumbar. Sacral,  Coccygeal. 
i 12 5 5 4 =o0 
The vertebre of which the column is built up, though displaying great diversity of 
characters in the regions above enumerated, yet preserve certain features in 
common. All possess a solid part, 
centrum or body (corpus vertebr) ; 
all have articular processes by which 
they are joined to their fellows; 
most have muscular processes de- 
veloped in connexion with them; 
whilst the majority display a verte- 
bral or spinal foramen (foramen verte- 
brale) formed by the union of a bony 
arch (arcus vertebre) with the body. 
These common characters may best 
be studied by selecting for descrip- 
tion an intermediate member of the 
series. or this purpose one of the 
middle or lower thoracic vertebrie 
may be chosen. 
A typical vertebra may be de- 
scribed as consisting of a body or 
centrum (corpus vertebrae) composed 
of a mass of spongy bone, more or 
less cylindrical in form. The size 
and shape of the body is lable to 
considerable variation according to 
the vertebra examined. The upper 
and lower surfaces of the body are 
very slightly concave from before 
backwards and from side to side, 
due to the thickening of the bone 
around itsmargins. Intherecentcon- 
dition these surfaces afford attach- 
ment for the intervertebral discs 
which are placed like pads between 
the bodies of the movable members 
of the series. The circumference of 
the body, formed as it is of more 
compact bone than the interior, is 
usually slightly concave from above 
downwards, though it becomes flat 
Superior 
articular process Pedicle 
B Demi-facet 
J for head 
of rib 
Body 
Facet for 
tubercle of rib 
Transverse 
process 
yemi-facet for 
head of rib 
Inferior 
notch 
Inferior 
articular 
process 
Spinous process 
(As viewed from the right side.) 
Spinous process 
Transverse 
process 
Facet for 
tubercle of 
rib 
Superior articular 
process 
SPINAL 
4 FORAMEN 
Pedicle 
Demi-facet for _| 
head of rib 
Body 
Fries. 54, 55.—FirrH THORACIC VERTEBRA. 
(As viewed from above.) 
behind, where the body forms the anterior boundary of the spinal or vertebral 
foramen, at which point it is usually slightly concave from side to side. The 
vertical surfaces of the body are pierced here and there by foramina for the 
