THORACIC VERTEBRA. 
79 
The first dorsal vertebra resembles the seventh cervical in the shape of its 
body and the length and direction of its spine. 
side of the body for the head 
of the first rib, and one demi- 
facet on each side at the 
lower border of its body, to 
complete the socket for the 
head of the second rib. Its 
transverse processes are long, 
and the superior inter- 
vertebral notch is better 
marked than in other mem- 
bers of the dorsal series. 
The superior articular sur- 
faces are directed backwards 
and upwards, not outwards 
as in the lower series. 
The ninth dorsal verte- 
bra occasionally has only 
the upper pair of demi- 
facets on its body; at other 
times it conforms to the 
usual type. 
The tenth dorsal verte- 
bra may have only one com- 
plete costal facet on each 
side for the X. rib, though 
sometimes the articular 
socket may be completed by 
the ninth dorsal vertebra. 
The facet on the transverse 
process is generally small, 
and sometimes absent. 
The eleventh dorsal 
vertebra has a complete 
circular facet on the outer 
side of each pedicle for 
articulation with the XI. rib. 
Its transverse processes are 
short and stunted, and have 
no facets. 
The twelfth dorsal 
vertebra has a single facet 
on the pedicle on each side 
for the XII. rib. Its trans- 
verse processes, which have 
no facets, are broken up 
into smaller tubercles, called 
respectively the external, 
superior, and inferior tuber- 
cles. These are homologous 
with the transverse mam- 
millary and accessory pro- 
cesses of the lumbar verte- 
bre. Indications of these 
processes may also be met 
bo 
There is an entire facet on either 
Fic. 60.—First, NintH, TenTH, ELEVENTH, AND TWELFTH THORACIC 
On 
. Inferior articular process with 
. Single facet for head of XII. rib ; 
. Single facet for head of XI. rib ; 
. Single or demi-facet for head of 
. Occasional demi-facet for head S. 
. Demi-facet for head of IX. 
VERTEBRE FROM THE LEFT SIDE. 
7. Demi-facet for head of IT. rib. 
8. Single facet for head of I. rib. 
9, Facet on transverse process for 
tuberosity of I. rib. 
10. Facet on transverse process for 
tuberosity of IX. rib. 
11. Facet on transverse process for 
tuberosity of X. rib. 
ee Tubercles ( Mammillary. 
out-turned facet. 
no facet on transverse process. 
no facet on transverse process. 
X. rib. 
of X. rib. 
| corre- Accessory. 
| sponding eager 
to . of lumbar. 
I. Inferior 
rib. E. External) 
with in the tenth and eleventh dorsal vertebre. The twelfth dorsal vertebra may 
usually be distinguished from the eleventh by the arrangement of its inferior 
articular processes, which resemble those of the lumbar series in being out-turned ; 
