_a_, Head; _b_, glenoid cavity; _c_, facet for head of rib; _d_,
transverse process; _e_, facet for tubercle of rib; _f_, mammillary
process; _g_, posterior articular process; _h_, spinous process.
(Ellenberger-Baum, Anat. d. Hundes.)
]
=Curves.=—A gentle curve, convex ventrally, is formed by the cervical
and the anterior part of the thoracic region. The posterior thoracic and
the lumbar vertebra form a second curve, concave ventrally. The sacral
promontory is well marked. The sacrum and the anterior part of the
coccygeal region constitute a third and more pronounced curve, concave
ventrally. In long-tailed dogs the sacro-coccygeal region is somewhat
=S=-shaped.
=Variations.=—Numerical variations are not common except in the
coccygeal region. The number of thoracic vertebræ may be twelve or
fourteen, with or without compensatory change in the lumbar region.
Girard recorded a case with eight lumbar and the usual number of
thoracic vertebra. Six lumbar with fourteen thoracic vertebræ have been
met with. The first coccygeal sometimes unites with the sacrum.