||Ver"te*bra (?), n.; pl. Vertebræ (#). [L. vertebra, fr. vertere to
||turn, change. See Verse.]
||
1. (Anat.) One of the serial segments of the spinal column.
In many fishes the vertebræ are simple cartilaginous disks or short
cylinders, but in the higher vertebrates they are composed of many
parts, and the vertebræ in different portions of the same column vary
very greatly. A well-developed vertebra usually consists of a more or
less cylindrical and solid body, or centrum, which is surmounted
dorsally by an arch, leaving an opening which forms a part of the canal
containing the spinal cord. From this dorsal, or neural, arch spring
various processes, or apophyses, which have received special names: a
dorsal, or neural, spine, spinous process, or neurapophysis, on the
middle of the arch; two anterior and two posterior articular processes,
or zygapophyses; and one or two transverse processes on each side. In
those vertebræ which bear well-developed ribs, a tubercle near the end
of the rib articulates at a tubercular facet on the transverse process
(diapophysis), while the end, or head, of the rib articulates at a more
ventral capitular facet which is sometimes developed into a second, or
ventral, transverse process (parapophysis). In vertebrates with
well-developed hind limbs, the spinal column is divided into five
regions in each of which the vertebræ are specially designated: those
vertebræ in front of, or anterior to, the first vertebra which bears
ribs connected with the sternum are cervical; all those which bear ribs
and are back of the cervicals are dorsal; the one or more directly
supporting the pelvis are sacral and form the sacrum; those between the
sacral and dorsal are lumbar; and all those back of the sacral are
caudal, or coccygeal. In man there are seven cervical vertebræ, twelve
dorsal, five lumbar, five sacral, and usually four, but sometimes five
and rarely three, coccygeal.
2. (Zoöl.) One of the central ossicles in each joint of the arms of an
ophiuran.
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Ver"te*bral (?), a. [Cf. F. vertébral.] 1. (Anat.) Of or pertaining to
a vertebræ, or the vertebral column; spinal; rachidian.