VERTEBRAS
Noun
vertebras
plural of vertebra
Source: Wiktionary
VERTEBRA
Ver"te*bra, n.; pl. Vertebræ. Etym: [L. vertebra, fr. vertere to
turn, change. See Verse.]
1. (Anat.)
Definition: One of the serial segments of the spinal column.
Note: 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.)
Definition: One of the central ossicles in each joint of the arms of an
ophiuran.
Source: Webster’s Unabridged Dictionary 1913 Edition