false vertebra

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false vertebra

one of the vertebral segments that form the sacrum and the coccyx. Also called fixed vertebra.


(ver'te-bra) plural.vertebrae [L.]
Any of the 33 bony segments of the spinal column: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal vertebrae. In adults, the five sacral vertebrae fuse to form a single bone, the sacrum, and the four rudimentary coccygeal vertebrae fuse to form the coccyx.

A typical vertebra consists of a ventral body and a dorsal or neural arch. In the thoracic region, the body bears on each side two costal pits for reception of the head of the rib. The arch that encloses the vertebral foramen is formed of two roots or pedicles and two laminae. The arch bears seven processes: a dorsal spinous process, two lateral transverse processes, and four articular processes (two superior and two inferior). A deep concavity, the inferior vertebral notch, on the inferior border of the arch provides a passageway for a spinal nerve. The successive vertebral foramina form the vertebral, or spinal, canal that encloses the spinal cord.

The bodies of successive vertebrae articulate with one another and are separated by intervertebral disks, disks of fibrous cartilage enclosing a central mass, the nucleus pulposus. The inferior articular processes articulate with the superior articular processes of the next succeeding vertebra in the caudal direction. Several ligaments (supraspinous, interspinous, anterior and posterior longitudinal, and the ligamenta flava) hold the vertebrae in position, yet permit a limited degree of movement. Motions of the vertebral column include forward bending (flexion), backward bending (extension), side bending (lateral flexion), and rotation. Lateral flexion and rotation motions are coupled so that whenever the vertebrae bend to the side, they also rotate and vice versa. See: sacrum for illus

basilar vertebra

The lowest of the lumbar vertebrae.

cervical vertebra

One of the seven vertebrae of the neck.

coccygeal vertebra

One of the rudimentary vertebrae of the coccyx.

vertebra dentata

The second cervical vertebra.

false vertebra

Fixed vertebra.

fixed vertebra

The sacral and coccygeal vertebrae that fuse to form the sacrum and coccyx.

lumbar vertebra

One of the five vertebrae between the thoracic vertebrae and the sacrum.

vertebra magna


odontoid vertebra

Axis (2).

vertebra prominens

The seventh cervical vertebra.

sacral vertebra

One of the five fused vertebrae forming the sacrum.
See: sacrum for illus

sternal vertebra

One of the segments of the sternum.

thoracic vertebra

One of the 12 vertebrae that connect the ribs and form part of the posterior wall of the thorax.
See: spinal column for illus

true vertebra

One of the vertebrae that remain unfused through life: the cervical, thoracic, and lumbar.


pl. vertebrae [L.] any of the separate segments comprising the spine (vertebral column). See also spine, vertebral.
The vertebrae support the body and provide the protective bony corridor through which the spinal cord passes. The number of bones in the vertebral column varies with the animal species and even within each species. Average numbers are given in Table 10.
The compression-resisting portion of a typical vertebra is the vertebral body, the most ventral portion. This is a cylindrical structure that is separated from the vertebral bodies in front and behind by disks of cartilage and fibrous tissue. These intervertebral disks act as cushions to spread and absorb the mechanical shock during body movements. See also slipped disk.
A semicircular arch of bone protrudes from the dorsum of each vertebral body, surrounding the spinal cord. Directly in its midline a bony projection, the spinous process, grows upward from the arch. Three pairs of outgrowths project from the arch. One of these protrudes horizontally on each side and in the thorax connects with the ribs. The remaining two form joints with the vertebrae in front and behind. The joints permit the spine to bend flexibly. The vertebrae are held firmly in place by a series of strong ligaments.

anticlinal vertebra
1. the vertebra whose spinous process is directed vertically at which point the backward slope of the cranial vertebrae changes to a forward inclination. Is usually the sixteenth thoracic vertebra in the horse.
2. (improperly) the diaphragmatic vertebra.
block vertebra
anomalous development in which two or more vertebrae are fused.
butterfly vertebra
anomalous development of a vertebra that is nearly divided in half by a longitudinal defect; caused by the persistence of the sagittal membrane remnant of the notochord. The vertebral body resembles a butterfly on ventrodorsal radiographs.
caudal vertebra
coccygeal vertebrae.
cranial vertebra
the segments of the skull and facial bones, regarded by some as modified vertebrae.
vertebra dentata
the second cervical vertebra, or axis.
diaphragmatic vertebra
the vertebra which marks the transition between those located cranially with a thoracic type of articular facet to those located caudally with a lumbar type. It is often the same vertebra as the anticlinal vertebra (above).
false vertebra
those vertebrae which normally fuse with adjoining segments such as the sacral vertebrae or the human coccygeal vertebrae.
vertebra magnum
the sacrum.
odontoid vertebra
the second cervical vertebra, or axis.
opisthocoelus vertebra
a vertebra with a concave caudal surface to the body.
vertebra plana
a condition of spondylitis in which the body of the vertebra is reduced to a sclerotic disk.
transitional vertebra
true vertebra
those segments of the vertebral column that normally remain unfused throughout life: the cervical, thoracic, lumbar and coccygeal vertebrae.
wedge-shaped vertebra