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Related to Vertebrae: Lumbar vertebrae, Thoracic vertebrae, Lumbar vertebræ, Cervical vertebræ, Cervical vertebrae, Thoracic vertebræ



the elements of the axial skeleton forming the spine of vertebrate animals and man.

A vertebra consists of a thickened ventral (in man, anterior) part, the vertebral body, and dorsal arch that fuses with the vertebral body and closes the cerebrospinal canal. In fishes, the lower vertebral arches form transversal processes in the truncal segment; the ribs are attached to these processes. In the caudal segment, the lower arches interlock in the hemal arch with the lower spinal process. The upper arch bears an unpaired upper spinal process. At the arch’s base in terrestrial vertebrates are paired anterior and posterior articular processes and a pair of transversal processes with facets for articulating with the tubercle of a rib. The facet for the head of a rib is usually located between two vertebrae, but it may be entirely displaced to the body of the second vertebra or even fuse with the facet for the tubercle of the rib. A vertebra may also have additional processes.

In fishes, some amphibians, and reptiles, the articular surfaces of the vertebrae may be biconcave, or amphicelous. In most amphibians and reptiles, the vertebral bodies become procelous (concave in front and convex in back) or opisthocelous (convex in front and concave in back) because of the need for mobility. The vertebral bodies are heterocelous, or saddle-shaped, in birds. Mammals have intervertebral cartilaginous disks, and consequently the vertebral bodies are platycelous, or flat in front and concave in back.

The vertebral bodies developed independently in different groups of animals. Their multiple origins may be clearly traced in ontogeny and especially in phylogeny. Up to four pairs of ossifications are formed in fishes: two correspond to the bases of the upper (epicentral) and lower (hypocentral) arches and two are pairs of intercalary (pleurocentral) elements. In most fishes the epicenters and hypocenters fused into a ring and the pleuro-centers were reduced. In crossopterygian fishes and many extinct amphibians, for example, the Stegocephalia, the hypocenters formed a crescent-shaped ventral element, paired in crossoptery-gians, with the pleurocenters remaining small and paired. The hypocenters are reduced in most reptiles as in all amniotes. The heads of the ribs, which originally articulated with the hypocenters, occupied a position between the vertebrae after the hypo-centers were lost. The hemal arches and the small lower spinal process fuse with the hypocenters in the caudal region.


References in periodicals archive ?
These individuals have a lesion called a Schmorl's node - a small hernia which can occur in the disc between the vertebrae - which is thought to be linked to stress and strain on the lower back.
Modeling of vertebrae and simulation of column deformations
The objective of this study was to compare the precision of age estimates obtained from the scales, otoliths, opercula, and vertebrae of American shad.
Predorsal vertebrae 2 (4), preanal vertebrae 79 (76); total vertebrae 183.
The genes corresponding to the cervical vertebrae, the thoracic vertebrae, the lumbar vertebrae and the tailbone become activated at exactly the right moment one after another.
Several researchers have studied its age and growth estimation by using different ageing structures such as spines (van der Waal & Schoonbee, 1975; Bruton & Allanson, 1980; Quick & Bruton, 1984), vertebrae (Pivnicka, 1974; Willoughby & Tweddle, 1978), and otoliths (Bruton & Allanson, 1980; Quick & Bruton, 1984).
It wasn't a chipped vertebrae or cracked vertebrae.
The former racing driver suffered three broken vertebrae but is expected to make a full recovery.
Dr Ahmed's third cervical vertebrae, one of several bones that house the spinal cord, had been crushed in an accident near Kandahar on February 25.
Chiropractic treatment, which is an alternative form of healing, works on correcting the alignment of the vertebrae in the spinal column through physical therapy and manipulation of the vertebrae.
The vertebra was recovered along with three cetacean vertebrae at a depth of 40-45 mat approximate latitude 39[degrees] 45' and longitude 73[degrees] 30' (Fig.