![]() Thetransverse processes are long and are vaguely palpable in vivoimmediately below the auricle. Each lateral mass presents upper and lower facets, forthe occipital condyle of the skull and for the axis, respectively. The atlas (C1), which has neither body nor spinous process, consistsof two lateral masses connected by a short anterior and a longerposterior arch. The C1vertebra, which supports the skull, is termed the atlas, and C2, whichserves as a pivot for the atlas, is termed the axis. The upper sixpairs of foramina transversaria transmit the vertebral artery. The seven vertebrae of the neck are characterized by an opening in eachtransverse process known as a foramen transversarium. The vertebrae of each region have special characteristics, which arenow described. C8 emerges betweenthe C7 and T1 vertebrae, and the remaining spinal nerves leave belowthe correspondingly numbered vertebrae. The first cervical nerve emerges between the skull and theatlas, and cervical nerves C2 to 7 continue to leave the vertebralcanal above the correspondingly numbered vertebrae. Relationship of Spinal Nervesto Vertebrae. When vertebraare in their anatomical position, notches between adjacent pediclesform intervertebral foramina, each of which typically transmitsneuralstructures including a spinal ganglion and a ventral root of a spinalnerve. Thesuperior and inferior articular processes project vertically from thevertebral arches on each side and bear articular facets. The transverse processesemerge laterally at the junction of the pedicles and laminae, and thespinous process proceeds posteriorly from the union of the laminae. ![]() The vertebral arch consists of right and left pedicles (which connectit to the body) and right and left laminae. The body is marked on its sidesby vascular foramina. The body is mainly spongy bone and red marrow,but the margins of the upper and lower surfaces consist of a ring ofcompact bone, the vertebral end-plates. The bodies of the vertebrae are separated from each other byintervertebral discs. Inaddition to the transverse and spinous processes, which serve as shortlevers, the 12 thoracic vertebrae are connected by joints with paired,long levers, namely the ribs. Between the body and the archis the vertebral foramen: the sum of the vertebral foramina constitutesthe vertebral canal, which houses the spinal cord (fig. Parts of a Vertebra.Ī typical vertebra consists of (1) a body and (2) a vertebralarch, which has several processes (articular, transverse, and spinous)for articular and muscular attachments. Thethoracic and sacral curvatures, termed primary, appear during theembryonic period proper, whereas the cervical and lumbar curvatures,termed secondary, appear later (although before birth) and areaccentuated in infancy by support of the head and by the adoption of anupright posture. The adult vertebral column presents four anteroposteriorcurvatures: thoracic and sacral, both concave anteriorly, and cervicaland lumbar, both concave posteriorly (fig. ![]() are used for the regions, and these are sometimesfollowed by V. Stability is providedby ligaments, muscles, and the form of the bones. The 24 presacral vertebrae allow movementand hence render the vertebral column flexible. The vertebral column usually consists of 33 vertebrae: 24 presacralvertebrae (7 cervical, 12 thoracic, and 5 lumbar) followed by thesacrum (5 fused sacral vertebrae) and the coccyx (4 frequently fusedcoccygeal vertebrae). 39-12and 39-13)Ĭhapter 39: The vertebral column Vertebral column in general
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