![]() ![]() The vertebral arch is formed by a pair of pedicles and a pair of laminae, and supports seven processes, four articular, two transverse, and one spinous, the latter also being known as the neural spine. Because the spinal cord ends in the lumbar spine, and the sacrum and coccyx are fused, they do not contain a central foramen. Together, these enclose the vertebral foramen, which contains the spinal cord. The vertebral arch is posterior, meaning it faces the back of a person. Two special vertebrae are the atlas and axis, on which the head rests.Ī typical vertebra consists of two parts: the vertebral body and the vertebral arch. The vertebrae of the sacrum and coccyx are usually fused and unable to move independently. The vertebrae of the cervical, thoracic, and lumbar spines are independent bones and generally quite similar. The number of those in the cervical region, however, is only rarely changed. The number of vertebrae in a region can vary but overall the number remains the same. There are seven cervical vertebrae, twelve thoracic vertebrae, and five lumbar vertebrae. These regions are called the cervical spine, thoracic spine, lumbar spine, sacrum, and coccyx. Vertebrae in these regions are essentially alike, with minor variation. The articulating vertebrae are named according to their region of the spine. The vertebrae in the human vertebral column is divided into different regions, which correspond to the curves of the vertebral column. Main article: Vertebra Numbering order of the vertebrae of the human spinal column There are ligaments extending the length of the column at the front and the back, and in between the vertebrae joining the spinous processes, the transverse processes and the vertebral laminae. The most frequent deviations are: 11 (rarely 13) thoracic vertebrae, 4 or 6 lumbar vertebrae, 3 or 5 coccygeal vertebrae (rarely up to 7). In about 10% of people, both the total number of pre-sacral vertebrae and the number of vertebrae in individual parts of the spine can vary. Excluding rare deviations, the total number of vertebrae ranges from 32 to 35. The number of those in the cervical region, however, is only rarely changed, while that in the coccygeal region varies most. There are 7 cervical vertebrae, 12 thoracic vertebrae and 5 lumbar vertebrae. The upper 24 pre-sacral vertebrae are articulating and separated from each other by intervertebral discs, and the lower nine are fused in adults, five in the sacrum and four in the coccyx, or tailbone. In a human vertebral column, there are normally 33 vertebrae. ![]() There are also many different spinal diseases in humans that can affect both the bony vertebrae and the intervertebral discs, with kyphosis/ scoliosis, ankylosing spondylitis, degenerative discs and spina bifida being recognizable examples. In clinical medicine, features on vertebrae (particularly the spinous process) can be used as surface landmarks to guide medical procedures such as lumbar punctures and spinal anesthesia. Individual vertebrae are named according to their corresponding body region ( neck, thorax, abdomen, pelvis or tail). The shape of the vertebral body does, however, vary somewhat between different groups of living species. The human vertebral column is one of the most-studied examples, as the general structure of human vertebrae is fairly typical ( homologous) of that found in other mammals, reptiles and birds. There are around 50,000 species of animals that have a vertebral column. The dorsal portion of the vertebral column houses the spinal canal, a cavity formed by alignment of the neural arches that encloses and protects the spinal cord. The vertebral column is the defining characteristic of vertebrate endoskeleton in which the notochord (a flexible collagen-wrapped glycoprotein rod) found in all chordates has been replaced by a segmented series of mineralized irregular bones (or sometimes, cartilages) called vertebrae, separated by fibrocartilaginous intervertebral discs (the center of which is a notochord remnant). The vertebral column, also known as the backbone or spine, is the core part of the axial skeleton in vertebrate animals. ![]()
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