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Each vertebra (pl.: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal segment and the particular species.
The number of vertebrae in a region can vary but overall the number remains the same. In a human spinal column, there are normally 33 vertebrae. [3] 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.
The lumbar vertebrae are located between the thoracic vertebrae and pelvis. They form the lower part of the back in humans, and the tail end of the back in quadrupeds. In humans, there are five lumbar vertebrae. The term is used to describe the anatomy of humans and quadrupeds, such as horses, pigs, or cattle.
The vertebral canal is enclosed anteriorly by the vertebral bodies, intervertebral discs, and the posterior longitudinal ligament; it is enclosed posteriorly by the vertebral laminae and the ligamenta flava; laterally, it is incompletely enclosed by the pedicles with the interval between two adjacent pedicles on either side creating an intervertebral foramen (allowing the passage of the spinal ...
The placement of hagfishes on the vertebrate tree of life has been controversial. Their lack of proper vertebrae (among other characteristics of jawless lampreys and jawed vertebrates) led phylogenetic analyses based on morphology to place them outside Vertebrata. [52] Molecular data, however, indicates they are vertebrates closely related to ...
The superior processes or prezygapophysis project upward from a lower vertebra, and their articular surfaces are directed more or less backward (oblique coronal plane). The inferior processes or postzygapophysis project downward from a higher vertebra, and their articular surfaces are directed more or less forward and outward.
The lumbar region is sometimes referred to as the lower spine, or as an area of the back in its proximity.. In human anatomy the five lumbar vertebrae (vertebrae in the lumbar region of the back) are the largest and strongest in the movable part of the spinal column, and can be distinguished by the absence of a foramen in the transverse process, and by the absence of facets on the sides of the ...