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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 proportions of the vertebrae differ according to their spinal segment and the particular species. The basic configuration of a vertebra varies; the vertebral body (also centrum) is of bone and bears the load of the vertebral column. The upper and lower surfaces of the vertebra body give attachment to the intervertebral discs.
The axial skeleton (80 bones) is formed by the vertebral column (32–34 bones; the number of the vertebrae differs from human to human as the lower 2 parts, sacral and coccygeal bone may vary in length), a part of the rib cage (12 pairs of ribs and the sternum), and the skull (22 bones and 7 associated bones).
The number of vertebrae in a region can vary but overall the number remains the same. In a human vertebral 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.
A fully grown adult features 26 bones in the spine, whereas a child can have 33. Cervical vertebrae (7 bones) Thoracic vertebrae (12 bones) Lumbar vertebrae (5 bones) Sacrum (5 bones at birth, fused into one after adolescence) Coccyx (set of 4 bones at birth)
The diameter of the spinal cord ranges from 13 mm (1 ⁄ 2 in) in the cervical and lumbar regions to 6.4 mm (1 ⁄ 4 in) in the thoracic area. The spinal cord functions primarily in the transmission of nerve signals from the motor cortex to the body, and from the afferent fibers of the sensory neurons to the sensory cortex.
[2] [3] In humans, cervical vertebrae are the smallest of the true vertebrae and can be readily distinguished from those of the thoracic or lumbar regions by the presence of a foramen (hole) in each transverse process, through which the vertebral artery, vertebral veins, and inferior cervical ganglion pass. The remainder of this article focuses ...
6 1 interspinales colli 1-6 Torso, Back, right/left spinous process: spinous process: posterior rami of spinal nerves: extends, flexes, and rotates vertebral column 12 1 intertransversarii, anterior colli 1-7 Torso, Back, right/left transverse process: transverse process above posterior rami of spinal nerves: laterally flexes trunk: 14 1