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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 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.
Functions of vertebrae include: Support of the vertebrae function in the skeletomuscular system by forming the vertebral column to support the body; Protection. Vertebrae contain a vertebral foramen for the passage of the spinal canal and its enclosed spinal cord and covering meninges. They also afford sturdy protection for the spinal cord.
In human anatomy, the five vertebrae are between the rib cage and the pelvis.They are the largest segments of the vertebral column and are characterized by the absence of the foramen transversarium within the transverse process (since it is only found in the cervical region) and by the absence of facets on the sides of the body (as found only in the thoracic region).
The fourth lumbar spinal nerve (L4) [4] originates from the spinal column from below the lumbar vertebra 4 (L4). L4 supplies many muscles, either directly or through nerves originating from L4. They are not innervated with L4 as single origin, but partly by L4 and partly by other spinal nerves. The muscles are: quadratus lumborum; gluteus ...
The erector spinae (/ ɪ ˈ r ɛ k t ər ˈ s p aɪ n i / irr-EK-tər SPY-nee) [1] or spinal erectors is a set of muscles that straighten and rotate the back. The spinal erectors work together with the glutes ( gluteus maximus , gluteus medius and gluteus minimus ) to maintain stable posture standing or sitting .
An intervertebral disc (British English), also spelled intervertebral disk (American English), lies between adjacent vertebrae in the vertebral column.Each disc forms a fibrocartilaginous joint (a symphysis), to allow slight movement of the vertebrae, to act as a ligament to hold the vertebrae together, and to function as a shock absorber for the spine.
A coccyx with four vertebrae below the sacrum. The coccyx is formed of three, four or five rudimentary vertebrae.It articulates superiorly with the sacrum.In each of the first three segments may be traced a rudimentary body and articular and transverse processes; the last piece (sometimes the third) is a mere nodule of bone.