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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 atlas (C1) and axis (C2) are the two topmost vertebrae. The atlas (C1) is the topmost vertebra, and along with the axis forms the joint connecting the skull and spine. It lacks a vertebral body, spinous process, and discs either superior or inferior to it. It is ring-like and consists of an anterior arch, posterior arch, and two lateral masses.
In anatomy, the atlas (C1) is the most superior (first) cervical vertebra of the spine and is located in the neck.. The bone is named for Atlas of Greek mythology, just as Atlas bore the weight of the heavens, the first cervical vertebra supports the head. [1]
A typical vertebra has a body (vertebral body), also known as the centrum, which consists of a large anterior middle portion, and a posterior vertebral arch, [2] also called a neural arch. [3] The body is composed of cancellous bone , which is the spongy type of osseous tissue , whose microanatomy has been specifically studied within the ...
Sectional organization of spinal cord. The spinal cord is the main pathway for information connecting the brain and peripheral nervous system. [3] [4] Much shorter than its protecting spinal column, the human spinal cord originates in the brainstem, passes through the foramen magnum, and continues through to the conus medullaris near the second lumbar vertebra before terminating in a fibrous ...
The suboccipital nerve (first cervical dorsal ramus) is the dorsal primary ramus of the first cervical nerve (C1). It exits the spinal cord between the skull and the first cervical vertebra, the atlas. [1] It lies within the suboccipital triangle along with the vertebral artery, where the artery enters the foramen magnum.
There are four main plexuses formed by the ventral rami: the cervical plexus contains ventral rami from spinal nerves C1–C4. Branches of the cervical plexus, which include the phrenic nerve, innervate muscles of the neck, the diaphragm, and the skin of the neck and upper chest.
The head rests on the top part of the vertebral column, with the skull joining at C1 (the first cervical vertebra known as the atlas).The skeletal section of the head and neck forms the top part of the axial skeleton and is made up of the skull, hyoid bone, auditory ossicles, and cervical spine.