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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. The axis (C2) forms the pivot on which the atlas rotates.
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 neck is the part of the body in many vertebrates that connects the head to the torso. It supports the weight of the head and protects the nerves that transmit sensory and motor information between the brain and the rest of the body. Additionally, the neck is highly flexible, allowing the head to turn and move in all directions.
Within the cervical spine, most joints are innervated by the medial branch nerve (a branch of the dorsal rami) from the same levels. In other words, the facet joint between C4 and C5 vertebral segments is innervated by the C4 and C5 medial branch nerves. However, there are two exceptions:
The spinal nerves arise from the spinal column. The top section of the spine is the cervical section, which contains nerves that innervate muscles of the head, neck and thoracic cavity, as well as transmit sensory information to the CNS. The cervical spine section contains seven vertebrae, C-1 through C-7, and eight nerve pairs, C-1 through C-8.
The body of the vertebra and the vertebral arch form the vertebral foramen, the larger, central opening that accommodates the spinal canal, which encloses and protects the spinal cord. Vertebrae articulate with each other to give strength and flexibility to the spinal column, and the shape at their back and front aspects determines the range of ...
The cervical spinal nerve 5 (C5) is a spinal nerve of the cervical segment. [1]It originates from the spinal column from above the cervical vertebra 5 (C5). It contributes to the phrenic nerve, long thoracic nerve, and dorsal scapular nerve before joining cervical spinal nerve 6 to form the upper trunk, a trunk of the brachial plexus, which then forms the lateral cord, and finally the ...
Cervical spinal nerve 4, also called C4, is a spinal nerve of the cervical segment. It originates from the spinal cord above the 4th cervical vertebra (C4). It contributes nerve fibers to the phrenic nerve , the motor nerve to the thoracoabdominal diaphragm .