In addition to the seven cervical vertebrae, cervical anatomy features eight cervical nerve roots (C1-C8) that branch from the spinal cord and control motor and sensory abilities for different parts of the body.
Each cervical nerve is named based on the lower cervical vertebra that it runs between. As an example, the C6 nerve root runs between the C5 vertebra and the C6 vertebra.
Cervical Nerve Functions
Each level of the cervical spine actually has two nerve roots—one on each side—that branch off from the spinal cord.
Keeping with the aforementioned example at the C5-C6 level, each C6 nerve root exits the spinal canal through a bony hole (foramina) on both sides of the neck. From there, the C6 nerve root feeds into nerves that run down their own side’s shoulder, arm, and hand.
Cervical nerves provide control and sensation to different parts of the body based on the spinal level from where they branch out. More specifically:
- C1, C2, and C3 (the first three cervical nerves) control the head and neck, including movements forward, backward, and to the sides. These nerves also play key roles in breathing. The C2 dermatome handles sensation for the upper part of the head, and the C3 dermatome covers the side of the face and behind the head. (C1 does not have a dermatome.)
- C4 helps control the shoulders as well as the diaphragm—the sheet of muscle that stretches to the bottom of the rib cage—for breathing. The C4 dermatome covers the neck and top of the shoulders.
- C5 controls upper body muscles like the deltoids (which form the rounded contours of the shoulders) and the biceps (which allow flexion of the elbow and rotation of the forearm). The C5 dermatome covers the shoulders and outer part of the arm down to about the elbow or close to the wrist.
- C6 controls the wrist extensors (muscles like the extensor carpi radialis longus, extensor carpi radialis brevis, and extensor carpi ulnaris that control wrist extension and hyperextension) and also provides some innervation to the biceps. The C6 dermatome covers the top of the shoulders and runs down the side of the arm and into the thumb side of the hand.
Continue reading the original article from Spine Health here.