Anatomy of the Neck
Structurally, the cervical spine is composed of 7 moderately small and unique vertebrae including associated muscles, ligaments, joints and nerves.
The cervical spine has many important functions which include providing support and mobility to the head and neck, providing essential information for the balance and coordination of the body, and protection for the upper spinal cord and associated spinal nerves.
Generous Amounts of Motion
The cervical spine is the most flexible region of the spine, providing the most generous amounts of flexion, extension, lateral flexion and rotation.
The 1st and 2nd cervical vertebrae, known as the atlas and axis respectively, have highly unique structures which allow them to form a pivot joint. This joint alone provides approximately 90 degrees of rotation in the cervical spine. These same vertebrae also contain special receptors within their joints which provide the brain with important information essential for the maintenance of balance and coordination. As you will see in “Causes”, injury or irritation to these mechanoreceptors results in balance disturbances and problems with coordination.
The remaining cervical vertebrae also provide large degrees of motion but mainly in flexion, extension and lateral flexion (side bending). Unfortunately, there’s an inverse relationship between mobility and stability. Thus, the cervical spine is more susceptible to injury compared with other areas of the spine.
Nervous System Protection
The cervical vertebrae immediately encase and protect the spinal cord as it descends from the skull.
The spinal cord travels through small holes in the rear of the cervical vertebrae, giving rise to spinal nerve roots at each vertebral level. These nerve roots exit through the small openings formed by adjacent vertebrae called the intervertebral foramina (IVF). The IVF is the “exit” out of the cervical spine as spinal nerves make their way to the head, face and arms. The IVF is a common location for nerve irritation and can give rise to a variety of head, neck and upper extremity symptoms in the cervical spine.
The Spinal Nerves
The nerves exiting the cervical spine are delicate and can become irritated or injured, giving rise to a number of different signs and symptoms.
The 1st through 3rd cervical nerves exiting from the cervical are responsible for providing sensations to the head and face. When these nerves are compressed, stretched or irritated they will cause pain and other altered sensations in regions of the head and face. Researchers have found irritation to the 2nd cervical nerve (the greater occipital nerve) to be a major source of head and face pain. The nerves from the mid and lower cervical spine combine to form the brachial plexus, a collection of nerves which innervate the arms. Compression, stretch or irritation to these nerves commonly cause pain, numbness, tingling and weakness in the arms.