The cervical spine is comprised of seven vertebrae: C1, C2, C3, C4, C5, C6, and C7.Two of which are given unique names:
- The first cervical vertebrae (C1) is known as the atlas.
- The second cervical vertebrae (C2) is known as the axis.
These vertebrae begin at the base of the skull and extend down to the thoracic spine.
The cervical vertebrae have three features which distinguish them from thoracic vertebrae:
- Triangular vertebral foramen.
- Bifid spinous process – this is where the spinous process splits into two distally.
- Transverse foramina – holes in the transverse processes. They give passage to the vertebral artery, vein and sympathetic nerves.
The atlas and axis have additional features that mark them apart from the other cervical vertebrae.
The atlas (C1) differs from the other cervical vertebrae in that it has no vertebral body and nospinous process. It also has an articular facet anteriorly, which articulates with the dens of the axis.
The atlas also has lateral masses on either side of the vertebral arch, which provide an attachment for the transverse ligament of the atlas.
The posterior arch has a groove for the vertebral artery and C1 spinal nerve.
The axis (C2) is easily identifiable due to its dens (odontoid process) which extends superiorly from the anterior portion of the vertebra. The dens articulates with the articular facet of the atlas, in doing so creating the medial atlanto-axial joint. This allows for rotation of the head independently of the torso.
The cervical vertebrae have cylindrical bones that lie in front of the spinal cord and stack up one on top of the other to make one continuous column of bones in the neck.At each level, the vertebrae protect their segment of the spinal cord and work with muscles, tendons, ligaments, and joints to provide a combination of support, structure, and flexibility to the neck.
There are 23 total discs in the entire spinal column, and 6 of them are in the cervical spine. Each cervical disc rests between the cervical vertebrae, acts as a shock absorber in the cervical spine, and enables the neck to handle various stresses and loads.Composed of collagen and ligaments, the cervical discs also hold the cervical vertebrae together and allow for flexibility and different movements of the neck.
Each cervical disc has two basic components:
- Outer layer. This tough exterior, called the annulus fibrosus, is comprised of collagen fibers that surround the inner core and distribute the forces placed on the structure.
- Inner core. This soft jelly interior, called the nucleus pulposus, is a loose, fibrous network suspended in mucoprotein gel that is sealed by the annulus fibrosus.
The discs need to be well-hydrated in order to maintain their strength and softness to serve as the body’s major carrier of axial load.
Common conditions of cervical disc include cervical degenerative disc disease, cervical disc herniation, cervical disc prolapse and cervical disc injury.
The neck muscles, including the sternocleidomastoid and the trapezius, are responsible for the gross motor movement in the muscular system of the head and neck. They move the head in every direction, pulling the skull and jaw towards the shoulders, spine, and scapula. Working in pairs on the left and right sides of the body, these muscles control the flexion and extension of the head and neck. Working individually, these muscles rotate the head or flex the neck laterally to the left or right. Neck muscles contract to adjust the posture of the head throughout the course of a day and have some of the greatest endurance of any muscles in the body.
There are six major ligaments to consider in the cervical spine. The majority of these ligaments are present throughout the entire vertebral column.
Present throughout Vertebral Column
- Anterior and posterior longitudinal ligaments: Long ligaments that run the length of the vertebral column, covering the vertebral bodies and intervertebral discs.
- Ligamentum flavum: Connects the laminae of adjacent vertebrae.
- Interspinous ligament: Connects the spinous processes of adjacent vertebrae.
Unique to Cervical Spine
- Nuchal ligament: A continuation of the supraspinous ligament. It attaches to the tips of the spinous processes from C1-C7, and also provides the proximal attachment for the rhomboids and trapezius.
- Transverse ligament of the atlas: Connects the lateral masses of the atlas, and in doing so anchors the dens in place.
Common conditions of cervical muscles and ligaments include cervical strain, cervical spine ligament injury, cervical spine trauma and cervical muscle spasm.
The joints of the cervical spine can be divided into two groups – those that are present throughout the vertebral column, and those unique to the cervical spine.
Present throughout Vertebral Column
There are two different joints present throughout the vertebral column:
- Between vertebral bodies – adjacent vertebral bodies are joined by intervertebral discs, made of fibrocartilage. This is a type of cartilaginous joint, known as a symphysis.
- Between vertebral arches – formed by the articulation of superior and inferior articular processes from adjacent vertebrae. It is a synovial type joint.
Unique to Cervical Spine
The atlanto-axial and atlanto-occipital joints are unique to the cervical spine. The atlanto-axial joints are formed by the articulation between the atlas and the axis:
- There are two lateral atlanto-axial joints which are formed by the articulation between the inferior facets of the lateral masses of C1 and the superior facets of C2. These are plane type synovial joints.
- The medial atlanto-axial joint is formed by the articulation of the dens of C2 with the articular facet of C1. This is a pivot type synovial joint.
The atlanto-occipital joints consist of an articulation between the spine and the cranium. They occur between then superior facets of the lateral masses of the atlas and the occipital condyles at the base of the cranium. These are condyloid type synovial joints, and permit flexion at the head i.e. nodding.
Common conditions of cervical joints include cervical osteoarthritis or cervical spondylosis, degenerative joint disease of the neck and cervical facet disease.
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. Each level of the cervical spine actually has two nerve roots—one on each side—that branch off from the spinal cord.
Common conditions of cervical nerves include cervical nerve injuries, cervical spinal stenosis, and cervical radiculopathy
For approximately the first 72 hours following an injury, the RICE regime should be followed to ensure control of inflammation and pain relief.
R – Rest
I – Ice
C - Compression
E - Elevation
Rest from aggravating activity.
Ice should be applied in the first 72 hours or when inflammation persists. Ice should be applied for 15 to 20 minutes at a time. Ice should not be applied directly to the skin, but through a wet towel or cloth.