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Is made up of seven vertebrae and eight sets of nerve roots, which innervate the upper extremity via the brachial plexus.
C1 and C2 vertebrae are connected by a complex ligamentous complex consisting of the alar and cruciate ligaments, the remainder of the subaxial spine connects through a series of facet joints and intervertebral disks.
Pain generated from within the spine occurs when structural elements elements of the spine compress the nervous system anatomy as seen with an herniated nucleus pulposis, or a facet joint cyst or arthritis.
Consists of 7 bones, from top to bottom, C1, C2, C3, C4, C5, C6 and C7.
Cervical vertebrae are the vertebrae of the neck, immediately below the skull.
The cervical spine is made up of the first 7 vertebrae, ref2242ed to as C1-7.
The cervical spine functions to provide mobility and stability to the head while connecting it to the relatively immobile thoracic spine.
The cervical spine is much more mobile than the thoracic or lumbar regions of the spine.
The cervical spine may be divided into 2 parts: upper and lower.
The upper cervical spine consists of the atlas (C1) and the axis (C2).
The atlas articulates superiorly with the occiput (the atlanto-occipital joint) and inferiorly with the axis (the atlantoaxial joint).
The atlas is ring-shaped and does not have a body, unlike the rest of the vertebrae.
The atlantoaxial joint is responsible for 50% of all cervical rotation.
The atlanto-occipital joint is responsible for 50% of flexion and extension.
Cervical vertebrae are the smallest of the true vertebrae.
Distinguished from vertebrae of the thoracic or lumbar regions by the presence of a foramen in each transverse process, through which the vertebral artery passes.
The cervical vertebrae are numbered, with the first one (C1) closest to the skull and higher numbered vertebrae (C2-C7) proceeding away from the skull and down the spine.
The bodies of these four cervical vertebrae are small, and broader from side to side than from front to back.
The spinous process is short and bifid, the two divisions being often of unequal size.
The spinous processes are so short, certain superficial muscles such as the trapezius and splenius capitis attach to the nuchal ligament rather than directly to the vertebrae.
The nuchal ligament itself attaches to the spinous processes of C2-C7 and to the posterior tubercle of the atlas.
The superior and inferior articular processes of cervical vertebrae are fused on either or both sides to form articular pillars, columns of bone that project laterally from the junction of the pedicle and lamina.
The articular facets are flat and of an oval form, with the superior aspect facing backward, upward, and slightly medially, and the inferior face forward, downward, and slightly laterally.
The transverse processes are pierced by the foramen transversarium.
The transversarium of the upper six vertebrae, provides passage to the vertebral artery and vein, as well as a plexus of sympathetic nerves.
Each transverse process consists of an anterior and a posterior part.
The anterior and a posterior parts of the transverse process are joined, outside the foramen, by a bar of bone that exhibits a deep sulcus on its upper surface for the passage of the corresponding spinal nerve.
The anterior portion is the homologue of the rib in the thoracic region, and is therefore named the costal process or costal element, the anterior tubercle.
The posterior part, the true transverse process, springs from the vertebral arch behind the foramen, and is directed forward and laterally; it ends in a flattened vertical tubercle, the posterior tubercle.
The anterior tubercle of the sixth cervical vertebra is known as the carotid tubercle or Chassaignac tubercle.
The anterior tubercle separates the carotid artery from the vertebral artery.
The carotid artery can be pressed against this tubercle to relieve the symptoms of supraventricular tachycardia.
The carotid tubercle is also used as a landmark for anaesthesia of the brachial plexus and cervical plexus.
The cervical spinal nerves emerge from above the cervical vertebrae.
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.
The atlas, C1 chief peculiarity is that it has no body, and this is due to the fact that the body of the atlas has fused with that of the axis.
The axis, C2, forms the pivot on which the atlas rotates.
The most distinctive characteristic of the axis is the strong odontoid process, the dens, that rises perpendicularly from the upper surface of the body.
The axis body is deeper in front than behind, and prolonged downward anteriorly so as to overlap the upper and front part of the third vertebra.
The vertebra prominens, or C7, has a distinctive long and prominent spinous process, which is palpable from the skin surface.
Sometimes, the seventh cervical vertebra is associated with an abnormal extra rib, known as a cervical rib, which develops from the anterior root of the transverse process.
Cervical ribs are usually small, but may occasionally compress the subclavian artery or subclavian vein, or nerves in the brachial plexus, causing pain, numbness, tingling, and weakness in the upper limb, a condition known as thoracic outlet syndrome.
Rarely, the cervical rib occurs in a pair.
The long spinous process of C7 is thick and nearly horizontal, is not bifurcated, and ends in a tubercle that the ligamentum nuchae attaches to.
C7 is not always the most prominent of the spinous processes, being found only about 70% of the time, while C6 or T1 can sometimes be the most prominent.
The transverse processes are large and their posterior roots are large and prominent, while the anterior are small and faintly marked.
The transverse foramen may be as large as that in the other cervical vertebrae, but is generally smaller on one or both sides; occasionally it is double, sometimes it is absent.
On the left side it occasionally gives passage to the vertebral artery; more frequently the vertebral vein traverses it on both sides; but the usual arrangement is for both artery and vein to pass in front of the transverse process, and not through the foramen.
Nodding the head takes place primarily through flexion and extension at the atlanto-occipital joint between the atlas and the occipital bone.
The cervical spine is comparatively mobile, and some component of this movement is due to flexion and extension of the vertebral column itself.
Shaking or rotating the head left and right happens almost entirely at the joint between the atlas and the axis, the atlanto-axial joint., but a small amount of rotation of the vertebral column itself contributes to the movement.
Injuries to the cervical spine are common.
C4 and C5 are the areas that see the highest amount of cervical spine trauma, and it may cause death or profound disability, including paralysis of the arms, legs, and diaphragm, which leads to respiratory failure.
Odontoid fracture and the hangman’s fracture, both of which are often treated with immobilization in a cervical collar or Halo brace.
A common practice is to immobilize a patient’s cervical spine to prevent further damage during transport to hospital.
Incidence rates of unstable spinal trauma can be as low as 2% in immobilized patients.
The vertebral column is often used as a marker of human anatomy.
At C1, base of the nose and the hard palate
At C2, the teeth of a closed mouth
At C3, the mandible and hyoid bone
At C4, the common carotid artery bifurcates.
From C4-5, the thyroid cartilage
From C6-7, the cricoid cartilage
At C6, the esophagus becomes continuous with the laryngopharynx and also where the larynx becomes continuous with the trachea.
At C6 is also the level where the carotid pulse can be palpated against the transverse process of the C6 vertebrae.
Fused remnants of the atlas body have become part of C2, where they are called the odontoid process, or dens.
The odontoid process is held in tight proximity to the posterior aspect of the anterior arch of the atlas by the transverse ligament, which stabilizes the atlantoaxial joint.
The apical, alar, and transverse ligaments, allow spinal column rotation, provide stabilization and prevent posterior displacement of the dens in relation to the atlas.
The atlas is made up of a thick anterior arch, a thin posterior arch, 2 prominent lateral masses, and 2 transverse processes.
The transverse foramen, through which the vertebral artery passes, is enclosed by the transverse process.
On each lateral mass is a superior and inferior facet the zygapophyseal joint.
The superior articular facets are kidney-shaped, concave, and face upward and inward.
These superior facets articulate with the occipital condyles, which face downward and outward.
Inferior articular facets face downward and inward to articulate with the superior facets of the axis.
At the level of the atlas, the odontoid process, the subarachnoid space, and spinal cord each occupy one third of the area of the spinal canal.
The axis has a large vertebral body, which contains the odontoid process.
The (dens) odontoid process articulates with the anterior arch of the atlas by the anterior articular facet and is held in place by the transverse ligament.
The axis is composed of a vertebral body, heavy pedicles, laminae, and transverse processes, which serve as attachment points for muscles.
The axis articulates with the atlas via its superior articular facets, which are convex and face upward and outward.
C2 is derived from 4 ossification centers: 1 for the body, 1 for the odontoid process, and 2 for the neural arches.
The dens is fed by anterior and posterior ascending arteries from the vertebral arteries around the C3 level and the carotid arterial arcade from the base of the skull.
The anastomotic arcade also receives tributaries from the ascending pharyngeal arteries that join the arcade after passing through the occipital condyle.
The craniocervical junction and the atlantoaxial joints are secured by the external and internal ligaments.
The external ligaments consist of the atlanto-occipital, anterior atlanto-occipital, and anterior longitudinal ligaments.
The internal ligaments have 5 components, as follows:
The transverse ligament holds the odontoid process in place against the posterior atlas, which prevents anterior subluxation of C1 on C2.
The accessory ligaments arise posterior to and in conjunction with the transverse ligament and insert into the lateral aspect of the atlantoaxial joint; the apical ligament lies anterior to the lip of the foramen magnum and inserts into the apex of the odontoid process?
The paired alar ligaments secure the apex of the odontoid to the anterior foramen magnum
The tectorial membrane is a continuation of the posterior longitudinal ligament to the anterior margin of the foramen magnum.
The accessory atlantoaxial ligament not only connects the atlas to the axis but also continues cephalad to the occipital bone.
The accessory atlantoaxial ligament becomes maximally taut with 5-8° of head rotation, lax with cervical extension, and maximally taut with 5-10° of cervical flexion
The accessory atlantoaxial ligament participates in craniocervical stability.
The 5 cervical vertebrae that make up the lower cervical spine, C3-C7, are similar to each other but very different from C1 and C2.
Each has a vertebral body that is concave on its superior surface and convex on its inferior surface.
On the superior surfaces of the bodies are raised processes or hooks called uncinate processes, each of which articulates with a depressed area on the inferior lateral aspect of the superior vertebral body, called the echancrure or anvil.
These uncovertebral joints are most noticeable near the pedicles and are usually ref2242ed to as the joints of Luschka.
They are believed to be the result of degenerative changes in the annulus, which lead to fissuring in the annulus and the creation of the joint.
These joints can develop osteophytic spurs, which can narrow the intervertebral foramina.
The spinous processes of C3-C6 are usually bifid, whereas the spinous process of C7 is usually nonbifid and somewhat bulbous at its end.
The subaxial cervical spine can be divided into anterior and posterior columns.
The anterior column consists of the typical cervical vertebral body sandwiched between supporting disks.
The anterior surface is reinforced by the anterior longitudinal ligament and the posterior body by the posterior longitudinal ligament, both of which run from the axis to the sacrum.
Cervical vertebralarticulations include disk-vertebral body articulations, uncovertebral joints, and facet joints.
Cervical disks are thicker anteriorly, contributing to normal cervical lordosis.
The uncovertebral joints in the posterior aspect of the body define the lateral extent of most surgical exposures.
The facet joints are oriented at a 45º angle to the axial plane, and 85° from the sagittal plane.
This alignment helps prevent excessive anterior translation and is important in weight-bearing. allowing a sliding motion.
The facet joints in the cervical spine are diarthrodial synovial joints with fibrous capsules.
The joint capsules are more lax in the lower cervical spine than in other areas of the spine to allow gliding movements of the facets.
The supporting ligamentum flavum, posterior, and interspinous ligaments strengthen the posterior column.
In the neuroanatomy of the cervical spine, the cord is enlarged, with lateral extension of the gray matter consisting of the anterior horn cells.
The lateral dimension of the spinal cord spans 13-14 mm, and the anterior-posterior extent measures 7 mm.
1 mm is necessary for cerebrospinal fluid (CSF) anteriorly and posteriorly, as well as 1 mm for the dura.
Exiting at each vertebral level is the spinal nerve, which is the result of the union of the anterior and posterior nerve roots.
The foramina are largest at C2-C3 and progressively decrease in size down to C6-C7.
C1 through C4 split and recombine to produce nerves that serve the neck and back of head.
Spinal nerve C1 is called the suboccipital nerve, which provides motor innervation to muscles at the base of the skull.
C2 and C3 form many of the nerves of the neck, providing both sensory and motor control.
These include the greater occipital nerve, which provides sensation to the back of the head, the lesser occipital nerve, which provides sensation to the area behind the ears, the greater auricular nerve and the lesser auricular nerve.
The phrenic nerve is a nerve essential for our survival which arises from nerve roots C3, C4 and C5.
It supplies the thoracic diaphragm, enabling breathing.
If the spinal cord is transected above C3, then spontaneous breathing is not possible.
The spinal nerve and spinal ganglion occupy 25-33% of the foraminal space.
The neural foramen is bordered anteromedially by the uncovertebral joints, posterolaterally by facet joints, superiorly by the pedicle of the vertebra above, and inferiorly by the pedicle of the lower vertebra..
Medially, the foramina are formed by the edge of the end plates and the intervertebral discs.
The spinal nerves exit above their correspondingly numbered vertebral body from C2-C7.
Because the numbering of the cervical spinal nerves begins above the atlas, 8 cervical spinal nerves exist.
The first spinal nerve exits between the occiput and the atlas (C1) and the eighth exiting between C7 and T1.
The blood vessel supply consists of a larger anterior spinal artery and paired posterior spinal arteries located on the dorsum of the cord.
The anterior spinal artery is located in the central sulcus of the cord.
The anterior two thirds of the cord is supplied by the anterior artery and the posterior one third is supplied by the posterior arteries.
The fibrous capsules of the facet joints are innervated by mechanoreceptors and free nerve endings.
There are more mechanoreceptors in the cervical spine than in the lumbar spine…
The facets provide neural input that may be important for proprioception and pain sensation..
The facets may modulate muscular reflexes important for preventing joint instability and degeneration.
Cervical spine facet joints are innervated by both the anterior and posterior rami.
Each joint from C3-C4 to C7-T1 is innervated by the medial branches above and below.
Intervertebral discs are located between the vertebral bodies of C2-C7.
These Intervertebral discs are located between each vertebral body caudad to the axis.
These discs are composed of 4 parts: the nucleus pulposus in the middle, the annulus fibrosis surrounding the nucleus, and 2 end plates that are attached to the adjacent vertebral bodies.
Intervertebral discs dissipate force, and transmit compressive loads throughout a range of motion.
The discs are thicker anteriorly and therefore contribute to normal cervical lordosis.
Intervertebral discs are involved in cervical spine motion, stability, and weight-bearing.
The annular fibers are composed of collagenous sheets and are vulnerable to injury by rotation forces
The middle and outer one third of the annulus is innervated by nociceptors.
A complex ligamentous network keeps the individual bony elements of the cervical spine acting as if they were a single unit.
As noted, the cervical spine can be viewed as being made up of anterior and posterior columns. It can also be useful to think in terms of a third (middle) column, as follows:
The anterior column of the cervical spine consists of the anterior longitudinal ligament and the anterior two thirds of the vertebral bodies, the annulus fibrosus, and the intervertebral discs.
The middle column is composed of the posterior longitudinal ligament and the posterior one third of the vertebral bodies, the annulus fibrosus, and the intervertebral discs.
The posterior column is made up of the posterior arches, including the pedicles, transverse processes, articulating facets, laminae, and spinous processes
The longitudinal ligaments maintain the integrity of the spinal column.
The anterior and posterior longitudinal ligaments maintain the structural integrity of the anterior and middle columns.
Thee posterior column alignment is stabilized by a complex of ligaments, including the nuchal and capsular ligaments, and the ligamentum flavum.
If 1 of the columns is disrupted by trauma, stability is provided by the remaining 2 columns and cord injury is usually prevented.
The transverse ligament is the major portion of the cruciate ligament.
The transverse ligament is the most important ligament for preventing abnormal anterior translation.
The alar ligaments prevent excessive lateral and rotational motion while allowing flexion and extension.
In whiplash, the joint complex becomes hypermobile if alar ligaments are damaged, which can lead to kinking of the vertebral arteries and stimulation of pain receptors.
The major stabilizers of the intervertebral joints are the anterior longitudinal ligament and the posterior longitudinal ligament.
Both ligaments are found throughout the entire length of the spine.
The anterior longitudinal ligament is not well developed in the cervical spine.
The supraspinous ligament, the interspinous ligaments, and the ligamentum flavum maintain stability between the vertebral arches.
The supraspinous ligament runs along the tips of the spinous processes.
The interspinous ligaments run between adjacent spinous processes.
The ligamentum flavum runs from the anterior surface of the cephalad vertebra to the posterior surface of the caudad vertebra.
The interspinous ligament and the ligamentum flavum control excessive flexion and anterior translation.
The supraspinous ligament and has a prominent role in stabilizing the cervical spine.
Surgical management of craniocervical junction instability indications for cervical fusion are similar to adults.
Children have significant anatomical variations in the craniocervical junction that complicates the use of internal fixation, and treatment is hindered by the diminutive bone and ligamentous structures.