THE CERVICAL SPINE VIBHUTI NAUTIYALMPT (MUSCULOSKELETAL)

STRUCTURE Consists of 7 vertebrae in total Divided into 2 distinct parts:a. The upper cervical spine or cranio-vertebral regionb. The lower cervical spine Cranio-vertebral region includes the occipital condyles and C1-C2 Lower cervical spine includes the vertebrae of C3-C7

CRANIO-VERTEBRAL REGIONA. ATLAS: Function of the atlas is to cradle the occiput and to transmit forces from the occiput to the lower cervical spine.

It has no V.B or spinous process Shaped like a ring There are 2 large lateral masses that have a vertical alignment under each occipital condyle that transmit forces

The lateral masses are connected by an anterior and posterior arch that form the ring structure and also creates large transverse process for muscle attachments

The lateral masses include 4 articulating facets:a. 2 superior facetsb. 2 inferior facets Atlas also possesses a facet on the internal surface of the anterior arch for articulation with the dens of axis

Superior zygapophseal facets:a. Largeb. Kidney shapedc. Deeply concave to accommodate the large convex articular surfaces

of the occipital condyles

Inferior zygapophyseal facets:a. Slightly convexb. Directed inferiorlyc. Articulates with the superior zygapophyseal facets of the axis

B. AXIS: Primary function of the axis are:a. Transmit the combined load of the head and the atlasb. Provide motion into axial rotation of the head and atlas Anterior portion of the body extends inferiorly and a vertical projection called the dens arises from the superior surface of the body

Dens has an anterior facet for articulation with the anterior arch of the atlas and a posterior groove for articulation with the transverse ligament

The arch of the axis has inferior and superior zygapophyseal facets for articulation

The spinous process is large and elongated with a bifid tip Superior facets face upward and laterally Inferior facets face anteriorly

ARTICULATIONSA. ATLANTO-OCCIPITAL JOINT: Composed of the right and left deep concave superior facets of the atlas that articulates with the right and left convex occipital condyles

True synovial joint Lie nearly in the horizontal plane

B. ATLANTO-AXIAL JOINT: 3 synovial joint 1 median (pivot joint) and 2 lateral joint Median joint consists of odontoid process of C2 that articulated with a facet on the internal surface of the atlas (C1)

2 lateral joints are composed of right and left superior facets of the axis that articulates with the right and left slightly convex inferior facet on the atlas

CRANIO VERTEBRAL LIGAMENTSA. 4 of the ligaments are continuation of the longitudinal tract

system:a. Posterior atlanto-occipital and atlanto-axial membranes: Continuation of the ligamentum flavum Less elastic Therefore permit greater ROM, especially into rotationb. Anterior atlanto-occipital and atlanto-axial membranes: Continuation of ALL

c. Tectorial membrane: Continuation of the PLL in the upper 2 segments Broad and strong Originates from the posterior V.B of axis Covers the dens and its cruciate ligament Inserts at the anterior rim of the foramen magnum

d. Ligamentum nuchae: Thick Extends from the spinous process of C7 to the external occipital protuberance

Evolution of the supraspinous ligament Resist the flexion moment of head

B. Transverse ligament: Stretches across the ring of the atlas Divides the ring into a large posterior section for the spinal cord Has a thin layer of articular cartilage on its anterior surface for articulation with the dens

Longitudinal fibres extend superiorly to attach to the occipital bone Inferior fibres descend to the posterior portion of the axis Transverse portion holds the dens in close approximation against the anterior ring of the atlas

Prevent anterior displacement of C1 and C2 Transverse atlantal ligament is very strong and the dens will fracture before the ligament will tearC. Alar ligament: 2 alar ligament Arise from the axis or either side of the dens Extend laterally and superiorly to attach to roughened areas on the medial sides of the occipital condyles and to the lateral masses of the atlas

Relaxed with the head in mid-position or neutral Taut in flexion and rotation of the head and neck Right upper and left lower portion limit left lateral flexion Prevent distraction of C1 and C2 Weaker than the transverse atlantal ligament Runs in a fan shaped arrangement from the apex of the dens to the anterior margin of the foramen magnum of the skull