The portion of spine encompassing neck region forms cervical spine. It is formed by first seven vertebra which are named as C1 to C7.
Anatomically, cervical spine starts where the top vertebra (C1) connects to the bottom of the skull. Normal cervical spine has a lordosis.That means it is curved with convexity on anterior aspect. It ends when C7 joins with first thoracic vertebra.
The base of the skull sits on top of C1.First vertebra or C1 is also called Atlas. It called so because it bears the direct weight of the skull, just as the mythical Greek hero Atlas bore the world on his shoulders. Structure of atlas is unique.Two thickened bony arches form a large hole through the center of the atlas. Because of its large size this opening is named as foramen magnum. Foramen magnum accommodates spinal cord which is wider here as compared to rest of it. The atlas has wide bony projections pointing out to each side.
The axis is the second of the seven cervical vertebrae, and is called such because it allows axial or rotational movement of the skull. The axis lies directly beneath the atlas vertebra. They articulate at lateral articular surfaces and articulation of dens with atlas. Dens is a large bony knob on top of axis that points up and fits through a hole in the atlas.
The joints of the axis give the neck most of its ability to turn to the left and right.
C3-C6 vertebrae have a typical structures which is more or less same as discussed earlier in previous post. Following are special features/variations in these vertebrae.
- The body of these four vertebrae is small, and broader from side to side than from front to back.
- Anterior and posterior surfaces are flattened and of equal depth former being on a lower level than the latter.
- The upper surface is concave transversely and presents a projecting lip on either side.
- The lower surface is concave from front to back and convex from side to side. On either side laterally they have shallow concavities which receive the corresponding projecting lips of the underlying vertebra.
- The pedicles are directed laterally and backward.
- The laminae are narrow, and thinner above than below
- The vertebral foramen is large and of a triangular form.
- The spinous process is short and bifid.
- The articular facets are flat. Superior articular facets face backward, upward, and slightly medially and inferior face forward, downward, and slightly laterally.
- The transverse processes are each pierced by the foramen transversarium, which, in the upper six vertebrae, gives passage to the vertebral artery and vein, as well as a plexus of sympathetic nerves.
C7 has enlarged spinous process called vertebra prominence. It is most prominent structure that can be palpated when we pass our finger downwards from skull.
Neural foramina of cervical spine allow exit of cervical spinal nerves which are eight in number and are named as C1 to C8.
The cervical nerves control many bodily functions and sensory activities.
C1: Head and neck
C2: Head and neck
C3: Diaphragm
C4: Upper body muscles (e.g. Deltoids, Biceps)
C5: Wrist extensors
C6: Wrist extensors
C7: Triceps
C8: Hands
Injury to cervical spine or involvement of spinal nerves affect the area they supply.
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The portion of spine encompassing neck region forms cervical spine. It is formed by first seven vertebra which are named as C1 to C7. Anatomically, cervical spine starts where the top vertebra (C1) connects to the bottom of the skull. Normal cervical s…