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The upper surface of each usually has a shallow sulcus for the eighth spinal nerve, and its extremity seldom presents more than a trace of bifurcation. The transverse foramen may be as large as that in the other cervical vertebrae, but it is generally smaller on one or both sides; occasionally, it is double, and sometimes it is absent.
In anatomy, the axis (from Latin axis, "axle") is the second cervical vertebra (C2) of the spine, immediately inferior to the atlas, upon which the head rests. The spinal cord passes through the axis. The defining feature of the axis is its strong bony protrusion known as the dens, which rises from the superior aspect of the bone.
C2 innervates the rectus capitis anterior and rectus capitis lateralis muscles, and provides sensory nerves to the trapezius and the back of the scalp and upper neck. [2] At the atlantoaxial joint, the C2 spinal nerve emerges from the spinal cord through a small bony opening known as the intervertebral foramen located above the C2 vertebra.
Image of base of the skull with several of the foramina labeled. The human skull has numerous openings , through which cranial nerves, arteries, veins, and other structures pass. These foramina vary in size and number, with age. [1] [2]
Specific to the cervical vertebra is the transverse foramen (also known as foramen transversarium). This is an opening on each of the transverse processes which gives passage to the vertebral artery and vein and a sympathetic nerve plexus. On the cervical vertebrae other than the atlas, the anterior and posterior tubercles are on either side of ...
They then proceed superiorly, in the transverse foramen of each cervical vertebra. [1] Once they have passed through the transverse foramen of C1 (also known as the atlas), the vertebral arteries travel across the posterior arch of C1 and through the suboccipital triangle [3] before entering the foramen magnum. [1]
Accessory transverse foramen of the atlas is present in 1.4–12.5% across the population. [7] Foramen arcuale or a bony bridge above the vertebral artery on the posterior arch of the atlas may be present. This foramen has an overall prevalence of 9.1%. [8]
The transverse cervical nerve (superficial cervical or cutaneous cervical) is a cutaneous (sensory) nerve of the cervical plexus that arises from the second and third cervical spinal nerves (C2-C3). It curves around the posterior border of the sternocleidomastoideus muscle, then pierces the fascia of the neck before dividing into two branches ...