The C4 vertebra is the fourth of the seven (7) cervical vertebrae that make up the spinal cord in the area of the neck. After the C1 and C2 vertebrae, the C3-C6 vertebrae are often grouped together as similar to one another in form and function. The C4 vertebra, like the other cervical vertebrae, is relatively small in relation to the other vertebrae but with a large vertebral foramen for the passage of the nerves of the spinal cord. Two transverse foramina pass through the vertebral arch, permitting the sympathetic nerves, vertebral vein, and vertebral artery to pass from the spinal column and out to the body. The vertebral body or centrum and the superior and inferior articular facets work in conjunction with the C3 vertebra above and C5 below to allow for smooth articulation of the spine, cushioned by intervertebral discs. Posterior to the vertebral arch, a notched (bifid) spinous process extends for connection of the spine to muscles and ligaments.