C1 vertebra (atlas)

At a glance

Level system

C1 vertebra (vertebral level)

Cord segments opposite its body

None: below the end of the cord in this model; the canal holds the cauda equina hereModel mapping. Frostell et al. 2016; De Leener et al. 2018; Cadotte et al. 2014

Canal, front to back × side to side

21.2 × 28.4 mmMeasured on one model: the Visible Human male, imaged as a supine cadaver. Not a normal range

C1 nerve

The C1 nerve exits between the occiput and the C1 vertebra, above the C1 vertebra.Betts et al. 2022, §13.4

C2 nerve

The C2 nerve exits between the C1 vertebra and the C2 vertebra, above the C2 vertebra.Betts et al. 2022, §13.4

What the sources say

“The first cervical (C1) vertebra is also called the atlas , because this is the vertebra that supports the skull on top of the vertebral column (in Greek mythology, Atlas was the god who supported the heavens on his shoulders).” Betts et al. 2022, §7.3

“In the neck, there are seven cervical vertebrae, each designated with the letter “C” followed by its number.” Betts et al. 2022, §7.3

“Figure 7.25 Cervical Vertebrae A typical cervical vertebra has a small body, a bifid spinous process, transverse processes that have a transverse foramen and are curved for spinal nerve passage.” Betts et al. 2022, §7.3

“A second set of vessels that supply the CNS are the vertebral arteries , which are protected as they pass through the neck region by the transverse foramina of the cervical vertebrae.” Betts et al. 2022, §13.3

“The adult vertebral column consists of 24 vertebrae, plus the sacrum and coccyx.” Betts et al. 2022, §7.3

“The large opening between the vertebral arch and body is the vertebral foramen , which contains the spinal cord.” Betts et al. 2022, §7.3

Connections to the rest of the body

• Joints

  The skull rests on the atlas

  The first cervical vertebra, the atlas, carries the skull: its upper joint surfaces meet the occipital condyles at the base of the skull.

  Betts et al. 2022, §7.3 · Show on the body

• Muscle attachments

  Muscles that hold up and turn the head

  Semispinalis capitis and splenius capitis run from the cervical and upper thoracic vertebrae to the back of the skull and tilt or turn the head.

  Betts et al. 2022, §11.3 · Show on the body

• Arterial supply

  Vertebral arteries climb through the neck vertebrae

  Each vertebral artery leaves the subclavian artery, climbs through the holes in the transverse processes of the cervical vertebrae and enters the skull to supply the brainstem, cerebellum and spinal cord.

  Betts et al. 2022, §20.5; Betts et al. 2022, §13.3 · Show on the body

• Arterial supply

  Anterior spinal artery: down the front of the cord

  Branches of the two vertebral arteries join into the anterior spinal artery, which runs down the front of the cord in its midline groove.

  Betts et al. 2022, §13.3 · Show on the body

• Venous drainage

  Vertebral veins drain the cervical cord

  Veins from the base of the brain and the cervical cord travel through the neck vertebrae beside the vertebral arteries and empty into the brachiocephalic veins.

  Betts et al. 2022, §20.5 · Show on the body

Read more

• The craniocervical junction

  Where the skull meets the spine. The atlas carries the skull, the axis lets the head turn, and a small set of ligaments, above all the transverse ligament, holds the joints together.

• The vertebral column

  The flexible stack of bones that carries the head and trunk, protects the spinal cord and lets the back move. Its five regions, its four curves and the parts every vertebra shares.