Bone
Atlas (C1)
Ring-shaped first neck vertebra supporting the skull
High-yield
Nodding occurs mainly between the atlas and the skull's occipital condyles. Rotation involves the atlas moving around the dens of C2, with the transverse ligament helping hold that pivot in place.
Overview
The atlas carries the skull on two thick lateral masses joined by front and back arches. It has no vertebral body or true spinous process, leaving a ring that surrounds the dens anteriorly and the upper spinal canal behind it.
Reference facts
- Bone type
- Irregular bone of the cervical spine
- Key landmarks
- Anterior and posterior arches; paired lateral masses; transverse foramina; articular surface for the dens behind the anterior arch
- Articulations
- Occipital condyles above; the axis below and at the dens
Clinical correlation
An axial load can split the anterior and posterior C1 arches in a Jefferson burst fracture. Injury to the transverse ligament is a major stability concern, but joint alignment and associated injuries also matter.
Frequently asked questions
What type of bone is the atlas (C1)?
The atlas (C1) is an irregular bone of the cervical spine bone.
What does the atlas (C1) articulate with?
Occipital condyles above; the axis below and at the dens.
What are the key landmarks of the atlas (C1)?
Anterior and posterior arches; paired lateral masses; transverse foramina; articular surface for the dens behind the anterior arch.