Atlas, Posterior View

Description

Seen from a posterior perspective, the atlas (C1) forms a broad osseous ring superior to the axis (C2), with the posterior arch curving between the right and left lateral masses and meeting in the midline at the posterior tubercle. Laterally, the transverse processes project to either side, and the transverse foramina sit within them, aligned with those of C2 through C7. Inferior to C1, the spinous processes of C2 and the lower cervical vertebrae step down in the midline, while the vertebral foramina stack to create the cervical spinal canal. No vertebral body is present at C1. Posterior anatomy at the craniovertebral junction matters because it frames the path of the vertebral arteries and the exit of the C1 spinal nerve, and it defines the bony margins encountered during posterior C1 to C2 instrumentation. The groove on the superior surface of the posterior arch (for the vertebral artery) sits immediately lateral to the posterior tubercle, a relationship that influences safe placement of C1 lateral mass screws and helps explain vascular injury risk. This is also the view that clarifies how the atlas articulates with the occiput and axis while remaining structurally distinct from C3 to C7. Designed for teaching cervical spine anatomy in gross anatomy, orthopaedic or neurosurgical training modules, and radiology correlation when orienting axial CT or 3D reconstructions of C1 through C7, this posterior view supports clear labeling of C1, C2 (including the dens region by context), and the midline posterior elements used as procedural landmarks. It also fits spine surgery atlases and patient education materials addressing atlantoaxial instability, fractures of the C1 ring, or posterior fusion strategies. Anatomical accuracy verified by SciePro's Medical Advisory Board.