Atlantooccipital Joint Capsule

Description

Viewed laterally, the occipital bone at the cranial base meets the atlas (C1) at the paired atlantooccipital joints, where the occipital condyles sit superior to the atlas’ concave superior articular facets. A fibrous atlantooccipital joint capsule surrounds each condylar articulation, attaching along the margins of the condyle and the rim of the C1 superior articular surface, then blending anteriorly and posteriorly with the local thickened membranes. Nearby bony landmarks include the squamous occipital region and cranial sutures (coronal, sagittal, lambdoid), with the mandible and maxillary dentition visible anteriorly and the upper cervical column extending inferiorly from C1 through C7. Head posture reads neutral. Clinically, the capsule and adjacent atlantooccipital membranes define the constraint system for flexion and extension of the head, while limiting rotation compared with the atlantoaxial complex below. Trauma at this junction matters. Occipital condyle fractures, atlantooccipital dislocation, and craniocervical instability after high energy injury can disrupt capsular attachments, widening the occipitoatlantal interval and threatening the medulla and upper cervical spinal cord. This lateral perspective also supports teaching how the craniovertebral junction differs from lower cervical zygapophysial joints, both in surface geometry and stabilizing soft tissue. Use this artwork for gross anatomy and neuroanatomy teaching when introducing the cranium, atlas, and craniocervical junction, or for radiology and trauma education alongside lateral cervical radiographs, CT reformats, and MR assessments of ligamentous injury. It also suits spine surgery and emergency medicine publications discussing atlantooccipital instability and fixation landmarks at the skull base and C1. Anatomical accuracy verified by SciePro's Medical Advisory Board.