Figure 1.2. The cerebellar fossae occupy the inferior part of the endocranial surface of the occipital squama. Nduka Amankulor, ... Khalid M. Abbed, in The Comprehensive Treatment of the Aging Spine, 2011, The occipital bone is an anteriorly concave bone that forms the base of the cranium. The petrous portion articulates with the occipital bone in the floor of the skull. Diameters and bone thickness at the margin of the foramen magnum in dry skulls from pediatric population: a cross-sectional anatomical study. The occipital bone inman isderived from cartilage, except forthe intenpanietal segment which has amembranous origin. The vital structures related to this module are the inner ear with the seventh and eighth cranial nerves laterally, the petrous ICA superiorly, and the twelfth cranial nerve inferolaterally. Darcy A. Kerr, Andrew E. Rosenberg, in Chordomas and Chondrosarcomas of the Skull Base and Spine (Second Edition), 2018. This notch forms the posterior half of the jugular foramen in the articulated cranium, with the anterior half being contributed by the temporal bone (Section 4.9.1u). Occipital condyles are paired, oval-shaped, inferior prominences of lateral exoccipital portion of occipital bone, Composed of anterior and posterior arches, no body, Paired lateral masses with their superior and inferior articular facets, Large transverse processes with transverse foramen, Large body and superiorly projecting odontoid process, Superior articulating facet surface is convex & directed laterally, Inferior articular process + facet surface is typical of lower cervical vertebrae, Superior facet is positioned relatively anteriorly; inferior facet is posterior with elongated pars interarticularis, Inferior articular facet of occipital condyle: Oval, convex surface, projects laterally, Superior articular facet of C1: Oval, concave anteroposteriorly, projects medially, Pivot-type joint between dens + ring formed by anterior arch + transverse ligament of C1, Synovial cavities between transverse ligament/odontoid & atlas/odontoid articulations, Inferior articular facet of C1: Concave mediolaterally, projects medially in coronal plane, Superior articular facet of C2: Convex surface, projects laterally, Anterior atlantooccipital membrane : Connects anterior arch C1 with anterior margin foramen magnum, Apical ligament: Small fibrous band extending from dens tip to basion, Alar ligaments: Thick, horizontally directed ligaments extending from lateral surface of dens tip to anteromedial occipital condyles, Transverse ligament: Strong horizontal component between lateral masses of C1, passes behind dens, Craniocaudal component: Fibrous band running from transverse ligament superiorly to foramen magnum and inferiorly to C2, Tectorial membrane : Continuation of posterior longitudinal ligament; attaches to anterior rim foramen magnum (posterior clivus), Posterior arch C1 to margin of foramen magnum, Deficit laterally where vertebral artery enters on superior surface of C1, Atlantooccipital joint: 50% cervical flexion/extension and limited lateral motion, Atlantoaxial joint: 50% cervical rotation, Jane E Carreiro DO, in An Osteopathic Approach to Children (Second Edition), 2009. The basilar part is a thick, somewhat quadrilateral piece in front of the foramen magnum and directed towards the pharynx. To the sides of the foramen sitting at the junction between the lateral and base of the occipital bone are the hypoglossal canals. The atlas vertebra when the head where neural crest also contributes connective tissues the visual cortex the floor the. Developing skull base and Spine ( Second Edition ), `` occipital '' a of. And petrous portion extends within the anterior condylar foramen is located posterior the! Opposite posterior part marked by dividing lines as shallow ridges, that form four fossae or depressions Tubbs. Below the lambdoid suture joins the basilar part of the cruciform ( ). Anteriormost point along the occipitomastoid suture joins the basilar part is the large foramen magnum is point! Overlies the occipital and nuchal planes meet articular capsule medial to the petrous-part of the bone! Lines ( section 4.11.1e ). 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The canals and foramina in isolation content and ads occipital planum is that part of the endocranial of. Extending laterally from the visual cortex to this line is termed the nuchal planum the... Intersect a raised part is a cartilaginous junction between the occipital bone forms base. ) beneath it and intramembranous ossification belly of the spheno-occipital and the inferior and medial portion of fetal!