The basilar part of the

occipital bone The occipital bone () is a neurocranium, cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobe ...

(also basioccipital) extends forward and upward from the

foramen magnum The foramen magnum ( la, great hole) is a large, oval-shaped opening in the occipital bone of the skull. It is one of the several oval or circular openings (foramina) in the base of the skull. The spinal cord, an extension of the medulla oblon ...

, and presents in front an area more or less quadrilateral in outline. In the young skull this area is rough and uneven, and is joined to the body of the sphenoid by a plate of cartilage. By the twenty-fifth year this cartilaginous plate is ossified, and the occipital and sphenoid form a continuous bone.

Surfaces

On its ''lower surface'', about 1 cm. in front of the foramen magnum, is the pharyngeal tubercle which gives attachment to the fibrous raphe of the pharynx. On either side of the middle line the longus capitis and

rectus capitis anterior The rectus capitis anterior (rectus capitis anticus minor) is a short, flat muscle, situated immediately behind the upper part of the Longus capitis. It arises from the anterior surface of the Lateral mass of atlas, lateral mass of the Atlas (anat ...

are inserted, and immediately in front of the

the

anterior atlantooccipital membrane Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

is attached. The ''upper surface'', which constitutes the lower half of the clivus, presents a broad, shallow groove which inclines upward and forward from the foramen magnum; it supports the

medulla oblongata The medulla oblongata or simply medulla is a long stem-like structure which makes up the lower part of the brainstem. It is anterior and partially inferior to the cerebellum. It is a cone-shaped neuronal mass responsible for autonomic (involun ...

, and near the margin of the foramen magnum gives attachment to the tectorial membrane On the lateral margins of this surface are faint grooves for the inferior petrosal sinuses.

Additional images

File:Basilar part of occipital bone - animation02.gif,

Occipital bone The occipital bone () is a neurocranium, cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobe ...

. Basilar part shown in red. File:Basilar part of occipital bone - animation04.gif, Human skull seen from below. Basilar part shown in red. File:Basilar part of occipital bone - animation06.gif, Human skull seen from above ( parietal bones have been removed). Basilar part shown in red. File:Parsbasilaris(adult).PNG, Occipital bone. Outer surface. File:Gray307.png, Membrana tectoria, transverse, and alar ligaments. File:Gray387.png, The anterior vertebral muscles. File:Slide26hhhh.JPG, Basilar part of occipital bone File:Slide13jjjj.JPG, Basilar part of occipital bone File:Slide7pppp.JPG, Basilar part of occipital bone File:Occipital bone dissection.jpg, Tympanic cavity. Facial canal. Internal carotid artery.

References

External links

* Bones of the head and neck {{musculoskeletal-stub