Base of the skull. Upper surface.
|- style="text-align: center;" class="hiddenStructure"
| colspan="2" |
|- style="text-align: center; line-height: 1;" class="hiddenStructure"
| colspan="2" |
|- class="hiddenStructure"
|Latin
|colspan="2"|fossa cranii posterior
|- class="hiddenStructure"
|[[List of subjects in Gray's Anatomy:47#Gray.27s_page_.23|Gray's]]
|colspan="2"|[subject #47 ]
|- class="hiddenStructure"
|System
|colspan="2"|
|- class="hiddenStructure"
|Precursor
|colspan="2"|
|- class="hiddenStructure"
|MeSH
|colspan="2"|[A01.456.830.200]
|- class="hiddenStructure"
|Dorlands/Elsevier
|colspan="2"|[/]
|}
The posterior cranial fossa is part of the intracranial cavity, located between the foramen magnum and tentorium cerebelli. It contains the brainstem and cerebellum.
This is the most inferior of the fossa. It houses the cerebellum, medulla and pons.
Anteriorly it extends to the apex of the petrous temporal. Posteriorly it is enclosed by the
occipital bone. Laterally portions of the squamous temporal and mastoid part of the
temporal bone form its walls.
The most conspicuous, large opening in the floor of the fossa. It transmits the
medulla, the ascending portions of the spinal accessory nerve (XI), and the vertebral
arteries.
Lies between the inferior edge of the petrous temporal bone and the adjacent
occipital bone and transmits the internal jugular v. (actually begins here), the
glossopharyngeal (IX), the vagus (X) and the accessory (XI) nerves.
Anterior condylar (hypoglossal) canal
Lies at the anterolateral margins of the f. magnum and transmits the hypoglossal
(XII) nerve.
Other
Also visible in the posterior cranial fossa are depressions caused by the venous
sinuses returning blood from the brain to the venous circulation:
Right and left transverse sinuses which meet at the confluence of sinuses (marked
by the internal occipital protuberance).
The transverse sinuses pass horizontally from the most posterior point of the occiput.
Where the apex of the petrous temporal meets the squamous temporal, the transverse sinuses lead into sigmoid (S-shaped) sinuses (one on each side).
These pass along the articulation between the posterior edge of the petrous
temporal and the anterior edge of the occipital bones to the jugular foramen where the
sigmoid sinus becomes the internal jugular vein.
Note that a superior petrosal sinus enters the junction of the transverse and sigmoid sinuses.
