Posterior cranial fossa

Posterior cranial fossa
Base of the skull. Upper surface. The Posterior cranial fossa is labeled in green.
Details
Identifiers
Latin	fossa cranii posterior
MeSH	A01.456.830.200
TA	A02.1.00.050
FMA	54368
Anatomical terminology []

The posterior cranial fossa is part of the cranial cavity, located between the foramen magnum and tentorium cerebelli. It contains the brainstem and cerebellum.

This is the most inferior of the fossae. 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 in the anterior wall of the posterior cranial fossa. It transmits the facial (VII) and vestibulocochlear (VIII) cranial nerves into a canal in the petrous temporal bone.

Lies between the inferior edge of the petrous temporal bone and the adjacent occipital bone and transmits the internal jugular vein (actually begins here), the glossopharyngeal (IX), the vagus (X) and the accessory (XI) nerves.

Lies at the anterolateral margins of the f. magnum and transmits the hypoglossal (XII) nerve.

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).