Posterior cranial fossa

The posterior cranial fossa is part of the intracranial cavity, located between the foramen magnum and tentorium cerebelli

Tentorium cerebelli

The tentorium cerebelli or cerebellar tentorium is an extension of the dura mater that separates the cerebellum from the inferior portion of the occipital lobes.-Anatomy:...

. It contains the brainstem and cerebellum

Cerebellum

The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...

.

This is the most inferior of the fossae

Fossa (anatomy)

In anatomical terminology, fossa has come to mean a depression or hollow, in general, in a bone. Other parts of the body may be involved, for example, the antecubital 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.

Foramen magnum

See main article at Foramen magnum

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.

Internal acoustic meatus

Lies in the anterior wall of the posterior cranial fossa. It transmits the facial (VII) and vestibulocochlear (VIII) cranial nerves

Cranial nerves

Cranial nerves are nerves that emerge directly from the brain, in contrast to spinal nerves, which emerge from segments of the spinal cord. In humans, there are traditionally twelve pairs of cranial nerves...

 into canal in the petrous temporal bone.

Jugular foramen

Lies between the inferior edge of the petrous temporal bone and the adjacent
occipital bone

Occipital bone

The occipital bone, a saucer-shaped membrane bone situated at the back and lower part of the cranium, is trapezoidal in shape and curved on itself...

 and transmits the internal jugular vein

Internal jugular vein

The two internal jugular veins collect the blood from the brain, the superficial parts of the face, and the neck.-Path:On both sides and at the base of the brain, the inferior petrosal sinus and the sigmoid sinus join to form the internal jugular vein...

 (actually begins here), the
glossopharyngeal (IX), the vagus (X) and the accessory

Accessory nerve

In anatomy, the accessory nerve is a nerve that controls specific muscles of the shoulder and neck. As part of it was formerly believed to originate in the brain, it is considered a cranial nerve...

 (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

Internal jugular vein

The two internal jugular veins collect the blood from the brain, the superficial parts of the face, and the neck.-Path:On both sides and at the base of the brain, the inferior petrosal sinus and the sigmoid sinus join to form the internal jugular vein...

.

Note that a superior petrosal sinus enters the junction of the transverse and sigmoid sinuses. Also an inferior petrosal sinus enters the sigmoid sinus

Sigmoid sinus

The sigmoid sinuses , within the human head, are two areas beneath the brain which allow blood to drain inferiorly from the posterior center of the head. They drain from the transverse sinuses and converge with the inferior petrosal sinuses to form the internal jugular vein...

 near the jugular foramen

Jugular foramen

The jugular foramen is a large aperture in the base of the skull. It is located behind the carotid canal and is formed in front by the petrous portion of the temporal, and behind by the occipital; it is generally larger on the right than on the left side....

.

The posterior cranial fossa is formed in the endocranium

Endocranium

For internal cast of the cranium, see Endocast.The endocranium in comparative anatomy is a part of the skull base in vertebrates and represent the basal, inner part of the cranium. The term is also applied to the outer layer of the dura mater in human anatomy.-Basic structure:Structurally, the...

, and holds the most basal parts of the brain.