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Encyclopedia > Posterior cranial fossa
Posterior cranial fossa
Base of the skull. Upper surface.
Latin fossa cranii posterior
Gray's subject #47
System
MeSH [1]
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The posterior cranial fossa is part of the intracranial cavity, located between the foramen magnum and tentorium cerebelli. It contains the brainstem and cerebellum. Image File history File links Download high resolution version (719x1057, 150 KB) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Latin is an ancient Indo-European language originally spoken in the region around Rome called Latium. ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ... In anatomy, the foramen magum is the large hole through the occipital bone in the base of the skull, through which the medulla oblongata (an extension of the spinal cord) exits the skull vault. ... The tentorium cerebelli (Latin: tent of the cerebellum) is an extension of the dura mater that seperates the cerebellum from the inferior portion of the occipital lobes. ... The brain stem is the stalk of the brain below the cerebral hemispheres. ... Figure 1a: A human brain, with the cerebellum in purple. ...


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.

Contents


Features

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. In anatomy, the foramen magum is the large hole through the occipital bone in the base of the skull, through which the medulla oblongata (an extension of the spinal cord) exits the skull vault. ... The accessory nerve is the eleventh of twelve cranial nerves. ...


Internal acoustic meatus

Lies in the anterior wall of the posterior cranial fossa. It transmits the facial (VII) and vestibulocochlear (VIII) cranial nerves into canal in the petrous temporal bone. The vestibulocochlear nerve is the eighth of twelve cranial nerves and also known as the auditory nerve or acoustic nerve. ... Cranial nerves are nerves that emerge from the brainstem instead of the spinal cord. ... The temporal bones (os temporales) are situated at the sides and base of the skull. ...


Jugular foramen

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. The occipital bone [Fig. ... Grays FIG. 791 - Plan of upper portions of glossopharyngeal, vagus, and accessory nerves. ... The vagus nerve is tenth of twelve paired cranial nerves and is the only nerve that starts in the brainstem (somewhere in the medulla oblongata) and extends all the way down past the head, right down to the abdomen. ... The accessory nerve is the eleventh of twelve cranial 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.


Also an inferior petrosal sinus enters the sigmoid sinus near the jugular foramen.


  Results from FactBites:
 
Dissector Answers - Scalp, Cranial Cavity, Meninges, & Brain (2510 words)
The bulk of the middle cranial fossa is composed of the greater wing of the sphenoid and the squamous portion of the temporal bone.
Anterior and posterior ethmoidal branches of the ophthalmic division of the trigeminal nerve in the anterior cranial fossa.
Meningeal branches of the vagus and hypoglossal nerves in the posterior cranial fossa.
  More results at FactBites »

 
 

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