What is the anterior boundary for the posterior cranial fossa?
- posterior clinoid processes (sphenoid)
- dorsum sella (sphenoid)
- apex of the petrous portion of the temporal bone
What is the posterior boundary for the posterior cranial fossa?
squamous part of the occipital bone
What forms the roof of the posterior cranial fossa?
tentorium cerebelli
What part of the cerebrum occupies the posterior cranial fossa?
none: the tentorium cerebelli separates the cerebrum into a space above the posterior cranial fossa
What part of the cranial nerve system occupies the posterior cranial fossa?
- cerebellum
- pons
- medulla oblongata
What bony feature is prominent in the median plane of the posterior cranial fossa?
the clivus or basilar part of the occipital bone
Which cranial nerves exit posterior cranial fossa ostia?
- VII (facial)
- VIII (vestibulocochlear/auditory)
- IX (glossopharyngeal)
- X (vagus)
- XI (spinal accessory)
- XII (hypoglossal)
Which ostia will allow exit from the posterior cranial fossa?
- foramen magnum
- internal acoustic meatus
- jugular foramen
- hypoglossal canal
- condylar canal
Which single opening will allow the exit of the greatest number of cranial nerves from the posterior cranial fossa?
jugular foramen
What feature is unique to the foramen magnum?
it is the largest unpaired foramen of the skull
What will the foramen magnum communicate with?
- posterior cranial fossa
- spinal canal
What part of the central nervous system is traditionally said to be present in the foramen magnum?
the junction between the brain and spinal cord
What are the contents of the foramen magnum?
- medulla oblongata
- spinal roots of the spinal accessory nerve
- meningeal branches from the C1-C3 spinal nerves
- the vertebral arteries
- anterior and posterior spinal arteries and veins
- meningeal coverings of the CNS
Which arteries arise in the posterior cranial fossa and descend through the foramen magnum to supply the spinal cord?
anterior and posterior spinal arteries
Which arteries ascend through the foramen magnum to supply the brain?
vertebral arteries
What will the internal acoustic meatus communicate with?
- posterior cranial fossa
- facial canal of the temporal bone
What are the contents of the internal acoustic meatus?
- cranial nerve VII (facial nerve)
- cranial nerve VIII (vestibulocochlear/auditory nerve)
- the nervus intermedius/nerve of Wrisberg/sensory root of VII
- motor root of VII
- the vestibular and cochlear roots of VIII
- internal auditory/internal labyrinthine artery and vein
Which ostium exiting the cranial fossae will not also exit the skull?
internal acoustic meatus
What will the jugular foramen communicate with?
- posterior cranial fossa
- neck
What bones converge to form the jugular foramen?
- temporal
- occipital
What are the contents of the jugular foramen?
- jugular bulb
- inferior petrosal sinus
- tympanic/jugular body/glomus
- cranial nerve IX (glossopharyngeal nerve)
- cranial nerve X (vagus)
- cranial nerve XI (spinal accessory)
What is the jugular bulb?
the venous expansion between the sigmoid dural venous sinus and the internal jugular vein
What is the jugular/tympanic body/glomus?
a chemoreceptive organ located in the wall of the jugular bulb
What is the function of the jugular/tympanic body/glomus?
a chemoreceptive organ that monitors hypoxia, hypercapnia, and increases in the hydrogen ion
What bone forms the hypoglossal canal?
occipital bone
What will the hypoglossal canal communicate with?
- posterior cranial fossa
- neck
What are the contents of the hypoglossal canal?
cranial nerve XII (hypoglossal)
What bone forms the condylar canal?
occipital bone
What will the condylar canal communicate with?
- posterior cranial fossa
- neck
What are the contents of the condylar canal?
an emissary vein connecting the sigmoid dural venous sinus and the vertebral venous plexus