Cranial Fossae and Cranial Nerves Flashcards
What bony projections form the anterior cranial fossa
- Frontal bone anteriorly
- Ethmoid bone in the middle
- Body and lesser wings of the sphenoid bone posteriorly
Name the 3 large depressions of the cranial base
- Anterior cranial fossa
- Middle cranial fossa
- Posterior cranial fossa
What section of the brain is found in the anterior cranial fossa
The frontal lobes
What does the anterior cranial fossa form
- Roof of the orbit
- Contributes to the nasal cavities
- Foramina related to the special senses of vision and smell (olfaction)
What is the crista galli
A bony ridge formed by the frontal bone that provides attachment for the dura mater
What structure related to the orbit does the sphenoid bone house
The optic canals
What does the sphenoid bone form in the middle cranial fossa
- The floor of the middle cranial fossa
2. Orbital fissures
Name the orbital fissures
- Foramen rotundum
- Foramen ovale
- Foramen spinosum
What does the trigeminal nerve form in the middle cranial fossa
A large ganglion that sits on the floor and divides into its 3 divisions:
- Ophthalmic
- Maxillary
- Mandibular
Where does CNV1 exit the cranial fossa, and what travels with it
Through the superior orbital fissure along with:
- CN III (oculomotor)
- CN IV (trochlear)
- CN VI (abducent)
What foramen does the CNV2 division pass through
Foramen rotundum to pass towards the maxilla
What foramen does the CNV3 division pass through
Foramen ovale to the infratemporal fossa, along with:
- Otic ganglion
- Accessory meningeal artery
- Lesser petrosal nerve
- Emissary veins
What does the foramen spinosum carry
Middle meningeal artery, a branch of the maxillary artery that supplies the dura
What is the foramen lacerum
A ragged hole that lies posterolateral to the hypophysial fossa; it is an artifact of a dried cranium
What passes through the foramen lacerum
It allows the internal carotid artery to enter the middle cranial fossa
What lobes of the brain sit in the middle cranial fossa
The temporal lobes
What parts of the brain does the posterior cranial fossa house
- Cerebellum
- Pons
- Medulla oblongata
What bone forms the majority of the floor of the posterior cranial fossa
The temporal bone
What important passageways does the posterior cranial fossa border
- Foramen magnum
- Jugular foramina
- Hypoglossal canals
What structures exit through the jugular foramina
- Internal jugular vein
- Glossopharyngeal nerve
- Vagus nerve
- Accessory nerve
What structures enter the skull through the foramen magnum
- Vertebral arteries
2. Spinal part of the accessory nerves
What structures exit the skull through the foramen magnum
- Start of the spinal cord
2. Meninges
Where is the internal acoustic meatus located
Sitting in the petrous part of the temporal bone
What structures exit the cranial cavity through the internal acoustic meatus
The structures enter the temporal bone:
- Facial nerve
- Vestibulocochlear nerve
Name the 12 cranial nerves (in order)
- Olfactory
- Optic
- Oculomotor
- Trochlear
- Trigeminal
- Abducent
- Facial
- Vestibulocochlear
- Glossopharyngeal
- Vagus
- Spinal accessory
- Hypoglossal
What does the trigeminal nerve form before it divides into its divisions
A ganglion before it branches into its 3 divisions:
- Ophthalmic
- Maxillary
- Mandibular