TBL28 - Cranial Fossae Flashcards
What forms the floor of the cranial cavity? From anterior to posterior, what forms the bowl-shaped floor?
1) The cranial base forms the floor of the cranial cavity
2) From anterior to posterior, the bowl-shaped floor is formed by three cranial fossae
What bones form the anterior cranial fossa? What are the posterior boundaries of the lesser wings created by?
1) The anterior cranial fossa is formed by the frontal bone anterolaterally, cribriform plate of the ethmoid bone in the midline, and the lesser wings of the sphenoid bone posteriorly
2) The posterior boundaries of the lesser wings are created by the sphenoidal crests and their medial terminations the anterior clinoid processes
Where are the frontal lobes of the cerebral hemispheres located?
The frontal lobes of the cerebral hemispheres are lodged in the anterior cranial fossa
What is the middle cranial fossa composed centrally by? What is the middle cranial fossa composed laterally by? What accomodates the pituitary gland (aka hypophysis)?
1) The middle cranial fossa is composed centrally by the body of the sphenoid bone
2) The middle cranial fossa is composed laterally by the greater wings of the sphenoid bone and the squamous and petrous parts of the temporal bone
3) The hypophyseal fossa in the body of the sphenoid bone accommodates the pituitary gland (aka hypophysis)
What is the square posterior wall of the body of the sphenoid bone called and what does it contain that project superiorly? What resides in the lateral walls of the body of the sphenoid bone? What do these structures convey into the pterygopalatine fossa?
1) The square posterior wall of the body of the sphenoid bone is called the dorsum sellae with posterior clinoid processes that project superiorly
2) Bilateral pterygoid canals reside in the lateral walls of the body of the sphenoid bone
3) The canals convey the greater petrosal and deep petrosal nerves into the pterygopalatine fossa
What are the superior orbital fissures located beneath and what are the superior orbital fissures conduits between?
The superior orbital fissures, which are located beneath the sphenoidal crests, are conduits between the middle cranial fossa and orbit
Where does the trigeminal ganglion reside? What does CN V1 traverse to enter the orbit? In the orbit, what two nerves does CN V1 generate? What is another orbital branch of CN V1?
1) The trigeminal ganglion resides in the middle cranial fossa
2) CN V1 traverses the superior orbital fissure into the orbit
3) In the orbit, CN V1 generates the frontal nerve and the lacrimal nerve
4) The nasociliary nerve is another orbital branch of CN V1
What is innervated by branches of the nasociliary nerve? How do branches of the nasociliary nerve enter the nasal cavity?
1) The mucosal regions labeled CN V1 in the nasal septum and lateral walls of the nasal cavity are innervated by branches of the nasociliary nerve (ignore names of the branches)
2) The branches enter the nasal cavity by piercing small fissures in the medial walls of the orbits
Where are the temporal lobes of the cerebral hemispheres found?
The temporal lobes of the cerebral hemispheres are lodged in the middle cranial fossae
What mostly forms the posterior cranial fossa? What contributes to the anterolateral sides of the posterior cranial fossa? What is the clivus located between?
1) The posterior cranial fossa is formed mostly by the occipital bone
2) The petrous temporal bone contributes to the anterolateral sides of the posterior cranial fossa
3) The clivus is located between the foramen magnum and dorsum sellae
What separates left and right halves of the occipital bone? What two nerves traverse the jugular foramen?
1) The internal occipital protuberance separates the left and right halves of the occipital bone
2) CN IX and CN X traverse the jugular foramen
Where does CN XII exit the posterior cranial fossa via? What muscles does the hypoglossal nerve transport C1 to and what muscles does the hypoglossal nerve innervate?
1) CN XII exits the posterior cranial fossa via the hypoglossal canal
2) The hypoglossal nerve transports C1 to the thyrohyoid and geniohyoid muscles and innervates the muscles of the tongue
Where do the medulla oblongata and pons of the brainstem reside? Where does the cerebellum reside? Where does the midbrain of the brainstem extend from and to?
1) The medulla oblongata and pons of the brainstem reside on the clivus
2) The cerebellum resides on the occipital bone in the posterior cranial fossa
3) The midbrain of the brainstem extends from the posterior cranial fossa into the middle fossa
