practical quiz cards

Question 1

why does fracture to petrous bone cause CSF ottorhoea??

Answer 1

external auditory meatus is within petrous bone.
bleeding from fractured petrous can bleed into parts of the ear.

also fracture tears the overlying dura.
therefore damaging the underlying arachnoid > point of exit for CSF to pass thru meningeal tear

Question 2

Which bones form the posterior boundary of the anterior cranial fossa

Answer 2

lesser wing of sphenoids laterally

frontal part of boy of sphenoid in middle

Question 3

maxillary division of trigeminal nerve passes thru which foramina

Answer 3

Foramen rotundum

Question 4

CNs which run thru the cavernous sinus are?

Answer 4

CN Vb (maxillary)
CN Va (ophthalmic)
CN 3 oculomotor
CN 4 trochlear
cN6 abducens

Question 5

why is CN 3 vulnerable to compression?

Answer 5

runs close to edge of tentorium cerebella before the nerve enters cavernous sinus

nipped by uncut herniating over edge of dural fold