Cranial Fossae and Cranial Nerves Flashcards
what are the notable features of the anterior fossa?
cribiform plate
crista galli
what are the notable features of the middle fossa?
foramen rotundum foramen ovale foramen lacerum foramen spinosum optic canal
what are the notable features of the posterior fossa?
groove for sigmoid dural venous sinus
jugular foramen
hypoglossal canal
foramen magnum
what is the route of the internal carotid artery?
through carotid canal in base of skull, crosses superior to the foramen lacerum as it exits the carotid canal
what passes through the foramen ovale?
O = otic ganglion V = trigeminal nerve A = accessory meningeal artery L = lesser petrosal nerve E = emissary vein --> OVALE
what passes through the cavernous sinus?
internal carotid artery occulomotor (CN III) trochlear (CN IV) opthalmic (CN V1) maxillary (CN V2) abducent (CN VI)
what is CN I?
olfactory nerve
what is the origin and route of CN I?
outgrowth of telencephalon
olfactory mucosa –> cribiform plate (ethmoid bone) –> synapse in olfactory bulb –> olfactory tracts –> pre-piriformis area of amygdala (primary olfactory cortex)
what is CN II?
optic nerve
what is the origin and route of CN II?
extension of diencephalon
retina –> optic canal –> form optic chiasm –> optic tracts –> geniculate body (thalamus) –> stritate area (visual cortex) (90% fibres) or medial root (non-geniculate) (10% fibres)
what is CN III?
oculomotor
what is the route of CN III?
midbrain –> superior orbital fissure –> orbit
runs in lateral wall of cavernous dural venous sinus, through annular ring
what does CN III innervate?
motor: inferior oblique, superior, inferior and middle rectus and levator palpabrae
parasympathetic: sphincter pupillae and ciliary muscle
superior division: levator palpabrae and superior rectus
what is CN IV?
trochlear
what is the route of CN IV?
midbrain –> superior orbital fissure –> orbit
runs in lateral wall of cavernous DVS, outside annular ring
which is the only CN from the posterior surface of the midbrain, has the longest intercranial (dural) root of all CNs and who’s fibres all cross to the opposite side?
CN IV
what does CN IV give motor fibres to?
superior oblique
what is CN V?
trigeminal
what are the 3 divisions of CN V?
CN V1 = opthalmic
CN V2 = maxillary
CN V3 = mandibular
what is the roue of CN V?
originates from pons
forms a ganglion and divides into it’s 3 divisions
what is the route of CN V1?
enters orbit through superior fissure
runs in lateral wall of cavernous DVS
what does CN V1 supply?
general sensory to eye, lacrimal gland, eyebrow, forehead skin, nose etc.
what is the route of CN V2?
enters pterygopalatine fossa through foramen rotundum
runs in lateral wall of cavernous DVS
what does CN V2 supply?
general sensroy to skin of cheek, lower lid, upper jaw and teeth, side of nose, mucosa of mouth etc.
what is the route of CN V3?
through foramen ovale to inferior surface of the base of skull
what does CN V3 supply?
sensory: ear canal, parotid gland, lower jaw and teeth
motor: muscles of mastication, anterior belly of digastric, mylohyoid, tensor tympani, veli tensor palatini
what is CN VI?
abducens
what is the route of CN VI?
pons –> superior orbital fissure –> orbit
passes through cavernous DVS w/ICA, through annular ring
what does CN VI innervate?
motor to lateral rectus
what is CN VII?
facial
what is the route of CN VII?
pons –> internal acoustic meatus –> temporal bone
motor fibres of facial expression exit via stylomastoid foramen
what does CN VII give rise to?
major branches before parotid: greater petrosal nerve, stapedial nerve and chorda tympani
branches in parotid gland: temporal, zygomatic, buccal, mandibular and cervical + posterior auricular nerve (before parotid) (to muscles of facial expression)
what does CN VII supply?
muscles of facial expression
stapedius
stylohyoid
posterior belly of digastric
what is CN VIII?
vestibulocochlear
what is the route of CN VIII?
pons/medulla oblongata –> internal auditory meatus –> vestibular/auditory apparatus
vestibular part: cerebellum, CN III, IV, VI and spinal tracts
cochlear part: inferior colliculi, medial geniculate nucleus of thalamus to auditory cortex
what is CN IX?
glossopharyngeal
what is the route of CN IX?
medulla oblongata –> jugular foramen
what does CN IX supply?
parasympathetic: parotid, buccal and labial glands
motor: pharyngeal plexus and stylopharyngeus
sensory: post. 1/3rd tongue (incl. taste), soft palate, pharynx, tympanic cavity and membrane, pharyngotympanic tube, external ear and auditory canal
what is CN X?
vagus
what is the route of CN X?
medulla oblongata –> jugular foramen
cranial, cervical, thoracic and abdominal distribution
what does CN X supply?
motor: pharyngeal plexus, soft palate and larynx
parasympathetic: thoracic and abdominal viscera
sensory: dura (post-cranial fossa), ear, external auditory canal, lower pharynx, laryngeal mucosa, thoracic and abdominal viscera
what is CN XI?
(spinal) accessory
what is the route of CN XI?
spinal cord –> foramen magnum –> joins ‘cranial root’ (part of CN X) –> jugular foramen
what does CN XI supply?
motor to trapezius and sternocleidomastoid
what is CN XII?
hypoglossal
what is the route of CN XII?
medulla oblongata (ant. to olive) –> hypoglossal canal –> root of tongue above hyoid bone
what does CN XII supply?
motor to all intrinsic muscles of the tongue and all extrinsic except palatoglossus
