Cranial fossa and cranial nerves Flashcards
Anterior fossa
cribriform plate
crista galli
optic canal
Middle fossa
foramen rontundum
foramen ovale
foramen spinosum -middle meningeal artery
foramen lacerum
carotid canal - internal carotid artery goes into foramen lacerum
Posterior fossa
groove for sigmoid dural venous sinus
jugular foramen
foramen magnum
hypoglossal canal
CN I
Olfactory
Olfactory
outgrowth of telencephalon
olfactory mucosa through cribiform plate to synapse with olfactory bulb
olfactory tracts to prepiriform area of amygdala - primary olfactory cortex
only sensory system not relayed through thalamus
CN II
Optic
Optic
Extension of diencephalon
From retina through the optic canal, form chiasm then optic tracts.
90% fibres to lateral geniculate body (thalamus) then striate area (visual cortex), 10% along medial root (non-geniculate) unconscious regulation.
CN III
Oculomotor
Oculomotor
Midbrain through superior orbital fissure to orbit
Run in lateral wall of cavernous dural venous sinus
Through annular ring
Somatic motor and parasympathetic (visceral efferent)
Motor to inferior oblique, superior rectus, inferior rectus and medial rectus, levator palpabrae
Parasympathetic to sphincter pupillae and ciliary muscle
Superior division = levator palpabrae and superior rectus
CN IV
Trochlear
Trochlear
Midbrain through superior orbital fissure to orbit
Run in lateral wall of cavernous dural venous sinus
Outside annular ring
Only cranial nerve in which all fibres cross to opposite sides.
Only cranial nerve from the posterior surface of the midbrain - longest intracranial (dural) route of cranial nerves
Motor fibres to superior oblique
CN V
Trigeminal
Trigeminal
Originates from the pons, forms a ganglion and divides into 3 divisions:
CN V1 = ophthalmic enter orbit through superior orbital fissure
CN V2= maxillary enters pterygopalentine fossa through foramen rotundum
CN V3= mandibular through foraman ovale to inferior surface of the base of the skull
Motor and sensory
Lacrimal (CN V1), Zygomatic ( CN V2), lingual and auriculotemporal (CN V3) allow passage of parasympathetic fibres from other cranial nerves
Opthalmic division CN V1
general sensory for eye, lacrimal gland, eyebrow, skin of forehead, nose etc.
Runs in lateral wall of cavernous dural venous sinus
Maxillary division CN V2
general sensory for skin of cheek, lower lid, upper jaw (and teeth), side of nose, mucosa of mouth etc
Runs in lateral wall of cavernous dural venous sinus
Mandibular division CN V3
Sensory to ear canal, parotid gland, lower jaw and teeth etc.
Motor muscles of mastication, anterior belly of digastric, mylohyoid, tensor tympani, veli tensor palatini
CN VI
Abducent
Abducent
Originates from pons and passes through the superior orbital fissure to reach the orbit.
Long extradural pathway
Passes through cavernous dural venous sinus with internal carotid artery.
Through annular ring
Motor to lateral rectus
CN VII
Facial
Facial nerve
Originates from the pons, through internal acoustic meatus into temporal bone
Greater petrosal, stapedial and chorda tympani
Motor fibres to muscles of facial expression leaves via stylomastoid foramen= temporal, zygomatic, buccal, mandibular, and cervical posterior auricular
Stapedius, stylohyoid and posterior belly of digastric
CN VIII
Vestibulocochlear
Vestibulocochlear
special somatic afferent
Vestibular apparatus and auditory apparatus through internal auditory meatus to pons/ medulla oblongata
Vestibular - cerebellum, CN III, IV, VI and spinal tracts
Cochlear - inferior colliculi, medial geniculate nucleus of thalamus to auditory cortex (area 41 temporal)
CN VIX
Glossopharyngeal
Glossopharyngeal
Originates from the medulla oblongata and passes through jugular foramen
Parasympathetic to parotid, buccal and labial glands
Taste from posterior 1/3rd tongue
Motor to pharyngeal plexus and stylopharyngeus
Sensory to posterior 1/3 rd tongue, soft palate, pharynx, tympanic cavity, membrane pharyngotympanic tube, external ear and auditory canal.
