Cranial Nerves Flashcards
What does the CN III innervate
Extraocular muscles except LR and SO
Sphincterpupillae and ciliary muscles via parasympathetic
Where is the third nerve nuclei?
Midbrain level of the superior colliculus
2 nuclei:
Motor nucleus - in atnieorr grey matter around cerebral aqueduct
Edinger Westphal (parasympathetic nucleus) - posterior to main motor
Where do preganglionic and postganglionic fibres from the Edinger WEstphal nucleus travel?
Preganglionic to orbit to synapse in the ciliary ganglion
Postganglionic along short ciliary nerves to ciliary muscles and pshincter pupillae
What other fibres does the edinger westphal nucleus receive?
Coriconuclear fibres for accommodation
Fibres from the pretectal nucleus for the direct and consensual light reflex
What is the path of third nerve?
Emerges anterior from midbrain, medial to cerebral peduncles
Subarachnoid space
Anterior between posterior cerebral artery and superior cerebellar arteries
Runs parallel with posterior communicating artery
Perforates dura materand enters cavernous sinus in lateral wall above CNIV
What nerves does the CN III receive prior to dividing?
Sensory communicating branch from the ophthalmic division of the trigeminal nerve
Sympathetic branch from the nerve plexus around the ICA
What is the path of the superior division of the CNIII
Through SOF within CTR
Upwards and lateral to optic nerve
Enters superior rectus at junction of proximal and middle thirds
Through superior rectus and to levator palpebrae superioris
Pathway of CNIII inferior division
SOF via CTA
Divides into three branches
MEdial rectus branch - passes medially below optic nerve to enter lateral surface of muscle
Inferior rectus branch - runs forward on upper surface of IR and enters between proximal and middle third
Inferior oblique branch - close to orbital floor and lateral to inferior rectus - enters posterior border
- Gives short branch to ciliary ganglion
= short ciliary nerves to sphincter pupillae and ciliary muscles
Whatis the levator supplied by?
Single central group of cells (central caudal nucleus) via both third nerve nuclei
Which muscle is supplied by contralateral CNIII nucleus?
Superior rectus
Others have ipsilateral supply
What artery puts the CNIII at risk
Posterior communicating artery aneurysm
Superior cerebellar artery
What does CNIV supply
Contralateral SO
What is the path of the CNIV
Fourth nere nuclei at inferior colliculus of bmidbrain
Entirely motor
Coriconuclear fibres from cerebral hemispheres
Tectobulbar fibres connecting visual cortex via superior colliculus
Fibres from medial longitudinal fasciculus - connect to the third, sixth and eighth nerves
Fibres decussate before midbrain
Rund forward in subarachnoid space
Enters carvernous sinus in lateral wall inferior to CNIII - exits above CNIII
Nerve passes through SOF outside CTR
Passes medially in orbit superior to root of levator to SO
What is the course of abducens
6th nucleus - near floor of fourth ventricle
Exits anteriorly - in subarachnoid space
To drosum sellae of sphnoid bone
Cavernous sinus
Inferonasally to internal carotid artery
SOF within CTR to orbit
To LR
What are the nuclei of the trigmeinal nucleus
Main sensory - posteiror pons
Spinal - continues down to C2 of spinal cord
Mesencephalic - lateral grey matter around cerebral aqueduct
Motor nucleus - posterior pons
Where is the trigeminal ganglion?
Apex of petrous part of temporal bone
What nerve runs through the cavernous sinus
Abducens CNVI
What is Gradenigo’s sydnrome?
PEtrous part of temporal bone breached in middle ear causing CNVI and CNVII palsy
What re the branches of the ophthamlic nerve
Frontal nerve
Lacrimal nerve
Nasocilliary nerve
Divides then enter the orbit by SOF
Where odes the lacrimal nerve enter the orbit
Through SOF external to CRT with frontal and trochlear
What provids the larimal nerve with parasympathetic fibres
Zyogmaticotemporal branch of V2 - maxillary
What is the function of lacrimal nerve
Provides secretomotor of lacrimal gland
Sensory to upper eyelid skin and conjunctiva
Path of the frontal nerve
Enters orbit between lacrimal and trochlear nerve within SOF external to CTR
Supraorbital branch - upper lid, conj, forehead skin, mucous membrane of frontal sinus
Supratrochlear branch - medial upper lid and medial forehead skin
What nerve supplies tip of nose
Nasociliary nerve
What are the branches of the nasocilairy nervw
Ramus communicans (to cilairy ganglion) - sensory fibres
Long ciliary nerves - forward from ciliary ganglion to pierce the eyeball near optic nerve - supply iris cilairy body and cornea - sensory to cornea, symapthetic fibres to dilator pupillar
Infratrochlear nerve - larcimal sac,conj, emdial aspect of both eyelids, lateral nose
What is the path of maxillary nerve CNV2
Trigeminal ganglion
Wall of cavernous sinus beneath V1
Most infeiror nerve in wall
Foramen rotundum
PTerygopalatine fossa - pterygopalatine ganglion
Inferior orbital fissure
Infraorbital nerve
Floor of orbit
What are branches of V2
MEningeal - supplies dural mater in medial cranial fossa
Ganglionic - susptend pterygopalatine ganglion from lower border of maxillary nerve - sensory nerves from oribtal periosteum and mucous membranes (nose, palate, pharynx)
Contain postganglionic fibres from facial nerve to lacrimal gland
Zygomatic - arises in pterygopalatine fossa, through SOF - zygomaticotemporal and zygomaticofaical - supply skin of forehead and cheek
Posterior superior alveolar
Middle superior alveolar
Anterior superior alveolar
FAcial nerves
What CN pass through SOF
CN III
CN IV
CN V1
CN VI
What CN passes through forament rotundum
CN V2 - maxillary
What CN passes through foramen ovale
CNV3 - mandibular
What CN passes through internal acoustic meatus?
VII
VIII
What cranial nerves pass through jugular foramen
CN IX - glossopharyngeal
CN X - vagus
CNXI - accessory
What does CN IX supply
Stylopharyngeus msucle
Parotid
General sensation and taste from posterior third of tongue
Pharyns
Carotid sinus (baroreceptor)
Carotid body (chemoreceptor)
