Lecture 4: Cranial Nerves Flashcards
Glossopharyngeal nerve does what?
Motor to stylopharyngeus muscle and parotid gland
Sensory to taste of posterior 2/3 of tongue, general sensation to tonsilar sinuses, pharynx and middle ear cavity
Vestibulocochlear nerve does what?
Vestibulo: sensory to equilibrium and motion
Cochlear: sensory to hearing
Olfactory nerve does what?
Sensory to smell
Optic nerve does what?
Sensory to vision
Oculomotor nerve does what?
Motor to extrinsic muscles of the eye ( except superior oblique and lateral rectus) , ciliary muscles and sphincter pupillae
Trochlear nerve does what?
Motor to superior oblique muscle
Trigeminal nerve does what?
Motor to muscles of mastication
Sensory to face, teeth and sinus
Abducens nerve does what?
Motor to lateral rectus muscle
Facial nerve does what?
Motor to muscles of facial expression, submandibular, sublingual and lacrimal glands
Sensory to anterior 2/3 of tongue
Vagus nerve does what?
Motor: larynx, pharynx, trachea, bronchial tree, heart, G.I tract to left colic flexure and palate
Sensory: larynx, pharynx, trachiobrochial tree, heart, lungs and G.I tract to left colic flexure
Spinal accessory nerve does what?
Motor to SCM and trapezius
Hypoglossal nerve does what?
All intrinsic and extrinsic muscles of the tongue
Olfactory nerve 1
Only nerve to enter cerebrum directly
Special Sensory
Travels through cribriform plate
Special visceral afferent
Olfactory nerve fibres synapses with mitral cells in olfactory bulb
Post synaptic axons form the olfactory tract
Terminates in the piriform cortex of temporal bone
Optic nerve 2
Special sensory to vision
Extension of forebrain
Terminate in lateral geniculate bodies of thalamus.
Post-synaptic axons to visual cortex in occipital lobe.
Oculomotor nerve 3
Somatic MOTOR (general somatic efferent) &
proprioceptive to:
* 4/6 extraocular muscles (superior, medial and inferior recti; inferior oblique)
*Superior eyelid (levator palpebrae superioris)
• Visceral motor (general visceral efferent –
parasympathetic).
*Post-synaptic fibres from ciliary ganglion to ciliary
muscle and sphincter pupillae muscle
Exit via superior orbital fissure
Trochlear nerve 4
• Smallest cranial nerve!
• Only nerve to originate on dorsal aspect of brainstem!
• Longest intra-cranial course!
Somatic MOTOR (general somatic efferent) and
proprioceptive to superior oblique.
Exits via superior orbital fissure
Trigeminal nerve 5
Three branches or trigeminal nerve
- Ophthalmic nerve CN V1 exiting brain through orbit
- Maxillary nerve CN V2 exiting brain through foramen rotundum
- Mandibular nerve CN V3 exiting brain through foramen ovale
Mandibular nerve
• Mandibular nerve (CN V3) is MOTOR supply to:
* muscles of mastication;
*mylohyoid;
*anterior belly of digastric;
*Tensor veli palatini;
*Tensor tympani.
Muscles of mastication are medial and lateral ptyergoids, masseter and temporlis
Abducens 6
- Longest intra-dural course!
* Supplies somatic MOTOR and proprioceptive fibres to LATERAL RECTUS muscles (abducts the eyes)
Facial nerve 7
• Longest intra-osseous course of any cranial nerve!
Cranial exit: stylomastoid foramine
*Secretomotor fibres originating in facial nerve are distributed to the lacrimal gland & submandibular/sublingual (salivary) glands
Sensory to anterior 2/3 of tongue
Chorda tympani => special sensory (taste) to anterior tongue
Lingual nerve (from CN V3) => general sensation (touch/temp)
to anterior tongue
Parasympathetic (secretomotor) => * Pterygopalatine ganglion
* Submandibular ganglion
Motor to muscles of facial expression:
Orbicularis oris, orbicularia oculi, buccinator, platysma and occipitofrontalis
Vestibulocochlear nerve 8
• Special sensory (special somatic afferent):
hearing/equilibrium/motion.
• Divides into vestibular and cochlear nerves.
• Cochlear nerve: sensory to spiral organ (for sense of hearing).
• Disturbances of cochlear function include deafness and tinnitus (ringing in ears).
• Vestibular nerve: sensory to semicircular ducts/saccule/utricle (for sense of equilibrium).
• Disturbances of vestibular function include vertigo (dizziness) and nystagmus (uncontrollable pendular movement of eyes).
Glossopharyngeal nerve 9
MOTOR innervation to stylopharyngeus muscle.
• SECRETOMOTOR to parotid gland:
* Pre-synaptic parasympathetic fibres to otic
ganglion.
• Post-synaptic parasympathetic fibres to parotid
gland.
• SENSORY (general and special (taste)) innervation to posterior 1/3 of tongue; pharynx; tympanic cavity; carotid body and
sinus.
Exits cranium via jugular foremen
Vagus nerve 10
• The Wanderer!!
• Longest and most extensive distribution of all thecranial nerves!
• MOTOR to muscles of pharynx.
• SENSORY to pharynx, larynx and reflex afferent (gag reflex).
• Pre-synaptic parasympathetic fibres to involuntary
muscles/glands of tracheobronchial tree; oesophagus; heart; digestive tract (up until left colic flexure).
• Left and right vagi become anterior/posterior in abdomen.
Spinal accessory nerve 11
- Cranial exit = jugular foramen.
- Somatic MOTOR to sternocleidomastoid and trapezius muscles.
- Pain and proprioceptive fibres to these muscles via cervical plexus (C2-C4).
Hypoglossal nerve 12
Exits cranium via hypoglossal canal
• Emerges anterior surface of medulla oblongata between the pyramid and olive.
• MOTOR to all muscles of tongue (except palatoglossus): styloglossus, hyoglossus, genioglossus.
