• Oculomotor nerve originates from the third nerve nucleus (vental to cerbral aqueduct, on pre-aqueductal grey matter) at the level of the superior colliculus
• Passes between superior cerebellar and posterior cerebral arteries and pierces dura mater lateral to clinoid processes
• Transverses cavernous sinus, and recieves filaments from SANS within the cavernous plexus, and branch of the opthalmic division of the trigeminal nerve
• Enters superior orbital fissure and divides into superior and inferior branch
• Superior branch supplies superior rectus and levator palpebrae superioris
• Inferior branch innervates medial rectus, inferior rectus and inferior oblique, as well as forming the root of the ciliary ganglion

• Nucleus beneath cerebral aqueduct, just below III nucleus
• Emerges from dorsal aspect of the brainstem just below the inferior colliculus. Circles around brainstem and runs within the subarachnoid space
• Pierces dura mater under free margin of tentorium cerebri and runs along lateral wall of cavernous sinus, joining III, VI and V_1/2 before entering orbit through superior orbital fissure and innervating superior oblique muscle
• Lesion prevents action of superior oblique muscle to depress and provide intorsion to eyeball - results in diplopia when attempting to look downward or medially

• Abducens nucleus located within pons, on the floor of the 4th venticle 
• Leaves brainstem at junction of pons and medulla, just medial to facial nerve
• Enters subarachnoid space and runs between pons and clivus
• Pierces dura mater and runs within Dorello's canal, then enteres cavernous sinus to run with ICA
• Enters through superior orbital fissure to innervate lateral rectus muscle
• Damage causes loss of lateral rotation of the eye, and therefore diplopia when looking to the side

• Nuclei - principal nucleus represents touch sensation (within pons), spinal trigeminal nucleus represents pain sensation from face - spinal tract of V, while motor efferent within motor nucleus
• Trigeminal ganglion within Meckel's cave contains cell bodies of sensory fibres
• From ganglion, single large sensory root enters brainstem at the level of the pons, next to whic a small motor root emerges which passes through trigeminal ganglion while their cell bodies are located within the 5th nerve nucleus
• Sensory - Opthalmic, maxillary and mandibular branches leave through the superior orbital fissure, foramen rotundum and foramen ovale respectively. Opthalmic division (V₁) carries sensory information from scalp, forhead, upper eyelid, conjunctiva, cornea, nose, nasal mucosae, frontal sinuses and meninges. Maxillary division (V₂) carries input from the lower eyelid, cheek, nares, upper lip, upper teeth and gums, nasal mucosae, palate, roof of pharynx and maxillary, ethmoid and sphenoid sinuses. Mandibular nerve (V₃) carries information from lower lip, teeth and gums, chin, jaw (example angle, C2-3) extenal ear. Also carries touch position and pain-temperature sensation from the mouth and lingual nerve branch carries sensation from tongue
• V₃ also controls movement of 4 muscles of mastication (masseter, temporal, medial and lateral pterygoids) as well as tensor veli palantini, mylohyoid, diastric (involved in biting, chewing and swallowing) and tensor tympani (downregulation of self-generated noise)
• V₁ and V₂ sensory afferents implicated in cough and sneeze reflex 
• Wallenburg syndrome - loss of pain sensation from ipsilateral side of face and contralateral body 
• Exams - sensation in cornea and face, jaw closes symmetrically 

• Motor section of facial nerve arises from facial nerve nucleus within pons whle sensory and parasympathetic divisions arise from intermediate nerve
• Motor and sensory parts join and traverse posterior cranial fossa before entering petrous temporal bone through IAM - exits IAM and runs through facial canal - divides into labyrinthine, tympanic and mastoid segments
• Labyrinthine segment ends at the geniculum of facial nerve forming the geniculate ganglion- first branch of the facial nerve is the greater superior petrosal nerve which arises from the geniculate ganglion to synapse at the pterygopalantine ganglion, from which it innervates the lacriminal gland
• Tympanic segment runs through tympanic cavity
• Mastoid segment - innervation of stapedius and gives rise to chorda tympani which supplies taste buds on anterior 2/3rds of the tongue and the submandibular ganglion (supplies sublingual and submandibular glands - parasympathetic)
• Emergence from stylomastoid foramen and forms parotid plexus which divides to innervate muscles of facial expression
• Examination - voluntary facial movement symmetry
• Lesion - Bell's palsy - facial paralysis and hyperacusis

• Cochlear nerve travels away from cochlea of inner ear (begins at spinal ganglia) along with vestibular nerve from the vestibular ganglion
• Travels along IAM and enters brain at pontomedullary junction
• Exams - Weber test for unilateral conductive hearing loss and unilateral sensorineural hearing loss. Tuning fork placed centrally on face, and if the sound is louder in one ear than the other there is a unilateral deficit. Rinne test - can tell conductive hearing loss if patient cannot hear tuning folk in air after mastoid test - blockage of passage of sound waves - while sensorineural deficits have equal deficit in bone and air conduction
• Vestibular function tested through caloric and rotational tests

Glossopharyngeal (IX) nerve

• Brachial motor component originates from nucleus ambiguus in reticular formation of medulla. Exits medulla with other compenents of CNIX between olive and inferior cerebellar peduncle
• Exits skull through jugular foramen and travels with X and XI
• Descending into temporal styloid process and innervates the stylopharyngeus muscle (voluntary)
• Visceral motor component (parasympathetic) - originate in the inferior salivatory nucleus of medulla and travels with other components of IX and pass through ganglia in jugular foramen without synapsing - makes tympanic nerve with general sensory fibres and enters petrous portion of temporal bone into tympanic cavity. 
• Forms plexus and becomes lesser petrosal nerve - emerges in middle cranial fossa and exits skull via foramen ovale with V₃.
•  Synapses in otic ganglion and innervates parotid gland
• Visceral sensory component - Sensory fibres arise from carotid sinus and body - ascening in sinus nerve and join CN IX components in inferior glossopharyngeal ganglion before entering jugular foramen - terminate in nucleus solitarius
• Somatic sensory component - Skin of external ear travel with CN X auricular branch while that of middle ear travels with CN IX visceral motor section as tympanic nerve
• Cell bodies within superior or inferior glossopharyngeal ganglion and synapse in caudal spinal nucleus of the trigeminal (gag reflex)
• Special sensoru - taste from posterior 1/3 of tongue travel with pharyngeal branches of CNIX to inferior glossopharyngeal ganglion to synapse on gustatory part of nucleus solitarius after entering through JC. 
• Damage - loss of taste, impaired swallowing 

• Nuclei - dorsal (parasympathetic), nucleus ambiguus (branchial efferent and preganglionic parasympathetic cardiac nerves), solitary nucleus (taste information and afferents from viscera), spinal trigeminal nucleus (touch, pain, temperature, dura)
• Leaves medulla between pyramid and inferior cerebellar peduncle, exits through jugular foramen and passes into carotid sheath down to neck, chest and abdomen 
• Motor parasympathetic fibres to all organs below neck (apart from adrenal glands)
• Control cricothyroid, levator veli palantini, palate muscles, pharyngeal constrictors and speech muscles of larynx
• Can test X through palatal movements

• Formed by lower motor neurons from upper segments of spinal cord (spinal accessory nucleus) within lateral aspect of anterior horn of spinal cord from C1 to C6
• Rootlets from spinal cord form roots, and finally forms accessory nerve
• Enters through foramen magnum and leaves skull through jugular foramen with IX and X. Spinal accesory nerve sends motor branches to sternocleidomastoid and trapezius muscles
• examination - evalulation of muscle function (one sided weakness in shrug or turning head)

• Hypoglossal nucleus at bottom of brainstem 
• Number of small rootlets in front of medulla between olive and pyramid - passes through subarachnoid space, pierces dura mater and travels through hypoglossal canal
• Gives off meningeal branch amd picks up branch from anterior ramus of C1
• Passes between carotid artery and jugular vein to level of angle of mandible where it advances forward to tip of tongue and distributes branches to intrinsic and extrinsic muscles of the tongue as well as hyoglossus, genioglossus and stylohyoid
• Damage - tongue deviates towards damaged side, can occur in medial medullar syndrome (lesion of anterior spinal artery)