First two are not really nerves, but outdrawn CNS.
Bipolar cells gather into 20 filaments ¨ foramina in the cribriform plate ¨ pierce dura / arachnoid.
Enter olfactory bulb pass to olfactory tract to anterior perforated substance and uncus.
- the second order neuron directly activates the conscious cortex (a primitive arrangement)
- ie thalamus is bypassed.
Rods and cones activate bipolar cells of retina (first sensory neurons), synapse on ganglion cells.
- these emerge together as the optic nerve from the back of they eye surrounded by CSF and meninges.
- Optic nerve enters the middle cranial fossa through the optic canal to the chiasma
- Nasal fibres of each side decussate above pituitary, pass around midbrain to
i) lateral geniculate body (thalamus) thence to visual cortex via optic radiation.
ii) pretectal nuclei for pupil constriction to light
iii) superior colliculus for body reflexes to light.
From medial surface of midbrain at base of cerebral peduncle.
Passes forward, lateral between posterior cerebral and superior cerebellar branches of basilar artery.
Enters the roof of the cavernous sinus, and continues forward in its lateral wall (Pl 98)
- slants down, medial to the trochlear nerve and the ophthalmic branch of the trigeminal.
- At the anterior cavernous sinus, it splits to superior and inferior divisions, enter the tendinous ring of the medial end of the superior orbital fissure.
¨ Superior division supplies superior rectus and levator palpebrae superioris
- in the lateral wall of the sinus, the oculomotor also picks up sympathetic fibres from the internal carotid plexus, passing to lid.
¨ Inferior division supplies medial rectus, inferior rectus and inferior oblique.
- PNS fibres pass to inferior oblique ¨ ciliary ganglion
- Post-ganglionics then run in the short ciliary nerves ¨ sphincter pupillae and ciliary muscle.
Crosses midline within midbrain; emerges from dorsal aspect of the inferior colliculus.
- passes around cerebral peduncle between posterior cerebral and superior cerebellar arteries
- clings to the tentorium cerebelli ¨ roof of cavernous sinus
- runs first below the third nerve, then above it at the anterior end of the sinus.
- Enters the superior orbital fissure lateral to the tendinous ring, and passes medial over levator palpebrae superioris to the superior oblique
Cell bodies = trigeminal ganglion
- large single root attached to ventral aspect of pons, well lateral.
- Motor root emerges separately, slightly cranial & medial to companion.
Pass together below tentorium to Ôtrigeminal caveÕ, arachnoid-lined dura passage to middle cranial fossa over the petrous bone.
Anterior half of ganglion gives V1-3 branches, V1&2 passing up in lateral cavernous fossa.
- motor root also passes through the foramen ovale to join the mandibular division just outside the skull to form the mixed mandibular nerve (V1&2 = sensory only)
Carries SNS fibres from cavernous plexus for the dilator pupillae.
Gives a meningeal branch at the anterior sinus; then ¨ lacrimal, frontal and nasociliary nerves.
Lacrimal: lateral to tendinous ring, picks up secretomotor br. from zygomatic nerve ¨ lacrimal gland
- sensory to lateral end of upper eyelid and both palpebral and ocular upper conjunctivae
Frontal: through superior orbital fissure ¨ supraorbital (frontal sinus, upper eyelid and all forehead except a central strip) and supratrochlear (upper lid and conjunctiva and strip of central forehead)
Nasociliary: sensory to whole eyeball and paranasal sinuses, medial wall of orbit, some of nasal cavity, and skin of external nose.
- carries hitch-hiking sympathetic fibres fro dilator pupillae muscles.
- Runs through the tendinous ring between the oculomotor nerve divisions
- Passes to anterior ethmoidal foramen, between orbital plate of ethmoid and the frontal bone as the anterior ethmoidal nerve (to ethmoid air cells and into anterosuperior nose wall and septum; emerging at the base of the nose as the external nasal nerve to supply the skin of the ala, tip and vestibule)
- Infratrochlear nerve braches off before it enters the anterior ethmoidal foramen, continues below the trochlea to skin and conjunctiva of the medial end of the upper eyelid and bridge of nose.
- Posterior ethmoidal nerve runs proximal to the infratrochlear to the posterior ethmoidal foramen ¨ posterior ethmoid air cells and adjacent sphenoidal tissues.
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Communicating branch passes through ganglion and via short ciliary nerve to cornea.
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Long ciliary nerves (2) run and enter sclera independently, carry SNS to dilator pupillae
and sensation to eye including cornea.
In lateral wall cavernous sinus ¨ meningeal nerve
Then passes through the foramen rotundum into the pterygopalatine fossa.
- from here passes through the inferior orbital foramen to enter as the infraorbital nerve.
Ganglionic Branches connect maxillary nerve to the pterygopalatine ganglion.
- most branches pass through the ganglion, to mingle with postganglionics of the greater petrosal and deep petrosal nerves (fibres of the nerve of the pterygoid canal)
- remember the motor root does the synapsing in ganglia; these sensory roots pass through only.
- Post-ganglionic PNS fibres from here destined for lacrimal gland pass into maxillary nerveÕs zygomatic branch.
Nasopalatine nerve enters sphenopalatine foramen, crosses roof of nose, slopes along nasal septum ¨ posteroinferior part.
Greater palatine nerve runs down greater palatine canal b/n perpendicular plate of palatin bone and body of maxilla. Branches ¨ lateral wall of nose and adjacent floor of nose.
- emerges from greater palatine foramen ¨ all of hard palate except incisor gum.
Passes through foramen ovale with small motor root of trigeminal nerve
Below foramen, join to form the mixed nerve in the infratemporal fossa between lateral pterygoid and tensor palati where the otic ganglion lies medial to the nerve.
¨ small anterior and large posterior branches.
Deep temporal nerves
N to masseter
Buccal nerve
Auriculotemporal nerve: two roots; pass around middle meningeal artery.
- picks up postganglionic secretomotor fibres from otic ganglion for the parotid gland.
- Passes back deep to the neck of the mandible ¨ major supply to mandibular jt.
- Ascends behind jt and superficial temporal vessels in front of ear in contact with parotid gland.
- Supplies external acoustic meatus, external surface of auricle above and skin of temporal region.