Sensory Nerves

• Ophthalmic and maxillary divisions of trigeminal nerves

Ophthalmic nerve

• Smallest division of the trigeminal
• Pure sensory
• Arises from trigeminal ganglion

• Enters lateral wall of cavernous sinus (below oculomotor and trochlear nerves, above the maxillary)

• Receives sympathetic branches from internal carotid plexus
• Gives off three branches prior to entering the orbit
• Branches
• Lacrimal 
• Smallest branch, enters outwith the tendinous ring

• Joins the branch from the zygomaticotemporal branch of the zygomatic branch of the maxillary nerve which contains parasympathetic secretomotor fibres from the facial nerve

• Also supplies the conjunctiva and skin of upper eyelid
• Frontal: largest branch
• Enters the orbit through the SOF outwith tendinous ring
• Passes forward on the surface of the levator and gives branches halfway along

• Supraorbital: leaves via the supraorbital notch to supply the skin and conjunctiva of upper eyelid

• Supratrochlear: also supplies skin and conjunctiva of upper eyelid
• Nasociliary
• Enters orbit through SOF within tendinous ring between branches of oculomotor

• Long ciliary branches arise as it crosses the optic nerve and pierce sclera close to optic nerve. Then pass forward in the choroid to the CB, iris (sympathetic) and cornea (sensory)

• Infratrochlear branch: supplies lacrimal sac, conjunctiva, skin of medial upper and lower eyelids and lateral nose

• Other branches supply ethmoidal (anterior and posterior ethmoidal nerves) and sphenoidal air sinuses

Facial nerve

• Both motor and sensory
• 3 nuclei
• Main motor: pons.

• Portion supplying muscles of the upper face receive bilateral innervation, whereas the portion supplying the lower face receive contralateral innervation only

• Parasympathetic: posterolateral to main motor nucleus
• Superior salivatory and lacrimal nuclei
• Afferent fibres from the hypothalamus
• Sensory: upper part of nucleus tractus solitarius
• Motor and sensory roots
• Emerge from the cerebellopontine angle
• Posterior cranial fossa
• Enters internal acoustic meatus then facial canal into inner ear

• Turns backwards to descend along posterior wall of middle ear to exit via the stylomastoid foramen

Olfactory nerve

• Originates in the epithelium of the nasal mucosa
• Neurones condense into the olfactory tract
• Passes along olfactory groove in the cribiform plate
• The anterior olfactory nucleus lies posterior to this
• Tract divides into medial and lateral striae

• Medial striae contains fibres from the anterior nucleus and pass to the anterior commissure

• Lateral striae terminates in the amygdala and the primary olfactory cortex at the anterior end of the parahippocampal gyrus and uncus