Eyelid and Nictitans Movement Michael Davidson Professor, Ophthalmology Diplomate, American College of Veterinary Ophthalmologists Department of Clinical Sciences College of Veterinary Medicine North Carolina State University Raleigh, North Carolina, USA Eyelid Muscles Opening: – levator palpebrae superioris m. (CN III) – frontalis m. – levator anguli medialis m. – retractor anguli m. – malaris m. – Muller’s mm. (upper and lower) Veteriankey.com Closure: – obicularis oculi m. Eyelid Innervation: Somatic and Visceral Efferent Dorsal ramus of CN III: – Levator palpebral superioris Palpebral and dorsal buccal branches of CN VII: – obicularis oculi – levator anguli oculi medialis, frontalis, retractor anguli Veteriankey.com – malaris mm. Eyelid Innervation: Sensory Afferent maxillary branch Ophthalmic and ophthalmic branch Maxillary mandibular branch Divisions of CN V trigeminal ganglion trigeminal n. Ophthalmic Division – 3 main branches Frontal, Lacrimal and Nasociliary Nerves Ophthalmic Division – 3 main branches Frontal nerve = upper eyelid, forehead, frontal sinus Supraorbital nerve Frontal nerve Ophthalmic Division – 3 main branches Lacrimal nerve = lateral orbit, lacrimal gland, upper eyelid, lateral canthus; parasympathetics to lacrimal gland Lacrimal nerve Branch from zygomatic nerve with parasympathetics from pterygopalantine ganglion Ophthalmic Division – 3 main branches Nasociliary nerve long ciliary nerve infratrochlear nerve Nasociliary Nerve Nasociliary Nerve Long ciliary nerve = sensory afferent to cornea, iris, ciliary body, sclera; parasympathetics and sympathetics to iris ciliary body Nasociliary Nerve Short ciliary nerves Long ciliary nerve Nasociliary Nerve Infratrochlear nerve = medial canthal skin, medial conjunctiva; sympathetics to upper Muller’s muscle Nasociliary Nerve Infratrochlear nerve Maxillary Division CN V: Zygomatic Nerve zygomatico-temporal = upper eyelid and conjunctiva, parasympathetics to lacrimal gland zygomatico-facial = lower eyelid and conjunctiva, sympathetics to lower Muller’s muscle zygomatico- temporal nerve Zygomatic nerve zygomatico- facial nerve Key Points from Previous Slides Names and innervation of muscles of eyelid in dog Names/innervation of 3 branches of ophthalmic division of CN V: – frontal n. – upper lid (supraorbital nerve) – lacrimal n. – lateral eyelid, parasympathetics to lacrimal gland – nasociliary n. – long ciliary n. = globe, parasympathetics and sympathetics to iris/c. body infratrochlear n. = medial canthus Sympathetic efferents distributed to eye and adnexa through both ophthalmic and maxillary divisions of CN V Eyelid Innervation: Sympathetic Efferent Through terminal Frontal n. branches of trigeminal Infratrochlear n. nerve: Short Ciliary n. Zygomaticotemporal – Infratrochlear n. Zygomaticofacial (ophthalmic division) = upper Muller’s mm. Long Ciliary n. – Zygomaticofacial n. Nasociliary n. (maxillary division) = lower Muller’s mm. Ophthalmic branch Zygomatic branch Maxillary branch Trigeminal ganglion Trigeminal n. Reflex Blinking optic dazzle (CN II) menace blink response (entire visual pathway to motor cortex to CN VII with connection to cerebellum) auditory stimuli (CN VIII to caudal colliculi) corneal blink reflex (CN V) Corneal Blink Reflex subcortical reflex closure of eyelids in response to tactile/painful stimuli (i.e. not in response to cortical perception of stimuli) short latency period, fellow eye sometimes responds with blink of lower amplitude afferent = ophthalmic branch of CN V efferent = CN VII head withdrawal with subsequent (cortical) perception Reflexive pathway Conscious pathway Corneal Blink Reflex www.osceskills.com Perform test outside visual field with cotton swab or wisp or Cochet-Bonnet esthesiometer www.scielo.br Palpebral Reflex Closure of eyelids following stimulation of medial canthal region CN V (ophthalmic division +/- maxillary division) and CN VII (obicularis oculi) Present 1-4 days postnatally in cats and dogs, and at birth in horses Ptosis (Greek; ptosis=fall) Drooping of Upper Eyelid Oculomotor (CNIII) Sympathetic Paradoxical ptosis (horses) Non-neurogenic ptosis Oculomotor Ptosis Denervation of levator palpebrae superioris mm. discussed previously as a component of “external ophthalmoplegia” Generally associated with pupillomotor signs, and with an intracranial lesion Sympathetic Ptosis and Reverse Ptosis Infratrochlear n. Long Ciliary n. Nasociliary n. Ophthalmic branch Zygomatic branch Maxillary branch Trigeminal ganglion Trigeminal n. Paradoxical Ptosis in Horses Facial nerve paralysis Atonic supraorbital muscles and paralysis of frontalis muscle cause eyelid drooping Opposite the clinical sign in small animals of “pseudoproptosis” www.horsesidevetguide.com Non-neurogenic ptosis Profound illness Emaciation Dehydration Pharmacologic Testing of Ptosis 10% phenylephrine: – Sympathetic ptosis temporarily resolves – Oculomotor (CNIII), paradoxical ptosis (CN VII) and other causes = no effect Facial Nerve Paralysis- ”Pseudoproptosis” Widened palpebral fissure increased scleral show (no antagonist to levator/Muller’s mm.) and illusion of proptosis Facial Nerve Paralysis “Neuroparalytic” (exposure) keratitis “Central” facial nerve paralysis (in parenchyma of brainstem, CN VII nuclei or main trunk) – possible concurrent neurogenic KCS “Peripheral” facial nerve paralysis (as CN VII courses through petrosal bone out stylomastoid foramen): Diagnosis? – no concurrent neurogenic KCS Neuroparalytic (CN VII) vs. Neurotrophic (CN V) Keratitis ophthalmic division of CN V (long ciliary n. to cornea) loss of corneal sensation and ulcerative keratitis (lack of tropic influence) following traumatic proptosis, laser ciliary body ablation Key Points from Previous Section Corneal blink reflex is a brainstem reflex Palpebral reflex present before eyelid opening in dogs and cats Mechanism of “paradoxical ptosis” in horses Mechanism of “pseudoproptosis” in dogs Neuroparalytic v. neurotropic keratitis Nictitans Anatomy Smooth muscle (sympathetic) that refracts nictitans, from fascial sheaths of ventral and medial recti mm. Fascial connections between nictitans and fascial sheets of extraocular muscles In cat, slips of striated mm. from lateral rectus attach to nictitans Nictitans Protrusion All mammals except cats = entirely passive (change in globe position): – globe retraction by retractor bulbii mm. (CN VI) – contraction of other extraocular mm. (CN III, IV, VI) through fascial connections from extraocular mm. to nictitans Cats = passive and/or active component – from slips of striated mm. from lateral rectus m. – protrusion can occur independent of globe and eyelid movement Nictitans Protrusion Non-neurologic protrusion: – changes in orbital volume or position of globe in orbit: • e.g. cellulitis, neoplasia….concurrent exophthalmos • e.g. phthsis bulbi, loss of orbital fat (emaciation).…concurrent enophthalmos Nictitans Retraction Remember sympathetics reach adnexa through ophthalmic and maxillary divisions of CN V! Sympathetic innervation to smooth muscle: – medial smooth mm. (to dorsal nictitans) • ophthalmic division of CN V nasociliary nerve infratrochlear nerve (also to upper Mueller’s mm.) – inferior smooth mm. (to ventral nictitans) • maxillary division of CN V infraorbital and zygomatic branches (also to lower Muller’s mm) Key Points from Previous Section Nictitans protrusion in dogs can be caused by contraction of retractor bulbi m. or contraction of extraocular muscles (fascial slips connection EOM to nictitans) Nictitans protrusion in cats can occur from above OR voluntarily through skeletal muscle slip from lateral rectus Randy Scagliotti DVM, MS, DACVO Neuro-ophthalmologist Extraordinaire Über-Localization of Horner Syndrome (Scaglotti thought experiment) E Efferent sympathetics reach orbit, eye, adnexae through terminal branches Frontal n. of Trigeminal n. (CN V) Infratrochlear n. Short Ciliary n. Zygomaticotemporal Zygomaticofacial Lesion prior to division of three branches of trigeminal n. = ptosis, Long Ciliary n. reverse ptosis, nictitans Nasociliary n. protrusion, miosis, +/- enophthalmos Ophthalmic branch Zygomatic branch Lesion in nasociliary n. Maxillary branch (ophthalmic division) = Trigeminal ganglion ptosis, nictitans protrusion, Trigeminal n. miosis, +/- enophthalmos, no reverse ptosis Über-Localization of Horner Syndrome (Scagliotti thought experiment) E Lesion in infratrochlear n. (ophthalmic division, Frontal n. branch of nasociliary n. Infratrochlear n. Short Ciliary n. Zygomaticotemporal after long ciliary nerve) = Zygomaticofacial ptosis and nictitans protrusion, no miosis or reverse ptosis Long Ciliary n. Nasociliary n. Lesion in infraorbital and Ophthalmic branch zygomatic nn. (maxillary Zygomatic branch division) = reverse ptosis Maxillary branch and protruded nictitans, Trigeminal ganglion no miosis or upper lid Trigeminal n. ptosis Randy Scagliotti DVM, MS, DACVO Hail to the King of Veterinary Neuro-ophthalmology! .