Eyelid and Nictitans Movement

Michael DavidsonProfessor, Ophthalmology

Diplomate, American College of Veterinary Ophthalmologists

Department of Clinical SciencesCollege of Veterinary MedicineNorth Carolina State University

Raleigh, North Carolina, USA

Eyelid Innervation: Efferent Motor

Dorsal ramus of CNIII:– Levator palpebral

superioris (opening) Palpebral and dorsal

buccal branches of CNVII: – obicularis oculi

(closure)– levator anguli oculi

medialis, frontalis, retractor anguli (opening)

– malaris mm. (lower eyelid depressor)

Eyelid Muscles Opening:

– levator palpebrae superioris m.

– frontalis m.– retractor anguli m.– malaris m. – Muller’s m.

Closure:– obicularis oculi m.

Eyelid Innervation: Sensory Afferent

Ophthalmic and Maxillary Divisions of CNV

maxillary branchophthalmic branch

mandibular branch

trigeminal ganglion

trigeminal n.

Eyelid Innervation: Sensory Afferent Ophthalmic division CNV:

– Frontal n. = upper eyelid, forehead, frontal sinus

– Lacrimal n. = lateral orbit, lacrimal gland, upper eyelid, lateral canthus

– Nasociliary n.:• Long ciliary nerve = cornea,

iris, ciliary body, sclera, sympathetics to eye; branches of short ciliary nerves (parasympathetics to eye) join long ciliary nerve and enter eye

• Infratrochlear nerve =medial canthal skin, medial conjunctiva, sympathetics to upper Muller’s mm.

Infratrochlear n.

Nasociliary n.

Trigeminal n.Trigeminal ganglion

Long Ciliary n.

Zygomatic branch

Maxillary branch

Ophthalmic branch

Frontal n.

Short Ciliary n.

Lacrimal n.

Eyelid Innervation: Sensory Afferent

Maxillary division of CNV:– Zygomatic n. to:

• zygomaticofacial = upper eyelid and conjunctiva

• zygomaticotemporal = lower eyelid and conjunctiva, sympathetics to lower Muller’s m. and parasympathetics to lacrimal gland

Infratrochlear n.

Nasociliary n.

Trigeminal n.Trigeminal ganglion

Long Ciliary n.

Zygomatic branch

Maxillary branch

Ophthalmic branch

ZygomaticotemporalZygomaticofacial

Frontal n.

Short Ciliary n.

Eyelid Innervation: Sympathetic Efferent

Through terminal branches of trigeminal nerve:– Infratrochlear n.

(ophthalmic division) = upper Muller’s mm.

– Zygomaticotemporal n. (maxillary division) = lower Muller’s mm.

Infratrochlear n.

Nasociliary n.

Trigeminal n.Trigeminal ganglion

Long Ciliary n.

Zygomatic branch

Maxillary branch

Ophthalmic branch

ZygomaticotemporalZygomaticofacial

Frontal n.

Short Ciliary 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 short latency period, fellow eye sometimes

responds with blink of lower amplitude afferent= ophthalmic branch of CN V (long

ciliary nerve) efferent= CN VII head withdrawal with subsequent (cortical)

perception perform test outside visual field with cotton

swab or wisp or Cochet-Bonnet esthesiometer

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Corneal Touch Threshold (CTT)

Minimum amount of force required to elicit corneal reflex

Humans < cat < rabbit < dog In dogs and humans, central cornea < nasal

quadrant < temporal quadrant < dorsal/ventral quadrants

Diabetes mellitus increased CTT

Palpebral Reflex Closure of eyelids following stimulation of

medial canthal region CN V (ophthalmic division +/- maxillary

division) and CNVII (obicularis oculi) Present 1-4 days postnatally in cats and

dogs, and at birth in horses

Ptosis (Greek; ptōsis=fall)Drooping of Upper Eyelid

Oculomotor (CNIII) Sympathetic Paradoxical ptosis (horses)Non-neurogenic ptosis

Oculomotor Ptosis denervation of levator palpebrae

superioris mm. (CNIII) innervated by a single midline

nucleus (caudal central nucleus)…so midline mesencephalic lesion=bilateral ptosis

pupillomotor & levator m. fibers proximate in CNIII so ptosis and internal ophthalmoplegia can be concurrent

“central” (nuclear or preganglionic) lesions generally assoc. with other midbrain signs

Sympathetic Ptosis and Reverse Ptosis

Infratrochlear n.

Nasociliary n.

Trigeminal n.Trigeminal ganglion

Long Ciliary n.

Zygomatic branch

Maxillary branch

Ophthalmic branch

Paradoxical Ptosis in Horses

Facial nerve paralysisAtonic supraorbital

muscles and paralysis of frontalis muscle cause eyelid drooping

Opposite clinical sign in small animals with facial nerve paralysis

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Non-neurogenic ptosis Profound illness EmaciationDehydration

Pharmacologic Testing of Ptosis

10% phenylephrine:– Sympathetic ptosis temporarily resolves– Oculomotor (CNIII), paradoxical ptosis (CN

VII) and other causes = no effect

Facial Nerve Paralysis Widened palpebral fissure (no

antagonist to levator/Muller’s m.) increased scleral show and illusion of proptosis (“pseudoproptosis”)

“Neuroparalytic” keratitis “Central” lesion (region of CNVII

nuclei or main trunk in medulla):– can also affect cranial nerves V,

VI, VIII– possible concurrent neurogenic KCS

“Peripheral” lesion (as CNVII courses through petrosal bone out stylomastoid foramen to eyelids): – can affect CN VIII but not other

cranial nerves– no concurrent neurogenic KCS

Neurotrophic Keratitis ophthalmic division of CN V

(long ciliary n. to cornea) loss of corneal sensation

and ulcerative keratitis (lack of tropic influence)

maxillary branchophthalmic branch

mandibular branch

trigeminal ganglion

trigeminal n.

Eyelid Closing Abnormalities: Hemifacial Spasm (Tetany)

irritative lesion to CN VII can progression to facial paralysis often from otitis media So Horner syndrome or neurogenic KCS

may accompany

Nictitans Anatomy Smooth muscle (sympathetic), arising from orbital

fascial sheaths of ventral and medial recti mm.

These fascial sheaths connect smooth muscle of nictitans to bellies of medial and ventral rectii and fascial sheath of dorsal oblique m.

In cat, slips of striated mm. from lateral rectus and levator palpebral superior mm. attach to ventral and dorsal nictitans respectively

Nictitans Protrusion All dogs = 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 = active component

– from slips of striated mm. from lateral rectus and levator palpebral superior mm

– protrusion can occur independent of globe movement and voluntarily

– VIDEO 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

Sympathetic innervation to smooth muscle:– medial smooth mm. (to dorsal nictitans)

• ophthalmic division of CN V ⇒ nasociliary nerve ⇒infratrochlear nerve (also to upper Muller’s m.)

– inferior smooth mm. (to ventral nictitans)• maxillary division of CN V ⇒ infraorbital and zygomatic

branches (also to lower Muller’s mm)

Über-Localization of Horner Syndrome

Efferent sympathetics reach orbit, eye, adnexae through terminal branches of trigeminal n.

Prior to division of three branches of trigeminal n. = ptosis, reverse ptosis, nictitans protrusion, miosis, +/-enophthalmos

Nasociliary n. (ophthalmic division) = ptosis, nictitans protrusion, miosis, +/-enophthalmos, no reverse ptosis

Infratrochlear n. (ophthalmic division, branch of nasociliary n. after long ciliary nerve) = ptosis and nictitans protrusion, no miosis or reverse ptosis

Infraorbital and zygomatic nn. (maxillary division) = reverse ptosis and protruded nictitans, no miosis or upper lid ptosis

Infratrochlear n.

Nasociliary n.

Trigeminal n.Trigeminal ganglion

Long Ciliary n.

Zygomatic branch

Maxillary branch

Ophthalmic branch

ZygomaticotemporalZygomaticofacial

Frontal n.

Short Ciliary n.

Scagliotti thought experiment