Anatomy: Eye Autonomics Flashcards by Rosa Bock

describe the sensory innervation of CNV1

upper eyelid

cornea and conjunctiva

skin of root/bridge/tip of nose

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name 2 branches of the CNV1 and their areas of innervation

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what notch does the supraorbital nerve (CNV1) pass through

supraorbital foramen

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describe the sensory innervation of CNV2 (maxillary nerve)

skin of lower eyelid

skin over maxilla

skin over ala of nose

skin/mucosa of upper lip

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infraorbital nerve

what CNV2 is called after it enters the infraorbital foramen

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describe the sensory innervation of CNV3 (mandibular nerve)

skin over mandible and TMJ

(apart from angle of mandible - C2, 3 spinal nerves)

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what is the only branch of CNV that has motor innervation

mandibular branch - muscles of mastication

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describe the corneal reflex

involuntary blinking of eyelids, stimulated by tactile, thermal or painful stimulation of cornea
CNV1 is the afferent branch - conducts APs from the cornea to the trigeminal ganglion, it then goes along CNV to pons
there are central CNS connections between CNV and CNVII, which is the motor efferent branch
causes contraction of orbicularis oculi

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describe the route of sympathetic axons

originate from autonomic centres in the brain

pass down spinal cord and exit with T1-L2 nerves (thoracolumbar outflow)

travel so sympathetic chains and into all spinal nerves, and then splanchnic nerves to eventually supply organs

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describe the presynaptic sympathetic axons from CNS

exit spinal cord in T1 spinal nerve and ascend within sympathetic trunk

synapse in superior cervical sympathetic ganglion

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describe the postsynaptic sympathetic axons

enter internal and external carotid nerves and pass onto the surface of internal and external carotid arteries

they are carried to the organs of the head on the surface of the branches of these arteries

ophthalmic artery carries the sympathetic axons into the orbit

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describe the parasympathetic outflow

all parasympathetic axons leave the CNS via cranial nerves III, VII, IX and X and via sacral spinal nerves (craniosacral outflow)

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describe the course of CNIII in the cranial cavity

originates from the anterior aspect of the midbrain

passes through cavernous sinus

exits cranial cavity via superior orbital fissure and divides into superior and inferior branches

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what does the superior branch of CNIII do

motor innervation to superior rectus and levator palpebrae superioris

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what does the inferior branch of CNIII do

motor innervation to inferior rectus, medial rectus and inferior oblique

parasympathetic fibres to ciliary ganglion, which ultimately innervates sphincter papillae and ciliary muscles

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where is the ciliary ganglion located

within the bony orbit

anteriorly to the superior orbital fissure, between the lateral rectus muscle and the optic nerve

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describe the sympathetic innervation with ciliary ganglion

preganglionic sympathetic fibres relay in superior cervical ganglion

postganglionic fibres are carried by long ciliary nerves (and some short) from sympathetic plexus around ICA to supply dilator pupillae muscle

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describe the parasympathetic innervation with ciliary ganglion

preganglionic fibres originate from Edinger-Westphal nucleus in midbrain and run with CNIII (inferior division) to relay in ciliary ganglion

postganglionic fibres are carried by short ciliary nerves to innervate ciliary muscles and sphincter pupillae muscles

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what are pre-ganglionic fibres of ciliary ganglion associated with

inferior division of CNIII

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which ciliary nerves form the first part of the corneal reflex

long ciliary nerves - sensory fibres from the surface of CNV1

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what are some autonomic reflexes of the eye

maximal eyelid elevation/wide eye opening

pupillary dilation/constriction to adjust light entry

focussing lens far and near vision

lacrimation reflex tear production

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vestibulo-ocular reflex

stabilizes gaze on an object during head movement by turning the eyes in the opposite direction of the head

involves connections between CN VIII and CNIII, IV and VI

oculocardiac reflex

reflex bradycardia in response to tension on extraocular muscles/pressure on eye

CNS connections betwen CNV1 and CNX

does sympathetic innervation cause one to focus on far or near objects

far

parasympathetic - near

reflex lacrimation arc

- afferent: CNV1 innervates the cornea - efferent: lacrimal gland under parasympathetic CNVII innervation to produce lacrimal fluid * - function is to wash away stimulant foreign body and clean the cornea*

how are eyes opened really wide in fight/flight situations

LPS contains skeletal and smooth muscle the LPS is innervated by CNIII (parasympathetic) and raises the eyelid the superior tarsus is innervated by the sympathetic nervous system and so can act to open the eye even wider??

mydiatric agent

drug that induces dilation of the pupil

what is a non-physiologically enlarged pupil called

a mydiatric pupil

dilator pupillae fibres

dilator pupillae fibres are innervated by **sympathetic nervous system** - when stimulated contract and widen the pupil the fibre originate around the external circumference of the iris (fixed) and insert around the internal circumference of the iris (mobile)

how are the dilator pupillae fibres arranged

radially

pupillary constriction

parasympathetics - the **sphincter pupillae** encircles the pupil around the internal circumference of the iris stimulation by **short ciliary nerve** results in **constriction** of the pupil

what is a non-physiologically constricted pupil called

miotic pupil

what drugs can cause miosis

opiates

what is a fixed dilated ('blown') pupil often a sign of

CNIII pathology

pupillary light reflex - afferent and efferent nerves

special sensory **(afferent)** nerve is ipsilateral **CNII** motor **(efferent)** nerve is bilateral **CNIII** a direct light reflex occurs in the stimulated eye and a consensual light reflex occur in the non-stimualted eye

pupillary light reflex

**4 neuron chains** **1.** retinal ganglion cells are stimulated and pass via ipsilateral **CNII,** cross optich chiasma and synapse in **pretectal nucleus** in the mid brain **2.** neurons (bilateral) in midbrain connect pretectal nucleus to next synapse in **Edinger-Westphal nucleus** **3.** neurons (bilateral) pass from EW nucleus via CNIII, inferior division and to synapse at **ciliary ganglion** **4. short ciliary nerves to sphincter pupillae muscles - constriction**

Edinger- Westphal nucleus

location of cell bodies of parasympathetic axons of CNIII

where is the lens of the eye located

anteriorly between vitreous humour and pupil shape is altered by **ciliary body** - changing it's **refractory power**

suspensory ligament of the lens

connects the circumferences of lens and ciliary body

contraction of ciliary muscle

contracts in parasympathetics, allows **near vision** as the ligament relaxes and lens becomes more spherical to focus on closer objects

relaxation of ciliary muscle

ligament tightens and the lens flattens to allow focus on objects in the distance

accomodation reflex

response of the eye to looking at near objects: - bilateral pupillary constriction (parasympathetic of sphincter pupillae) - bilateral convergence of both eyes towards the midline (medial rectus) - bilateral relaxation of the lens (spherical due to contraction of ciliary muscles) * All innervated by CNIII*

importance of basal tears

important in corneal health as they clean and nourish and hydrate the avascular cornea contain **lysosome** which is an enzyme that hydrolyses bacterial cell walls

reflex tears

extra tears in response to mechanical/chemical stimulation - afferent limb is CNV1 from cornea/conjunctiva - efferent limb is parasympathetic axons originating from CNVII

which foramen does CNVII pass through on the temporal bone

stylomastoid foramen

which nerve supplies the stapedius

CNVII

where does CNVII exit the cranial cavity

internal acoustic meatus

chorda tympani branch of CNVII

carries parasympathetic axons for submandibular and sublingual glands

nerve for sensory component of lacrimal gland

CNV1 (after V2)

what is Horner's syndrome often a result of

impaired sympathetic innervation to the head and neck - sympathetic trunk may be compressed