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Chapter 7: Ocular Motor system

Valentin Dragoi, Ph.D., department of Neurobiology and Anatomy, McGovern clinical School Last review 20 Oct 2020
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7.1 Introduction

The simplicity of the motor systems connected in controlling eye musculature do them appropriate for depicting the mechanisms and principals you have been examining in the preceding product on motor systems. Lock involve the action of couple of muscles and also of well defined neural circuits.

We use our eyes to monitor our exterior environment and depend on our ocular motor solution to protect and also guide our eyes. The ocular engine systems control eye lid closure, the quantity of light the enters the eye, the refractive nature of the eye, and also eye movements. The intuitive system gives afferent input come ocular motor circuits that use visual stimuli come initiate and also guide the engine responses. Neuromuscular systems regulate the muscles in ~ the eye (intraocular muscles); the muscle attached come the eye (extraocular muscles) and also the muscles in the eyelid. Ocular motor responses include ocular reflexes and also voluntary engine responses to visual and also other stimuli. The intricacy of the circuitry (the chain or network the neurons) controlling a ocular motor response increases v the level that processing involved in initiating, monitoring, and also guiding the response.

You are watching: Which type of muscle decreases the size of the pupils of your eyes in bright light

In this chapter we will begin at the level the reflex responses and move ~ above more complicated voluntary responses in the complying with lecture. The eye blink reflex is the simplest an answer and go not require the joining of cortical structures. In contrast, voluntarily eye activities (i.e., visual tracking of a moving object) involve multiple areas of the cerebral cortex and also basal ganglion, brain stem and also cerebellar structures.

7.2 Ocular Reflex Responses

The ocular reflexes room the most basic ocular engine responses. Ocular reflexes compensate because that the condition of the cornea and also for alters in the visual stimulus. For example, the eye blink reflex protects the cornea from drying out and also from contact with foreign objects. The pupillary light reflex compensates for alters in illumination level, conversely, the accommodation responses compensate for changes in eye-to-object-viewed distance. Note that reflex responses are initiated by sensory stimuli that activate afferent neurons (e.g., somatosensory stimuli because that the eye blink reflex and also visual stimuli because that the pupillary light reflex and accommodation responses).

In general, ocular reflexes are consensual (i.e., the solution is bilateral involving both eyes). Consequently, a irradiate directed in one eye elicits responses, pupillary constriction, in both eyes. In this chapter you will learn of the structures normally connected in performing these ocular responses and the obstacle that result from damage to contents of neural circuit controlling these responses.

A. The Eye Blink Reflex

Tactile stimulation the the cornea outcomes in one irritating sensation that normally evokes eyelid closure (an eye blink). The solution is consensual (i.e., bilateral) - entailing automatic eyelid closure in ~ both eyes.

The corneal eye blink reflex neural circuit: This neural circuit (Figure 7.1) is fairly simple, consisting of the

trigeminal1° afferent (free nerve end in the cornea, trigeminal nerve, ganglion, root, and spinal trigeminal tract), which finish on trigeminal 2° afferent in the spinal trigeminal nucleus, some of which send your axons to reticular development interneurons, i m sorry send your axons bilaterally to facial motor neurons in the face nucleus, which send their axons in the facial nerve to orbicularis oculi, which features to reduced the eyelid

Figure 7.1 The corneal eye blink reflex is initiated by the complimentary nerve endings in the cornea and also involves the trigeminal nerve and ganglion, the spinal trigeminal tract and nucleus, interneurons in the reticular formation, motor neurons in the face nucleus and also nerve, and the orbicularis oculi. Together the afferent info from each cornea is dispersed bilaterally come facial engine neurons by the reticular development interneurons, the eye blink solution is consensual, that is, both eye lids will certainly close come stimulation the the cornea of one of two people eye.


B. Pupillary light Reflex

The pupillary irradiate reflex requires adjustments in pupil size with changes in light levels.

The reflex is consensual: generally light the is command in one eye produce pupil constriction in both eyes. The direct solution is the adjust in pupil dimension in the eye to which the light is directed (e.g., if the irradiate is shone in the right eye, the ideal pupil constricts). The consensual an answer is the change in pupil size in the eye opposite to the eye to which the irradiate is directed (e.g., if the irradiate is shone in the appropriate eye, the left pupil likewise constricts consensually).

The pupillary light reflex permits the eye to adjust the lot of light getting to the retina and protects the photoreceptors indigenous bright lights. The iris has two set of smooth muscles that control the dimension of the pupil (Figure 7.2).

The sphincter muscle fibers type a ring at the pupil margin therefore that as soon as the sphincter contracts, the decreases (constricts) pupil size. The dilator muscle fibers radiate from the pupil aperture so that once the dilator contracts, it rises (dilates) pupil size.

Both muscles act to regulate the amount of irradiate entering the eye and the depth of ar of the eye1.

The iris sphincter is managed by the parasympathetic system, conversely, the iris dilator is controlled by the sorry system. The action of the dilator is antagonistic to that of the sphincter and also the dilator have to relax to allow the sphincter come decrease pupil size.

Normally the sphincter activity dominates during the pupillary light reflex.


The pupillary irradiate reflex neural circuit: The pathway managing pupillary light reflex (Figure 7.3) requires the

retina, optic nerve, optic chiasm, and also the optic street fibers that join the brachium the the premium colliculus, which terminate in the pretectal area the the midbrain, i m sorry sends most of that axons bilaterally in the posterior commissure to end in the Edinger-Westphal nucleus of the oculomotor complex, which consists of parasympathetic preganglionic neurons and also sends its axons in the oculomotor nerve to terminate in the ciliary ganglion, which sends out its parasympathetic postganglionic axons in the short ciliary nerve, which ends on the iris sphincter

Figure 7.3 The pupillary light reflex pathway. The lines ending with an arrowhead indicate axons end in the structure at the pointer of the arrow. The lines start with a dot suggest axons originating in the framework containing the dot. Bilateral damages to pretectal area neurons (e.g., in neurosyphilis) will create Argyll-Robertson student (non-reactive to light, active during accommodation).


Recall the the optic street carries visual information from both eyes and also the pretectal area projects bilaterally come both Edinger-Westphal nuclei: Consequently, the regular pupillary an answer to irradiate is consensual. That is, a irradiate directed in one eye outcomes in constriction the the student of both eyes.

C. Pupillary Dark an answer

The pupils usually dilate (increase in size) as soon as it is dark (i.e., once light is removed). This an answer involves the be sure of the iris sphincter and also contraction of the iris dilator. The iris dilator is controlled by the sympathetic concerned system.

The pupillary dark reflex neural circuit: The pathway controlling pupil dilation involves the

retina and also the optic tract fibers end on neurons in the hypothalamus and the axons the the hypothalamic neurons the descend to the spinal cord to end on the sympathetic preganglionic neurons in the lateral horn that spinal cord segments T1 come T3, i m sorry send your axons out the spinal cord to end on the forgiveness neurons in the superior cervical ganglion, i m sorry send their sorry postganglionic axons in the lengthy ciliary nerve come the iris dilator.

Axons native the remarkable cervical ganglion additionally innervate the challenge vasculature, sweat and lachrymal glands and also the eyelid tarsal muscles. Once the premium cervical ganglion or that axons space damaged, a constellation the symptoms, well-known as Horner\"s syndrome, result. This syndrome is identified by miosis (pupil constriction), anhidrosis (loss of sweating), pseudoptosis (mild eyelid droop), enopthalmosis (sunken eye) and flushing the the face.

D. The house Response

The accommodation response is elicited once the viewer directs his eye from a far-off (greater than 30 ft. Away) thing to a nearby object (Nolte, number 17-40, Pg. 447). The economic stimulation is one “out-of-focus” image. The accommodation (near point) response is consensual (i.e., it entails the action of the muscle of both eyes). The accommodation solution involves 3 actions:

Pupil accommodation: The action of the iris sphincter was spanned in the section on the pupillary irradiate reflex. During accommodation, pupil constriction uses the \"pin-hole\" effect and also increases the depth of focus of the eye by prevent the light scattered through the periphery of the cornea (Nolte, number 17-39, Pg. 447). The iris sphincter is innervated by the postganglionic parasympathetic axons (short ciliary nerve fibers) of the ciliary ganglion (Figure 7.3).

Lens accommodation: Lens accommodation increases the curvature the the lens, which rises its refractive (focusing) power. The ciliary muscles are responsible because that the lens accommodation response. They regulate the stress on the zonules, which room attached to the elastic lens capsule in ~ one end and also anchored to the ciliary human body at the other finish (Figure 7.4).


Figure 7.4 The ciliary muscles, which regulate the position of the ciliary processes and the tension on the zonule, manage the shape of the lens. The ciliary muscles function as a sphincter and also when contracted pull the ciliary body toward the lens come decrease anxiety on the zonules (see figure 7.5). The reduced tension permits the lens to boost its curvature and also refractive (focusing) power. As soon as the ciliary muscle is relaxed, the ciliary body is not pulled toward the lens, and also the stress and anxiety on the zonules is higher. High stress and anxiety on the zonules pulls radially top top the lens capsule and flattens the lens for distance vision. The ciliary muscles are innervated through the postganglionic parasympathetic axons (short ciliary nerve fibers) of the ciliary ganglion


Figure 7.5 The accommodation response of the lens: to compare the lens shape throughout near vision (contraction that the ciliary muscle throughout accommodation) with lens shape throughout distance vision (relaxation of the ciliary muscle).


Convergence in accommodation: when shifting one\"s check out from a distant object come a surrounding object, the eyes converge (are directed nasally) to store the object\"s image concentrated on the foveae that the 2 eyes. This action involves the contraction of the medial rectus muscle of the two eyes and relaxation the the lateral rectus muscles. The medial rectus attaches come the medial aspect of the eye and its convulsion directs the eye nasally (adducts the eye). The medial rectus is innervated by engine neurons in the oculomotor nucleus and also nerve.

The house neural circuit: The circuitry the the accommodation solution is more complicated than that of the pupillary light reflex (Figure 7.6).

The afferent body of the circuit has the

retina (with the retinal ganglion axons in the optic nerve, chiasm and tract), lateral geniculate body (with axons in the optic radiations), and visual cortex.

Ocular motor regulate neurons space interposed in between the afferent and efferent limbs of this circuit and also include the

visual association cortex, which determines the photo is \"out-of-focus\" sends out corrective signal via the internal capsule and crus cerebri to the supraoculomotor nuclei, which is located immediately superior to the oculomotor nuclei generates motor manage signals the initiate the accommodation response sends out these control signals bilaterally come the oculomotor complex.

The efferent body of this system has actually two components: the

Edinger-Westphal nucleus, which sends its axons in the oculomotor nerve come manage the ciliary ganglion, which sends it axons in the brief ciliary nerve to regulate the iris sphincter and also the ciliary muscle/zonules/lens that the eye oculomotor neurons, i beg your pardon sends out its axons in the oculomotor nerve to control the medial rectus converge the 2 eyes.

Figure 7.6 The house pathway contains the afferent limb, which consists of the whole visual pathway; the greater motor regulate structures, which consists of an area in the intuitive association cortex and also the supraoculomotor area; and the efferent limb, which contains the oculomotor nuclei and also ciliary ganglion. The lines ending with an arrow indicate axons terminating in the framework at the tip of the arrow. The lines beginning with a dot indicate axons originating in the structure containing the dot. Throughout accommodation 3 motor responses occur: convergence (medial rectus contracts to straight the eye nasally), pupil constriction (iris sphincter contracts to decrease the iris aperture) and also lens accommodation (ciliary muscle contract to decrease anxiety on the zonules).


7.3 Clinical Examples

An excellent method to check your expertise of the product presented thus far is by assessing the impacts of damage to frameworks within the ocular motor pathways. The observed motor loss(s) provide clues come the pathway(s) affected; and also the muscle(s) and eye affected administer clues come the level that the damage.

Cranial nerve damage: damage to cranial nerves may result in sensory and also motor symptoms. The sensory losses would involve those emotion the cranial nerve usually conveys (e.g., taste from the anterior 2 thirds that the tongue and also somatic sensations from the skin of the ear - if facial nerve is damaged). The motor losses might be serious (i.e., a lower motor neuron loss that produces total paralysis) if the cranial nerve contains all of the engine axons regulating the muscle of the typically innervated area.

The cranial nerves connected in the eye blink solution and pupillary solution are the optic, oculomotor, trigeminal and also facial nerves.

The optic nerve tote visual information from the eye. The oculomotor nerve contains lower motor axons innervating extraocular muscles: the medial, superior and inferior rectus muscles, the worse oblique muscle, eyelid muscle: the remarkable levator palpebrae, and also parasympathetic preganglionic axons come the ciliary ganglion. The trigeminal nerve consists of the 1° somatosensory afferents for the face, dura, oral and nasal cavities the lower motor axons because that the jaw muscles. The facial nerve consists of the lower motor neurons innervating the superficial muscles of the face, the 1° gustatory afferents come the anterior tongue the parasympathetic preganglionic axons to parasympathetic ganglia because that the lachrymal and salivary glands. 7.4 Clinical example #1

Symptoms. The patient, who shows up with a bloodshot left eye, complains that an inability to close his left eye. When asked to rise his eyebrows, he deserve to only elevate the right eyebrow. Once asked to close both eyes, the right eyelid closes but the left eyelid is only partially closed. Emotional the appropriate or left cornea with a wisp of cotton elicits the eye blink reflex in the ideal eye, but not the left eye (Figure 7.7). However, the patience reports he deserve to feel the cotton once it touches one of two people eye. He have the right to smile, whistle and show his teeth, which suggests his reduced facial muscles room functioning normally. Physics examination determines the touch, vibration, position and pain sensations are normal over the whole the body and face. There are no various other motor symptoms.


Observation: friend observe the the patient

has not shed cutaneous sensation in the upper left confront area does no blink when his left cornea is touch can not close his left eye voluntarily

You conclude the his left eye\"s useful loss is

no sensory a reduced motor neuron dysfunction

Pathway(s) affected: you conclude that structures in the complying with motor pathway have actually been affected

the eye blink pathway (Figure 7.8)

Figure 7.8 The eye blink pathway requires the trigeminal nerve, spinal trigeminal tract and also nucleus, the reticular formation, and the facial motor nucleus and nerve.


Side & Level the damage: together the eye blink ns involves

just motor function both reflex and voluntary motor attributes the upper part of the confront only one eye lid eyelid closure

Conclusion: you conclude that the damages involves

the face nerve a branch the the nerve innervating the upper confront a reduced motor neuron paralysis that the left orbicularis oculi motor innervation top top the left side (i.e., the symptoms are ipsilesional)

When reduced motor neurons room damaged, there is a flaccid paralysis the the muscle typically innervated. The action of the muscle will be weakened or lost depending on the extent of the damage. There will be a dilute or no reflex response and the muscle will certainly be flaccid and may atrophy v time.

The face Nerve. Ar of the facial nerve top top one side will an outcome in paralysis of the muscle of face expression on the ipsilesional next of the face. There will certainly be an i can not qualify to nearby the denervated eyelid voluntarily and reflexively. The eyelids may have some mobility if the oculomotor innervation to the levator is unaffected.

7.5 Clinical example #2

Symptoms. The patience complains that a bad infected left eye. As soon as he is asked to close both eyes, both eyelids close. Poignant the appropriate cornea through a wisp of cotton elicits the eye blink reflex in the both eyes (Figure 7.9, Right). However, touching the left cornea with a wisp of cotton does no elicit the eye blink reflex in the either eye (Figure 7.9, Left). The patient cannot detect pinpricks come his left forehead. However, the reports that pinpricks to remainder of his face are painful. He can blink, wrinkles his brows, smile, and whistle and show his teeth, which indicates his face muscles are functioning normally. Physical examination determines the touch, vibration, position and also pain sensations space normal over the whole the body and also over the reduced left and right side of his face.


Observation: friend observe that the patient

responds v direct and also consensual eye blink once his ideal cornea is touched can close his left eye voluntarily has lost cutaneous sensation in the upper left face area does not blink as soon as his left cornea is touched

You conclude the his left eye\"s functional loss is

not motor sensory

Pathway(s) affected: you conclude that frameworks in the adhering to reflex pathway have been affected

the eye blink pathway (Figure 7.8)

Side & Level of damage: as the eye blink loss requires

just one eye a sensory lose the upper part of the challenge

Conclusion: you conclude that the damages involves

a loss of the afferent body of the eye blink response the trigeminal nerve a branch the the nerve innervating the upper challenge the innervation the the left next (i.e., the symptoms room ipsilesional)

The Trigeminal Nerve. Ar of the trigeminal nerve will get rid of somatosensory sensation from the face and the eye blink reflex (e.g., with ar of the left trigeminal nerve, irradiate touch the the left cornea will not create an eye blink in the left or appropriate eye). However, irradiate touch the the ideal cornea will certainly elicit a bilateral eye blink. The effect of sectioning the trigeminal nerve is to eliminate the afferent input because that the eye blink reflex.

7.6 Clinical instance #3

Symptoms. The patient complains of pain in her left eye. She left pupil shows up dilated and also is no reactive to irradiate directed at one of two people the left or best eye (Figure 7.10). The best pupil appears normal in size and reacts come light once it is directed in the ideal or left eye. Both eyelids have the right to be elevated and also lowered and both eye exhibit common movement. Touch, vibration, position and pain sensations space normal over the whole the body and face. There are no other motor symptoms.


Figure 7.10 observe the reaction the the patient\"s student to light directed in the left or ideal eye.


Observation: you observe that the patient has actually

a left pupil that does no react come light straight or consensually a best pupil the reacts to irradiate directly and consensually normal eye movements

You conclude the his left eye\"s sensible loss is

no sensory (the appropriate pupil reaction to light directed in ~ the left eye) a motor dysfunction

Pathway(s) affected: girlfriend conclude that structures in the following motor pathway have been affected

the pupillary irradiate reflex pathway (Figure 7.11)

Figure 7.11 The pupillary irradiate reflex pathway requires the optic nerve and also the oculomotor nerve and also nuclei.


Side & Level of damage: together the pupillary light reflex loss

involves only one eye requires only motor role does no involve eyelid or ocular motility is minimal to pupil constriction in the left eye

Conclusion: friend conclude the the damage

requires structures peripheral come the oculomotor nucleus (i.e., eye movement unaffected) does not involve the oculomotor nerve requires the ciliary ganglion or the short ciliary nerve is ~ above the left side (i.e., the symptoms are ipsilesional)

Parasympathetic Innervation of the Eye. Ar of the parasympathetic preganglionic (oculomotor nerve) or postganglionic (short ciliary nerve) innervation to one eye will an outcome in a loss (motor) the both the direct and also consensual pupillary light responses the the denervated eye. Section of the left short ciliary nerve or a benign lesion in the left ciliary ganglion will an outcome in no direct response to irradiate in the left eye and no consensual an answer in the left eye when light is directed on the best eye (a.k.a., tonic pupil). As soon as the damages is restricted to the ciliary ganglion or the quick ciliary nerve, eyelid and also ocular mobility room unaffected.

7.7 Clinical instance #4

Symptoms. The patient presents v a left eye characterized by ptosis, lateral strabismus, and dilated pupil. As soon as asked to climb his eyelids, he have the right to only advanced the lid of the appropriate eye. As soon as asked to close both eyes, both eyelids near fully. His left pupil does not react to light directly or consensually (Figure 7.12). As soon as asked to look come his right, his left eye moves to a central position, but no further. The right eye is completely mobile. Once the patient is asked to look straight ahead, you keep in mind his left eye stays directed come the left and also depressed. Physical examination determines that touch, vibration, position and pain sensations room normal end the entire the body and also face. There space no various other motor symptoms.


Figure 7.12 The patience presents with a left eye defined by ptosis, lateral strabismus and also dilated pupil. Observe the reaction the the patient\"s college student to light directed in the left or best eye.


Observation: you observe the the patience

has not lost cutaneous emotion in the challenge area has a left ptosis cannot adduct his left eye (i.e., relocate it toward the nose) has a left dilated pupil the is no reactive to light in one of two people eye

You conclude the his left eye\"s functional loss is

not sensory a lower motor neuron dysfunction entailing an autonomic dysfunction

Pathway(s) affected: friend conclude that structures in the adhering to motor pathway have actually been affected

the pupillary/oculomotor pathway (Figure 7.11)

Side & Level that damage: as the ocular loss involves

just motor role both reflex and voluntary motor functions both somatic and also autonomic attributes just the left eye

Conclusion: girlfriend conclude the the damages

entails the oculomotor nerve is a lower motor neuron paralysis the the premium levator palpebrae is a reduced motor neuron paralysis that the medial, exceptional & inferior rectus muscles and also inferior oblique muscle of the eye is one autonomic disorder including the axons the the Edinger-Westphal nucleus is top top the left side (i.e., the symptoms space ipsilesional)

The Oculomotor Nerve. Section of the oculomotor nerve produces a non-reactive pupil in the ipsilesional side and other symptoms concerned oculomotor nerve damages (e.g., ptosis and lateral strabismus). Section of the oculomotor nerve ~ above one next will an outcome in paralysis the the superior levator palpebrae, which generally elevates the eyelid. It will also paralyze the medial, superior & worse rectus muscles and also the worse oblique, i beg your pardon will allow the lateral rectus come deviate the eye laterally and the remarkable oblique to boring the eye. The parasympathetic preganglionic axons the the Edinger-Westphal nucleus, which normally travel in the oculomotor nerve, will be cut off from the ciliary ganglion, disrupting the circuit normally used to manage the iris sphincter solution to light.

7.8 Clinical instance #5

Symptoms. The patient complains of decreased vision in the left eye. Pupil dimension in both eyes appears normal. However, both pupils carry out not show up to constrict together rapidly and also strongly as soon as light is directed into his left eye (Figure 7.13). That is, contrasted to the response to light in the left eye, irradiate in the ideal eye produce a much more rapid constriction and also smaller pupil in both eyes. Physics examination determines the touch, vibration, position and also pain sensations space normal end the entire the body and also over the reduced left and also right side of his face.


Figure 7.13 watch the reaction the the patient\"s student to irradiate directed in the left or best eye.


Observation: you observe the the patient\"s pupils

respond when light is directed into either eye has weaker direct and also consensual responses to irradiate directed in the left eye

You conclude the his left eye\"s sensible loss is

no motor sensory (because the responses in both eyes space weaker as soon as light is directed in the left eye)

Pathway(s) affected: friend conclude that frameworks in the adhering to motor pathway have been affected

the pupillary irradiate reflex pathway (Figure 7.11)

Side & Level of damage: as the pupillary light solution deficit involves

just stimulation the one eye a sensory lose the left eye

Conclusion: friend conclude the the damages

is in the afferent limb of the pupillary light solution requires the optic nerve or retina is top top the left next (i.e., the symptoms space ipsilesional) developed a left pupillary afferent defect

The Optic Nerve. Partial damages of the retina or optic nerve reduces the afferent ingredient of the pupillary reflex circuit. The lessened afferent input to the pretectal areas is reflected in weakened direct and consensual pupillary reflex responses in both eyes (a.k.a., a relative afferent pupillary defect).

Section that one optic nerve will an outcome in the finish loss of the straight pupillary light reflex yet not the consensual reflex that the blinded eye. That is, if the left optic nerve is sectioned, light directed ~ above the left (blind) eye will not elicit a pupillary response in the left eye (direct reflex) or the ideal eye (consensual response). However, light directed in the appropriate eye will elicit pupillary responses in the appropriate eye and the left (blind) eye. The impact of sectioning one optic nerve is to remove the afferent input because that the straight reflex the the blinded eye and the afferent input for the consensual reflex of the normal eye. Ar of one optic tract will certainly not get rid of the direct or consensual reflex of either eye as the making it through optic tract consists of optic nerve fibers from both eyes. However, the responses to light in both eyes may be weaker because of the reduced afferent input come the ipsilesional pretectal area.

7.9 Clinical instance #6

Symptoms. A patient that is enduring from the so late stages the syphilis is sent to you for a neuro-ophthalmological work-up. His vision is normal as soon as corrected because that refractive errors. He has actually normal ocular mobility and his eyelids deserve to be elevated and also depressed at will. Check of his pupillary responses indicates a lose of the pupillary irradiate reflex (no pupil constriction to light in either eye) however normal pupillary accommodation solution (pupil constricts once the patient\"s eyes space directed indigenous a remote object to one nearby).

Observation: you observe that the patient has normal vision however that his pupils

carry out not respond once light is directed right into the one of two people of his eyes perform respond during accommodation

You conclude the his eye\"s sensible loss is

no sensory (his vision is normal) engine (the pupillary light responses in both eyes room absent) higher-order engine (because he has actually a typical pupillary accommodation response)

Pathway(s) affected: you conclude the structure(s) in the

house pathway have not been damaged (Figure 7.14) pupillary irradiate reflex pathway have been damaged (Figure 7.11)

Side & Level that damage: as the pupillary an answer deficit

does no involve a sensory ns does not involve the pupil accommodation an answer entails only the pupillary light reflex an answer

Conclusion: girlfriend conclude that the damage

involves the pretectal area bilaterally pardon the supraoculomotor area created the Argyll Robertson response

Figure 7.14 The house pathway contains the supraoculomotor area, which features as a \"higher-order\" motor control stage managing the motor neurons and also parasympathetic neurons (i.e., the Edinger-Westphal neurons) of the oculomotor nucleus. This area to be spared by syphilis.


In the Argyll Robertson response, there is an absence of the pupillary irradiate reflex through a regular pupillary house response. The Argyll Robertson response is attributed to bilateral damages to pretectal areas (which regulate the pupillary light reflex) through sparing that the supraoculomotor area (which controls the pupillary house reflex).

The accommodation an answer involves plenty of of the structures connected in the pupillary light response and, v the exception of the pretectal area and supraoculomotor area, damages to one of two people pathway will certainly produce typical the symptoms. The most common complaint involving the accommodation solution is the loss v aging (i.e., presbyopia). Recall that presbyopia most frequently results indigenous structural transforms in the lens which impedes the lens accommodation response.

7.10 summary

This chapter described three species of ocular motor responses (the eye blink, pupillary light and also accommodation responses) and also reviewed the nature the the responses and the effectors, efferent neurons, higher-order motor regulate neurons (if any), and also afferent neurons normally connected in performing this ocular responses. Table ns summarizes these structures and the function(s) of this ocular engine responses. Reader should recognize the anatomical basis for disorders that result from damages to components of neural circuit controlling these responses.

Table I classification of Consensual Ocular Responses & their Motor control Structures
Ocular Responses Function Afferent Input* & Motor control Structures
Eye Blink Reflex Protects cornea from contact with international objects

Free Nerve end in cornea that space afferent end of the Trigeminal Nerve, Ganglion, root & Spinal Trigeminal Tract*

Spinal Trigeminal Nucleus*

Reticular development (bilaterally to)

Facial engine Nuclei & face Nerves

Orbicularis Oculi

Pupillary light Reflex Decreases pupil size (constriction) – to reduce the quantity of light that enters the eye.

Retina, Optic Nerve, Chiasm & Tracts and also Brachium of remarkable Colliculus*

Pretectal locations of Midbrain (bilaterally to)

Edinger-Westphal Nuclei & Oculomotor Nerves

Ciliary Ganglia & quick Ciliary Nerves

Iris Sphincters

Pupillary accommodation

Lens house

Increases depth of focus of eye lens system

boosts refractive power of lens

Visual System* consisting of Visual combination Cortex

Supraoculomotor Nuclei (bilaterally to)

Edinger-Westphal Nuclei & Nerve III

Ciliary Ganglia & short Ciliary Nerves

Iris Sphincters & Ciliary Muscles

Convergence eye directed nasally throughout accommodation

Visual System* including Visual combination Cortex

Supraoculomotor Nuclei (bilaterally to)

Oculomotor Nuclei

Medial Rectus Muscles

* Afferent structures proving sensory input.

Test Your expertise


A patience is capable of pupillary constriction throughout accommodation yet not in solution to a light directed to one of two people eye. The lesion is most likely present in the...

A. Optic nerve

B. Abducens nucleus

C. Edinger-Westphal nucleus

D. Pretectal areas

E. Supraoculomotor nucleus


A patience is capable of pupillary constriction during accommodation however not in an answer to a light directed to one of two people eye. The lesion is most likely existing in the...

A. Optic nerve This price is INCORRECT.

Optic nerve is not correct as ar of one nerve would certainly not obliterate the consensual response to stimulation that the contralesional eye.

B. Abducens nucleus

C. Edinger-Westphal nucleus

D. Pretectal areas

E. Supraoculomotor nucleus


A patience is capable of pupillary constriction during accommodation but not in an answer to a irradiate directed to one of two people eye. The lesion is most likely current in the...

A. Optic nerve

B. Abducens cell core This prize is INCORRECT.

Abducens nucleus is incorrect together it is not connected in pupillary responses. Its motor neurons innervate the lateral rectus muscle.

C. Edinger-Westphal nucleus

D. Pretectal areas

E. Supraoculomotor nucleus


A patient is capable of pupillary constriction during accommodation however not in solution to a light directed to one of two people eye. The lesion is many likely existing in the...

A. Optic nerve

B. Abducens nucleus

C. Edinger-Westphal cell nucleus This prize is INCORRECT.

Edinger-Westphal is not correct as damages to this nucleus would certainly diminish the pupil an answer both come light and also during accommodation.

D. Pretectal areas

E. Supraoculomotor nucleus


A patience is capable of pupillary constriction during accommodation but not in solution to a light directed to one of two people eye. The lesion is most likely current in the...

A. Optic nerve

B. Abducens nucleus

C. Edinger-Westphal nucleus

D. Pretectal areas This answer is CORRECT!

The pretectal area administer bilateral input come the Edinger-Westphal nucleus for the direct and also consensual pupillary irradiate response.

E. Supraoculomotor nucleus


A patient is capable of pupillary constriction during accommodation but not in response to a irradiate directed to one of two people eye. The lesion is many likely present in the...

A. Optic nerve

B. Abducens nucleus

C. Edinger-Westphal nucleus

D. Pretectal areas

E. Supraoculomotor nucleus This answer is INCORRECT.

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Supraoculomotor cell core is incorrect due to the fact that it is affiliated in the pupillary accommodation solution and not in the pupillary irradiate reflex response.