The corneal eye blink reflex neural circuit: This neural circuit (Figure 7.1) is relatively simple, consisting of the. When testing the pupillary reflexes, the diameter of the pupil should be measured in dim lighting. Palpebral oculogyric reflex (Bells reflex). the 1 somatosensory afferents for the face, dura, oral and nasal cavities. Efferent Pathway - The efferent pathway begins in the parasympathetic nucleus of cranial nerve III (oculomotor nerve) located in the midbrain (mesencephalon) on the stimulated side. Nerve impulses pass along the optic nerve, to the co-ordinating cells within the midbrain. Pupil size in both eyes appears normal. ) Isolated accommodation deficits can occur in healthy persons or in patients with neurological or systemic conditions (such as in children after a viral illness and in women before or after childbirth). Consensual light reflex of left pupil involves the right optic nerve and left oculomotor nerve, which are both undamaged. Eyelid closure reaction. For each point choose one: north, south, east, west, or nonexistent? {\displaystyle M} the Pacinian corpuscle and the free nerve ending. The distinction between the light-reflex and near-reflex pathways forms the basis for some forms of pupillary light-near dissociation (i.e., pupils that do not react to light but react to near stimuli) in which the dorsal midbrain and pretectal nuclei are damaged, but the near-reflex pathways and the Edinger-Westphal nuclei are spared ( Fig . The patient complains of pain in her left eye. Fibers from the facial nuclei motor neurons send axons through the facial nerve to the orbicularis oculi muscle, which lowers the eyelid. For example, if a bright stimulus is presented to one eye, and a dark stimulus to the other eye, perception alternates between the two eyes (i.e., binocular rivalry): Sometimes the dark stimulus is perceived, sometimes the bright stimulus, but never both at the same time. Ocular motor responses include ocular reflexes and voluntary motor responses to visual and other stimuli. is the luminous intensity reaching the retina in a time Receptor, sensory neuron, integration center, motor neuron and effector. The pretectal nucleus projects crossed and uncrossed fibers to the ipsilateral and contralateral Edinger-Westphal nuclei, which are also located in the midbrain. Eye reflex which alters the pupil's size in response to light intensity, "Eyeing up the Future of the Pupillary Light Reflex in Neurodiagnostics", "Understanding the effects of mild traumatic brain injury on the pupillary light reflex", "Perceptual rivalry: Reflexes reveal the gradual nature of visual awareness", "Attention to bright surfaces enhances the pupillary light reflex", "The pupillary response to light reflects the focus of covert visual attention", "The pupillary light response reflects exogenous attention and inhibition of return", "Pupil size and social vigilance in rhesus macaques", "Pupil constrictions to photographs of the sun", "Bright illusions reduce the eye's pupil", "Photorealistic models for pupil light reflex and iridal pattern deformation", "The pupillary light reflex in normal subjects", https://en.wikipedia.org/w/index.php?title=Pupillary_light_reflex&oldid=1132093314, Short description is different from Wikidata, Creative Commons Attribution-ShareAlike License 3.0, Retina: The pupillary reflex pathway begins with the photosensitive. Clinicians can use pupillary reflexes to distinguish between damage to the optic nerve (cranial nerve II), the oculomotor nerve (cranial nerve III), or the brainstem by observing each eye's response to light. Analytical cookies are used to understand how visitors interact with the website. {\displaystyle \mathrm {d} t_{d}} {\displaystyle S} VOR can also be assessed via dynamic visual acuity, during which multiple visual acuity measurements are taken as the examiner oscillates the patients head. When there is a problem with your pupils the black part at the center of your eyeball you have whats known as a pupillary abnormality. [12][13] This shows that the pupillary light reflex is modulated by subjective (as opposed to objective) brightness. The Trigeminal Nerve. The iris dilator is controlled by the sympathetic nervous system. The reflex describes unilateral lacrimation when a person eats or drinks[14]. J Neurosurg. Founded, designed and operated by: - Ali Feili MD, MBA, -About us -Contact us -Privacy Policy -Sitemap - RSS FEED. This action involves the contraction of the medial rectus muscles of the two eyes and relaxation of the lateral rectus muscles. The simplest reflexes are monosynaptic, such as the stretch or myotatic reflex. What is the major purpose for vitreous humor? The accommodation pathway includes the afferent limb, which consists of the entire visual pathway; the higher motor control structures, which includes an area in the visual association cortex and the supraoculomotor area; and the efferent limb, which includes the oculomotor nuclei and ciliary ganglion. However, touching the left cornea with a wisp of cotton does not elicit the eye blink reflex in the either eye (Figure 7.9, Left). There are no other motor symptoms. The pupil is the space within the eye that permits light to project onto the retina. It is often concealed by controlled ventilation, however, spontaneously breathing patients should be monitored carefully, as the reflex may lead to hypercarbia and hypoxemia. The corneal eye blink reflex neural circuit: The pupillary light reflex neural circuit, Protects cornea from contact with foreign objects. Thats why the pupil of one eye can change when you shine the light into your other eye. [4][5] Examples are provided as below: For example, in a person with abnormal left direct reflex and abnormal right consensual reflex (with normal left consensual and normal right direct reflexes), which would produce a left Marcus Gunn pupil, or what is called left afferent pupillary defect, by physical examination. Physical examination determines that touch, vibration, position and pain sensations are normal over the entire the body and face. The Basilica-Cathedral of Our Lady of the Pillar (Spanish: Catedral-Baslica de Nuestra Seora del Pilar) is a Roman Catholic church in Zaragoza, Aragon, Spain.The Basilica worships Blessed Virgin Mary, under her title Our Lady of the Pillar.According to its website, this church is the first church dedicated to Mary. The effect of sectioning the trigeminal nerve is to remove the afferent input for the eye blink reflex. Clinical Significance. We also use third-party cookies that help us analyze and understand how you use this website. Both muscles act to control the amount of light entering the eye and the depth of field of the eye1. Havelius U, Heuck M, Milos P, Hindfelt B. Ciliospinal reflex response in cluster headache. stimulus(light)(simulus):retinal An RAPD can occur due to downstream lesions in the pupillary light reflex pathway (such as in the optic tract or pretectal nuclei)[4]. The lacrimatory reflex causes tear secretion in response to various stimuli: 1. physical and chemical stimuli to the cornea, conjunctiva and nasal mucosa, 2. bright light, 3. emotional upset, 4. vomiting, 5. coughing, 6. yawning[1]. The afferent limb has nerve fibers running within the optic nerve (CN II). 4 days ago. Papillary muscle definition, one of the small bundles of muscles attached to the ventricle walls and to the chordae tendineae that tighten these tendons during ventricular contraction. The integration center consist soft one or more neurons in the CNS. At the same time, observe whether his other eye blinks (consensual corneal reflex). Figure 7.4 Light is the stimulus; impulses reach the brain via the optic nerve; and the response is conveyed to the pupillary musculature by autonomic nerves that supply the eye. The ciliospinal reflex (pupillary-skin reflex) consists of dilation of the ipsilateral pupil in response to pain applied to the neck, face, and upper trunk. Atropine eye drops are used to temporarily paralyze the accommodation reflex and as a long-lasting pupil dilating agent, or mydriatic. Which of the following was able to detect pressure? Therefore, options (d), (f), and (g), which all includes segment 3, are eliminated. It can also occur due to a generalized sympathetic response to physical stimuli and can be enhanced by psychosensory stimuli, such as by a sudden noise or by pinching the back of the neck, or a passive return of the pupil to its relaxed state. transmit sound vibrations to the spiral organ. . But opting out of some of these cookies may affect your browsing experience. When asked to close both eyes, both eyelids close fully. trigeminal1 afferent (free nerve endings in the cornea, trigeminal 2 afferent in the spinal trigeminal nucleus, some of which send their axons to, reticular formation interneurons, which send their axons bilaterally to. This helps to protect the photoreceptors in the retina from damage as a result of bright light. This video will describe the mechanism for pupil constriction and dilation, list the autonomic reflex components, discuss the pupillary light reflex pathway, and demonstrate the procedure for testing the pupillary light reflex. Most reflexes are polysynaptic (more than one synapse) and involve the activity of interneurons in the integration center. t As with all experiments, it is important to establish a standard of comparison (control group). Parasympathetic neurons from the oculomotor nerve synapse on ciliary ganglion neurons. The accommodation (near point) response is consensual (i.e., it involves the actions of the muscles of both eyes). Right direct reflex is normal, therefore segments 2, 6, and 8 are normal. The ipsilateral efferent limb transmits nerve signals for direct light reflex of the ipsilateral pupil. The cookies is used to store the user consent for the cookies in the category "Necessary". Segment 2 is the afferent limb. Ophthalmologic considerations: This reflex most common in children, particularly during strabismus surgery[17]. In patients with an RAPD, when light is shined in the affected eye, there will be dilation of both pupils due to an abnormal afferent arm [3]. lens are respectively the This extensive pathway is being tested when a light is shined in the eyes. His left pupil does not react to light directly or consensually (Figure 7.12). Ophthalmologic considerations: This reflex may explain why patients undergoing ophthalmic surgery that involves extensive manipulation of extraocular muscles are prone to develop post-operative nausea and vomiting[21]. and When your pupil shrinks (constricts), its called miosis. The medial rectus attaches to the medial aspect of the eye and its contraction directs the eye nasally (adducts the eye). The accommodation pathway includes the supraoculomotor area, which functions as a "higher-order" motor control stage controlling the motor neurons and parasympathetic neurons (i.e., the Edinger-Westphal neurons) of the oculomotor nucleus. t Axons from the superior cervical ganglion also innervate the face vasculature, sweat and lachrymal glands and the eyelid tarsal muscles. Ophthalmologic considerations: Testing of the pupillary light reflex is useful to identify a relative afferent pupillary defect (RAPD) due to asymmetric afferent output from a lesion anywhere along the afferent pupillary pathway as described above[1]. View Available Hint(S) Reset Help Optic Nerve Retinal Photoreceptors Sphincter Pupillae Midbrain Ciliary Ganglion Oculomotor Nervo Stimulus Receptor Sensory Integration Efectos Neuron Submit, (Rate this solution on a scale of 1-5 below). It usually follows a Bells palsy or traumatic facial paralysis, and occurs due to misdirection of regenerating gustatory fibers from either the facial or glossopharyngeal nerves that are responsible for taste. During accommodation three motor responses occur: convergence (medial rectus contracts to direct the eye nasally), pupil constriction (iris sphincter contracts to decrease the iris aperture) and lens accommodation (ciliary muscles contract to decrease tension on the zonules). The observed motor loss(s) provide clues to the pathway(s) affected; and the muscle(s) and eye affected provide clues to the level of the damage. A transient RAPD can occur secondary to local anesthesia[4]. Blanc, VF, et al. Anisocoria is an inequality in the size of the pupils. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. {\displaystyle \mathrm {d} t_{c}} The pupillary light reflex is an example of a(n) ________. [6] Sympathetic fibers from the upper thoracic and lower cervical spinal cord make up the efferent portion of the ciliospinal reflex. The left direct reflex is lost. Testing the pupillary light reflex is easy to do and requires few tools. This reflex is especially visible in patients with Bell palsy, an acute disorder of the facial nerve, due to failure of adequate eyelid closure[10]. The Oculomotor Nerve. Read More. VOR can be assessed in several ways. t A stimulus could be many. Observe the reaction of the patient's pupils to light directed in the left or right eye. Observe the reaction of the patient's pupils to light directed in the left or right eye. The oculorespiratory reflex revisited. These intrinsic photosensitive ganglion cells are also referred to as melanopsin-containing cells, and they influence the circadian rhythms and the pupillary light reflex. Drag the appropriate labels to their respective targets. The accommodation response is elicited when the viewer directs his eyes from a distant (greater than 30 ft. away) object to a nearby object (Nolte, Figure 17-40, Pg. Which eye structure is primarily responsible for making the adjustments required to focus on objects both near and far? Cranial nerve damage: Damage to cranial nerves may result in sensory and motor symptoms. However, light touch of the right cornea will elicit a bilateral eye blink. equalize pressure between the environment and the middle ear, A&P I Chapters 14 and 15 Lab - Autonomic Nerv, Myer's AP Psychology: Unit 5 Review (TO COMBI. Readers should understand the anatomical basis for disorders that result from damage to components of neural circuit controlling these responses. If one eye only is stimulated, both pupils constrict, the so-called consensual reflex. 447). Five Components of the Reflex Arc: 1. receptor 2. afferent pathway (sensory neurons) 3. integration center 4. efferent pathway (motor neurons) 5. effector Reflex Arc the pathway through which a stimulus can directly cause a response involuntarily Receptor (reflex arc component) detects the stimulus Afferent Pathway (reflex arc component) Thus, the pupillary light reflex regulates the intensity of light entering the eye. d Alternatively, if the reactive pupil constricts more with the consensual response than with the direct response, then the RAPD is in the reactive pupil. brain(inegration center) : occulomotor nerve(motor neuron) It is the response of the eye that is not being stimulated by light. The oculo-emetic reflex causes increased nausea and vomiting due to extensive manipulation of extraocular muscles[21]. Pupillary escape is an abnormal pupillary response to a bright light, in which the pupil initially constricts to light and then slowly redilates to its original size[4]. Five basic components of reflex arcs. Pupillary reflex is conceptually linked to the side (left or right) of the reacting pupil, and not to the side from which light stimulation originates. Sensory transduction is defined as _______. {\displaystyle D} Another reflex involving the eye is known as the lacrimal reflex. Recall that the optic tract carries visual information from both eyes and the pretectal area projects bilaterally to both Edinger-Westphal nuclei: Consequently, the normal pupillary response to light is consensual. In this setting, it is very unlikely that left consensual reflex, which requires an intact segment 4, would be preserved. Felten, DL, OBanion, MK, Maida, MS. Chapter 14: Sensory Systems. Reflex arcs have five basic components. The accommodation neural circuit: The circuitry of the accommodation response is more complex than that of the pupillary light reflex (Figure 7.6). The oculo-respiratory reflex can lead to shallow breathing, slowed respiratory rate or respiratory arrest due to pressure on the eye or orbit or stretching of the extraocular muscles. Segments 5 and 7 form the efferent limb. Symptoms. Parasympathetic innervation leads to pupillary constriction. The diagram may assist in localizing lesion within the pupillary reflex system by process of elimination, using light reflex testing results obtained by clinical examination. View Available Hint (s) Reset Help Optic nerve Retinal photoreceptors Sphincter pupillae Midbrain Ciliary ganglion Oculomotor nervo Stimulus Receptor Sensory Integration Efectos neuron Submit The visual system provides afferent input to ocular motor circuits that use visual stimuli to initiate and guide the motor responses. Ophthalmic Problems and Complications. In this chapter you will learn of the structures normally involved in performing these ocular responses and the disorders that result from damage to components of neural circuit controlling these responses. The OKN response can also be used to evaluate for suspected subclinical internuclear ophthalmoplegia, which will show a slower response by the medial rectus on the side of the lesion, and for suspected Parinauds syndrome, in which the use of a downward OKN target will accentuate convergent retraction movements on attempted upgaze. Referring to the neural pathway schematic diagram, the entire pupillary light reflex system can be visualized as having eight neural segments, numbered 1 through 8. (dilation of the pupil with light touch to the back of the neck . Part B - Pupillary Light Reflex Pathway Drag The Labels To Identify The Five Basic Components Of The Pupillary Light Reflex Pathway. Dilation lag can be tested by observing both pupils in dim light after a bright room light has been turned off. Observe the reaction of the patient's pupils to light directed in the left or right eye. If his acceleration is the same size at two points, display that fact in your ranking. 2.) d myasthenia gravis, botulism toxin, tetanus), focal or generalized neurologic disease (e.g. -Shine the flashlight into the subject's left eye and measure the diameter of the left pupil. [11] This shows that the pupillary light reflex is modulated by visual attention and trial-by-trial variation in visual attention. Approaching his eye from the side, out of his line of vision, lightly touch a thin strand of clean cotton (as from a cotton ball) to his cornea. VOR can be evaluated using an ophthalmoscope to view the optic disc while the patient rotates his or her head; if the VOR is abnormal, catch-up saccades will manifest as jerkiness of the optic disc. Light is the stimulus; impulses reach the brain via the optic nerve; and the response is conveyed to the pupillary musculature by autonomic nerves that supply the eye.. (b) What are the directions of his velocity at points A,BA, BA,B, and CCC? A direct pupillary reflex is pupillary response to light that enters the ipsilateral (same) eye. d Autonomic Reflexes- The autonomic reflexes include the pupillary reflexes as well as many others. In the early stages of development, the sepals resemble two individual, yet partially joined, orbs which gradually lengthen and split lengthwise as the developing flower prepares to bloom. M High tension on the zonules pulls radially on the lens capsule and flattens the lens for distance vision. The optic nerve carries visual information from the eye. Pupillary constriction occurs via innervation of the iris sphincter muscle, which is controlled by the parasympathetic system [2]. Figure 7.1 Section of one optic nerve will result in the complete loss of the direct pupillary light reflex but not the consensual reflex of the blinded eye. A cataract occurs when the lens becomes cloudy. It is the response of the eye that is being stimulated by light. Pupils should be examined in light and then in the dark. If his acceleration is zero, display that fact. Cataracts typically affect which eye structure? (effector) When the damage is limited to the ciliary ganglion or the short ciliary nerve, eyelid and ocular mobility are unaffected. The pupillary light reflex neural circuit: The pathway controlling pupillary light reflex (Figure 7.3) involves the. The accommodation reflex (or accommodation-convergence reflex) is a reflex action of the eye, in response to focusing on a near object, then looking at a distant object (and vice versa), comprising coordinated changes in vergence, lens shape (accommodation) and pupil size. Optic nerve is incorrect as section of one nerve would not obliterate the consensual response to stimulation of the contralesional eye. Were the solution steps not detailed enough? :sphincter pupilae. Pathway: Afferent signals are from the ophthalmic branch of the trigeminal nerve[1]. An abnormal blink reflex may be present in patients with various posterior fossa disorders, including acoustic neuroma, multiple sclerosis, Parkinson disease, trigeminal nerve lesions, and brainstem strokes, tumors, or syrinxes[4]. The ciliary muscles function as a sphincter and when contracted pull the ciliary body toward the lens to decrease tension on the zonules (see Figure 7.5). Ophthalmologic considerations: The corneal reflex can be utilized as a test of corneal sensation in patients who are obtunded or semicomatose[4]. When left eye is stimulated by light, afferent signals from the left eye cannot pass through the transected left optic nerve to reach the intact efferent limb on the right. However, he reports that pinpricks to rest of his face are painful. This cookie is set by GDPR Cookie Consent plugin. Donations to Neuroscience Online will help fund development of new features and content. This cookie is set by GDPR Cookie Consent plugin. This response involves the relaxation of the iris sphincter and contraction of the iris dilator. [1] Light shone into one eye will cause both pupils to constrict. The reflex describes the finding of pupillary constriction in darkness or as part of closing eyelids when going to sleep. The left direct reflex is lost. The afferent limb carries sensory input. Signals from the pneumotaxic respiratory center in the ventrolateral tegmentum of the pons reach the medullary respiratory area and travel through the phrenic and other respiratory nerves, which lead to bradypnea, irregular respiratory movements, and respiratory arrest[20]. Option (e) involves a combined lesion of segments 1 and 5. It is hypothesized that it is due to oculomotor disinhibition. free nerve endings in the cornea, which continue through the trigeminal nerve, Gasserian ganglion, root, and spinal trigeminal tract)[2]. Pupillary light reflex is modeled as a physiologically-based non-linear delay differential equation that describes the changes in the pupil diameter as a function of the environment lighting:[14]. [6] Second order sympathetic neurons then exit the cervicothoracic cord from C8-T2 through the dorsal spinal root and enter the paravertebral sympathetic chain and eventually the superior cervical ganglion[6] Third order neurons from the superior cervical ganglion travel up on the internal and external carotid arteries with the pupil receiving sympathetic innervation from sympathetic fibers on the ophthalmic artery after branching off the internal carotid artery. The accommodation response involves many of the structures involved in the pupillary light response and, with the exception of the pretectal area and supraoculomotor area, damage to either pathway will produce common the symptoms. Gamlin, D.H. McDougal, in Encyclopedia of the Eye, 2010 Description Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. When asked to rise his eyebrows, he can only elevate the right eyebrow. Which of the following will cause the reaction time of a reflex to increase? Symptoms. 2. The pupillary light reflex pathway. Chapter 7: Ocular Motor System. An absent reflex may be the only neurological abnormality in patients with idiopathic epilepsy, Sturge-Weber syndrome, and tuberous sclerosis. The reflex is consensual: Normally light that is directed in one eye produces pupil constriction in both eyes. Left direct light reflex involves neural segments 1, 5, and 7. This cookie is set by GDPR Cookie Consent plugin. Light Reflex: When light is shone to either of the eyes both the pupil constrict. It will also paralyze the medial, superior & inferior rectus muscles and the inferior oblique, which will allow the lateral rectus to deviate the eye laterally and the superior oblique to depress the eye. The Argyll Robertson response is attributed to bilateral damage to pretectal areas (which control the pupillary light reflex) with sparing of the supraoculomotor area (which controls the pupillary accommodation reflex). Figure 7.14 There will be a weakened or no reflex response and the muscle will be flaccid and may atrophy with time. The parasympathetic preganglionic axons of 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 control the iris sphincter response to light. t The right direct reflex is intact. How does civil disobedience relate to society today? [3] Each afferent limb has two efferent limbs, one ipsilateral and one contralateral. {\displaystyle T_{p}} Eyes directed nasally during accommodation. The medial rectus is innervated by motor neurons in the oculomotor nucleus and nerve. Section of the left short ciliary nerve or a benign lesion in the left ciliary ganglion will result in no direct response to light in the left eye and no consensual response in the left eye when light is directed on the right eye (a.k.a., tonic pupil). Immediately following denervation injury, there is a dilated pupil that is unresponsive to light or near stimulation. CONTINUE SCROLLING OR CLICK HERE. Contents 1Background 2Eye Reflexes 2.1Pupillary light reflex 2.2Pupillary dark reflex 2.3Other Pupil Reflexes 2.4Ciliospinal Reflex 2.5Near accommodative triad 2.6Corneal reflex 2.7Vestibulo-ocular reflex 2.8Palpebral oculogyric reflex (Bell's reflex) 2.9Lacrimatory reflex 2.10Optokinetic reflex 2.11Oculocardiac reflex 2.12Oculo-respiratory reflex The normal pupil size in adults varies from 2 to 4 mm in diameter in bright light to 4 to 8 mm in the dark. A single lesion anywhere along segment 1, the left afferent limb, which includes the left retina, left optic nerve, and left pretectal nucleus, can produce the light reflex abnormalities observed. Fibers from the LGN then project to the visual cortex. While light stimulates the parasympathetic output, giving rise to the light reflex, it can both inhibit and stimulate the sympathetic output. Caloric stimulation can also be used to examine the VOR[4]. The main types of pupillary abnormalities include: Anisocoria: unequal pupil sizes. What are the five methods of dispute resolution? Figure 7.5 c The neural pathway of the pupillary light reflex as first described by Wernicke [1, 2] in 1880s consists of four neurons (Fig. The oculomotor nerve is responsible for the efferent limb of the pupillary reflex; it drives the iris muscles that constrict the pupil.[1]. Pathway: Short ciliary nerves come together at the ciliary ganglion and converge with the long ciliary nerve to form the ophthalmic division of the trigeminal nerve, which continues to the Gasserian ganglion and then the main sensory nucleus of the trigeminal nerve[20]. (c) What are the directions of his acceleration at points A,BA, BA,B, and CCC? Pupillary escape can occur on the side of a diseased optic nerve or retina, most often in patients with a central field defect. London, R. Optokinetic nystagmus: a review of pathways, techniques and selected diagnostic applications. Observation: You observe that the patient's pupils, Side & Level of damage: As the pupillary light response deficit involves. retina, optic nerve, optic chiasm, and the optic tract fibers that join the ; brachium of the superior colliculus, which terminate in the ; pretectal area of the midbrain, which sends most of its axons bilaterally in the posterior commissure to terminate in the Symptoms. Physical examination determines that touch, vibration, position and pain sensations are normal over the entire the body and over the lower left and right side of his face. The Parasympathetic nervous system predominately controls the pupillary light reflex. However, the responses to light in both eyes may be weaker because of the reduced afferent input to the ipsilesional pretectal area. Section of the trigeminal nerve will eliminate somatosensory sensation from the face and the eye blink reflex (e.g., with section of the left trigeminal nerve, light touch of the left cornea will not produce an eye blink in the left or right eye). Postganglionic fibers travel with the lacrimal nerve to reach the lacrimal gland and cause reflex tearing. Therefore, options (a), (d), (e), (f), and (g) are possible. Among the physiological reflexes of the human body, the muscle strain reflex and the pupillary reflex stand out. This syndrome is characterized by miosis (pupil constriction), anhidrosis (loss of sweating), pseudoptosis (mild eyelid droop), enopthalmosis (sunken eye) and flushing of the face. Which of the following cranial nerve mediates the corneal reflex? In human nervous system: Reflex actions.
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