Levy DL, Holzman PS, Proctor LR. There are 12 of them, each named for its function or structure. are four recti muscles; superior rectus, inferior rectus, medial rectus and lateral rectus. These signals instruct the oculomotor nucleus to send signals to medial rectus of the right eye to adduct simultaneously (so that both eyes look in the same direction). Sciatica is a common problem and can be treated in a number, Foot numbness is the loss of sensory nerve function, usually caused by a decrease in blood flow, to the foot's nerves. There are evaluation techniques that include casual observation and simple tests that require no equipment and can be done in the psychiatrists office. Trochlear nerve: Ability to move your eyes up and down or back and forth. Neuroanatomy, cranial nerve. Frequent lateral gazes (shifty eyes) sometimes implies anxiety or deception, but also may be assumed to reflect hypervigilance, paranoia, or hallucination. The sequence begins with light-induced activation of retinal fibers (the afferent component of the reflex). The inferior rectus muscle originates at the inferior part of the common tendinous ring below the optic canal, and inserts on the inferior surface of the sclera approximately 6 mm from limbus. Perhaps because of this, isolated lesions of CNVI, manifested by ipsilateral loss of lateral gaze (and inward deviation or esotropia at rest), are more common than of the others. It starts in the medulla oblongata and moves down into the jaw, where it reaches the tongue. The axons of the facial nerve loop around the abducens nucleus and form bulge in the floor of fourth ventricle called facial colliculus. Omnipause neurons, which inhibit the burst neurons, are in the pons. Original Author(s): Oliver Jones Last updated: December 22, 2022 Download the cranial nerve examination PDF OSCE checklist, or use our interactive OSCE checklist. Siegle GJ, Steinhauer SR, Thase ME. Eye movement includes the voluntary or involuntary movement of the eyes. (2021). In the vestibulo-ocular reflex, brief, rapid head movements provoke rapid compensatory eye movements. Vestibular responses in schizophrenia. Optic nerve (CN II) enables vision. Responsible for eye movement - Recti and oblique muscles. Which cranial nerve does not deal with eye movement? If a condition or injury affects your cranial nerves, you may have problems with your sense of taste, smell or vision. In contrast to the LPS, the superior tarsal muscle is innervated by the sympathetic nervous system. As such, deficits include contralateral hemiplegia due to damage to corticospinal fibers; ipsilateral eye movement paralysis with a fixed, dilated pupil and drooping lid due to oculomotor nerve damage; and cerebellar tremor and rubral ataxia due to damage to cerebellothalamic fibers and the red nucleus. The information received by your rods and cones is sent from your retina to your optic nerve. Cleveland Clinic is a non-profit academic medical center. They are elicited by having the patient rapidly shift gaze between two targets. Nystagmus is more common in schizophrenia than in health and mood disorders, with rates of 5 to 20 percent.8,19,20 It is more common in alcoholism (not during intoxication) than common psychiatric disorders.20 Phencyclidine intoxication, which often resembles idiopathic psychosis, presents with nystagmus in more than 50 percent of acute cases.21, Strabismus was more frequent in one large sample with schizophrenia (13%) than in healthy controls (4.4%); this was particularly true of exotropia (8.2% vs. 0.6%).22 Strabismus in childhood also predicts adult schizophrenia-spectrum disorder.23. - Test pursuit eye movement without head movement - Strabismus and impaired eye movement - CN III: Ptosis, pupil dilation - CN . The information we provide is grounded on academic literature and peer-reviewed research. This is present when the eyes protrude from the contour of the face, when viewed from behind and directly over the crown. Most people who develop optic neuritis have eye pain that's worsened by eye movement. Axons arisingfrom the nucleus course dorsally around the periaqueductal grey matter and cerebral aqueduct and cross the midline. Bordoni B, et al. Normally the eyes will displace in such a way as to maintain the direction of gaze (in spite of the changed position of the head). Abducens nerve contains only somatic efferent fibers to innervate only one muscle of the orbit, lateral rectus. Acute phencyclidine intoxication: incidence of clinical findings in 1,000 cases. . Abducens nerve: Ability to move your eyes. A small portion of this musclecontains a collection of smooth muscle fibres known as the superior tarsal muscle. The presence of large or rapidly expanding supratentorial lesion (i.e. Coming to a Cleveland Clinic location?Hillcrest Cancer Center check-in changesCole Eye entrance closingVisitation and COVID-19 information. It's also known as the abducens nerve. Eat a diet full of nutrient-dense foods like fruits, vegetables and whole grains. A cranial nerve disorder might affect your: You can keep your brain, cranial nerves and entire nervous system healthier with a few lifestyle changes. Helwany M, et al. Again, the contralateral hemiplegia is due to fact that the corticospinal fibers have not yet decussated to the side of the body that they are intended to innervate, so compression of corticospinal tract fibers prior to their decussation in the medulla leads to loss of motor innervation to the opposite side of the body. (2021). Your cranial nerves are pairs of nerves that connect your brain to different parts of your head, neck, and trunk. Fig 1 Attachment of the levator palpebrae superiors to the superior tarsal plate. Contact your healthcare provider if you experience: A note from Cleveland ClinicYour cranial nerves are nerve pairs in your brain. This occurs due to the intricacies of connectivity between the abducens and oculomotor nuclei. Symptoms might include: Pain. Cranial nerve mnemonics to remember the names of the nerves in order include: To remember cranial nerve functions, the words in the mnemonic start with: The word order mirrors the numerical order of nerves one through 12: Some conditions or injuries can damage parts of the brain where cranial nerves are located. They can also change the way you perceive sensation on the face and prevent or alter the movement of the head, eyes, neck, shoulders, throat, and tongue. Fig 4 Left sided Horners syndrome. Reviewer: The .gov means its official. Lesions of the lateral pons and their associated clinical presentations are often referred to as Gubler syndrome, or Miller-Gubler syndrome; but basilar pontine lesions specifically involving the trigeminal root may also be referred to as midpontine base syndrome. Necessary cookies are absolutely essential for the website to function properly. The sensory root of your trigeminal nerve branches into the ophthalmic, maxillary, and mandibular divisions. and grab your free ultimate anatomy study guide! Ever wondered how our eyes move? A tumor in this location may arise from a variety of different types of cells, and as such may be a germinoma, astrocytoma, pineocytoma, or pineoblastoma. Eyelids. The monograph by Leigh and Zee (1983) and the book by Miller (1985) are excellent sources of further information. Rather than affecting the oculomotor nerve and crus cerebri on the same side of the brain, shifting of the midbrain leads to stretching of the ipsilateral oculomotor nerve (i.e. Vision loss in one eye. You may receive rehabilitation from professionals including: The symptoms of cranial nerve injuries or conditions vary depending on which nerve is affected. This involves a complex circuit: Dorsal stream signals proceed from the diencephalons lateral geniculate nucleus to occipital and posterior parietal cortex. Ooh, ooh, ooh to touch and feel very good velvet. Olfactory nerve (CN I) enables sense of smell. To change visual fixation or to maintain fixation on an object that is moving relative to the observer, the eyes have to move with exquisite precision, and both eyes must . This is in contrast with the oblique eye muscles, which have an angular approach to the eyeball. Get useful, helpful and relevant health + wellness information. Normally, the eyes stay focused on the object (via the vestibular ocular reflex). Heterotropia (strabismus) of early onset is not associated with diplopia, as only one eye functions.1,2, Impaired upgaze, or raising the eyebrows or forehead during upgaze, may be a Parkinsonian sign,10 but is also attributed to normal aging. We also use third-party cookies that help us analyze and understand how you use this website. In addition to their value in localizing lesions, these three oculomotor nerves (sensory function is limited to proprioception) can reveal subtle changes in general skeletal and smooth muscle activity. Parasympathetic axons branch from the nerve to inferior oblique and terminate in the ciliary ganglion. Ocular motor cranial nerves: want to learn more about it? 9500 Euclid Avenue, Cleveland, Ohio 44195 |, Important Updates + Notice of Vendor Data Event, (https://www.aans.org/en/Patients/Neurosurgical-Conditions-and-Treatments/Anatomy-of-the-Brain). The nerve enters the orbit via the superior orbital fissure along with the oculomotor nerve, the trochlear nerve, and the ophthalmic division of the trigeminal nerve. These cookies will be stored in your browser only with your consent. This is the muscle thats in charge of downward, outward, and inward eye movements. Stevens JR. Disturbances of ocular movements and blinking in schizophrenia. Your brainstem connects your brain and spinal cord. Responsible for superior eyelid movement - Levator palpebrae superioris. Neurological signs and psychomotor performance in patients with schizophrenia, their relatives and healthy controls. As there are now doubts about the validity of bedside assessments, it is probably best left to specialists. In normal light, during extraocular motor testing, observe the pupils response during convergence. Each nerve pair splits to serve the two sides of your brain and body. Pupils. Saccades, being more sensitive to supranuclear dysfunction, are probably more useful in psychiatric assessment. If the lesion extends to affect medial lemniscus and trigeminothalamic fibers, an affected individual may also present with a loss or reduction in position, vibration, and fine touch sensation in the contralateral arm and parts of the contralateral face respectively. This nerve is the fourth set of cranial nerves (CN IV or cranial nerve 4). Muehlig WA. Eventually, the two nerves fuse together to form the facial nerve. Rods are found in large numbers and are highly sensitive to light. Posterior parietal output to the pons is relayed to cerebellum, which projects to the oculomotor nuclei. Pupillary light reflex testing reveals a symmetrical response of pupillary constriction. Contraction of the inferior rectus depresses, adducts, and laterally rotates the eye, and as such it is the main muscle responsible for downward gaze. Your vagus nerve has both sensory and motor functions. Weber syndrome, otherwise known as medial midbrain syndrome, presents with a constellation of symptoms referred to as a superior alternating hemiplegia. (2022). Causes include frostbite and, Healthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. This cranial nerve examination OSCE guide provides a clear step-by-step approach to examining the cranial nerves, with an included video demonstration. An official website of the United States government. Your cranial nerves help you taste, smell, hear and feel sensations. Motor nerves control the movement and function of muscles or glands. Cranial nerve mnemonics are memory devices to help you remember the names of the nerves in order of one through 12. I would honestly say that Kenhub cut my study time in half. By Waster [CC-BY-2.5] via Wikimedia Commons, [caption id="attachment_8508" align="aligncenter" width="581"], [caption id="attachment_8510" align="aligncenter" width="599"], [caption id="attachment_37471" align="aligncenter" width="477"], [caption id="attachment_10244" align="aligncenter" width="188"]. Fourth nerve (superior oblique) palsy. If you want to learn more about the cranial nerves, check out our summary. This can result in damage to a number of structures, including: It should be noted that the exact constellation of symptoms observed will depend significantly on whether the lesion occurs in the rostral or caudal regions of the pons. They begin in the nuclei of the brain and travel different paths to help control your senses and movement. Contraction of the medial rectus adducts the eye, both medial recti act together for convergence. This connection allows it to play a crucial role in synchronizing horizontal gaze. The optokinetic response consists of slow tracking pursuit movements and quick resetting saccades. (2021). You can keep your entire nervous system healthier by eating nutritious foods, exercising and managing any health conditions. Smooth pursuit is famously impaired in schizophrenia, as well as in mood disorders.5. This complex is located at the level of superior colliculus near the midline. Dacso CC, Bortz DL. Pupillary reactivity to emotional information in child and adolescent depression: links to clinical and ecological measures. The nerve arises from motor neurons in the trochlear nucleus, which lies . They also help you make facial expressions, blink your eyes and move your tongue. It stimulates receptors that generate nerve impulses that move to your olfactory bulb. Kenny BJ, et al. Neuroanatomy, cranial nerve 3 (oculomotor). The reflection from both eyes should appear symmetric and generally slightly nasal to the center of the pupil. These fibers synapse with neurons in pretectal region, which in turn project to the oculomotor nucleus. Herniating tissue puts pressure on the ipsilateral oculomotor nerve and crus cerebri. Silk JS, Dahl RE, Ryan ND, et al. Influencing the nuclei are widespread, higher (supranuclear) systems.1,2. Nystagmus (in this case, gaze-evoked nystagmus) consists of more or less rhythmic excursions from and back to the target. loss of function of the levator palpebrae superioris; medial, superior, and inferior recti; and inferior oblique muscles) with retention of special visceral afferent function of the constrictor pupillae muscle. The glossopharyngeal nerve has both motor and sensory functions, including: The glossopharyngeal nerve originates in a part of your brainstem called the medulla oblongata. Sensory nerves involve your senses, such as smell, hearing, and touch. Tregellas JR, Tanabe JL, Miller DE, et al. Vestibular and cochlear nerves (CN VII) enable balance and hearing. Graves disease. Read more. Because projections from the pretectal to the Edinger-Westphal nuclei are bilateral, the pupils should respond about equally to light shined on either eye. These nerves are paired and present on both sides of the body. But opting out of some of these cookies may affect your browsing experience. Neuroanatomy, cranial nerve 6 (abducens). You also have the option to opt-out of these cookies. If rebound nystagmus is seen, cerebellar disease is virtually confirmed. Because of factors such as ambient light, arousal, and attention, subtle variations in pupil size are difficult to interpret in clinical practice. (2021). Anatomy Cranial nerves and Eye movements Get a hint Which cranial nerves supply the eye and its muscles? Neuroanatomy, cranial nerve 2 (optic). Sixth nerve palsy is a disorder that affects eye movement. Technically it is a mononeuropathy because it, Experiencing a numb mouth on its own is usually not a sign of anything serious, but it can make you wonder. Smith AM, et al. Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. Cerebral ocular motor signs. As such, it is frequently associated with hypertension, diabetes, or hyperlipidemia. They can be divided into two groups; the four recti muscles, and the two oblique muscles. According to the National Institute of Neurological Disorders and Stroke (NINDS), certain practices may reduce your risk for a stroke or cardiovascular disease. Shaunak S, OSullivan E, Kennard C. Eye movements. Smooth pursuit movements, the most commonly tested extraocular movements, are tested by asking the patient to visually track a target (follow this with your eyes only), and then the clinician moves the target (e.g., the tip of your finger or pen) smoothly to the vertical and horizontal extremes of the patients tracking ability. Thus, alesion of each cranial nerve has its own characteristic appearance: (A good tool to remember the innervation of the extraocular muscles is LR6 SO4 R3), Fig 3 Right oculomotor nerve palsy, characterised by the down and out dilated pupil with ipsilateral ptosis. The patient is asked to focus on some distant object, even if the view of the object is obstructed. Dulak D, et al. Proptosis or exopthalmia can reflect thyroid disease. Fibers originating from the frontal eye fields project to two regions: the rostral interstitial nucleus of the MLF (riMLF), known as the vertical gaze center; and in the paramedian pontine reticular formation (PPRF), the pontine horizontal gaze center. Anatomical substrates of oculomotor control. (2021). That's why we've put together these 8, The telltale symptoms of sciatic nerve pain are severe pain in your back, buttocks, and legs. Such heaven! 3rd cranial nerve Cranial Nerve IV (Trochlear) controls downward eye movement toward the nose, and Cranial Nerve VI (Abducens) controls horizontal eye movement toward the temple. Spontaneous eye movements also have conventionally accepted implications. Anisocoria was found in 5 to 11 percent of patients with schizophrenia, more than in healthy persons.7,8 More recently, pupillary findings were no more prevalent in schizophrenia than in health.9 Pupil studies are now generally conducted using tightly controlled conditions and instrumentation that cannot be matched in usual clinical settings. The signals of Edinger-Westphal nucleus to sphincter like pupillary muscles result in the smaller pupil to sharpen the image on retina. Motor activity affecting the direction of gaze, the position of the eyelids, and the size of the pupils are served by cranial nerves III, IV, and VI. In some cases, a condition may damage only one cranial nerve. The longest cranial nerve is the vagus nerve. Burst neurons, which activate saccades, are in the pons and the midbrain. Trigeminal: Associated with collecting information. Nadia Solomon Pupillary assessment and computational modeling of the Stroop task in depression. This is a ring of fibrous tissue,which surrounds the optic canal at the back of the orbit. National Library of Medicine Your cranial nerves are pairs of nerves that connect your brain to different parts of your head, neck, and trunk. When the eyes revert to their resting forward position, observe for rebound nystagmus (a few beats of conjugate jerk nystagmus in a direction opposite to the previous lateral gaze). This chapter deals with the examination of five aspects of ocular function: fixation, saccadic movements, pursuit movements, compensatory movements and opticokinetic nystagmus. The neurological evaluation scale (NES): a structured instrument for the assessment of neurological signs in schizophrenia. This condition causes problems with eye movement. At the medial corner of each eye, the epicanthal fold (obscuring the caruncle) is a common anomaly; its most common pathological significance is Down syndrome (trisomy 21). The spinal accessory nerve is responsible for controlling the muscles of the neck, along with cervical spinal nerves. Gaze fixation freezes the gaze in a new position after a saccade. The trochlear nerve is a purely motor nerve with only a GSE component. The vestibular portion begins in your pons and medulla. 2023 HHS Vulnerability Disclosure, Help Simply from the name then, it is easy to know that the oculomotor nerve will innervate muscles that move the eye itself or components of the eye. Light-near dissociation, an uncommon finding of pupils constricting briskly with near vision but not on exposure to light, might be due to an afferent CNII lesion (Argyll-Robertson pupil), disrupted parasympathetic efferents (Adies tonic pupil), or injury to the dorsal midbrain (dorsal midbrain syndrome or Parinauds syndrome). There are several anatomically distinguishable types of eye movement.3,4 Saccades are high-velocity movements used for visual search. This information is intended for medical education, and does not create any doctor-patient relationship, and should not be used as a substitute for professional diagnosis and treatment. Copyright The nucleus is in the midbrain. In the awake person at rest, eyelids usually slightly cover the superior iris but leave a small white gap beneath the inferior iris. Unusual oculomotor activity is often encountered in psychiatric patients and can be quite informative. When the right abducens nucleus sends signals to the right lateral rectus muscle to contract, which pulls the right eye laterally to look right, it also sends signals via the MLF to the left oculomotor nucleus. These muscles receive their signals from the brain from a group of nerves called the cranial nerves. Median pontine syndrome typically occurs when there is occlusion of the paramedian branches of the basilar arteryand subsequent ischemia of the medial aspect of the pons. This means the ipsilateral eye cannot abduct, and the contralateral eye cannot adduct. All rights reserved. This nerve originates in the front part of your midbrain, which is a part of your brainstem. It should be noted that in specialized labs pupilometry can reveal the extent of a subjects interest or effort, and can reveal much about autonomic nervous function.2528, Extraocular motor function. The oculomotor nerve is the third cranial nerve (CN III), and one instance in which the name is a clear indication of the function of the nerve (Oculo = pertaining to the eye, motor = producing movement). In some cases, rehabilitation can be helpful to restore your nerve function. Kim Bengochea, Regis University, Denver. Author: Beyond screening for diseases and localizing lesions, these tests yield useful information about the individuals higher cortical function, extrapyramidal motor functioning, and toxic/pharmacologic state. Cranial nerves III (CNIII) (oculomotor), IV (trochlear), and VI (abducens) control the position of the eyeballs; CNIII influences the position of the eyelids and the size of the pupils. (2021). Or they can help you remember whether nerves are sensory, motor or both. The abducens nerve (CNVI) originates in the pons, thus travelling farther to its destination (the lateral rectus muscle) than the others. Damage to one of the cranial nerves will cause paralysis of its respective muscles. Our experts continually monitor the health and wellness space, and we update our articles when new information becomes available. The patient relaxes the neck as the examiner holds the head on either side. Through each optic tract, the nerve impulses eventually reach your visual cortex, which then processes the information. There are a total of 12 cranial nerves (CN): Of these, CN I, CN II, CN VII, CN VIII, CN IX and CN X play roles in special sensory functions (i.e. Anatomy Nerves The Anatomy of the Cranial Nerves These 12 nerves control facial and eye movements and sensation By Heidi Moawad, MD Updated on May 31, 2023 Medically reviewed by Lissette Pichardo, MD Table of Contents View All Olfactory Nerve Optic Nerve Oculomotor Nerve Trochlear Nerve Trigeminal Nerve There are 12 pairs of cranial nerves. The patient is an overweight, 64 year-old male with a medical history significant for hypertension and type II diabetes mellitus. A patient appears at your clinic complaining of diplopia, periorbital pain, and headache. 0 Shop NowFind Eye Doctor Conditions Conditions Eye Conditions, A-Z Eye Conditions, A-Z Neurodevelopmental indices and the development of psychotic symptoms in subjects at high risk of schizophrenia. Your vestibulocochlear nerve has sensory functions involving hearing and balance. (2021). You have 12 cranial nerve pairs. Grounded on academic literature and research, validated by experts, and trusted by more than 2 million users. (2021). It originates in the part of your brainstem called the medulla. Convergence of the eyes is brought about by both medial recti muscles supplied by somatic efferent component of the oculomotor nerve. Their functions are usually categorized as being either sensory or motor. Thus the width of the eye opening is under both voluntary and autonomic control.1,2 Blinking, either spontaneously or in response to a stimulus, is affected by the orbicularis oculi, innervated by CNVII, and will be covered in the next article of this series. Your hypoglossal nerve is the 12th cranial nerve. This is in contrast with the oblique eye muscles, which have an angular approach to the eyeball. Some say my mother bought my brother some bad beer, my, my. Recti muscles The eye has four recti muscles, all of which attach to the front half of the eye (anterior to the equator of the eye). With the patient sitting, the examiner holds the patient's head and asks the patient to focus on an object, such as the examiner's nose. Advertising on our site helps support our mission. The following article focuses on these muscles, their functions, and the nerves that innervate them. Revisions: 37. Contraction of the levator palpebrae superioris elevates the upper eyelid, opening the eye. Influence of age on clinical findings. The lateral rectus muscle originates at the lateral part of the common tendinous ring where it bridges the superior orbital fissure, and inserts on the lateral surface of the anterior aspect of the sclera. Most people have at least some temporary reduction in vision, but the extent of loss varies. The name recti is derived from the latin for 'straight' - this represents the fact that the recti muscles have a direct path from origin to attachment. Asymmetric pupils usually result from iris trauma or surgery.1,2, Pupillary responses to light (response) and near vision (accommodation) can be important. Isolated nerve dysfunction (IND) is a type of neuropathy (nerve damage) that occurs in a single nerve. The optic nerve is the sensory nerve that involves vision. National Institute of Neurological Disorders and Stroke (NINDS), ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Bells-Palsy-Fact-Sheet, ninds.nih.gov/Disorders/Patient-Caregiver-Education/Preventing-Stroke, ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Trigeminal-Neuralgia-Fact-Sheet. We tend to associate sunken eyes, prominent folds beneath the eyes, discoloration beneath the eyes, and conjunctival injection with distress and fatigue. Auditory/vestibular nerve: Sense of hearing and balance. Neuroanatomy, cranial nerve 9 (glossopharyngeal). You would use a saccadic eye movement to look from the page to someone in the room or if you were told to look up. Joyce C, et al. The lateral width of the palpebral fissure (apparent size of the eye) can be reduced in fetal alcohol syndrome and several other developmental syndromes. The frontal eye fields and parietal eye field also provide cortical input to the superior colliculus, which also provides input to the riMLF and PPRF. after they have crossed over from the opposite abducens nucleus). Learn what causes this condition and how to treat it. Cranial nerve V (the trigeminal nerve) supplies somatosensory innervation to the eyelid via its ophthalmic (V1) and maxillary (V2) divisions. Premorbid childhood ocular alignment abnormalities and adult schizophrenia-spectrum disorder. They act to control the movements of the eyeball and the superior eyelid. Attention to the functional integrity of cranial nerves III, IV, and VI can yield important information to the psychiatrist. It moves forward from that area until it reaches the area of your eye sockets. Most common among these is arcus senilis, a brownish-yellow ring. Dr. Gillig is Professor of Psychiatry and Faculty of the Graduate School, Department of Psychiatry, Boonshoft School of Medicine, Wright State University, Dayton, Ohio; Dr. Sanders is Associate Professor, Departments of Psychiatry and Neurology, Boonshoft School of Medicine, Wright State University, and Ohio VA Medical Center, Dayton, Ohio; psychiatry and neurology, oculomotor, extraocular movements, eye movements, nystagmus, pupil, examination of the visual system, cranial nerve III, cranial nerve IV, cranial nerve VI, oculomotor nerve, trochlear nerve, abducens nerve. If the oculomotor and abducens nerves are unaffected, the actions of the recti and inferior oblique muscles will be unopposed. There are six extraocular muscles: four rectus muscles (superior, inferior, lateral, medial) and two oblique (superior and inferior). The cranial part starts in your medulla oblongata. Bilaterally large pupils may represent stimulant, hallucinogen, or anticholinergic intoxication. The oculomotor nerve innervates the majority of extraocular muscles: the superior rectus and levator palpebrae superioris are innervated by superior division while inferior division innervate , medial, and inferior recti and the inferior oblique. We avoid using tertiary references. Bethesda, MD 20894, Web Policies Impaired down-gaze suggests progressive supranuclear palsy,10 but thyroid myopathy and orbital fractures may be responsible. You can: An injured nerve may recover with time. Eye movements are used by a number of organisms (e.g. This reflex has two main components, an afferent (sensory) component involving the optic nerve and an efferent (motor) component involving the oculomotor nerve.
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