The oculomotor nerve , also known as the third cranial nerve , cranial nerve III , or simply CN III , is a cranial nerve that enters the orbit through the superior orbital fissure and innervates extraocular muscles that enable most movements of the eye and that raise the eyelid. The nerve also contains fibers that innervate the intrinsic eye muscles that enable pupillary constriction and accommodation (ability to focus on near objects as in reading). The oculomotor nerve is derived from the basal plate of the embryonic midbrain . Cranial nerves IV and VI also participate in control of eye movement .
43-409: The oculomotor nerve originates from the third nerve nucleus at the level of the superior colliculus in the midbrain. The third nerve nucleus is located ventral to the cerebral aqueduct , on the pre-aqueductal grey matter . The fibers from the two third nerve nuclei located laterally on either side of the cerebral aqueduct then pass through the red nucleus . From the red nucleus fibers then pass via
86-446: A nucleus ( pl. : nuclei ) is a cluster of neurons in the central nervous system , located deep within the cerebral hemispheres and brainstem . The neurons in one nucleus usually have roughly similar connections and functions. Nuclei are connected to other nuclei by tracts , the bundles (fascicles) of axons (nerve fibers) extending from the cell bodies. A nucleus is one of the two most common forms of nerve cell organization,
129-550: A clear view of the world, the brain must turn the eyes so that the image of the object of regard falls on the fovea. Eye movement is thus very important for visual perception, and any failure can lead to serious visual disabilities. To see a quick demonstration of this fact, try the following experiment: hold your hand up, about one foot (30 cm) in front of your nose. Keep your head still, and shake your hand from side to side, slowly at first, and then faster and faster. At first you will be able to see your fingers quite clearly. But as
172-477: A large "H" in front of the patient. By observing the eye movement and eyelids , the examiner is able to obtain more information about the extraocular muscles , the levator palpebrae superioris muscle , and cranial nerves III, IV, and VI. Loss of function of any of the eye muscles results in ophthalmoparesis . Since the oculomotor nerve controls most of the eye muscles, it may be easier to detect damage to it. Damage to this nerve, termed oculomotor nerve palsy ,
215-403: A scene has an influence on subsequent eye movements. In bottom-up factors, the local contrast or prominence of features in an image, such as a large contrast in luminance or a greater density of edges, can affect the guidance of eye movements. However, the top-down factors of scenes have a greater impact in where eyes fixate. Areas containing more meaningful features, or areas where colour aids
258-414: A small cortical region in the brain's frontal lobe . This is corroborated by removal of the frontal lobe. In this case, the reflexes (such as reflex shifting the eyes to a moving light) are intact, though the voluntary control is obliterated. Six extraocular muscles facilitate eye movement. These muscles arise from the common tendinous ring (annulus of Zinn) in the orbit (eye cavity), and attach to
301-481: A specialised type of tissue containing photoreceptors , senses light. These specialised cells convert light into electrochemical signals. These signals travel along the optic nerve fibers to the brain, where they are interpreted as vision in the visual cortex . Primates and many other vertebrates use three types of voluntary eye movement to track objects of interest: smooth pursuit , vergence shifts and saccades . These types of movements appear to be initiated by
344-422: A third nerve palsy with loss of the pupillary reflex (in fact, this third nerve finding is considered to represent an aneurysm—until proven otherwise—and should be investigated). Cranial nerves III, IV, and VI are usually tested together as part of the cranial nerve examination . The examiner typically instructs the patient to hold his head still and follow only with the eyes a finger or penlight that circumscribes
387-480: A wide variety of sensory, motor, and regulatory functions. In the peripheral nervous system (PNS), a cluster of cell bodies of neurons (homologous to a CNS nucleus) is called a ganglion . The fascicles of nerve fibers in the PNS (homologous to CNS tracts) are called nerves . This neuroanatomy article is a stub . You can help Misplaced Pages by expanding it . Eye movement (sensory) Eye movement includes
430-431: Is a large variability in this approximation. This variability is mostly due to the properties of an image and in the task being carried out, which impact both bottom-up and top-down processing. The masking of an image and other degradations, such as a decrease in luminance , during fixations (factors which affect bottom-up processing), have been found to increase the length of fixation durations. However, an enhancement of
473-406: Is due to the action of the inferior rectus. When the eye is adducted, the oblique muscles are the prime vertical movers. Elevation is due to the action of the inferior oblique muscle, while depression is due to the action of the superior oblique muscle. The oblique muscles are also primarily responsible for torsional movement. The muscles are supplied by the oculomotor nerve , with the exception of
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#1732883877607516-565: Is in some cases used rather loosely, to mean simply an identifiably distinct group of neurons, even if they are spread over an extended area. The reticular nucleus of the thalamus , for example, is a thin layer of inhibitory neurons that surrounds the thalamus. Some of the major anatomical components of the brain are organized as clusters of interconnected nuclei. Notable among these are the thalamus and hypothalamus , each of which contains several dozen distinguishable substructures. The medulla and pons also contain numerous small nuclei with
559-439: Is known by its down and out symptoms, because of the position of the affected eye (lateral, downward deviation of gaze). The oculomotor nerve also controls the constriction of the pupils and thickening of the lens of the eye. This can be tested in two main ways. By moving a finger toward a person's face to induce accommodation , their pupils should constrict. Shining a light into one eye should result in equal constriction of
602-401: Is related to the photoreceptors and the ganglion cells. It appears that a constant visual stimulus can make the photoreceptors or the ganglion cells become unresponsive; on the other hand a changing stimulus will not. So the eye movement constantly changes the stimuli that fall on the photoreceptors and the ganglion cells, making the image clearer. Saccades are the rapid movement of eyes that
645-442: Is the division of eye movements into the rapid movement of the eyes ( saccades ), and the focus of the eyes on a point (fixations). Several factors can influence eye movement in scene viewing, including the task and knowledge of the viewer (top-down factors), and the properties of the image being viewed (bottom-up factors). Typically, when presented with a scene, viewers demonstrate short fixation durations and long saccade amplitudes in
688-521: Is the movement of both eyes to make sure that the image of the object being looked at falls on the corresponding spot on both retinas. This type of movement helps in the depth perception of objects. Pursuit movement or smooth pursuit is the movement the eyes make while tracking an object's movement, so that its moving image can remain maintained on the fovea . The eyes are never completely at rest: they make frequent fixational eye movement even when fixated at one point. The reason for this movement
731-434: Is used while scanning a visual scene. In our subjective impression, the eyes do not move smoothly across the printed page during reading. Instead, they make short and rapid movements called saccades. During each saccade the eyes move as fast as they can and the speed cannot be consciously controlled in between the fixations. Each movement is worth a few minutes of arc, at regular intervals about three to four per second. One of
774-410: The eyeball . The six muscles are the lateral , medial , inferior and superior recti muscles , and the inferior and superior oblique muscles. The muscles cause movement of the eyeball by pulling the eyeball towards the muscle when contracting and by letting it go when relaxing. For example, the lateral rectus is on the lateral side of the eyeball. When it contracts, the eyeball moves so that
817-409: The substantia nigra to emerge from the substance of the brainstem at the oculomotor sulcus (a groove on the lateral wall of the interpeduncular fossa ). On emerging from the brainstem , the nerve is invested with a sheath of pia mater , and enclosed in a prolongation from the arachnoid . It passes between the superior cerebellar (below) and posterior cerebral arteries (above), and then pierces
860-428: The superior oblique muscle , and the abducens nerve , which controls the lateral rectus muscle. In addition to the movement of muscles, numerous areas in the brain contribute to involuntary and voluntary eye movement. These include providing the conscious perception of vision , as well as areas that facilitate tracking . Eye movement can be classified according to two systems: Vergence movement or convergence
903-436: The voluntary or involuntary movement of the eyes. Eye movements are used by a number of organisms (e.g. primates , rodents , flies , birds , fish , cats , crabs , octopus ) to fixate, inspect and track visual objects of interests. A special type of eye movement, rapid eye movement , occurs during REM sleep . The eyes are the visual organs of the human body, and move using a system of six muscles . The retina ,
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#1732883877607946-434: The classical sense, occurs with sparing (or preservation) of the pupillary reflex. This is thought to arise due to the anatomical arrangement of the nerve fibers in the oculomotor nerve; fibers controlling the pupillary function are superficial and spared from ischemic injuries typical of diabetes. On the converse, an aneurysm which leads to compression of the oculomotor nerve affects the superficial fibers and manifests as
989-489: The discrimination of objects, can influence eye movements. Images which are related to previous images shown can also have an effect. Eye movements can also be guided towards items when they are heard verbally at the same time as seeing them. Cross-culturally, it has been found that Westerners have an inclination to concentrate on focal objects in a scene, whereas East Asians attend more to contextual information. Average fixation durations last for about 330 ms, although there
1032-412: The dura mater anterior and lateral to the posterior clinoid process , passing between the free and attached borders of the tentorium cerebelli . It traverses the cavernous sinus , above the other orbital nerves receiving in its course one or two filaments from the cavernous plexus of the sympathetic nervous system, and a communicating branch from the ophthalmic division of the trigeminal nerve. As
1075-473: The earlier phases of viewing an image. This is followed by longer fixations and shorter saccades in the latter phases of scene viewing processing. It has also been found that eye movement behaviour in scene viewing differs with levels of cognitive development - fixation durations are thought to shorten and saccade amplitudes lengthen with an increase in age. Where eye movements fixate is affected by both bottom-up and top-down factors. Even an initial glimpse of
1118-537: The extrinsic muscles except superior oblique and lateral rectus.) The nerve also includes axons of type GVE, general visceral efferent , which provide preganglionic parasympathetics to the ciliary ganglion. From the ciliary ganglion postganglionic fibers pass through the short ciliary nerve to the constrictor pupillae of the iris and the ciliary muscles. Paralysis of the oculomotor nerve, i.e., oculomotor nerve palsy , can arise due to: In people with diabetes and older than 50 years of age, an oculomotor nerve palsy, in
1161-422: The eye is slightly different in that the eyes are not rigidly attached to anything, but are held in the orbit by six extraocular muscles . When reading, the eye moves continuously along a line of text, but makes short rapid movements (saccades) intermingled with short stops (fixations). There is considerable variability in fixations (the point at which a saccade jumps to) and saccades between readers and even for
1204-429: The eye. In the primary position (eyes straight ahead), both of these groups contribute to vertical movement. Elevation is due to the action of the superior rectus and inferior oblique muscles, while depression is due to the action of the inferior rectus and superior oblique muscles. When the eye is abducted, the recti muscles are the prime vertical movers. Elevation is due to the action of the superior rectus, and depression
1247-400: The eyes move over the page in fixations and saccades, picking up and processing coded meanings. However, music is nonlinguistic and involves a strict and continuous time constraint on an output that is generated by a continuous stream of coded instructions. Eye movement in scene viewing refers to the visual processing of information presented in scenes. A core aspect of studies in this area
1290-420: The frequency of shaking passes about 1 Hz , the fingers will become a blur. Now, keep your hand still, and shake your head (up and down or left and right). No matter how fast you shake your head, the image of your fingers remains clear. This demonstrates that the brain can move the eyes opposite to head motion much better than it can follow, or pursue, a hand movement. When your pursuit system fails to keep up with
1333-444: The images are slipping across the retina at more than a few degrees per second. Thus, to be able to see while we are moving, the brain must compensate for the motion of the head by turning the eyes. Another specialisation of visual system in many vertebrate animals is the development of a small area of the retina with a very high visual acuity . This area is called the fovea , and covers about 2 degrees of visual angle in people. To get
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1376-403: The larger, divides into three branches. All these branches enter the muscles on their ocular surfaces, with the exception of the nerve to the inferior oblique, which enters the muscle at its posterior border. The oculomotor nerve (CN III) arises from the anterior aspect of the mesencephalon (midbrain). There are two nuclei for the oculomotor nerve: Sympathetic postganglionic fibres also join
1419-427: The lateral and medial recti muscles, the superior and inferior recti muscles, and the superior and inferior oblique muscles. These muscles are responsible for movement of the eye along three different axes: horizontal, either toward the nose (adduction) or away from the nose (abduction); vertical, either elevation or depression; and torsional, movements that bring the top of the eye toward the nose (intorsion) or away from
1462-454: The main uses for saccades is to scan a greater area with the high-resolution fovea of the eye. Research conducted by the University of South Australia in partnership with the University of Stuttgart showed a relationship between eye moment and personality traits , which artificial intelligence could then predict. The visual system in the brain is too slow to process that information if
1505-412: The moving hand, images slip on the retina and you see a blurred hand. The brain must point both eyes accurately enough that the object of regard falls on corresponding points of the two retinas to avoid the perception of double vision . In most vertebrates (humans, mammals, reptiles, birds), the movement of different body parts is controlled by striated muscles acting around joints. The movement of
1548-439: The nerve from the plexus on the internal carotid artery in the wall of the cavernous sinus and are distributed through the nerve, e.g., to the smooth muscle of superior tarsal (Mueller's) muscle. The oculomotor nerve includes axons of type GSE, general somatic efferent , which innervate skeletal muscle of the levator palpebrae superioris, superior rectus, medial rectus, inferior rectus, and inferior oblique muscles. (Innervates all
1591-423: The nose (extorsion). Horizontal movement is controlled entirely by the medial and lateral recti muscles; the medial rectus muscle is responsible for adduction, the lateral rectus muscle for abduction. Vertical movement requires the coordinated action of the superior and inferior recti muscles, as well as the oblique muscles. The relative contribution of the recti and oblique groups depends on the horizontal position of
1634-403: The oculomotor nerve enters the orbit via the superior orbital fissure it then divides into a superior and an inferior branch. The superior branch of the oculomotor nerve or the superior division , the smaller, passes medially over the optic nerve . It supplies the superior rectus and levator palpebrae superioris . The inferior branch of the oculomotor nerve or the inferior division ,
1677-449: The other being layered structures such as the cerebral cortex or cerebellar cortex . In anatomical sections, a nucleus shows up as a region of gray matter , often bordered by white matter . The vertebrate brain contains hundreds of distinguishable nuclei, varying widely in shape and size. A nucleus may itself have a complex internal structure, with multiple types of neurons arranged in clumps (subnuclei) or layers. The term "nucleus"
1720-517: The other eye. Fibers from the optic nerves cross over in the optic chiasm with some fibers passing to the contralateral optic nerve tract. This is the basis of the " swinging-flashlight test ". Loss of accommodation and continued pupillary dilation can indicate the presence of a lesion on the oculomotor nerve. [REDACTED] This article incorporates text in the public domain from page 884 of the 20th edition of Gray's Anatomy (1918) Nucleus (neuroanatomy) In neuroanatomy ,
1763-471: The pupil looks outwards. The medial rectus causes the eyeball to look inwards; the inferior rectus downwards and outwards, and the superior rectus upwards and outwards. The superior oblique muscle and inferior oblique muscle attach at angles to the eyeball. The superior oblique muscle moves the eye downwards and inwards whereas the inferior oblique muscle moves the eye upwards and outwards. Three antagonistic pairs of muscles control eye movement:
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1806-428: The same person reading a single passage of text. Eye movement in music reading is the scanning of a musical score by a musician's eyes. This usually occurs as the music is read during performance, although musicians sometimes scan music silently to study it, and sometimes perform from memory without score. Eye movement in music reading may at first appear to be similar to that in language reading, since in both activities
1849-414: The superior oblique, which is supplied by the trochlear nerve , and the lateral rectus, supplied by the abducens nerve . The brain exerts ultimate control over both voluntary and involuntary eye movement. Three cranial nerves carry signals from the brain to control the extraocular muscles. These are the oculomotor nerve , which controls the majority of the muscles, the trochlear nerve , which controls
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