Information about Oculomotor Nerve
| Nerve: Oculomotor nerve | ||
|---|---|---|
| Nerves of the orbit. Seen from above. | ||
| Latin | nervus oculomotorius | |
| subject #198 884 | ||
| Innervates | Superior rectus, Inferior rectus, Medial rectus, Inferior oblique, Ciliary | |
| From | oculomotor nucleus, Edinger-Westphal nucleus | |
| To | superior branch, inferior branch | |
| MeSH | Oculomotor+Nerve | |
Path
Nuclei
The oculomotor nerve arises from the anterior aspect of mesencephalon (midbrain). There are two nuclei for the oculomotor nerve:- The oculomotor nucleus originates at the level of the superior colliculus. The muscles it controls are the ciliary muscle (affecting accommodation), and all extraocular muscles except for the superior oblique muscle and the lateral rectus muscle.
- The Edinger-Westphal nucleus supplies parasympathetic fibres to the eye via the ciliary ganglion, and thus controls pupil constriction.
Emergence from brain
On emerging from the brain, 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 the dura mater in front of and lateral to the posterior clinoid process, passing between the free and attached borders of the tentorium cerebelli.
It runs along the lateral wall of the cavernous sinus, above the other orbital nerves, receiving in its course one or two filaments from the cavernous plexus of the sympathetic, and a communicating branch from the ophthalmic division of the trigeminal.
Superior and inferior rami
It then divides into two branches, which enter the orbit through the superior orbital fissure, between the two heads of the lateral rectus.Here the nerve is placed below the trochlear nerve and the frontal and lacrimal branches of the ophthalmic nerve, while the nasociliary nerve is placed between its two rami:
Testing the oculomotor nerve
Eye muscles
Cranial nerves III, IV and VI are usually tested together. The examiner typically instructs the patient to hold his head still and follow only with the eyes a finger or penlight that circumscribes a large "H" in front of the patient. By observing the eye movements 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.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 is also known by the down n' out symptoms, because of the position of the affected eye.
Pupillary reflex
The oculomotor nerve also controls the constriction of the pupils. This can be tested in two main ways. By moving a finger towards a person's face to induce accommodation, as well as them going cross-eyed, their pupils should constrict.Shining a light into their eyes should also make their pupils constrict. Both pupils should constrict at the same time, independent of what eye the light is actually shone on.
Additional images
Dura mater and its processes exposed by removing part of the right half of the skull, and the brain. | ) Tentorium cerebelli from above. | Coronal section through mid-brain. | Mesal aspect of a brain sectioned in the median sagittal plane. |
Hind- and mid-brains; postero-lateral view. | Median sagittal section of brain. | Dissection showing the course of the cerebrospinal fibers. | ) Plan of oculomotor nerve. |
Nerves of the orbit, and the ciliary ganglion. Side view. | Alveolar branches of superior maxillary nerve and sphenopalatine ganglion. | Figure showing the mode of innervation of the Recti medialis and lateralis of the eye. | ) Oblique section through the right cavernous sinus. |
Dissection showing origins of right ocular muscles, and nerves entering by the superior orbital fissure. | ) Pathways in the Ciliary Ganglion. |
See also
External links
- MedEd at Loyola GrossAnatomy/h_n/cn/cn1/cn3.htm
- oph/183 at eMedicine - "Oculomotor nerve palsy"
- MeSH Oculomotor+Nerve
- NeuroNames hier-479
- Norman/Georgetown cranialnerves (III)
Latin}}}
Official status
Official language of: Vatican City
Used for official purposes, but not spoken in everyday speech
Regulated by: Opus Fundatum Latinitas
Roman Catholic Church
Language codes
ISO 639-1: la
ISO 639-2: lat
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Official status
Official language of: Vatican City
Used for official purposes, but not spoken in everyday speech
Regulated by: Opus Fundatum Latinitas
Roman Catholic Church
Language codes
ISO 639-1: la
ISO 639-2: lat
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The superior rectus muscle is a muscle in the orbit. It is one of the extraocular muscles.
It is innervated by the superior division of the oculomotor nerve (Cranial Nerve III).
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It is innervated by the superior division of the oculomotor nerve (Cranial Nerve III).
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The inferior rectus muscle is a muscle in the orbit.
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Actions
It depresses, adducts, rotates laterally, and extorts the eye.Innervation
As with most of the muscles of the orbit, it is innervated by the oculomotor nerve (Cranial Nerve III)...... Click the link for more information.
The medial rectus muscle is a muscle in the orbit.
As with most of the muscles of the orbit, it is innervated by the inferior division of the oculomotor nerve (Cranial Nerve III).
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As with most of the muscles of the orbit, it is innervated by the inferior division of the oculomotor nerve (Cranial Nerve III).
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The Obliquus oculi inferior (inferior oblique) is a thin, narrow muscle, placed near the anterior margin of the floor of the orbit.
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Action
Its actions are lateral rotation, elevation and abduction of the eye...... Click the link for more information.
The ciliary muscle is a smooth muscle that affects zonular fibers in the eye (fibers that suspend the lens in position during accommodation), enabling changes in lens shape for light focusing.
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The fibers of the oculomotor nerve arise from a nucleus in the midbrain, which lies in the gray substance of the floor of the cerebral aqueduct and extends in front of the aqueduct for a short distance into the floor of the third ventricle.
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The Edinger-Westphal nucleus (also known as the accessory oculomotor nucleus ) is the accessory parasympathetic cranial nerve nucleus of the oculomotor nerve (cranial nerve III), supplying the constricting muscles of the iris.
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The superior branch of the oculomotor nerve or the superior division, the smaller, passes medialward over the optic nerve.
It supplies the Superior rectus and Levator palpebrae superioris.
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It supplies the Superior rectus and Levator palpebrae superioris.
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The inferior branch of the oculomotor nerve or the inferior division, the larger, divides into three branches.
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- One passes beneath the optic nerve to the medial rectus.
- Another, to the inferior rectus.
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Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. Created and updated by the United States National Library of Medicine (NLM), it is used by the MEDLINE/PubMed
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Cranial nerves are nerves that emerge directly from the brain in contrast to spinal nerves which emerge from segments of the spinal cord. Although thirteen cranial nerves in humans fit this description, twelve are conventionally recognized.
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The trochlear nerve (the fourth cranial nerve, also called the fourth nerve or simply IV) is a motor nerve (a “somatic efferent” nerve) that innervates a single muscle: the superior oblique muscle of the eye.
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The abducens nerve (the sixth cranial nerve, also called the sixth nerve or simply VI) is a motor nerve (a “somatic efferent” nerve) that controls the movement of a single muscle, the lateral rectus muscle of the eye.
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In biological anatomy, the mesencephalon (or midbrain) is the middle of three vesicles that arise from the neural tube that forms the brain of developing animals. Caudally the mesencephalon adjoins the pons (metencephalon) and rostrally it adjoins the diencephalon
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The fibers of the oculomotor nerve arise from a nucleus in the midbrain, which lies in the gray substance of the floor of the cerebral aqueduct and extends in front of the aqueduct for a short distance into the floor of the third ventricle.
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The superior colliculus (Latin, higher hill) is a paired structure that is part of the brain's tectal area.
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Structure and relations
The two superior colliculi sit below the thalamus and surround the pineal gland in the mesencephalon of vertebrate brains...... Click the link for more information.
The ciliary muscle is a smooth muscle that affects zonular fibers in the eye (fibers that suspend the lens in position during accommodation), enabling changes in lens shape for light focusing.
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The accommodation reflex is a reflex action of the eye, in response to focusing on a near object, then looking at distant object (and vice versa), comprising coordinated changes in vergence, lens shape and pupil size.
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extraocular muscles are the six muscles that control the movements of the eye. The actions of the extraocular muscles depend on the position of the eye at the time of muscle contraction.
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For the abdominal muscle see: External oblique muscle
The superior oblique muscle, or obliquus oculi superior, is a fusiform muscle in the upper, medial side of the orbit whose primary action is intorsion and whose secondary actions are to abduct (laterally
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The superior oblique muscle, or obliquus oculi superior, is a fusiform muscle in the upper, medial side of the orbit whose primary action is intorsion and whose secondary actions are to abduct (laterally
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lateral rectus muscle is a muscle in the orbit. It is one of six extraocular muscles that control the movements of the eye (abduction in this case) and the only muscle innervated by the abducens nerve, cranial nerve VI.
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The Edinger-Westphal nucleus (also known as the accessory oculomotor nucleus ) is the accessory parasympathetic cranial nerve nucleus of the oculomotor nerve (cranial nerve III), supplying the constricting muscles of the iris.
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parasympathetic nervous system (PSNS) is one of three divisions of the autonomic nervous system (ANS). The ANS -a subdivision of the peripheral nervous system (PNS)- is subdivided into the sympathetic (SNS), parasympathetic (PSNS) and enteric (bowels) nervous system (ENS).
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The ciliary ganglion is a parasympathetic ganglion located in the posterior orbit. It measures 1- 2 millimeters in diameter and contains approximately 2,500 neurons[1]. Preganglionic axons from the Edinger-Westphal nucleus form synapses with these cells.
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pupillary reflexes-
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- The pupillary light reflex is the reduction of pupil size in response to light.
- The pupillary accommodation reflex is the reduction of pupil size in response to an object coming close to the eye.
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The pia mater (Latin: "tender mother", itself a translation from Arabic) is the delicate innermost layer of the meninges - the membranes surrounding the brain and spinal cord.
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The arachnoid mater is one of the three meninges, the membranes that cover the brain and spinal cord. It is interposed between the two other meninges, the more superficial dura mater and the deeper pia mater, and is separated from the pia mater by the subarachnoid space.
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The superior cerebellar artery arises near the termination of the basilar.
It passes lateralward, immediately below the oculomotor nerve, which separates it from the posterior cerebral artery, winds around the cerebral peduncle, close to the trochlear nerve, and, arriving
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It passes lateralward, immediately below the oculomotor nerve, which separates it from the posterior cerebral artery, winds around the cerebral peduncle, close to the trochlear nerve, and, arriving
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