Citizendia
Your Ad Here

Nerve: Oculomotor nerve
Nerves of the orbit. Seen from above.
Latin nervus oculomotorius
Gray's 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

The oculomotor nerve is the third of twelve paired cranial nerves. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. This is a list of the subjects in Gray's Anatomy: IX Neurology The superior rectus muscle is a Muscle in the orbit. It is one of the Extraocular muscles. The inferior rectus muscle is a Muscle in the orbit. Actions It depresses, adducts, Rotates laterally, and extorts 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 The Obliquus oculi inferior (inferior oblique is a thin narrow muscle placed near the anterior margin of the floor of the orbit. The Ciliary Muscle is a muscle in the eye that controls the eye's accommodation for viewing objects at varying distances 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 The Edinger-Westphal nucleus (also known as the accessory oculomotor nucleus) is the accessory parasympathetic Cranial nerve nucleus of the Oculomotor The superior branch of the oculomotor nerve or the superior division, the smaller passes medialward over the Optic nerve. The inferior branch of the oculomotor nerve or the inferior division, the larger divides into three branches Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books Cranial nerves are Nerves that emerge directly from the Brain stem in contrast to Spinal nerves which emerge from segments of the Spinal cord. It controls most of the eye's movements, constriction of the pupil, and maintains an open eyelid. (Note: cranial nerves IV and VI also participate in control of eye movement. 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 The abducens nerve (the sixth cranial nerve, also called the sixth nerve or simply VI) is a “somatic efferent” nerve that controls the movement of a )

Contents

Path

Nuclei

The oculomotor nerve arises from the anterior aspect of mesencephalon (midbrain). In biological anatomy the mesencephalon (or midbrain) comprises the Tectum (or corpora quadrigemini Tegmentum, the ventricular mesocoelia (or "iter" There are two nuclei for the oculomotor nerve:

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. The pia mater (Latin "tender mother" itself a translation from Arabic) is the delicate innermost layer of the Meninges - the membranes surrounding the The arachnoid mater is one of the three Meninges, the membranes that cover the Brain and Spinal cord.

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. The superior cerebellar artery (SCA arises near the termination of the Basilar artery In Human anatomy, the posterior cerebral artery is the Blood vessel that supplies oxygenated Blood to the posterior aspect of the brain ( Occipital In the Sphenoid bone, the anterior boundary of the Sella turcica is completed by two small eminences one on either side called the Anterior clinoid processes, while The tentorium cerebelli or cerebellar tentorium ( Latin: "tent of the Cerebellum " is an extension of the Dura mater that separates

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. The cavernous sinus (or lateral sellar compartment) within the human head is a large collection of thin-walled Veins creating a cavity bordered by the Sphenoid The zygomatic nerve ( temporomalar nerve; orbital nerve) is a branch of the Maxillary nerve (a Trigeminal nerve branch that enters the orbit The cavernous plexus is situated below and medial to that part of the Internal carotid artery which is placed by the side of the Sella turcica in the Cavernous The ophthalmic nerve is one of the three branches of the Trigeminal nerve, the fifth Cranial nerve. The trigeminal nerve (the fifth Cranial nerve, also called the fifth nerve or simply V) is responsible for sensation in the face

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. For the muscle of the neck see Rectus capitis lateralis muscle The lateral rectus muscle is a Muscle in the orbit.

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 trochlear nerve (the fourth cranial nerve, also called the fourth nerve or simply IV) is a motor nerve (a “somatic efferent” nerve that innervates The nasociliary nerve is a branch of the Ophthalmic nerve. It is intermediate in size between the two other main branches of the ophthalmic nerve the Frontal nerve The superior branch of the oculomotor nerve or the superior division, the smaller passes medialward over the Optic nerve. The inferior branch of the oculomotor nerve or the inferior division, the larger divides into three branches There are six Orbital Muscles; Four of the muscles control the movement of the eye going up and down and side to side 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. An eyelid is a thin fold of skin that covers and protects an Eye. The extraocular muscles are the six Muscles that control the movements of the (human eye. The levator palpebrae superioris (or levator muscle of upper eyelid) is the Muscle in the orbit that elevates the superior (upper Eyelid.

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. Oculomotor nerve palsy is an eye condition resulting from damage to the third cranial nerve or a branch thereof

Pupillary reflex

The oculomotor nerve also controls the constriction of the pupils. The pupil is the hole that is located in the center of the iris of the eye and that controls the amount of light that enters the Eye. 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. 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

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. In Anatomy, the orbital bone is the cavity or socket of the Skull in which the Eye and its appendages are situated The ciliary ganglion is a parasympathetic Ganglion located in the posterior orbit. 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

Anisocoria is a condition characterized by an unequal size of the Pupils Causes In the absence of any deformities of the iris or eyeball proper anisocoria is 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 Loyola University Chicago is a private co-educational Jesuit university established in Chicago in 1870 as Saint Ignatius College eMedicine is an online clinical medical knowledge base that was founded in 1996 by Scott Plantz and Richard Lavely two medical doctors Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books NeuroNames is a system of nomenclature for the human and/or macaque Brain. Georgetown University is a Jesuit Private university located in Georgetown Washington D
© 2009 citizendia.org; parts available under the terms of GNU Free Documentation License, from http://en.wikipedia.org
 Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic