Table of ContentsView AllTable of ContentsAnatomyFunctionAssociated ConditionsTreatment
Table of ContentsView All
View All
Table of Contents
Anatomy
Function
Associated Conditions
Treatment
The oculomotor nerve enables most of your eye movements, some aspects of vision, and raising the eyelid. It’s the third cranial nerve and works with cranial nerves four (trochlear) and five (trigeminal) to coordinate eye movement. The oculomotor nerve contains both motor and parasympathetic fibers, which classifies it as a mixed nerve.
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You have 12 cranial nerves that originate in the brain andbrainstemand mainly perform functions in your face and throat. This sets them apart from the rest of your nerves, which branch out from the spinal column and travel throughout your body.
Cranial nerves come in pairs, with generally symmetrical courses on each side of your head. However, each pair is typically referred to collectively as a single nerve, or, when it’s necessary to distinguish one from the other, as the right or left nerve.
The 12 Cranial Nerves
Structure
The oculomotor nerve begins at the brainstem, which is a structure low in the back of your brain that connects the brain to the spinal column. In the brainstem, two clusters of neurons called nuclei give rise to the oculomotor nerve.
They’re called:
Each of these nuclei supplies the nerve with a different type of fiber.
As it travels through your head toward the eyes, the oculomotor nerve branches out to innervate (supply nerve function to) various muscles.
Its major branches are:
These branches further divide before reaching their destinations.
Thesuperior branchsplits into:
Theinferior branchgives off:
Location
From where it emerges from the nuclei in the brainstem, the oculomotor nerve passes in front of the cerebral aqueduct and emerges from the midbrain, then passes between two arteries—the superior cerebellar artery and the posterior cerebral.
Next, it pierces the dura mater, which is the outermost membrane surrounding the brain and spinal cord, and moves into the cavernous sinus (a sinus cavity), which is about level with your ear.
The oculomotor nerve then leaves the cranial cavity through what’s called the superior orbital fissure. Your “eye socket,” is the orbit and the superior orbital fissure is a hole in the bone, behind the eye and on the inside of the eye socket.
Once the oculomotor nerve is inside the orbit, it divides into its superior and inferior branches.
Anatomical Variations
Symptoms of congenital oculomotor palsy include:
When symptoms of congenital oculomotor palsy are present at birth, it may be a sign of other serious malformations, such as:
As a mixed nerve, the oculomotor nerve supplies motor function and parasympathetic function. It does not have any sensory function, which has to do with sensation.
Motor Function
Motor function means movement, and the oculomotor nerve is responsible for much of the movement associated with your eyes.
They are:
The sympathetic fibers from the internal carotid plexus that travel with the oculomotor nerve provide motor function to thesuperior tarsal muscle, which keeps the eyelid open once the levator palpabrae superioris raises it.
The inferior branch and its offshoots innervate:
Parasympathetic Function
Parasympathetic function has to do with the parasympathetic nervous system, whose functions tend to oppose and balance those of the sympathetic nervous system."
The sympathetic nervous system takes over during stressful or dangerous situations and is responsible for “fight or flight” functions, such as increasing your adrenaline levels and dilating your eyes. When the parasympathetic nervous system is in control, it’s often referred to as “rest and digest” mode. It lowers your heart rate to conserve energy, aids with optimal function of your intestines, and returns your pupils to their normal size.
The parasympathetic fibers from the oculomotor nerve innervate two muscles inside the iris:
The oculomotor nerve can be damaged or paralyzed in numerous ways. This is called acquired oculomotor palsy and is different from congenital oculomotor palsy, which was discussed above.
Symptoms of Oculomotor Nerve Palsy
Symptoms of damage to the oculomotor nerve include:
Depending on the cause, immediate treatment of oculomotor nerve palsy is typically conservative. Depending on the specific symptoms and the part(s) of the nerve that’s damaged, it may include:
Conservative treatment results in a full recovery in about 63% of people with acquired oculomotor palsy.If this approach hasn’t lead to much improvement after six months, surgery may be considered.
Surgery involves cutting and repositioning the muscles so that functional muscles can take over for those that aren’t working properly.
1 SourceVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Fang C, Leavitt JA, Hodge DO, Holmes JM, Mohney BG, Chen JJ.Incidence and Etiologies of Acquired Third Nerve Palsy Using a Population-Based Method.JAMA Ophthalmol. 2017 Jan 01;135(1):23-28. doi:10.1001/jamaophthalmol.2016.4456Additional ReadingAnatomy Next.Oculomotor nerve (CN III).Joyce C, Le PH, Peterson DC.Neuroanatomy, Cranial Nerve 3 (Oculomotor). In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019.Leanage N.The Oculomotor Nerve (CN III). TeachMe Anatomy. Updated March 13, 2019.Rubin M.Third Cranial (Oculomotor) Nerve Disorders. Merck Manual: Professional Version. Updated June, 2019.
1 Source
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Fang C, Leavitt JA, Hodge DO, Holmes JM, Mohney BG, Chen JJ.Incidence and Etiologies of Acquired Third Nerve Palsy Using a Population-Based Method.JAMA Ophthalmol. 2017 Jan 01;135(1):23-28. doi:10.1001/jamaophthalmol.2016.4456Additional ReadingAnatomy Next.Oculomotor nerve (CN III).Joyce C, Le PH, Peterson DC.Neuroanatomy, Cranial Nerve 3 (Oculomotor). In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019.Leanage N.The Oculomotor Nerve (CN III). TeachMe Anatomy. Updated March 13, 2019.Rubin M.Third Cranial (Oculomotor) Nerve Disorders. Merck Manual: Professional Version. Updated June, 2019.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Fang C, Leavitt JA, Hodge DO, Holmes JM, Mohney BG, Chen JJ.Incidence and Etiologies of Acquired Third Nerve Palsy Using a Population-Based Method.JAMA Ophthalmol. 2017 Jan 01;135(1):23-28. doi:10.1001/jamaophthalmol.2016.4456
Anatomy Next.Oculomotor nerve (CN III).Joyce C, Le PH, Peterson DC.Neuroanatomy, Cranial Nerve 3 (Oculomotor). In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019.Leanage N.The Oculomotor Nerve (CN III). TeachMe Anatomy. Updated March 13, 2019.Rubin M.Third Cranial (Oculomotor) Nerve Disorders. Merck Manual: Professional Version. Updated June, 2019.
Anatomy Next.Oculomotor nerve (CN III).
Joyce C, Le PH, Peterson DC.Neuroanatomy, Cranial Nerve 3 (Oculomotor). In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019.
Leanage N.The Oculomotor Nerve (CN III). TeachMe Anatomy. Updated March 13, 2019.
Rubin M.Third Cranial (Oculomotor) Nerve Disorders. Merck Manual: Professional Version. Updated June, 2019.
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