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Superior rectus muscle

AI overview

The superior rectus muscle is one of the extraocular muscles located in the orbit, innervated by the superior division of the oculomotor nerve (III), with a primary function of elevating the eye.

Key points
  • The superior rectus muscle is innervated by the superior division of the oculomotor nerve (III).
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    It is innervated by the superior division of the oculomotor nerve (III).
  • Its primary function is elevation, but it also contributes to intorsion and adduction.
    source quote
    its primary function is elevation , although it also contributes to intorsion and adduction
  • The muscle originates from the annulus of Zinn and inserts into the anterosuperior surface of the eye.
    source quote
    The superior rectus muscle originates from the annulus of Zinn . It inserts into the anterosuperior surface of the eye
  • Each superior rectus muscle is innervated by the contralateral oculomotor nucleus in the mesencephalon.
    source quote
    Each superior rectus muscle is innervated by contralateral oculomotor nucleus in the mesencephalon.
  • It is the only muscle capable of elevating the eye when the eye is in a fully abducted position.
    source quote
    The superior rectus muscle is the only muscle that is capable of elevating the eye when it is in a fully abducted position.
Symptoms
  • Obstruction to venous drainage near the superior rectus muscle may cause exophthalmos (bulging eyeball).
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    Obstruction to this venous drainage can cause venous congestion in the eye, which may cause exophthalmos (bulging eye ball).
  • Weakness or paralysis of the superior rectus muscle impairs the ability to elevate the eye.
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    This causes a reduced ability to elevate the eye.
  • Overreaction of the superior rectus muscle may elevate the eye and prevent its use in normal vision.
    source quote
    This may elevate the eye, and prevent its use in normal vision.
Diagnosis
  • Exophthalmos caused by venous congestion may be shown with CT scans.
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    This may be shown with CT scans.
  • Testing the superior rectus muscle involves assessing elevation of the eye when it is in a fully abducted position.
    source quote
    The superior rectus muscle is the only muscle that is capable of elevating the eye when it is in a fully abducted position.
Treatment
  • Overreaction of the superior rectus muscle may be treated with eye surgery that weakens or repositions the muscle.
    source quote
    Treatment may involve eye surgery that weakens or repositions the superior rectus muscle, which generally has good outcomes.
  • Congenital absence of the superior rectus muscle may be treated with surgery using parts of the medial and lateral rectus muscles.
    source quote
    It may be treated with eye surgery that uses parts of the medial rectus muscle and the lateral rectus muscle to restore the functions normally performed by the superior rectus muscle.
Red flags
  • Weakness or paralysis may be caused by head injuries (acquired) or congenital factors with a familial genetic link.
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    This may be congenital , often with a familial genetic link , or acquired, most often caused by head injuries
  • Congenital absence of the superior rectus muscle may be caused by Apert syndrome.
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    This may be caused by Apert syndrome
  • Local anaesthetics used in cataract surgery may weaken the inferior rectus muscle, leading to overreaction of the superior rectus muscle.
    source quote
    Local anaesthetics used in cataract surgery may weaken the inferior rectus muscle , despite efforts to use minimal anaesthetic and to avoid placing the needle into the muscle.
Prognosis

Surgical treatment for overreaction of the superior rectus muscle generally has good outcomes.

AI-synthesized from the Wikipedia article “Superior rectus muscle”. Not medical advice. Verify source →
Superior rectus
View of the eye from above, showing the action of the superior rectus muscle.
Details
OriginAnnulus of Zinn at the orbital apex
Insertion7.9 mm superior to the corneal limbus
NerveOculomotor nerve
ActionsElevation, adduction, intorsion
Identifiers
Latinmusculus rectus superior bulbi
TA98A15.2.07.010
TA22042
FMA49035
Anatomical terms of muscle

The superior rectus muscle is one of the extraocular muscles located in the orbit. It is innervated by the superior division of the oculomotor nerve (III). In the primary position (looking straight ahead), its primary function is elevation, although it also contributes to intorsion and adduction. It is associated with a number of medical conditions, and may be weak, paralysed, overreactive, or even congenitally absent in some people.

Lacrimal nerveTrochlear nerveTrochlear nerveTrochlear nerveAbducens nerveAbducens nerveOculomotor nerveOculomotor nerveSupraorbital nerveSupratrochlear nerveSupratrochlear nerveOphthalmic arteryOphthalmic arteryOphthalmic arteryOphthalmic arteryOphthalmic arteryOphthalmic arteryOphthalmic arteryMaxillary nerveMandibular nerveTrigeminal nerveTrochlear nerveTrochlear nerveTrochlear nerveTrochlear nerveOphthalmic nerveLacrimal nerveFrontal nervePupilIrisCorneaLimbusSuperior rectus muscleSuperior oblique muscleSuperior oblique muscleSuperior oblique muscleSuperior oblique muscleSuperior oblique muscleTrochlea of superior obliqueLevator palpebrae superior muscleLateral rectus muscleLateral rectus muscleLateral rectus muscleLateral rectus muscleMedial rectus muscleMedial rectus muscleOptic nerveTrigeminal ganglion
The superior rectus muscle is shown in this image of the right eye from above. Hover the mouse over the structures for their names.

The superior rectus muscle originates from the annulus of Zinn. It inserts into the anterosuperior surface of the eye. This insertion has a width of around 11 mm.[1] It is around 7.7 mm from the corneal limbus.[1]

Nerve supply

The superior rectus muscle is supplied by the superior division of the ipsilateral oculomotor nerve (III). Each superior rectus muscle is innervated by contralateral oculomotor nucleus in the mesencephalon.[2]

Relations

The superior rectus muscle is related to the other extraocular muscles, particularly to the medial rectus muscle and the lateral rectus muscle.[3] The insertion of the superior rectus muscle is around 7.5 mm from the insertion of the medial rectus muscle, around 7.1 mm from the insertion of the lateral rectus muscle, and around 7.9 from the corneal limbus.[1] There is an between it and the lateral rectus muscle.[3]

Variation

Variations of the superior rectus muscle is rare.[4] It may rarely have two muscle bellies parallel to each other.[4] More rarely, it may be congenitally absent.[5][6]

The superior rectus muscle elevates, adducts, and helps intort (rotate the superior pole of the eye medially) the eye.

Testing

The superior rectus muscle is the only muscle that is capable of elevating the eye when it is in a fully abducted position.[7]

Exophthalmos

Much of the venous drainage of the orbit and the extraocular muscles passes close to the superior rectus muscle.[8] Obstruction to this venous drainage can cause venous congestion in the eye, which may cause exophthalmos (bulging eye ball).[9] This may be shown with CT scans.[8]

Weakness and paralysis

The superior rectus muscle may be weakened or paralysed by problems with nerve conduction of the oculomotor nerve (III).[9] This may be congenital, often with a familial genetic link, or acquired, most often caused by head injuries.[9]

Overreaction

Local anaesthetics used in cataract surgery may weaken the inferior rectus muscle, despite efforts to use minimal anaesthetic and to avoid placing the needle into the muscle.[10] Weakness of the inferior rectus muscle may strengthen the superior rectus muscle, causing it to be overreactive.[10] This may elevate the eye, and prevent its use in normal vision.[10] Treatment may involve eye surgery that weakens or repositions the superior rectus muscle, which generally has good outcomes.[10]

Absence

Very rarely, the superior rectus muscle may be congenitally absent. This may be caused by Apert syndrome.[5] This causes a reduced ability to elevate the eye.[6] It may be treated with eye surgery that uses parts of the medial rectus muscle and the lateral rectus muscle to restore the functions normally performed by the superior rectus muscle.[6]

  1. 1 2 3 Apt, L (1980). "An anatomical reevaluation of rectus muscle insertions". Transactions of the American Ophthalmological Society. 78: 365–375. ISSN 0065-9533. PMC 1312149. PMID 7257065.
  2. ↑ Anderson, B.C.; McLoon, L.K. (2010), "Cranial Nerves and Autonomic Innervation in the Orbit", Encyclopedia of the Eye, Elsevier, pp. 537–548, doi:10.1016/b978-0-12-374203-2.00285-2, ISBN 978-0-12-374203-2, retrieved 2023-02-02
  3. 1 2 Nam, Yong Seok; Park, Yooyeon; Kim, In-Beom; Shin, Sun Young (2019-07-10). "Detailed Anatomy of the Lateral Rectus Muscle-Superior Rectus Muscle Band". Journal of Ophthalmology. 2019 e5374628. doi:10.1155/2019/5374628. ISSN 2090-004X. PMC 6652029. PMID 31360544.
  4. 1 2 Nayak, Satheesha B.; Shetty, Surekha D.; Kumar, Naveen; Aithal, Ashwini P. (2019-06-01). "Double-bellied superior rectus muscle". Surgical and Radiologic Anatomy. 41 (6): 713–715. doi:10.1007/s00276-019-02211-0. ISSN 1279-8517. PMID 30847519. S2CID 71147157.
  5. 1 2 Cuttone, James M.; Brazis, Peter J.; Miller, Marilyn T.; Folk, Eugene R. (1979-11-01). "Absence of the Superior Rectus Muscle in Apert's Syndrome". Journal of Pediatric Ophthalmology & Strabismus. 16 (6): 349–354. doi:10.3928/0191-3913-19791101-04. PMID 521875.
  6. 1 2 3 Mather, Thomas R.; Saunders, Richard A. (1987-11-01). "Congenital Absence of the Superior Rectus Muscle: A Case Report". Journal of Pediatric Ophthalmology & Strabismus. 24 (6): 291–295. doi:10.3928/0191-3913-19871101-06. PMID 3320326.
  7. ↑ "Eye Theory". Cim.ucdavis.edu. Retrieved 2012-12-02.
  8. 1 2 Hudson, Henry L.; Levin, Lori; Feldon, Steven E. (1991-10-01). "Graves Exophthalmos Unrelated to Extraocular Muscle Enlargement: Superior Rectus Muscle Inflammation May Induce Venous Obstruction". Ophthalmology. 98 (10): 1495–1499. doi:10.1016/S0161-6420(91)32099-2. ISSN 0161-6420. PMID 1961633.
  9. 1 2 3 White, James Watson (1933). "Paralysis of the Superior Rectus Muscle". Transactions of the American Ophthalmological Society. 31: 551–584. ISSN 0065-9533. PMC 1315454. PMID 16692992.
  10. 1 2 3 4 Grimmett, Michael R.; Lambert, Scott R. (1992-07-01). "Superior Rectus Muscle Overaction After Cataract Extraction". American Journal of Ophthalmology. 114 (1): 72–80. doi:10.1016/S0002-9394(14)77415-X. ISSN 0002-9394. PMID 1621788.