Superior oblique muscle
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| Superior oblique | ||
|---|---|---|
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| Rectus muscles: 2 = superior, 3 = inferior, 4 = medial, 5 = lateral Oblique muscles: 6 = superior, 8 = inferior Other muscle: 9 = levator palpebrae superioris Other structures: 1 = Annulus of Zinn, 7 = Trochlea, 10 = Superior tarsus, 11 = Sclera, 12 = Optic nerve | ||
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| Sagittal section of right orbital cavity. | ||
| Latin | musculus obliquus superior bulbi | |
| Gray's | subject #227 1022 | |
| Origin: | annulus of Zinn at the orbital apex, medial to optic canal | |
| Insertion: | Outer posterior quadrant of the eyeball | |
| Artery: | lateral muscular branch of the ophthalmic artery | |
| Nerve: | trochlear nerve | |
| Action: | primary action is intorsion; secondary actions are to abduct (laterally rotate) and depress the eyeball (i.e. it makes the eye move outward and downward) | |
| Dorlands/Elsevier | m_22/12549898 | |
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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 rotate) and depress the eyeball (i.e. it makes the eye move outward and downward). One of the extraocular muscles, the superior oblique is the only muscle innervated by the trochlear nerve.
The primary action of the superior oblique muscle is intorsion; the secondary action is depression (primarily in the adducted position); the tertiary action is abduction. A brief survey of neurology and physiology texts and websites reveals much confusion about the role of the superior oblique muscle, with many sources claiming that its role is to move the eye towards the nose. In fact, because of its positioning, it is able to rotate the eye away from the nose so that when the eye is already adducted (looking directly "inwards") its rotational action turns the pupil downwards to look towards the mouth, which many texts misinterpret as its primary action.
Usually the eye muscles do not work alone, which leads to the confusion of the primary actions. The superior oblique intorts, depresses, abducts the eye if it were to work by itself. Normally, the superior oblique, in conjunction with the medial rectus, causes the eye to ADduct.
The origin for the superior oblique is the annulus of Zinn at the orbital apex. It loops through a pulley like structure (the trochlea of superior oblique) and inserts on the posterotemporal surface of the eyeball.
It arises immediately above the margin of the optic foramen, above and medial to the origin of the superior rectus, and, passing forward, ends in a rounded tendon, which plays in a fibrocartilaginous ring or pulley attached to the trochlear fovea of the frontal bone.
The contiguous surfaces of the tendon and ring are lined by a delicate mucous sheath, and enclosed in a thin fibrous investment.
The tendon is reflected backward, lateralward, and downward beneath the superior rectus to the lateral part of the bulb of the eye, and is inserted onto the scleral surface, behind the equator of the eyeball, the insertion of the muscle lying between the superior rectus and Rectus lateralis.
Clinical significance
Superior oblique palsy is a common complication of closed head trauma. Restriction of superior oblique movement is found in Brown syndrome, leading to difficulty elevating the eye in the adducted position.
Superior oblique myokymia is an uncommon neurological condition caused by vascular compression of the trochlear nerve resulting in repeated, brief, involuntary episodes of movement of the eye.
Operations of the superior oblique include tenotomy, recession, silicone expander lengthening, split tendon lengthening, tucking, and the Harada-Ito procedure.
Additional images
 Eye movement of lateral rectus muscle, superior view |
 Eye movement of medial rectus muscle, superior view |
 Eye movement of inferior rectus muscle, superior view |
 Eye movement of superior rectus muscle, superior view |
 Eye movement of superior oblique muscle, superior view |
 Eye movement of inferior oblique muscle, superior view |
 Anterior view |
credit: Patrick J. Lynch
 Nerves of the orbit. Seen from above. |
 Dissection showing origins of right ocular muscles, and nerves entering by the superior orbital fissure. |
External links
This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.
hu:Musculus obliquus superior bulbi
nl:Musculus obliquus superior
ja:上斜筋
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Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
