Inferior rectus muscle
The inferior rectus muscle is a muscle in the orbit near the eye. It is one of the extraocular muscles. It originates from the annulus of Zinn, and inserts into the anteroinferior surface of the eye. It depresses the eye (downwards).
|Origin||annulus of Zinn at the orbital apex|
|Insertion||6.8 mm inferior to the corneal limbus|
|Artery||inferior muscular branch of the ophthalmic artery, infraorbital artery|
|Vein||inferior muscular branch of the ophthalmic vein|
|Nerve||inferior branch of oculomotor nerve|
|Actions||depression and adduction|
|Latin||musculus rectus inferior bulbi|
|Anatomical terms of muscle|
The inferior rectus muscle originates from the annulus of Zinn. It inserts into the anteroinferior surface of the eye. This insertion has a width of around 10.5 mm. It is around 7 mm from the corneal limbus.
The inferior rectus muscle is supplied by an inferior muscular branch of the ophthalmic artery. It may also be supplied by a branch of the infraorbital artery. It is drained by the corresponding veins: the inferior muscular branch of the ophthalmic vein, and sometimes a branch of the infraorbital vein.
The insertion of the inferior rectus muscle is around 6 mm from the insertion of the medial rectus muscle, and around 8 mm from the insertion of the lateral rectus muscle. A parasympathetic branch that supplies the ciliary muscles of the pupil passes close to the inferior rectus muscle.
If the inferior rectus muscle is damaged, weak, or paralysed, this can cause strabismus. This can lead to elevation of the eye, as the superior rectus muscle remains stronger. For minor cases, prism glasses can be used to gradually realign the eye. Alternatively for serious cases, it may be surgically corrected by slightly weakening the superior rectus muscle (opposite) - this reduces the elevation of the eye, and corrects the strabismus. This procedure may lead to overcorrection of the strabismus, but is otherwise generally successful.
Any surgery on the inferior rectus muscle may damage the parasympathetic branches to the ciliary muscles of the pupil. This may cause problems with control of the pupil. Nearby blood vessels and nerves may also be damaged.
This gallery of anatomic features needs cleanup to abide by the medical manual of style.
- Shumway, Caleb L.; Motlagh, Mahsaw; Wade, Matthew (2021), "Anatomy, Head and Neck, Eye Inferior Rectus Muscle", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 30085520, retrieved 2021-09-27
- 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.
- Astle, William F; Hill, Vivian E; Ells, Anna L; Chi, Nguyen Thi Thanh; Martinovic, Elaine (2003-10-01). "Congenital absence of the inferior rectus muscle—diagnosis and management". Journal of American Association for Pediatric Ophthalmology and Strabismus. 7 (5): 339–344. doi:10.1016/S1091-8531(03)00214-3. ISSN 1091-8531.
- Ingham, Peter N.; McGOVERN, Stephen T.; Crompton, John L. (1986). "Congenital Absence of the Inferior Rectus Muscle". Australian and New Zealand Journal of Ophthalmology. 14 (4): 355–358. doi:10.1111/j.1442-9071.1986.tb00471.x. ISSN 1440-1606.
- "Eye Theory". Cim.ucdavis.edu. Archived from the original on 2014-05-27. Retrieved 2010-11-27.
- Paysse, Evelyn A.; Saunders, Richard A.; Coats, David K. (2000-06-01). "Surgical management of strabismus after rupture of the inferior rectus muscle". Journal of American Association for Pediatric Ophthalmology and Strabismus. 4 (3): 164–167. doi:10.1016/S1091-8531(00)70007-3. ISSN 1091-8531.
- Sprunger, Derek T.; Helveston, Eugene M. (1993-05-01). "Progressive Overcorrection After Inferior Rectus Recession". Journal of Pediatric Ophthalmology & Strabismus. 30 (3): 145–148. doi:10.3928/0191-3913-19930501-04.