Inferior rectus muscle

Source: Wikipedia, the free encyclopedia.
Inferior rectus
extorsion
Identifiers
Latinmusculus rectus inferior bulbi
TA98A15.2.07.011
TA22043
FMA49036
Anatomical terms of muscle]

The inferior rectus muscle is a

extraocular muscles. It originates from the common tendinous ring
, and inserts into the anteroinferior surface of the eye. It depresses the eye (downwards).

Structure

See also: Extraocular muscles

The inferior rectus muscle originates from the common tendinous ring (annulus of Zinn).[1] It inserts into the anteroinferior surface of the eye.[2] This insertion has a width of around 10.5 mm.[2] It is around 7 mm from the corneal limbus.[2]

Blood supply

The inferior rectus muscle is supplied by an inferior muscular branch of the ophthalmic artery.[1] It may also be supplied by a branch of the infraorbital artery.[1] It is drained by the corresponding veins: the inferior muscular branch of the ophthalmic vein, and sometimes a branch of the infraorbital vein.[1]

Nerve supply

The inferior rectus muscle is supplied by the inferior division of the oculomotor nerve (III).[1]

Development

The inferior rectus muscle develops from the embryonic mesoderm in the orbit of the skull.[1][3] This is similar to the other extraocular muscles.[3]

Relations

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.[2] A parasympathetic branch that supplies the ciliary muscles of the pupil passes close to the inferior rectus muscle.[1]

Variation

Very rarely, the inferior rectus muscle may be congenitally absent.[3][4] This may cause inferior rectus palsy, where the eye cannot be depressed.[3]

Function

See also: Eye movement

The inferior rectus muscle

extort the eye.[1] It is the only muscle that is capable of depressing the pupil when it is in a fully abducted position.[5]

Clinical significance

Strabismus

If the inferior rectus muscle is damaged, weak, or paralysed, this can cause strabismus.[1][6] This can lead to elevation of the eye, as the superior rectus muscle remains stronger.[6] For minor cases, prism glasses can be used to gradually realign the eye.[6] 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.[6] This procedure may lead to overcorrection of the strabismus, but is otherwise generally successful.[7]

Surgery

Any surgery on the inferior rectus muscle may damage the parasympathetic branches to the ciliary muscles of the pupil.[1] This may cause problems with control of the pupil.[1] Nearby blood vessels and nerves may also be damaged.[1]

Additional images

  • Inferior rectus muscle
    Inferior rectus muscle
  • Extrinsic eye muscle. Nerves of orbita. Deep dissection.
    Extrinsic eye muscle. Nerves of orbita. Deep dissection.

References

  1. ^
    PMID 30085520
    , retrieved 2021-09-27
  2. ^
    PMID 7257065
    .
  3. ^
    PMID 14566316
    .
  4. PMID 3814423
    .
  5. ^ "Eye Theory". Cim.ucdavis.edu. Archived from the original on 2014-05-27. Retrieved 2010-11-27.
  6. ^
    PMID 10849393
    .
  7. PMID 8350221
    .

External links
Retrieved from "https://en.wikipedia.org/w/index.php?title=Inferior_rectus_muscle&oldid=1173063379"