Inferior rectus muscle

The inferior rectus muscle is a muscle in the orbit.

Inferior rectus
The inferior rectus muscle, is shown in this superior view of the eye, along with its axis of rotation. The other muscle is the superior oblique muscle, which angles around the trochlea.
Details
Origin	annulus of Zinn at the orbital apex
Insertion	6.5 mm inferior to the limbus
Nerve	inferior branch of oculomotor nerve
Actions	depression and adduction
Identifiers
Latin	musculus rectus inferior bulbi
TA98	A15.2.07.011
TA2	2043
FMA	49036
Anatomical terms of muscle

Structure

Innervation

As with most of the muscles of the orbit, it is innervated by the inferior division of oculomotor nerve (Cranial Nerve III).

Function

It depresses, adducts, and helps extort the eye.

The inferior rectus muscle is the only muscle that is capable of depressing the pupil when it is in a fully abducted position.[1]

Additional images

• 
  Dissection showing origins of right ocular muscles, and nerves entering by the superior orbital fissure.
• 
  The right eye in sagittal section, showing the fascia bulbi (semidiagrammatic).
• 
  Inferior rectus muscle
• 
  Inferior rectus muscle
• 
  Extrinsic eye muscle. Nerves of orbita. Deep dissection.
• 
  Extrinsic eye muscle. Nerves of orbita. Deep dissection.
• 
  Extrinsic eye muscle. Nerves of orbita. Deep dissection.
• 
  Extrinsic eye muscle. Nerves of orbita. Deep dissection.

References

1. "Eye Theory". Cim.ucdavis.edu. Archived from the original on 2014-05-27. Retrieved 2010-11-27.

External links

• Anatomy figure: 29:01-07 at Human Anatomy Online, SUNY Downstate Medical Center
• lesson3 at The Anatomy Lesson by Wesley Norman (Georgetown University) (orbit5)
• Diagram at mun.ca