Inferior rectus muscle

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The inferior rectus muscle is one of the six extraocular muscles that control the movements of the eye. It is responsible for the downward movement of the eye, as well as its extorsion and adduction.

Anatomy

The inferior rectus muscle originates from the Annulus of Zinn, a tendinous ring located at the apex of the orbit. It inserts approximately 6.5 mm inferior to the corneal limbus on the anterior surface of the sclera.

Innervation

The inferior rectus muscle is innervated by the oculomotor nerve (cranial nerve III), which also supplies most of the other extraocular muscles.

Blood Supply

The muscle receives its blood supply from branches of the ophthalmic artery, which is a branch of the internal carotid artery.

Function

The primary function of the inferior rectus muscle is to depress the eye, moving it downward. Additionally, it contributes to the extorsion (outward rotation) and adduction (movement towards the midline) of the eye. These actions are essential for coordinated eye movements and proper binocular vision.

Clinical Significance

Dysfunction of the inferior rectus muscle can result in strabismus, where the eyes do not properly align with each other. This can lead to diplopia (double vision) and other visual disturbances. Conditions such as thyroid eye disease can affect the function of this muscle.

See Also

• Superior rectus muscle
• Medial rectus muscle
• Lateral rectus muscle
• Superior oblique muscle
• Inferior oblique muscle
• Extraocular muscles
• Oculomotor nerve