Hey everyone! This is Matt from Kenhub, and in this tutorial, we will be discussing the inferior oblique muscle, its origin and insertion, function, innervation and blood supply.
The inferior oblique muscle is one of the six extraocular muscles that control movements of the eye. Of the six extraocular muscles, four are rectus muscles and two are oblique muscles. The inferior oblique is situated primarily on the inferior aspect of the eye while the other oblique extraocular muscle – the superior oblique – lies primarily on the superior aspect of the eye.
The inferior oblique muscle originates from the orbital surface of the maxilla just lateral to the nasolacrimal groove. It is important to note that this is the only extraocular muscle that does not originate from the common tendinous ring also known as the annulus of Zinn.
The inferior oblique muscle inserts onto the posterior, inferolateral surface of the eye just inferior to the insertion of the superior oblique muscle. The inferior oblique's point of insertion is covered by the lateral rectus muscle as you can see here.
When the eye is in a neutral position, the inferior oblique is responsible for extorsion which is rotation of the eye outwards, elevation which is movement of the eye superiorly, and abduction which is movement of the eye laterally away from the nose.
The nerve supply to the inferior oblique comes from the inferior branch of the oculomotor nerve – the third cranial nerve. Arterial blood is supplied to the inferior oblique muscle by branches off of the infraorbital artery.
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