Extraocular muscles

  • The extraocular muscles (also extrinsic muscles of eyeball, extra-ocular muscles, latin: musculi externi bulbi oculi) are a set of seven muscles located within each orbit and connected with the eye. There are six extraocular muscles responsible for the eye movements and one providing the elevation of the upper eyelid.

    The six extraocular muscles controlling eye movements include four rectus muscles - superior rectus, inferior rectus, medial rectus, lateral rectus, and two oblique muscles - superior oblique and inferior oblique. There is the seventh extraocular muscle that provides the elevation of the upper eyelid, and that is the levator palpebrae superioris.

    The motor innervation of the extraocular muscles is provided by three cranial nerves: oculomotor (CN III), trochlear (CN IV), and abducens (CN VI). The oculomotor nerve supplies five extraocular muscles: three out of the four rectus muscles (superior, inferior, medial), inferior oblique muscle, and levator palpebrae superioris muscle. The trochlear nerve innervates only the superior oblique, while the abducens nerve supplies the lateral rectus muscle.