Question

Five extrinsic muscles of the eye are the superior rectus, superior oblique, lateral rectus, inferior oblique, and inferior rectus. The sixth one is the ________.

1) medial rectus
2) levator palpebrae superioris
3) orbicularis oculi
4) trochlearis

Answer 1

The sixth extraocular muscle responsible for eye movement is the medial rectus, which is involved in moving the eye towards the nose. It is innervated by the oculomotor nerve, similar to most other extraocular muscles.

Step-by-step explanation:

The sixth extraocular muscle that, along with the other five, is responsible for eye movement is the medial rectus. This muscle works in coordination with the lateral rectus of the opposite eye to control horizontal movement, specifically adduction, moving the eye towards the nose. The lateral rectus is controlled by the abducens nerve, while the medial rectus, along with the rest of the extraocular muscles except for the superior oblique and lateral rectus, is innervated by the oculomotor nerve.

it is worth noting that the levator palpebrae superioris is not an extraocular muscle, though also innervated by the oculomotor nerve, because it elevates the upper eyelid rather than moving the eyeball itself.