Certified Ophthalmic Medical Technologist (COMT) Practice Exam

Which extraocular muscle includes actions of extorsion, elevation, and abduction?

1. Medial Rectus

2. Inferior oblique

3. Superior rectus

4. Lateral Rectus

The correct answer is: Inferior oblique

The correct answer is the inferior oblique muscle, which is responsible for the actions of extorsion, elevation, and abduction of the eyeball. This muscle plays a unique role in ocular movement due to its anatomical position and the way it is oriented within the orbit. Extorsion refers to the outward rotation of the top of the eye, and the inferior oblique contributes to this motion primarily when the eye is adducted (turned inward). Elevation involves the movement of the eye upward, which the inferior oblique also assists in, especially when the eye is in an adducted position. Lastly, abduction is the movement of the eye away from the midline, and the inferior oblique facilitates this action, contributing to the overall range of motion available to the eye. The other muscles mentioned do not fulfill these movements to the same extent. The medial rectus primarily adducts the eye, the superior rectus elevates the eye but mainly in straight ahead orientation and does not contribute significantly to extorsion, while the lateral rectus primarily abducts the eye. Thus, the inferior oblique is distinct in its combination of actions, accounting for the correct choice in the context of the question.