Which muscle is innervated by the inferior division of CN III?

• A. Medial Rectus
• B. Superior Rectus
• C. Lateral Rectus
• D. Inferior Rectus

Answer: (A)

The answer hinges on how the oculomotor nerve divides to provide targeted motor control to the eye muscles. The inferior division carries motor fibers to three muscles: the medial rectus, the inferior rectus, and the inferior oblique, and it also provides the parasympathetic supply to the pupil and ciliary muscle via the ciliary ganglion. Because of this distribution, the medial rectus is innervated by the inferior division, making it the best example among the options. The medial rectus pulls the eye inward toward the nose, which aligns with the role of the inferior division’s innervation pattern. For contrast, the superior rectus is supplied by the superior division, and the lateral rectus is controlled by the abducens nerve, not CN III. The inferior rectus is also supplied by the inferior division, so multiple muscles share this innervation, but medial rectus illustrates the correct innervation by the inferior division.