**Question:** Intraocular muscle supplied by Edinger Westphal nucleus is

A. rectus inferior
B. rectus superior
C. rectus lateralis
D. rectus medialis

**Core Concept:** Edinger-Westphal (EW) nucleus is a part of the parasympathetic system in the midbrain that controls the pupillary sphincter pupillae, dilator pupillae, and ciliary smooth muscle. These muscles are responsible for controlling pupillary size and accommodation.

**Why the Correct Answer is Right:** The rectus inferior muscle is part of the extraocular muscles responsible for eye movement. It is supplied by the oculomotor (CN III) nerve, which has a different source than the Edinger-Westphal nucleus. The EW nucleus innervates the smooth muscles of the pupil and ciliary body, not the rectus muscles.

**Why Each Wrong Option is Incorrect:**

A. Rectus inferior (correct answer): The rectus inferior muscle is supplied by the oculomotor nerve (CN III), not the Edinger-Westphal nucleus.

B. Rectus superior: Wrong answer. The rectus superior muscle is supplied by the trochlear nerve (CN IV), which has a different source than the EW nucleus.

C. Rectus lateralis: This muscle does not exist in humans. It is a term from anatomy textbooks and does not correspond to any real muscle in the eye.

D. Rectus medialis: Wrong answer. The rectus medialis muscle does not exist in humans. It is a term from anatomy textbooks and does not correspond to any real muscle in the eye.

**Clinical Pearl:** Understanding the anatomy and innervation of the eye muscles is essential for understanding ophthalmological disorders, such as Horner's syndrome, where a lesion affecting the EW nucleus can cause pupillary abnormalities.

**Correct Answer:** D. rectus medialis (correct answer)

The rectus medialis is the correct answer because it is the muscle that is innervated by the Edinger-Westphal nucleus. However, this answer is incorrect because the rectus medialis muscle does not exist in humans. The rectus medialis is a term from anatomy textbooks and does not correspond to any real muscle in the eye.

The rectus medialis is a term used in anatomy textbooks for the medial rectus muscle, which is a real muscle in the eye. However, this answer is incorrect because the question is specifically asking for the muscle supplied by the Edinger-Westphal nucleus.

The Edinger-Westphal nucleus is responsible for the innervation of the pupillary sphincter and dilator muscles, as well as the ciliary smooth muscle of the iris. The correct answer should be the muscle supplied by the Edinger-Westphal nucleus, not the medial rectus muscle itself.

**Why the Correct Answer is Right:**

The rectus medialis muscle is the correct answer because it is innervated by the Edinger-Westphal nucleus. However