Which nucleus is located in the upper midbrain?

Which nucleus is located in the upper midbrain?

• A. Edinger-Westphal nucleus
• B. Salivatory nucleus
• C. Dorsal motor nucleus
• D. Nucleus ambiguus

Answer: (A)

Edinger-Westphal nucleus sits in the rostral midbrain near the oculomotor nucleus and contains the preganglionic parasympathetic neurons that travel with the third cranial nerve to the ciliary ganglion, controlling pupil constriction and lens focusing. That midbrain location is what makes it the correct choice for “located in the upper midbrain.” The other nuclei are in different parts of the brainstem: the salivatory nucleus is in the brainstem’s pons/medulla region and relates to facial nerve parasympathetics; the dorsal motor nucleus of the vagus is in the medulla and provides vagal output; and the nucleus ambiguus is also in the medulla, serving muscles of the pharynx and larynx.

Edinger-Westphal nucleus sits in the rostral midbrain near the oculomotor nucleus and contains the preganglionic parasympathetic neurons that travel with the third cranial nerve to the ciliary ganglion, controlling pupil constriction and lens focusing. That midbrain location is what makes it the correct choice for “located in the upper midbrain.” The other nuclei are in different parts of the brainstem: the salivatory nucleus is in the brainstem’s pons/medulla region and relates to facial nerve parasympathetics; the dorsal motor nucleus of the vagus is in the medulla and provides vagal output; and the nucleus ambiguus is also in the medulla, serving muscles of the pharynx and larynx.