Question

Select all that apply

Where does cranial nerve III (the oculomotor nerve) terminate?
a) Retina
b) External eye muscles
c) Superior orbital fissure
d) Constrictor of the iris
e) Ciliary muscle of the lens

Answer 1

The oculomotor nerve (cranial nerve III) terminates in the external eye muscles, the constrictor of the iris, and the ciliary muscle of the lens. It is responsible for various eye movements and functions, but does not terminate at the retina or solely within the superior orbital fissure.

Step-by-step explanation:

The cranial nerve III, known as the oculomotor nerve, terminates at several locations that are responsible for eye movements and other functions related to vision. Specifically, the oculomotor nerve innervates the following:

• External eye muscles, which include the medial rectus, inferior rectus, superior rectus, and inferior oblique muscles.
• The constrictor of the iris, which is responsible for the pupillary reflex, adjusting the amount of light that enters the eye.
• The ciliary muscle of the lens, which controls the shape of the lens for focusing on near and distant objects.

The retina is not a termination point for the oculomotor nerve; it is innervated by the optic nerve. Additionally, while the oculomotor nerve passes through the superior orbital fissure to reach its target muscles, it does not terminate there.

To summarize, the correct options where cranial nerve III terminates are external eye muscles, constrictor of the iris, and ciliary muscle of the lens.