Which of the following cranial nerves is primarily motor?Multiple ChoiceOptic nerve (II)Trochlear nerve (IV)Trigeminal nerve (V)Facial nerve (VII)

Break Down the Problem

1. Identify the classifications of cranial nerves concerning motor and sensory functions.
2. Evaluate each of the provided cranial nerves to determine their primary functions.

Relevant Concepts

• Cranial nerves can be classified as primarily motor, primarily sensory, or mixed (having both motor and sensory functions).
• Optic nerve (II): Primarily sensory (vision).
• Trochlear nerve (IV): Primarily motor (eye movement).
• Trigeminal nerve (V): Mixed (sensory and motor — mainly responsible for facial sensations and chewing).
• Facial nerve (VII): Mixed (controls facial expressions and provides taste sensations).

Analysis and Detail

2. From the descriptions:
   • The Optic nerve (II) is responsible for vision, indicating it does not primarily serve motor functions.
   • The Trochlear nerve (IV) controls the superior oblique muscle of the eye, which is involved in eye movement and therefore is primarily a motor nerve.
   • The Trigeminal nerve (V) primarily supports sensation in the face but also includes motor functions for muscles of mastication, thus not qualifying as primarily motor.
   • The Facial nerve (VII) is also mixed, governing facial expressions and taste.

Verify and Summarize

4. Of all the cranial nerves listed, the one classified strictly as primarily motor is the Trochlear nerve (IV).

Final Answer

The cranial nerve that is primarily motor is the Trochlear nerve (IV).