Definition

1. Noun:
   • The fourth cranial nerve: A motor nerve that innervates the superior oblique muscle of the eye, controlling downward and inward eye movement.

Usage

• The trochlear nerve is the smallest cranial nerve and has the longest intracranial course.
• Damage to the trochlear nerve can result in vertical double vision and head tilt.

Examples

Advanced Usage

• "Trochlear nerve palsy": A condition characterized by weakness or paralysis of the nerve, leading to specific eye alignment issues.
  • The most common cause of isolated trochlear nerve palsy is trauma.

Variants and Related Words

• Trochlear (Adjective): Pertaining to a trochlea (a pulley-like structure) or the trochlear nerve.
  • The trochlear nucleus is located in the midbrain.
• Cranial Nerve IV: An alternative name for the trochlear nerve.
• Superior oblique muscle: The eye muscle controlled by the trochlear nerve.

Synonyms

• Fourth cranial nerve
• Pathetic nerve (an older, less common term)

Related Phrases

• Trochlear nucleus: The cluster of neurons in the brainstem from which the trochlear nerve originates.

Noun

1. either of the two cranial nerves on either side that control the superior oblique muscles of the eyes