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What is the origin and course of Ttochlear nerve?
Trochlear nerve Is the IVth cranial nerve. it is the smallest cranial nerve. Is purely motor nerve.
Origin: Its nucleus is located in the midbrain at the level of inferior colliculus.
Course:
- Emerges on the dorsal surface of midbrain below the inferior colliculi (is the only cranial nerve to emerge on the dorsal surface of brainstem).
- The two nerves decussate and wind around the cerebral peduncles to reach the ventral aspect of midbrain.
- Run in the lateral wall of the cavernous sinus below the oculomotor nerve.
- Enter the orbit by passing through the superior orbital fissure.
Name the nuclei, functional components and structures supplied by trochlear nerve.
Following are the nuclei, functional components and the structures supplied by the nerve:
Nucleus Function component Structures innervated Trochlear nucleus (in midbrain) GSE (General Somatic Efferent) Superior oblique muscle of eyeball
Applied Aspect
Trochlear nerve lesion
The symptoms are:
- Diplopia on looking downward: due to paralysis of superior oblique muscle.
- Patient faces difficulty while going downstairs or reading a book.