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==Trochlear nerve (IV)==

==Trochlear nerve (IV)==

The trochlear nerve is part of the cranial nerve group responsible for innervation of the [[Skull and Facial Muscles - Anatomy & Physiology#Facial_Muscles|muscles of the head]]. The trochlear nerve originates from the dorsal midbrain and is a motor nerve. It is composed of '''general somatic efferent fibres''' and is the smallest of the cranial nerves.

The trochlear nerve is part of the cranial nerve group responsible for innervation of the [[Skull and Facial Muscles - Anatomy & Physiology#Facial_Muscles|muscles of the head]]. The trochlear nerve originates from the dorsal [[Equine Brain - Horse Anatomy#Midbrain|midbrain]] and is a motor nerve. It is composed of '''general somatic efferent fibres''' and is the smallest of the cranial nerves.

After leaving the dorsal midbrain, its axons decussate (cross) and then run in a rostral direction through the cavernous sinus before exiting the skill via the [[Skull and Facial Muscles - Anatomy & Physiology#Major Foramen and Canals|'''orbital fissure''']].  In the horse, it may also exit via a seperate trochlear foramen.  Finally, it runs to innervate the 'dorsal oblique muscle' muscle of the contralateral eye.

After leaving the dorsal midbrain, its axons decussate (cross) and then run in a rostral direction through the cavernous sinus before exiting the skill via the [[Skull and Facial Muscles - Anatomy & Physiology#Major Foramen and Canals|'''orbital fissure''']].  In the horse, it may also exit via a seperate trochlear foramen.  Finally, it runs to innervate the ''dorsal oblique'' muscle of the contralateral eye.

During a clinical examination, a dorso-lateral strabismus may indicate a problem with this nerve.

During a clinical examination, a dorso-lateral strabismus may indicate a problem with this nerve.