Through which foramen does CN VI exit the skull?
Superior orbital fissure
What type of nerve is CN VI?
Motor
What is the central connection of CN VI?
Nucleus in pons
What is the peripheral distribution of CN VI?
Lateral Rectus muscle
What is the general function of CN VI?
Moves eyeball laterally
Which modality applies to CN VI?
General somatic efferent - general motor to skeletal muscle Abducent nerve innervates the lateral rectus muscle.
Where is the nucleus of the abducent nerve located?
Floor of the fourth ventricle in the caudal pons.
A thrombosis or damaeg in which sinus could compress the abducent nerve?
Cavernous sinus
An aneurysm of which artery can make the abducent nerve vulnerable to compression?
Internal carotid artery
Why is the long intracranial course of the abducent nerve of clinical importance?
Susceptible to stretching in the event of a rise in intracranial pressure. A space occupying lesions such as a brain tumour may compress the nerve causing paralysis of the lateral rectus muscle.
What does the lateral rectus muscle do?
Abducts the eye
The abducent nucleus distributes nerve fibres contained within what?
Medial longitudinal fasciculus (MLF)
What is the medial longitudinal fasciculus and what is its role?
Main central connection for the oculomotor, abducent and trochlear nerves. Creates conjugate eye movements.
What is the PPRF?
Paramedian Pontine Reticular Formation - centre for lateral gaze.
What does a lesion of the medial longitudinal fasciculus between the nuclei of CN III and VI cause?
Inter nuclear ophthalmoplegia
What is internuclear ophthalmoplegia ?
Disorder of conjugate lateral gaze - affected eye has impaired adduction.
What is internuclear ophthalmoplegia normally caused by?
Multiple sclerosis
What happens in internuclear ophthalmoplegia ?
Interruption of fibres going from the abducent nucleus of the opposite side to the oculomotor nucleus of the same side causes inability to adduct the eye on the side of the lesion and the patient will normally have nystagmus of the adducting eye.