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trochlear_nerve [2022/12/28 11:20] – [Trochlear Nerve] tomtrochlear_nerve [2023/04/26 17:13] (current) – [Muscles] sabs
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 +{{tag>Anatomy}} 
 ==== Trochlear Nerve ==== ==== Trochlear Nerve ====
  
-Andrew T. Austin has hypothesised that it may be the trochlear nerve[(Trochlear_nerve>Trochlear nerve[[https://en.wikipedia.org/wiki/Trochlear_nerve|Wikipedia]])] +Andrew T. Austin has hypothesised that it may be the trochlear nerve[(Trochlear_nerve>Trochlear nerve[[https://en.wikipedia.org/wiki/Trochlear_nerve|Wikipedia]])] that provides the organic mechanism for the changes brought about by the utilisation of eye movements within the [[iemt_wiki|Integral Eye Movement Therapy (IEMT)]] model. 
- that provides the organic mechanism for the changes brought about by the utilisation of eye movements within the Integral Eye Movement Therapy (IEMT) model. +
  
 The trochlear nerve, also known as cranial nerve IV, is responsible for supplying one of the extraocular muscles of the eye: the superior oblique muscle. Additionally, the trochlear nerve is a somatic efferent or motor nerve, and alongside the oculomotor and abducens nuclei, it is responsible for eye movement. The trochlear nerve, also known as cranial nerve IV, is responsible for supplying one of the extraocular muscles of the eye: the superior oblique muscle. Additionally, the trochlear nerve is a somatic efferent or motor nerve, and alongside the oculomotor and abducens nuclei, it is responsible for eye movement.
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 The muscle also creates abduction of the eye, moving the pupil away from the nose, and intrusion, rotating the eye such that the top of the eye moves toward the nose. The muscle also creates abduction of the eye, moving the pupil away from the nose, and intrusion, rotating the eye such that the top of the eye moves toward the nose.
  
-The superior oblique muscle is the only extraocular muscle that can lower the pupil with the eye adducted. Thus, to isolate the function of the superior oblique muscle from the other additional extraocular muscles, the muscle can be tested by requesting the patient to adduct the eye and then ask to depress the eye. Failure to depress the eye during adduction indicates a problem with the superior oblique muscle or the trochlear nerve. In addition, a general rule of thumb is that “obliques go opposite”; the left superior oblique is tested by having the patient look right, while the right superior oblique is tested with the patient looking left.+The superior oblique muscle is the only extraocular muscle that can lower the pupil with the eye adducted. Thus, to isolate the function of the superior oblique muscle from the other additional extraocular muscles, the muscle can be tested by requesting the patient to adduct the eye and then asking to depress the eye. Failure to depress the eye during adduction indicates a problem with the superior oblique muscle or the trochlear nerve. In addition, a general rule of thumb is that “obliques go opposite”; the left superior oblique is tested by having the patient look right, while the right superior oblique is tested with the patient looking left.
  
 ==== Origin ==== ==== Origin ====
  
-The trochlear nerve originates in a small nucleus in the midbrain. The nerve fibers cross over to the other side of the brainstem before leaving it near the junction of the midbrain and pons. The trochlear nerve is the single cranial nerve that leaves the brainstem from the back of the brainstem's posterior surface. Additionally, it's also the only cranial nerve to entirely originate from a nucleus contralateral to the structure it supplies.+The trochlear nerve originates in a small nucleus in the midbrain. The nerve fibers cross over to the other side of the brainstem before leaving it near the [[saccades_eye_movements|junction of the midbrain and pons]]. The trochlear nerve is the single cranial nerve that leaves the brainstem from the back of the brainstem's posterior surface. Additionally, it's also the only cranial nerve to entirely originate from a nucleus contralateral to the structure it supplies.
  
 The trochlear nerve is also a  very delicate nerve that can get damaged relatively easily. Damage can be congenital, the most common cause, or occurs due to other causes such as trauma. However, the symptoms of trochlear nerve palsy aren't typically as noticeable as those that result from the damage done to the oculomotor or abducens nerve. The trochlear nerve is also a  very delicate nerve that can get damaged relatively easily. Damage can be congenital, the most common cause, or occurs due to other causes such as trauma. However, the symptoms of trochlear nerve palsy aren't typically as noticeable as those that result from the damage done to the oculomotor or abducens nerve.
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 The diplopia in trochlear nerve palsy can be vertical or diagonal and worse with a downward gaze. Compensation for nerve palsy usually includes a head tilt to the opposite side and a tucking of the chin, so the affected eye's pupil can move up and out, instead of downwards and in. The eyes will display hypertropia during clinical examination, with the affected eye being slightly elevated relative to the other normal eye. Undercover, the affected eye will show an upward drift relative to the other eye. The diplopia in trochlear nerve palsy can be vertical or diagonal and worse with a downward gaze. Compensation for nerve palsy usually includes a head tilt to the opposite side and a tucking of the chin, so the affected eye's pupil can move up and out, instead of downwards and in. The eyes will display hypertropia during clinical examination, with the affected eye being slightly elevated relative to the other normal eye. Undercover, the affected eye will show an upward drift relative to the other eye.
  
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  • Last modified: 2022/12/28 11:20
  • by tom