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Abducent nerve

6) Abducent nerve

Abducent nerve
Abducent nerve
  • The longest cranial nerve (More prone to damage)
  • Emerges from the groove between the lower border of the pons & the medulla oblongata
  • Supplies the lateral rectus muscle
  • Function is to turn the eye laterally

Examination of eye movements & pupils (Cranial nerve III, IV & VI)

  • Pupil
  1. Dilated & become fix to light
  2. Consensual light reflex is absent in the affected eye
  • Ptosis
  1. Eyelid droops over the eye (Also can be due to sympathetic lesion – Levator palpabrae has both skeletal & smooth muscle)
  • Ocular movements
  1. Observe horizontal & vertical movements on 6 different directions of gaze
  2. Question the patient about Diplopia
  3. Example            : Diplopia is maximum when deviates to right & downwards (Right inferior rectus or Left superior oblique can be weak)
  • Conjugated movements
  1. Check the ability to fix the gaze on one object (Ability of the eyes to move together)
  • Nystagmus
  1. Disturbance in the normal balance of the eye control
  2. Need to check vertically & horizontally
  3. There’s a slow drift, followed by a fast corrective movement (Direction is given according to the fast phase)

Muscles involved in 6 different gazes

Muscles involved in 6 different gazes

Abducent nerve Abducent nerve Reviewed by Radiology Madeeasy on August 08, 2010 Rating: 5
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