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Third Nerve Palsy

In this article, we discuss
The third cranial nerve innovates the following muscles:

  • Medial rectus
  • Superior Rectus
  • Inferior Oblique
  • Inferior Rectus
  • Levator Palpebrae Superioris (lifts the eyelid)
  • Sphincter pupillae (constricts the pupil)
  • Ciliary muscles (focuses the eye)

Therefore, a complete palsy of this nerve will result in:

  • Limitation in adduction
  • Limitation in elevation
  • Some limitation in depression
  • Ptosis
  • A fixed, dilated pupil

Some Causes of a Third Nerve Palsy:

  • Microvascular (hypertension or diabetes)
  • Trauma
  • Compression (tumour or aneurysm)
  • Iatrogenic (post-neurosurgery)

‘See also’ below how an Orthoptist would record the eye movements of a right third nerve palsy.

© King’s College Hospital NHS Foundation Trust
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