title: Superior divisional third cranial nerve paresis: clinical and anatomical observations of 2 unique cases.
abstract: BACKGROUND
  Within the midbrain, the third nerve nucleus is composed of a complex of subnuclei. The fascicular portion of the nerve courses through the red nucleus and exists in the midbrain just medial to the cerebral peduncle. The cisternal portion of the nerve is a single structure that divides into a superior branch and an inferior branch in the region of the cavernous sinus and superior orbital fissure.
  
  
  OBJECTIVE
  To describe 2 patients with superior divisional third cranial nerve paresis resulting from a lesion involving the cisternal portion of the nerve prior to its anatomical bifurcation.
  
  
  METHODS
  Case 1 was a 77-year-old man with a superior divisional third nerve palsy as the presenting manifestation of a posterior communicating artery aneurysm. Case 2 was a 41-year-old woman who developed a superior divisional third nerve palsy following anterior temporal lobectomy for epilepsy.
  
  
  RESULTS
  In both cases, the presumed location of the lesion was the cisternal portion of the third cranial nerve.
  
  
  CONCLUSIONS
  Although the anatomical division of the third cranial nerve occurs in the region of the anterior cavernous sinus or superior orbital fissure, there is a topographical arrangement of the motor fibers within the cisternal portion of the nerve. The clinical evaluation of a patient with a third cranial nerve paresis requires an understanding of the regional neuroanatomy and topographical organization of the nerve.
authors: Department of Neurology, College of Medicine, University of Florida, Gainesville, FL 32610, USA. tbhatti@eye.ufl.edu
authors: M Tariq
authors: MT
authors: Bhatti
authors: Stephen
authors: S
authors: Eisenschenk
authors: Steven N
authors: SN
authors: Roper
authors: John R
authors: JR
authors: Guy