The oculomotor nerve: biometry and endoneural fascicular systematization

Area of Science:

• Neuroanatomy
• Cranial Nerves

Background:

• The oculomotor nerve (cranial nerve III) controls eye movement and eyelid opening.
• Understanding its anatomical variations is crucial for surgical and clinical applications.

Purpose of the Study:

• To investigate the macroscopic and microscopic anatomical variations of the oculomotor nerve.
• To determine the fascicular structure of the oculomotor nerve in relation to its dural penetration.

Main Methods:

• Macroscopic dissection of 60 hemifaces.
• Histological examination of serial sections of the oculomotor nerve.

Main Results:

• Detailed mapping of the oculomotor nerve's course from origin to orbital cavity, highlighting numerous variations.
• Histological analysis revealed a true fascicular structure only distal to dural penetration.
• Significant variability in the number of fasciculi was observed between individuals and between sides of the same individual.

Conclusions:

• The oculomotor nerve exhibits substantial anatomical variability in its course and fascicular arrangement.
• Dural penetration marks a critical point for the development of the nerve's distinct fascicular organization.