Mediterr J Otol 2005:1(3):117-121.

Anatomy of the extratemporal facial nerve in rats

Sertac Yetiser, Erkan Kahraman, Bulent Satar, Serdar Karahatay, Timur Akcam
Gulhane Medical School Dept of ORL & HNS Etlik,   06018  Ankara Turkey  syetiser@yahoo.com

OBJECTIVE This study aims to measure peripheral branching of the facial nerve and to describe electromyographic findings after transection of the nerve in rats.

MATERIALS AND METHOD: Ten male Wistar rats were anaesthetized by an intramuscular injection of ketamine and Xylocaine. The facial nerve was skeletonized after a skin incision extending from the postauricular area to the angle of the mouth. The length of the peripheral branches was measured. The mandibular, buccal, and ocular branches of the facial nerve were transected in 5 of the rats to follow the acute functional and electrophysiological outcome of traumatic facial paralysis. The latency, amplitude, and duration of motor unit action potentials were obtained from the orbicularis and buccal muscles after stimulation of the main trunk of the facial nerve with a needle electrode.

RESULTS: Mean length of the main trunk, postauricular, frontal, buccal and mandibular branches were 4.8±0.62 mm, 6.5±0.91 mm, 12.3±3.04 mm, 22.8±1.39 mm, and 21.9±2.11 mm,  respectively. The latency of the evoked potentials ranged from 1.50 msec to 1.58 msec, and the amplitude of the potentials was 6.3 mV. The duration of the potential was 2.4 to 4.1 msec. No response was observed after transection of the facial nerve.

CONCLUSION: The rat model provides an excellent platform for facial nerve research.