The zygomaticotemporal branch of the trigeminal nerve: Part II. Anatomical variations.

Background: Musculofascial and vascular entrapments of peripheral branches of the trigeminal nerve have been thought to be trigger points for migraine headaches. Surgical decompression of these sites has led to complete resolution in some patients. The zygomaticotemporal branch of the trigeminal nerve has been shown clinically to have sites of entrapment within the temporalis. A cadaveric study was undertaken to elucidate and delineate the location of this nerve's foramen and intramuscular course.

Methods: The periorbital and temporal regions of 50 fresh cadaveric hemiheads were dissected. The deep temporal fascia and lateral orbital wall were exposed through open dissection. The zygomaticotemporal nerve was located and followed through the temporalis muscle to its exit from the zygomatic bone. The muscular course was documented, and the nerve foramen was measured from anatomical landmarks.

Results: In exactly half of all specimens, the nerve had no intramuscular course (n = 25). In the other half, the nerve either had a brief intramuscular course (n = 11) or a long, tortuous route through the muscle (n = 14). The foramen was located at an average of 6.70 mm lateral to the lateral orbital rim and 7.88 mm cranial to the nasion-lateral orbital rim line, on the lateral wall of the zygomatic portion of the orbit. Two branches were sometimes seen.

Conclusions: The zygomaticotemporal branch of the trigeminal nerve is a site for migraine genesis; surgical decompression or chemodenervation of the surrounding temporalis can aid in alleviating migraine headache symptoms. Advances in the understanding of the anatomy of this branch of the trigeminal nerve will aid in more effective surgical decompression.