Integration of nociceptive activity from orofacial, cranial and cervical regions in the trigeminocervical nucleus: a scoping review with clinical implications.

A connection between orofacial, cranial and cervical regions has been documented through the trigeminocervical nucleus (TCN), but the predominant direction (orofacial/cranial-to-cervical or cervical-to-orofacial/cranio) of this connection still remains unclear. This scoping review was designed to determine the dominant direction of the connection between these two areas. Searches were conducted by combining these concepts: TCN, cervical and face/jaw/head region. Eighty-three studies were included. The most predominant direction was reported to be from the orofacial/cranial to the cervical region, with most of the studies conducted in mammals. The clinical implications of these findings for the spread and referral of pain between these regions are examined and discussed.