Localisation of the supraorbital, infraorbital and mental foramina: A review

Introduction: The efficacy of the trigeminal nerve block varies between 70% and 98%, relying heavily on the accurate identification of anatomical landmarks. The anatomical position and incidence of supernumerary foramina of the supraorbital (SOF), infraorbital (IOF) and mental (MF) foramina vary amongst population groups, sex, age, and climate conditions. Hence, the localisation of the foramina is crucial in the administration of anaesthesia to the related nerves. The objective of this study was to document evidence of the morphology and morphometry of the SOF, IOF, and MF – in the form of a narrative review. Materials and methods: This review analyses reports on the localisation of the SOF, IOF and MF, and their variations (if any). A literature search was conducted on multiple electronic databases (PubMed, MEDLINE, Google Scholar and Science Direct). A total of 149 articles were eligible for inclusion in this review. Discussion and conclusion: The results of the literature search shows that the SOF has not been studied as extensively as the IOF and MF. Therefore, it is suggested that further research be conducted on the anatomy and clinical relevance of the SOF. The SOF, however, presents frequently as a notch and is, therefore, called the supraorbital notch. The IOF is often an oval-shaped opening and may present with one accessory foramen. The MF is often in line with the 2nd mandibular premolar tooth and may also have accessory openings. This review revealed that the IOF and MF frequently lie lateral to the SOF, contradicting standard anatomical literature which states that they all lie on the same vertical plane. Medical professionals should consider the location and shape of the studied foramina, and the occurrence of accessory foramina, to successfully administer the corresponding nerve block. Landmarks used to localise the foramina highlighted in this review may be applied to evaluate their clinical relevance.