Reply: Facial Nerve Supply to the Orbicularis Oculi around the Lower Eyelid: Anatomy and Its Clinical Implications.

Abstract

Sir: We thank Dr. Hwang for his interest and comments on our article on facial nerve supply to the orbicularis oculi muscle around the lower eyelid.1 Dr. Hwang argues that atonic lower lids occur more frequently on the lateral side than on the medial side, and thus, raises a question whether the pretarsal branch comes from the lateral area and anastomosed. However, we do not agree with his assertion. We found just one or two very fine motor branch(es) from the lateral palpebral area. The nerve was not prominent and its anastomosis with the pretarsal branch was not found. These findings might explain why, empirically, the lateral orbicularis oculi muscle paralysis does not occur after lateral muscular incision. Postoperative lid margin malposition after lower blepharoplasty might be caused not by denervation sequelae of the lateral pretarsal orbicularis oculi muscle but by overzealous excision of the skin and the orbicularis oculi muscle or postoperative scar contracture at the middle lamella.2 Dr. Hwang compares our results to those of his previous study.3 His findings indicate that the buccal, the zygomatic, and the uppermost zygomatic branches innervate the medial, middle, and lateral orbicularis oculi muscle portions, respectively. In contrast, our results demonstrate that the pretarsal branch derived from the lower palpebral branch and one or two fine motor branch(es) in the lateral canthal area supply the lower orbicularis oculi muscle. This discrepancy might have resulted from the differences in the dissection technique and cadaver sample. The en bloc sample that he used has merits for handling during dissection. However, losing the three-dimensional anatomical structure is a critical shortcoming. The location, direction, and relationship among anatomical structures are distorted, as the three-dimensional structure is changed into a flat two-dimensional sample. Moreover, his dissection (Fig. 1 of Dr. Hwang’s comment) appears somewhat incautious, as the zygomatic and buccal branches of the facial and infraorbital nerves and the zygomaticofacial nerve are intermingled without distinction, leading to misinterpretation. Based on our meticulous in situ cadaver dissection (Figs. 5 and 8),1 the misinterpreted buccal, zygomatic, and uppermost zygomatic branches may be the lower palpebral branch from the zygomatic branch, infraorbital, and zygomaticofacial nerves, respectively. We provide the sensory nerve distribution and course to the orbicularis oculi muscle in the lower eyelid in an in situ preparation (Figs. 1 and 2 and Video 1).1 These results are consistent with Dr. Hwang’s results.4 As shown in Figure 2 of Dr. Hwang’s comment, the similarity with our results is that the infraorbital nerve vertically ascends to the lower eyelid, although the nerves in his en bloc preparation appear to have a tortuous course. Lastly, a key finding of our study is the first identification of the lower palpebral branch, upper medial palpebral branch, and pretarsal branch, which are distinguished from the angular nerve. These nerves have great clinical importance. Therefore, we named them to be remembered by surgeons. To conclude, our study provides surgeons with essential motor nerve anatomy for safe and effective surgery in lower blepharoplasty and midface lift. ETHICS STATEMENT All authors were informed of the World Medical Association Declaration of Helsinki, Ethical Principles for Medical Research Involving Human Subjects, and confirm that the present study firmly fulfilled the declaration. None of the authors has financial or private relationships with commercial, academic, or political organizations or people that could have improperly influenced this research. All cadaveric objects in this study were legally donated to The Catholic University of Korea. DISCLOSURE The authors have no financial interest to declare in relation to the content of this communication. Yeop Choi, M.D., Ph.D.Department of AnatomyInstitute for Applied AnatomyCollege of MedicineThe Catholic University of Korea, and Choi-Yeop Plastic Surgery Clinic In-Beom Kim, M.D., Ph.D.Department of AnatomyInstitute for Applied AnatomyCollege of MedicineThe Catholic University of KoreaSeoul, Republic of Korea