Anatomical Variations and Surgical Implications of the Cervical Branch of the Facial Nerve: A Systematic Review.

The cervical branch of the facial nerve (CBFN) innervates the platysma and contributes to lower facial animation. Due to its anatomical variability and proximity to critical structures, including the marginal mandibular branch, great auricular nerve, and submandibular gland, it is vulnerable to iatrogenic injury during neck dissection and rhytidectomy, which can lead to functional and aesthetic complications. This systematic review evaluates the CBFN's course, branching patterns, and surgical relevance. A PRISMA-compliant systematic review was conducted across PubMed, Web of Science, SCOPUS, and ScienceDirect. Eligible studies included anatomical or cadaveric investigations detailing the CBFN's trajectory, branching, and anastomoses. Of 402 screened records, 10 met inclusion criteria. Data were extracted on topography and inter-nerve communications. Risk of bias was assessed using a qualitative appraisal tool due to the anatomical nature of the studies. The CBFN presented as a single trunk in 61.3% to 80% of specimens and as double branches in 20% to 38.7%. Anastomoses occurred with the transverse cervical (16%-100%), great auricular (24%-38.7%), and marginal mandibular nerves (24%). The CBFN coursed deep to the platysma in all cases and inferior to the mandible, though its relation to the cervical fascia and submandibular gland varied. Injury may indirectly affect the marginal mandibular branch via anastomoses, resulting in lower lip paresis. The cervical branch exhibits substantial anatomical variation, particularly in its branching and inter-nerve connections. Intraoperative preservation requires meticulous dissection technique, and the high frequency of anastomoses highlights the need for caution during subplatysmal dissection in cervicofacial surgery. Further anatomical standardization studies are recommended to refine operative planning and improve surgical outcomes.