Surgical anatomy of the mandibular ramus of the facial nerve in Chinese adults.

One hundred and twenty Chinese adults' facial halves were selected for this study. The description of the mandibular ramus of the facial nerve was presented under 4 items: (1) the relationship with the lower border of the mandible, (2) the number of its rami, (3) the relationship with the retromandibular vein, the facial vein or the facial artery, and (4) its anastomoses with the buccal ramus and/or the cervical ramus. In these specimens, anterior to the facial artery, 90% of the mandibular rami ran above the lower border of the mandible, and 10% of the mandibular rami ran below the lower border of the mandible. Posterior to the facial artery, 67% of the mandibular rami ran above the lower border of the mandible, and 33% of the lowest mandibular rami passed in an arc with an average of 0.95 cm (the lowest point being 3 cm or less) below the lower border of the mandible. In 32% of the specimens, the mandibular ramus had no branch and in 68% of the specimens, the mandibular ramus had two or more rami. There were 100% of the mandibular rami lying superficially to the retromandibular vein and the facial vein, while in 5% of the specimens, some other mandibular rami ran deeply to the facial vein. In 83% of the specimens, the mandibular rami lay only superficially to the facial artery and in only 2% deeply to the facial artery. The remaining 15% ran both deeply and superficially to the facial artery. There were 60% of the specimens in which the mandibular rami had one or more anastomoses with the buccal rami.(ABSTRACT TRUNCATED AT 250 WORDS)