Fig. 1.

Anatomy of the submandibular gland and injection point. A, The submandibular gland is located in the submandibular triangle, inferior to the mandibular border between the anterior and posterior belly of the digastric muscle with the platysma muscle forming the roof. The submandibular gland consists of a superficial portion and a deep portion, which are divided by the mylohyoid muscle. B, The distance from the angle of the mandible to the gnathion was divided into thirds, and ultrasonography was used to measure the mediolateral diameter at the lateral two-thirds point preoperatively and at 1, 2, 3, 4, 5, and 6 months postoperatively (blue dot: injection point).