Botulinum Toxin Injection-Site Selection for a Smooth Shoulder Line: An Anatomical Study.

This study aimed to improve the accuracy of manual needle placement into the trapezius (TM) for smooth shoulder line. For macroscopic study 12 TMs and for microscopic study 4 cadavers were detached and then sampled, 1⁎1 cm at the four points from the origin to insertion site (0% at the most lateral point of external occipital protuberance and 100% at the most lateral point of acromion). Most of the nerve endings observed during macroscopic investigations were concentrated in the 60-80% region, and the second most distributed region was the 40-60% region. The microscopic results revealed that the 60-80% region on the reference line had the most dense neuromuscular junction area, while the 40-60% and 80-100% areas were similar in their neuromuscular junction densities. These anatomical results will be useful in clinical settings especially for cosmetic surgeons.