Figure 1a: The surface anatomy of the left neck region of an 81-year-old male cadaver in the supine position. The black dashed lines represents the transverse plane of the laryngeal prominence. The black solid line indicates the posterior border of the sternocleidomastoid (SCM) muscle. The white solid line represents the distance of 2.08 cm (~1 thumb IPJ width) at which the injection was performed. The blue pin indicates the injection site.