Fig. 1.

Sonographic appearance of frequently injected muscles (mainly a, b) and more difficult accessible, small, or deeper located muscles (mainly c, d, e). Muscles: IH infrahyoid, SCM sternocleidomastoideus, SA scalenus anterior, SMP scalenus medius posterior, LEV levator scapulae, TRA trapezius, SEM semispinalis capitis, SPL splenius capitis, OCI obliquus capitis inferior, LC longissimus capitis, LCo longus colli, LCa longus capitis, RMi rectus capitis posterior minor, RMa rectus capitis posterior major, and OCS obliquus capitis superior. Others are CA carotid artery, BP brachial plexus, VC5 vertebra C5, RC5 root C5, and VN vagus nerve