“…[12][13][14]25 The accessory nerve To ensure effective blockade of the sensory branches of the cervical plexus supplying the lower portion of the sternocleidomastoid muscle, and the corresponding skin and platysma muscle, unlike the carotid endarterectomy, we attempted to maintain the injection at the C4-C5 level, because the cervical plexus is situated between the longus capitis and middle scalene muscles. 28 If the injection were to be made at a level higher than C4, it would be possible to spare the lower cutaneous branches of the cervical plexus-the transverse cervical and supraclavicular nerves-in the PCS, 29 especially when using a small volume of local anesthetic. If the injection were to be made too medially in the PCS, it would also be possible to spare the superficial branches of the cervical plexus.…”