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A high-frequency transducer is preferred for this block due to the shallow nature of the cervical plexus.
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This approach is for the superficial cervical plexus nerve block, which aims to spare the motor components and avoid serious complications that are more associated with the deep cervical plexus block.
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This block can be used for surgeries such as a carotid endarterectomy, superficial neck surgery, lymph node dissection, vascular access surgery, and excision of thyroglossal duct cysts or brachial cleft cysts.
Sonoanatomy
The cervical plexus, which originates from the anterior rami of the cervical vertebrae 2 to 4, provides sensory innervation to the ipsilateral neck, jaw, occiput, and anterior supraclavicular area ( Fig. 23.1 ). It begins at the level of the first cervical vertebra, anterior to the levator scapulae and middle scalene muscles before piercing the platysma muscle near the posterior border of the sternocleidomastoid muscle. The cervical plexus divides into four terminal cutaneous branches: the lesser occipital nerve, greater auricular nerve, transverse cervical nerve, and supraclavicular nerve ( Fig. 23.2 ). Before the cutaneous branches, the cervical plexus also divides to supply motor innervation to the phrenic nerve, the ansa cervicalis (innervation to the geniohyoid and infrahyoid muscles), components of the accessory nerve to sternocleidomastoid and trapezius muscles, and direct branches to the prevertebral muscles of the neck. The location of the division of the motor and sensory components is at the posterior border of the sternocleidomastoid. The fascia planes at this location allow for selective sensory blockade without compromising the neck and accessory muscles. Several authors use these planes to divide the cervical plexus block into superficial, intermediate, and deep blocks. This chapter focuses on the superficial cervical plexus block to target only the sensory portion of the nerve. This technique to correctly place a superficial cervical plexus block is easy, safe, and provides most anesthetic goals. For this nerve block technique, local anesthetic should be injected above the deep cervical fascia.
