Ultrasound-guided superficial cervical plexus block is useful in the diagnosis and treatment of painful conditions subserved by the nerves of the superficial cervical plexus, including posttrauma pain of the ear, neck, and clavicular region as well as pain of malignant origin. This technique is also used to provide surgical anesthesia in the distribution of the superficial cervical plexus for lesion removal, laceration repair, treatment of clavicular fractures, acromioclavicular joint dislocations, and carotid endarterectomy (Fig. 21.1). Neurodestructive procedures of the superficial cervical plexus may be indicated for pain of malignant origin that fails to respond to conservative measures.

The superficial cervical plexus arises from fibers of the primary ventral rami of the first, second, third, and fourth cervical nerves. Each nerve divides into an ascending and a descending branch providing fibers to the nerves above and below, respectively. This collection of nerve branches makes up the cervical plexus, which provides both sensory and motor innervation. The most important motor branch is the phrenic nerve, with the plexus also providing motor fibers to the spinal accessory nerve and to the paravertebral and deep muscles of the neck. Each nerve, with the exception of the first cervical nerve, provides significant cutaneous sensory innervation. The four terminal branches of the cervical plexus are the (1) greater auricular, (2) lesser occipital, (3) transverse cervical, and (4) suprascapular nerves. These nerves converge at the midpoint of the sternocleidomastoid muscle at its posterior margin at the level of the superior pole of the thyroid cartilage to provide sensory innervation to the skin of the lower mandible, neck, and supraclavicular fossa (Fig. 21.2). Terminal sensory fibers of the superficial cervical plexus contribute to nerves including the greater auricular and lesser occipital nerves.