Regional anesthesia is commonly used for postoperative pain management to decrease postoperative pain and opioid consumption following head and neck surgery. Myriad techniques can be used for both acute and chronic pain management either diagnostic or therapeutic procedures. Because of the vicinity of cranial and cervical nerves to many vital structures in a compact area, the efficacy and safety of cephalic blocks are based on precise and detailed knowledge of the anatomical relationships of the selected nerve, its deep and superficial courses, and the final sensory territories.
Sensory innervation of the face and neck is supplied by the trigeminal nerve (fifth cranial or V) and the C2–C4 cervical nerve roots that constitute the superficial cervical plexus (Figure 31–1A).
Innervation of the face. A: Dermatomes of the head, neck, and face. B: Distribution of the three branches of the trigeminal nerve.
This chapter outlines clinically applicable regional blocks of the face that for perioperative and chronic pain management. For each block, practical anatomy, indications, technique, and type of complications are specifically described.
The fifth cranial nerve carries both sensory and motor components. The trigeminal ganglion (semilunar or Gasserian ganglion) lies in Meckel’s cave, an invagination of the dura mater near the apex of the petrous part of the temporal bone in the posterior cranial fossa. Postganglionic fibers exit the ganglion to form three nerves:
The ophthalmic nerve (V1), a sensory nerve, divides into three branches (lacrimal, frontal, and nasociliary nerves) before entering the orbit through the superior orbital fissure. It innervates the forehead, eyebrows, upper eyelids, and anterior area of the nose (Figure 31–1B).
The maxillary nerve (V2), a purely sensory nerve, exits the middle cranial fossa via the foramen rotundum, passes forward and laterally through the pterygopalatine fossa, and reaches the floor of the orbit by the infraorbital foramen. It innervates the lower eyelid, the upper lip, the lateral portion of the nose and nasal septum, cheek, roof of the mouth, bone, teeth and sinus of the maxilla, and the soft and hard palates (Figure 31–1B).
The mandibular nerve (V3) is a mixed sensory and motor (for the mastication muscles) nerve. After exiting the cranium through the foramen ovale, it delivers sensory branches that supply the front of the ear, the temporal area, the anterior two-thirds of the tongue and the skin, mucosa, and teeth and bone of the mandible (Figure 31–1B).
These sensory nerves can be blocked either at their emergence point from the cranium (V2 and V3) or, more distally and superficially, at their exit from the facial bones (V1, V2, V3) (Figure 31–1).