76 - Facial Trauma

temporal bones. The orbit consists of the maxilla, zygoma, frontal, sphenoid, orbital, and lacrimal bones (Fig. 76.1). The face is conventionally divided into thirds: upper, middle, and lower. The borders of each third are loosely defined by branches of the trigeminal nerve, which provides sensory innervation to the face. Identification of the exiting foramen for the distributing branches of the trigeminal nerve (cranial nerve V) is crucial when providing local nerve anesthesia (Fig. 76.2). The facial nerve (cranial nerve VII) intricately courses through the parotid duct and provides parasympathetic innervation, special sensory function to the tongue and soft palate, and general motor function to the 44 muscles of facial expression. Deep facial lacerations between the tragus and lateral canthus may jeopardize the integrity of the facial nerve. Any damage to the facial nerve distal to the stylomastoid foramen can result in facial nerve dysfunction, commonly referred to as Bell palsy. The parotid duct lies in a plane with the tragus and inferior corner of the nasal vestibule. Competency of the parotid duct must be considered in patients with deep lacerations in this region of the face (Fig. 76.3). The external carotid artery is the major vascular supply to the face. This vessel provides extensive collateral supply to the midline tissues through anastomosis (Fig. 76.4).