Surgical Anatomy of the Mandibular Region for Reconstructive Purposes

Abstract

Surgical anatomy of the mandibular region for reconstructive purposes In the current era of contemporary reconstruction of the mandible, microvascular free tissue transfer is the method of choice for large bony and soft tissue defects. As outlined in various articles in this Atlas, there are other reconstructive modalities, such as pectoralis major myocutaneous flap and costochondral free grafts. Regardless of the method of reconstruction, the surgical anatomy of the perimandibular region remains unchanged. It is imperative that the reconstructive surgeon be familiar with this anatomy and particular areas of interest as they relate to the microvascular anastomosis. This article reviews the clinically relevant anatomy of the upper neck and the submandibular triangle, with emphasis on surgical pearls of each region. Fascia of the perimandibular region There are two basic fascias of the upper neck and the perimandibular space: superficial and deep (Fig. 1). The superficial fascia is the fibrofatty layer just deep to the dermal plexus of skin. This superficial fascia (superficial cervical fascia) overlies the platysma muscle and is continuous with the superficial fascia of the face between the inferior border of the mandible and the zygomatic arch known as the superficial musculo-aponeurotic system. The function of this fascia is to prevent propagation of superficial infections to the deeper structures. Just deep to the platysma muscle is the most superficial layer of the deep fascia of the neck. There are many names for this fascia, which only adds to the confusion for the reader. The most commonly used and appropriate names for this fascia include superficial layer of the deep cervical fascia (SDCF) and the investing fascia of the neck. This fascia is of clinical significance when performing mandibular reconstruction. This fascia completely encircles the neck and, in doing so, envelopes the sternocleidomastoid and trapezius muscles on both sides. The SDCF also forms the capsule of the submandibular gland; as it travels onto the face, the name changes to the parotido-masseteric fascia, the deep fascia of the face that comprises the fascia (capsule) of the parotid gland. The SDCF contains the marginal mandibular and cervical branches of the facial nerve and the facial artery and vein. There is a specific anatomic relationship between these structures that is discussed later. Just deep to the SDCF exists the middle layer of the deep cervical fascia (MDCF). This fascia is also known as the pretracheal (a misnomer, because it actually encircles the trachea completely) or visceral fascia and contains the buccopharyngeal fascia as one its more cephalad components. The middle layer of the deep cervical fascia encircles the trachea, esophagus, thyroid, and parathyroid glands of the neck. This fascia is encountered during a tracheostomy as the last layer before entering the trachea.