Masseteric Region

9 Masseteric Region

Fig. 9.1. The masseteric region. The parotid gland and the facial nerve branches have been removed.

The zygomaticus major muscle, the masseter muscle, and the temporal fascia and lateral ligament are the structures which are attached to the zygomatic arch.

The origin of the zygomaticus major muscle is the subzygomatic fossa, which is located posterior and inferior to the malar eminence and anterior to the zygomaticotemporal suture. The subzygomatic fossa is usually an easily palpable landmark.

The retromandibular vein usually divides into anterior and posterior branches near the tail of the parotid gland. Outside the gland, anterior branch joins the facial vein to form the common facial vein, while the posterior branch unites with the posterior auricular vein to form the external jugular vein. The common facial vein drains into the internal jugular vein (see Fig. 11.2 and Fig. 12.3).

The temporomandibular joint has one major ligament, the temporomandibular ligament, also termed the lateral ligament, which is actually the thickened lateral portion of the capsule. It has two parts: an outer oblique portion and an inner horizontal portion. The base of this triangular ligament is attached to the zygomatic process of the temporal bone and the articular tubercle. Its apex is fixed to the lateral side of the neck of the mandible.

Fig. 9.2. The masseteric region. The superficial part of the masseter muscle has been reflected.

The masseter muscle is one of the muscles of mastication. It is quadrilateral in shape and consists of three layers. The layers are fused anteriorly, but diverge posteriorly. The most pronounced layer is superficial. It originates from the anterior two-thirds of the inferior border of the zygomatic arch up to the zygomatic process of the maxilla. Initially, it is aponeurotic and passes obliquely in an inferomedial direction. It inserts into the inferior border of the external surface of the angle of the mandible. Its insertion extends anteriorly to the junction of the ramus with the body of the mandible.

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