Читать книгу Salivary Gland Pathology - Группа авторов - Страница 32

The superficial lobe lies within the digastric triangle. Its anterior pole reaches the anterior belly of the digastric muscle and the posterior pole reaches the stylomandibular ligament. This structure is all that separates the superficial lobe of the submandibular gland from the parotid gland. It is important to realize just how close the lower pole of the parotid is to the posterior pole of the submandibular gland as confusion can arise if a mass in the region is incorrectly ascribed to the wrong anatomical structure (Figure 1.2). Superiorly, the superficial lobe lies medial to the body of the mandible. Inferiorly, it often overlaps the intermediate tendon of the digastric muscles and the insertion of the stylohyoid muscle. The lobe is partially enclosed between the two layers of the deep cervical fascia that arise from the greater cornu of the hyoid bone and is in intimate proximity of the facial vein and artery (Figure 1.11). The superficial layer of the fascia is attached to the lower border of the mandible and covers the inferior surface of the superficial lobe. The deep layer of fascia is attached to the mylohyoid line on the inner aspect of the mandible and therefore covers the medial surface of the lobe.

Figure 1.11 Superficial dissection of the left submandibular gland. The investing layer of the deep cervical fascia is elevated off the submandibular gland and the facial vein is identified.

The inferior surface, which is covered by skin, subcutaneous fat, platysma, and the deep fascia, is crossed by the facial vein and the cervical branch of the facial nerve which loops down from the angle of the mandible and subsequently innervates the lower lip. The submandibular lymph nodes lie between the salivary gland and the mandible. Sometimes one or more lymph nodes may be embedded within the salivary gland.

The lateral surface of the superficial lobe is related to the submandibular fossa, a concavity on the medial surface of the mandible, and the attachment of the medial pterygoid muscle. The facial artery grooves its posterior part lying at first deep to the lobe and then emerging between its lateral surface and the mandibular attachment of the medial pterygoid muscle from which it reaches the lower border of the mandible.

The medial surface is related anteriorly to the mylohyoid from which it is separated by the mylohyoid nerve and submental vessels. Posteriorly, it is related to the styloglossus muscle, the stylohyoid ligament, and the glossopharyngeal nerve separating it from the pharynx. Between these, the medial aspect of the lobe is related to the hyoglossus muscle from which it is separated by the styloglossus muscle, the lingual nerve, the submandibular ganglion, the hypoglossal nerve, and the deep lingual vein. More inferiorly, the medial surface is related to the stylohyoid muscle and the posterior belly of digastric.