Superficial views of right submandibular and carotid triangles. The platysma muscle has been raised (a portion remains attached at the upper right side of the image) from the superficial neck to reveal underlying structures associated with the submandibular and carotid triangles. The apex of the parotid gland extends below the angle of the mandible and rests upon the anterior border of the sternocleidomastoid muscle. It also covers part of the masseter muscle. The submandibular triangle is bounded by the posterior and anterior bellies of the digastric muscle and the lower border of the mandible. Its floor is formed by the hyoglossus and mylohyoid muscles. The principal contents are the submandibular gland, facial artery, and frequently the marginal mandibular branch of the facial nerve, which crosses superficial to the facial artery to the muscles of the lower lip and chin. The tortuous facial artery, a branch of the external carotid, courses deep to the posterior digastric and deep surface of the submandibular gland. It gives rise to several glandular branches, the submental artery, and then loops onto the mandible and face at the anteroinferior border of the masseter. Here, its pulse can be palpated. The mylohyoid nerve is a motor branch of the inferior alveolar nerve and emerges from the lower border of the mandible to supply the mylohyoid and anterior digastric muscles. The carotid triangle is bounded by the posterior digastric, superior belly of omohyoid, and upper anterior border of the sternocleidomastoid muscles. The sternocleidomastoid covers and protects the carotid sheath containing the internal jugular vein, internal carotid artery, and vagus nerve. The superior thyroid vein is tributary to the internal jugular vein. Near the apex of the parotid gland emerges the cervical branch of the facial nerve to the platysma muscle. The external jugular vein, formed by the union of the posterior branch of the retromandibular and posterior auricular veins, descends obliquely across the sternocleidomastoid to empty into the subclavian vein within the lateral triangle of the neck. It is crossed superficially by the transverse cervical nerve, a sensory branch of the cervical plexus, which supplies skin of the anterior neck. Posterior to and coursing in company with the vein is the great auricular nerve containing C2 and C3 fibers from the cervical plexus. Its posterior branch supplies skin over the mastoid process while its anterior branch supplies skin of the lobule of the ear and angle of the mandible. The lesser occipital nerve, also a branch of the cervical plexus, courses along the posterior border of the sternocleidomastoid to supply skin of the posterolateral scalp. (Image courtesy of PA Rubino)