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Retromandibular and Proximal Neck Dissection, Left Side

Surgical Correlation


Retromandibular and proximal neck dissection, left side. Skin, superficial fascia, and the parotid gland have been removed on the face and neck to reveal underlying structures. These include the masseter muscle covering the ramus of the mandible and subcutaneous fatty tissue anterior to it. In the retromandibular region the facial nerve is giving rise to branches as it courses through the parotid gland (removed). Deep to it is the retromandibular vein (not  labeled) and the external carotid artery. The latter terminates with its maxillary and superficial temporal branches. Below the body of the mandible is the submandibular triangle bounded by this bone and the anterior and posterior bellies of the digastric muscles. The floor of this triangle is formed by the hyoglossus (posteriorly, not visible here) and mylohyoid (anteriorly) muscles. The principal content of this triangle is the submandibular gland. The stylohyoid muscle splits to enclose the intermediate tendon of the digastric muscle. Between the right and left anterior digastric muscles and body of the hyoid bone is the unpaired submental triangle whose floor is the mylohyoid muscle. Inferior to the body of the hyoid are the infrahyoid muscles consisting here of the superior belly of the omohyoid and the underlying thyrohyoid muscle. The latter muscle partially covers the thyrohyoid membrane into which passes the superior laryngeal artery and internal laryngeal nerve to supply the upper part of the laryngeal interior. The inferior pharyngeal constrictor muscle is shown as well before it attaches to the thyroid and cricoid cartilages of the larynx. The superior thyroid artery descends on the muscle enroute to the thyroid gland. In the lateral neck the internal jugular vein has been cut and reflected to reveal the common carotid and internal carotid arteries. The vagus nerve descends in the neck between the internal jugular and internal carotid vessels. The hypoglossal nerve courses deep to the digastric muscles toward the oral cavity and tongue. Near the bifurcation of the common carotid artery C1 fibers leave the epineurial sheath of this nerve as the superior root of the ansa cervicalis to supply infrahyoid muscles. Removal of the sternocleidomastoid muscle exposes the anterior and middle scalene muscles and levator scapulae. In addition, removal of deep neck musculature has exposed the suboccipital muscles, obliquus capitis inferior and superior. A portion of the vertebral artery is shown before it enters the transverse foramen of the atlas. It is crossed superficially by the ventral ramus of the C2 spinal nerve. Posterior to this, the greater occipital nerve, the dorsal ramus of C2, emerges from the lower border of obliquus capitis inferior. A portion of the skull and meninges have been removed to expose the cerebellum, sigmoid sinus, and superior petrosal vein. (Image courtesy of PA Rubino)