These videos have been excerpted from Netter’s Video Dissection Modules on Student Consult.
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Step 3
Determine the position of the parotid gland, anterior to the ear and extending over the ramus of the mandible. Note the dense parotid capsule and the anterior margin of the gland. With the buccal fat pad removed, identify and trace the parotid duct anteriorly to the point just inferior to the zygomaticus major muscle, where it penetrates the buccinator muscle On this side of the face, identify the main branches of the facial nerve emerging from the substance of the parotid gland: temporal; zygomatic; buccal, which has a branch running on either side of the parotid duct; the mandibular, which runs just below the margin of the mandible; and the cervical, which is not seen here.
Key Terms
• Parotid gland: the largest of the salivary glands. It overlies the ramus of the mandible, anterior and inferior to the external ear, extending from the zygomatic arch to the angle of the mandible N3 N2 N24. The gland resembles a three-sided pyramid, with the apex directed inferiorly. The facial nerve and its branches pass through the parotid gland, but do not innervate it. The external carotid artery gives off its two terminal branches, the maxillary artery and the superficial temporal artery, inside the gland. The parotid duct (also known as Stensen’s duct) empties within the buccal cavity opposite the upper second molar. Serous fluid (as opposed to mucous fluid) is produced by the parotid gland to facilitate mastication and swallowing. Secretion of saliva by the parotid gland is controlled via presynaptic parasympathetic fibers traveling in the tympanic branch of glossopharyngeal nerve (CN IX), which pass through the tympanic plexus in the middle ear and then form the lesser petrosal nerve that travels to otic ganglion N61 N126 N135. After synapsing in the otic ganglion, the postganglionic fibers travel as part of the auriculotemporal nerve (a branch of the mandibular nerve (V3)) to reach the parotid gland. Sympathetic nerves reach the gland from the superior cervical ganglion via the carotid plexus, traveling along branches of the external carotid artery. Parasympathetic stimulation produces a watery, serous saliva, while sympathetic stimulation leads to the production of a low volume, enzyme-rich saliva. Branches of the external carotid artery supply the gland via the transverse facial artery, and numerous local veins drain to tributaries of external and internal jugular veins.
• Buccal fat pad: an encapsulated mass of fat in the cheek, external to the buccinator muscle and between it and the masseter muscle. It is well developed in infants, and is frequently extracted in cosmetic surgery on adults to provide a slightly more chiseled look. N35
• Buccinator muscle: the muscle that forms the bulk of the cheek N25 N45. It arises from the pterygomandibular raphe, which stretches between the pterygoid hamulus and the lingula of the mandible and which represents the junction between the buccinator muscle and superior pharyngeal constrictor. The superior and inferior parts of this muscle are also attached to the outer surfaces of the alveolar bone of the maxilla and mandible, and anteriorly they blend with the orbicularis oris. The muscle pulls back on the corners of the lips, squeezes the cheek and compresses the vestibule (cheek pouch) against the teeth so that food and fluids in the vestibule are forced into the oral cavity, This squeezing occur during the initial phase of swallowing and can be appreciated by inserting a finger between the cheek and gums while attempting to swallow. N54 N55
• ABOUT:
The project was made possible by several very dedicated faculty and staff at University of North Carolina, Chapel Hill--especially O.W. Henson and Noelle A. Granger--and partner schools, and by a grant from the Fund for the Improvement of Post-Secondary Education of the US Department of Education. This channel includes over 400 short videos highlighting the steps in a full-body human dissection in the gross anatomy lab. Each step is narrated and key structures labeled.
