Parotid gland

The parotid gland (or simply parotid, latin: glandula parotis, glandula parotidea) is the largest of the salivary glands and is located on each side of the head in front of the ears.

The parotid gland is a paired organ and has two portions: the deep portion that is located topographically in the retromandibular fossa, and the superficial portion of the parotid gland that is situated within superficial tissue on the lateral side of the face in front of and below the ear.

The parotid gland is situated in the region around the ramus of the mandible and lies on the masseter muscle, it extends upward to the zygomatic arch, downward to the mandibular angle, and at the back reaches the external acoustic meatus. The parotid gland is covered by the parotid fascia. The parotid gland secretes saliva via a duct opening in the oral cavity, called the parotid duct. The parotid duct is five to six centimeters long and passes through the cheek, piercing the buccinator muscle. The duct of the parotid gland opens into the oral vestibule at the level of the second upper molar tooth.

The secretomotor functions of the parotid gland provide salivation and are controlled by the parasympathetic nervous system via the postganglionic parasympathetic fibers arising from the otic ganglion. The preganglionic parasympathetic neurons are located in the inferior salivatory nucleus in the brain stem and reach the otic ganglion via the glossopharyngeal nerve (CN IX) and its branches. The sympathetic fibers innervating the parotid gland arise from the superior cervical ganglion of the sympathetic trunk and reach the gland via blood vessels, and is mainly responsible for vasoconstriction of the vessels supplying the gland. The sensory nerve supply to the parotid gland is provided by the parotid branches of the auriculotemporal nerve, a branch of the mandibular nerve (CN V3), which also carry the postganglionic parasympathetic fibers mentioned above.