Parotid gland

The parotid gland is the largest of the salivary glands. It is found in the subcutaneous tissue of the face, overlying the mandibular ramus and anterior and inferior to the external ear. The duct to this gland (also known as Stensen's duct) empties within the buccal cavity (the inside of the cheek). Serous fluid (as opposed to mucous fluid) is produced by the parotid gland. The facial nerve and its branches pass through the parotid gland as do the external carotid artery and its branches.

Although the facial nerve (VII) runs through this gland, it does not control it. Secretion of saliva by the parotid gland is controlled by the glossopharyngeal nerve (IX). The parotid receives secretory fibres from the auriculotemporal nerve which arises from the otic ganglion - the preganglionic fibres which control parotid secretion originate in the inferior salivary nucleus and leave the brain via the glossopharyngeal nerve (IX).

Inflammation of one or both parotid glands is known as parotitis. The most common cause of parotitis was mumps. Widespread vaccination against mumps has markedly reduced the incidence of mumps parotitis. Other infections such as bacterial infections can cause parotitis as may blockage of the duct, whether from salivary duct calculi or external compression. Stones mainly occur within the main confluence of the ducts and within the main parotid duct. The patient usually complains of intense pain when salivating and tends to avoid foods which produce this symptom. In addition the parotid gland may become enlarged upon trying to eat. The pain can be reproduced in clinic via squirting lemon juice into the patient's mouth. Surgery depends upon the situation of the stone, if within the anterior aspect of the duct a simple incision into the buccal mucosa with sphinterotomy may allow removal, however if further posterior within the main duct, complete gland excision may be necessary.

the commonest of tumors in the parotid gland are benign and only affect the superficial glnd. These include pleomorphic adenoma and adenolymphoma. Their importance is in relation to their anatomical position. Critically, the relationship of the tumor to the branches of the cranial nerve VII must be defined because resection may damage the nerves. If the tumor is deep within the gland, the patient should give consent for potential damage of the facial nerve.