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 Stenson'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 - it should be noted that widespread vaccination against mumps has markedly reduced the incidence of mumps parotitis. Other infections such as bacterial infections can cause parotitis. The symptoms include enlarged, painful and tender parotid glands.