Parotid gland

At a glance

English

Parotid gland

Latin (TA2)

Glandula parotidea

System

Digestive

Region

Whole body

Side

Paired, left and right

About the parotid gland

There is a parotid gland on each side of the face, filling the hollow between the ramus of the mandible in front and the mastoid process and sternocleidomastoid behind. Its upper edge reaches the zygomatic arch and its lower pole drops below the angle of the jaw. Seen from the side it is roughly a wedge or inverted pyramid, and it pushes deep towards the side wall of the pharynx. A tough sheet of deep cervical fascia forms its capsule, which is why swelling of the gland is so painful.

Several important structures pass through the gland rather than around it. From superficial to deep these are the facial nerve with its branches, the retromandibular vein, and the external carotid artery, which divides within the gland into the maxillary and superficial temporal arteries. The facial nerve splits into its five main branches inside the parotid and fans out from its front border; surgeons speak of superficial and deep lobes of the gland on either side of that nerve plane. The parotid lymph nodes lie in and on it. Its duct leaves the front border and crosses the masseter to the cheek.

The gland makes a thin, watery (serous) saliva rich in the starch-splitting enzyme amylase. Output is small at rest and rises sharply with chewing and taste. The secretomotor nerve supply takes an unusual route: fibres start in the glossopharyngeal nerve, relay in the otic ganglion and reach the gland with the auriculotemporal nerve.

Viral parotitis (mumps) makes both glands swell and ache, especially on chewing. Most salivary gland tumours arise here and most are benign, the commonest being the pleomorphic adenoma. Removing them puts the facial nerve at risk, so surgery is planned around it. A later complication of parotid surgery is gustatory sweating (Frey's syndrome), in which cut secretory fibres regrow into sweat glands of the cheek skin.

Function and supply

Function

Secretes serous, amylase-rich saliva, which the parotid duct delivers to the mouth mainly during chewing.

Nerve supply

Parasympathetic secretomotor fibres from the glossopharyngeal nerve via the otic ganglion and auriculotemporal nerve; sympathetic fibres from the external carotid plexus; the great auricular nerve supplies the capsule.

Blood supply

Twigs of the external carotid artery and of its two end branches, especially the transverse facial artery; veins drain to the retromandibular vein.