Parotid Gland
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Direct answer
The largest salivary gland, purely serous, occupies the space between the sternocleidomastoid behind, the ramus of the mandible in front and the external acoustic meatus above — the parotid bed. Three structures pass through it, and their order is the single most examined fact: from superficial to deep run the facial nerve and its branches, the retromandibular vein, and the external carotid artery with its terminal branches. Its duct, about 5 cm long, crosses the masseter, pierces buccinator and opens into the vestibule of the mouth opposite the upper second molar. Parotidectomy is an operation on the facial nerve, and gustatory sweating — Frey's syndrome — is its famous complication.
What you must remember
- The gland is shaped like an inverted three-sided pyramid wedged in the parotid box; the deep lobe extends medially towards the pharynx through the stylomandibular tunnel.
- Structures within, superficial to deep: facial nerve, retromandibular vein (formed by maxillary and superficial temporal veins), external carotid artery; plus intraparotid lymph nodes and great auricular nerve fibres to the skin over the gland.
- The facial nerve leaves the stylomastoid foramen, divides into upper temporofacial and lower cervicofacial trunks, then fans into five terminal branches within the gland.
- The parotid duct (Stensen's) is surface-marked along the middle third of a line from the lower border of the tragus to the midpoint between the ala of the nose and the angle of the mouth.
- Secretomotor supply: glossopharyngeal fibres relay in the otic ganglion and reach the gland with the auriculotemporal nerve; sensation is by the great auricular and auriculotemporal nerves.
- The gland is enclosed in the investing layer of deep cervical fascia, which forms the stylomandibular ligament separating it from the submandibular gland.
- Frey's syndrome follows aberrant regeneration of auriculotemporal parasympathetic fibres to sweat glands — gustatory sweating over the temple and cheek.
Walking through a parotidectomy with the facial nerve in mind
A forty-year-old has a slowly growing, mobile, firm swelling at the angle of the mandible, painless and present for three years — the classical pleomorphic adenoma. Plan the operation along the nerve. The surgeon identifies the main trunk first: the tragal pointer cartilage directs the incision, and the nerve lies about 1 cm deep and slightly inferior to it, just above the posterior belly of digastric at the stylomastoid foramen; the tendon of digastric and the tympanomastoid fissure are supporting landmarks. Once the trunk is secured, superficial parotidectomy peels the tumour-bearing superficial lobe off the branching nerve; total parotidectomy for deep-lobe or malignant tumours dissects the nerve free from its bed.
Complications read as the contents list. Temporary facial weakness follows any handling of the branches; permanent palsy suggests malignant invasion — a pre-operative facial palsy with a parotid mass is itself a sign of malignancy, since benign tumours push the nerve aside. Sacrifice of the great auricular nerve during flap raising numbs the earlobe, the commonest untold complaint after surgery. Frey's syndrome appears months later with sweating and flushing over the cheek during meals, confirmed by the starch-iodine (Minor's) test, and managed per current practice with antiperspirants, topical anticholinergics or botulinum toxin injection. Mumps, by contrast, is the medical presentation — painful parotid swelling with earlobe elevation, and the anatomical detail that mumps involves the gland, testis, pancreas and meninges.
Where students slip
The order of structures within the gland is recited backwards more often than correctly; the nerve is the most superficial because it enters the gland's lateral surface after emerging at the stylomastoid foramen, and the artery deepest because it ascends from below medially. The second slip is the duct opening: "opposite the upper second molar" is expected, and candidates substitute the first molar or buccal vestibule near the commissure. Third, the parotid's nerve supply is muddled: students give the facial nerve because it passes through, but motor fibres pass through without supplying, and secretion rides the glossopharyngeal–otic–auriculotemporal route — a distinction that also explains why Frey's involves the auriculotemporal territory alone.
Frequently asked questions
What is the order of structures within the parotid gland from superficial to deep?
The facial nerve and its branches, then the retromandibular vein, then the external carotid artery with its terminal branches.
Where does the parotid duct open?
Into the vestibule of the mouth opposite the crown of the upper second permanent molar, after piercing buccinator.
How is the facial nerve located during parotidectomy?
About 1 cm deep and just inferior to the tragal pointer cartilage, above the posterior belly of digastric, at the stylomastoid foramen.
What is Frey's syndrome and what causes it?
Gustatory sweating and flushing over the auriculotemporal territory after parotidectomy, caused by parasympathetic fibres regenerating into severed sympathetic pathways to sweat glands.
Which nerve carries the parotid's secretomotor supply?
The auriculotemporal nerve, carrying postganglionic fibres from the otic ganglion of the glossopharyngeal nerve.