Submandibular duct

At a glance

English

Submandibular duct

Latin (TA2)

Ductus submandibularis

System

Digestive

Region

Whole body

Side

Paired, left and right

About the submandibular duct

The submandibular duct, known by the eponym Wharton's duct, drains saliva from the submandibular gland into the front of the mouth. It is around 5 cm long and thinner-walled than the parotid duct. It leaves the deep part of the gland, which curls round the back edge of the mylohyoid muscle into the floor of the mouth.

From there it travels forwards and slightly upwards. It lies first between the mylohyoid outside and the hyoglossus inside, then runs with the sublingual gland on its outer side and genioglossus on its inner side. The lingual nerve has a close and important relation to it: the nerve starts out above and lateral to the duct, hooks down under it on its outer side, and then climbs on its inner side towards the tongue. The hypoglossal nerve lies lower down on the hyoglossus. Many small ducts of the sublingual gland open into the duct along this stretch, or directly onto the overlying fold.

The duct opens on the sublingual caruncle, a small papilla on either flank of the tongue's frenulum, just behind the lower front teeth. Gentle pressure under the tongue can often produce a jet of saliva from it. The submandibular glands supply most of the saliva made at rest, which is a mixture of thin serous fluid and thicker mucus.

This is the commonest site for salivary stones. The duct runs uphill against gravity, its saliva is relatively viscous and rich in calcium, and its outlet is narrow, all of which favour stone formation. A stone typically causes swelling and pain under the jaw just before or during meals, and may be felt by pressing one finger inside the mouth and one under the jaw. When a stone near the opening is removed through the floor of the mouth, the surgeon must protect the lingual nerve that crosses the duct.

Function and supply

Begins at

Leaves the deep part of the submandibular gland, between the mylohyoid and hyoglossus muscles.

Ends at

Opens on the sublingual caruncle beside the frenulum of the tongue in the floor of the mouth.

Function

Carries mixed serous and mucous saliva of the submandibular gland, and part of the sublingual secretion, into the mouth.

Nerve supply

Crossed by the lingual nerve, which loops beneath it from lateral to medial; its wall gets autonomic fibres with the gland.

Blood supply

Supplied by small branches of the sublingual and submental arteries in the floor of the mouth.