Submandibular gland

At a glance

English

Submandibular gland

Latin (TA2)

Glandula submandibularis

System

Digestive

Region

Whole body

Side

Paired, left and right

About the submandibular gland

Each submandibular gland sits in the digastric (submandibular) triangle of the neck, partly hidden under the body of the mandible, where it leaves a shallow hollow on the bone called the submandibular fossa. It is about the size of a walnut. The gland is shaped like a J: a larger superficial part lies below and outside the mylohyoid muscle, and a smaller deep part hooks round that muscle's free back edge into the floor of the mouth. The duct starts from the deep part.

The superficial part is covered by skin, platysma and the investing layer of deep cervical fascia, and the facial vein runs across it. The facial artery grooves the back of the gland and then turns up over the lower border of the mandible. Deeply the gland lies against the mylohyoid, hyoglossus and the lingual and hypoglossal nerves. The submandibular ganglion hangs from the lingual nerve just above the deep part. Lymph nodes sit on and around the gland, so a swelling under the jaw may be either.

The submandibular glands produce most of the saliva in the resting mouth, a mixed secretion of watery serous fluid and sticky mucus that keeps the mouth moist and starts the digestion of starch. Output rises when food is tasted or smelt. The duct carries it forwards to the sublingual caruncle beside the frenulum of the tongue.

Salivary stones are most often found in this gland and its duct, because the secretion is thicker and the duct climbs upwards to its opening. A blocked duct gives a painful swelling under the jaw at mealtimes. When the gland has to be removed, the surgeon works through a neck incision kept low enough to spare the marginal mandibular branch of the facial nerve, and must also guard the lingual and hypoglossal nerves deep to it.

Function and supply

Function

Secretes mixed serous and mucous saliva through the submandibular duct, providing most unstimulated saliva.

Nerve supply

Parasympathetic fibres from the facial nerve via the chorda tympani and lingual nerve, relayed in the submandibular ganglion; sympathetic fibres follow the facial artery.

Blood supply

Glandular branches of the facial artery and submental artery; veins drain to the facial vein.