Submandibular duct

The submandibular duct (Whartons duct) is the main excretory duct of the submandibular gland and is approximately 5 cm long with a relatively thin wall compared to the parotid duct. It arises from numerous tributaries on the deep surface of the gland and begins at the hilum of the deep part of the submandibular gland. The duct passes forwards in the floor of the mouth between the mylohyoid muscle laterally and the hyoglossus and genioglossus muscles medially. Anteriorly, it continues between the sublingual gland and genioglossus muscle before opening into the oral cavity at the sublingual caruncle, a small papilla situated on either side of the lingual frenulum.

Important anatomical relations

The submandibular duct has important anatomical relations with the lingual and hypoglossal nerves. Initially, the lingual nerve lies lateral to the duct, then loops inferiorly beneath it (from lateral to medial) and finally ascends medially as the duct approaches its termination at the sublingual caruncle. The hypoglossal nerve lies inferior to the duct along part of its course.

Structurally, the duct is lined by epithelium continuous with the oral mucosa and functions in the transport of mixed serous and mucous saliva into the oral cavity.

Clinical correlates

The submandibular duct is the most common site of sialolithiasis (salivary stones) due to its long ascending course and the relatively viscous nature of submandibular saliva, which predispose to salivary stasis and obstruction.