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Submandibular duct

The submandibular duct, also known as Wharton’s duct, is the excretory duct of the submandibular gland. It extends from the deep lobe of the gland, courses anteriorly along the floor of the mouth, and opens at the sublingual caruncle beside the lingual frenulum. Accurate knowledge of its anatomy, function, and imaging appearance is essential for radiologists, ENT specialists, dentists, and oral surgeons, particularly in evaluating sialolithiasis, strictures, or neoplasms.

Synonyms

  • Wharton’s duct

  • Submandibular salivary duct

  • Excretory duct of the submandibular gland

  • Sublingual excretory duct of submandibular gland

Function

  • Drains saliva from the submandibular gland into the oral cavity

  • Facilitates digestion and oral lubrication

  • Helps maintain oral pH and prevent infection

  • Enables flow of salivary enzymes and antimicrobial proteins into the mouth

MRI Appearance
T1-weighted images:

  • The duct appears as a linear, low-to-intermediate signal structure along the floor of the mouth.

  • Surrounded by high-signal fat in the submandibular space, providing natural contrast.

  • Salivary stones (sialoliths) appear as low signal within the duct lumen.

T2-weighted images:

  • The duct lumen is hyperintense if filled with saliva or fluid, while duct walls remain intermediate signal.

  • Surrounded fat and soft tissue provide contrast to delineate duct course.

  • Strictures, stones, or dilatation are easily visible.

STIR (Short Tau Inversion Recovery):

  • Fat suppression highlights the duct and any pathological edema or inflammation in surrounding tissue.

  • Normal duct lumen appears hyperintense, while inflamed walls may show high signal.

CT Appearance

  • The submandibular duct lumen may appear as a hypodense tubular structure on non-contrast CT if fluid-filled, while air within the oral cavity adjacent to the duct appears black (signal void).

  • Sialoliths are easily detected as hyperdense structures within the duct.

  • The surrounding submandibular gland and floor of mouth muscles appear soft tissue density, providing clear anatomical context.

  • CT is particularly useful for evaluating stone size, location, ductal obstruction, or bony involvement.

MRI images

submandibular duct mri axial image -img-00000-00000