Lingual frenulum

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Overview of the structure of the tongue seen from the cranial view of the dorsum.

The lingual frenulum also called the frenulum of tongue is a thin fold of mucous membrane on the inferior surface of the tongue, that connects the tongue to the floor of the oral cavity.

This midline fold arises near the base of the tongue and extends anteriorly towards the tip of the tongue, along the lingual midline sagittal septum. Inferiorly, it is continuous with the mucosal covering of the oral cavity floor.

On either side of the base of the frenulum is a small sublingual caruncle (papilla) which bears the opening of each submandibular duct. As well, the deep lingual veins which drain the tongue, are usually visible as blue lines on the underside of the tongue running on each side of the frenulum.

The lingual frenulum plays a role in stabilizing the tongue and providing support during activities like speaking, eating, and swallowing. Typically, the lingual frenulum does not extend so far forward to cause restriction in tongue movement, a condition called ankyloglossia or "tongue-tie". This condition can interfere with normal activities such as speaking and eating, and in infants, breastfeeding.