What is a Frenulum?

A frenulum is a small segment of tissue that anchors and controls an organ or other body part. Frenula – which is plural for frenulum – exist in the oral cavity, the digestive tract, the brain, and the genital tissue of both men and women. A tight frenulum can be the cause of developmental difficulties in children or a diagnostic sign of an underlying disorder.

Ankyloglossia – also known as tongue-tie – is a commonly known problem associated with the frenulum linguae, the fold of tissue that anchors the tongue to the floor of the mouth. While it is sometimes diagnosed at birth, the first sign of ankyloglossia often is when an infant is not gaining weight as expected, and the mother has sore nipples and signs of poor milk supply. In an older child, ankyloglossia can exhibit symptoms in the form of speech articulation disorders since motor control of the tongue can be severely limited. Once discovered, the condition can be treated by a simple surgery known as frenuloplasty, after which improvement in the child's feeding or speech can be seen almost immediately.

In some cases, abnormalities of the oral frenula can be a symptom rather than a diagnosis. Abnormalities in the maxillary frenulum, which connects the upper lip to the gumline directly above the front teeth, have been shown to be a possible predictor of a pediatric heart condition known as hypoplastic left heart syndrome. Similarly, an absence of this same structure has been associated with a congenital malformation of the brain known as holoprosencephaly.

Hypertrophic frenula are sometimes seen in the genital frenula of both men and women, resulting in a lack of mobility of either the labia minora or the foreskin. In men, this condition was once thought to necessitate circumcision, but typically is easily treated by a frenectomy or frenuloplasty. Among women, hypertrophic frenula are most likely to arise as a result of trauma during childbirth or forced sexual intercourse, but are usually treated in a similar fashion.

In entomology, the frenulum is a wing structure seen in certain butterfly and moth species, and in cicadas. The term describes a structure which connects the hind wings for the purpose of synchronized motion in flight. Among butterflies and moths, the female version of the structure is compound, while the male version is simple. As a result, the details of the structure can be used as a reliable sexing trait for many species.