Mylohyoid boutonniere

Last revised by Eid Kakish on 13 Jan 2024

Mylohyoid boutonniere is a normal focal discontinuity in the mylohyoid muscle, which may permit the sublingual salivary gland, fat or vessels - or a combination thereof - to protrude out from the sublingual space into the submandibular space.

The finding has been observed in up to 77% of normal individuals undergoing head and neck cross-sectional imaging studies, of whom it is seen bilaterally in 67% 1.

The mylohyoid muscle is a sling-like structure that forms the floor of the oral cavity. This muscle divides the sublingual space from the submandibular space; however, communication between the two spaces posterior to the mylohyoid muscle is maintained.

The mylohyoid muscle consists of two halves, both of which have a broad origin from the mylohyoid line along the inner mandible and the body of the hyoid bone. The two halves insert centrally at the fibrous median raphe to form a sling. Traditionally, the mylohyoid muscle is depicted as a continuous muscle sling; however, recent cross sectional imaging (CT and MRI) studies have demonstrated discontinuity in the mylohyoid muscle, allowing normal structures of the sublingual space to protrude through the defect 1.

Boutonnière is French for buttonhole, a befitting term as the morphology resembles a buttonhole.

Rarely, pathologic entities (e.g. ranula) can also extend through the boutonniere defect.

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