A gelasin, commonly known as a dimple, is a small natural indentation in the flesh on a part of the human body, most notably in the cheek or on the chin.
Dimples may appear and disappear over an extended period. Most cultures consider dimples as a sign of attractiveness and veracity. Dimples may be genetically inherited and have been called a simple dominant trait.
Dimples are a facial muscle deformity. Dimples may be caused by variations in the structure of the facial muscle known as zygomaticus major. Specifically, the presence of a double or bifid zygomaticus major muscle may explain the formation of cheek dimples. This bifid variation of the muscle originates as a single structure from the zygomatic bone. As it travels anteriorly, it then divides with a superior bundle that inserts in the typical position above the corner of the mouth. An inferior bundle inserts below the corner of the mouth.
See also 
- Cleft chin
- "Dimples" (John Lee Hooker song)
- Dimples (Shirley Temple Film)
- Dimples of Venus
- List of Mendelian traits in humans
Gelasin comes from the Greek word gelaein which means 'to laugh'.
- Am J Med Genet. 1990 Jul;36(3):376. Cheek dimples.
- Pessa, JE; Zadoo, VP; Garza, PA; Adrian Jr, EK; Dewitt, AI; Garza, JR (1998). "Double or bifid zygomaticus major muscle: anatomy, incidence, and clinical correlation". Clinical Anatomy 11 (5): 310–3. doi:10.1002/(SICI)1098-2353(1998)11:5<310::AID-CA3>3.0.CO;2-T. PMID 9725574.
- "Dimple Creation – Cute as a button, who pays for a deformity?".
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