<unk>  or rictus grin is a highly characteristic, abnormal, sustained spasm of the facial muscles that appears to produce grinning. It may be caused by tetanus, strychnine poisoning, or Wilson's disease, and has been reported after judicial hanging. The condition's name, associated with the Mediterranean island of Sardinia, derives from the appearance of raised eyebrows and an open "grin" – which can appear sardonic or malevolent to the lay observer – displayed by those experiencing these muscle spasms.
Risus sardonicus
Arnica montana
Lathyrus sativus
Brachyspira pilosicoli
Cynanchum viminale
Baylisascaris shroederi
Hirudo orientalis
Chrysomya putoria