risus sardonicus

risus /ri·sus/ (ri´sus) [L.] laughter.

---

risus sardo´nicus  a grinning expression produced by spasm of facial muscles.

---

risus sardonicus

[särdon′ikəs]

Etymology: L, laughter; Gk, sardonius, mocking

a wry masklike grin caused by spasm of the facial muscles, as seen in tetanus.

---

risus

[L.] laughter.

---

risus sardonicus

a grinning expression produced by spasm of the facial muscles, typical of tetanus in humans. The term is also applied to dogs with tetanus in which the lips are drawn back by muscle spasms.

---

risus sardonicus

A fixed 'sarcastic' grimace and anxious expression with drawing up of the eyebrows and corners of the mouth due to spasms of the masseter and other facial muscles, accompanied by rigidity of neck and trunk muscles and arching of back; the RS  is seen in generalized tetanus, and caused by a neurotoxin produced by Clostridium tetani, a soil contaminant with a 7-10 day incubation Prognosis Up to 90% mortality in the unvaccinated/susceptible–eg, narcotic addicts