Risorius
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The risorius muscle is a highly variable muscle of facial expression. It has numerous and very variable origins, and inserts into the angle of the mouth. It receives motor innervation from branches of facial nerve (CN VII). It may be absent or asymmetrical in some people. It pulls the angle of the mouth sidewise, such as during smiling.
The risorius muscle is a highly variable muscle of facial expression. It has numerous and very variable origins, and inserts into the angle of the mouth. It receives motor innervation from branches of facial nerve (CN VII). It may be absent or asymmetrical in some people. It pulls the angle of the mouth sidewise, such as during smiling. ===Innervation=== The risorius receives motor innervation from the buccal branch of the facial nerve (CN VII). ===Variation=== The risorius muscle is highly variable. It ranges in form from one or more slender bundles to a wide (yet thin) fan. It may be absent in a significant minority of people, and may be asymmetrical. ==Function== The risorius muscle draws the angle of the mouth lateral-ward. It participates in producing facial expressions like a smile, grin, or laugh. ==Etymology== From the Latin rīsor ("laugher, mocker") + -ius (adjectival suffix), literally, "the laughing muscle". ==Additional images== File:Risorius animation small.gif|Position of risorius. ==References== ==External links== PTCentral
Text derived from https://en.wikipedia.org/w/index.php?oldid=1377830845 under CC BY-SA 4.0; modifications have been made.