Risorius muscle
Updates to Article Attributes
The risorius muscle (TA: musculus risorius) is one of the muscles of the mouth, a subset of the muscles of facial expression. It is often absent and has been described as an accessory muscle.
Summary
- origin: fascia overlying the parotid or masseter/platysma muscle
- insertion: angle of the mouth
- innervation: facial nerve (VII)
- action: pulls backtheangle of the mouth
Gross anatomy
The risorius muscle arises from the superficial fascia as a bundle of muscle fibres which pass anteriorly to insert into the angle of the mouth. The bundle is widest at its origin, narrowing towards its insertion.
Origin
- parotid fascia 4
- fascia overlying the masseter muscle 4
- fascia enveloping the platysma muscle 4
Insertion
- angle of the mouth 4
Arterial supply
Venous drainage
Innervation
- buccal branch of the facial nerve (VII) 1
Action
- pulls backtheangle of the mouth 2
Variant anatomy
The risorius muscle is commonly absent. Occasionally the risorius muscle is duplicated or markedly larger than normal. The fibres of risorius may be merged into the platysma muscle 2 or fused with the transversus nuchae muscle 45.
History and etymology
Giovanni Domenico Santorini (1681-1737), described the risorius muscle, hence its historical name, muscle of Santorini 6. The German born, naturalised Dutch, anatomist Bernhard Siegfried Albinus (1697-1770), wrote a detailed treatise on the risorius muscle, such that it was also called the muscle of Albinus in the past 7.
-</li></ul><h4>Variant anatomy</h4><p>The risorius muscle is commonly absent. Occasionally the risorius muscle is duplicated or markedly larger than normal. The fibres of risorius may be merged into the <a href="/articles/platysma-muscle">platysma muscle</a> <sup>2</sup> or fused with the <a href="/articles/transversus-nuchae-muscle">transversus nuchae muscle</a> <sup>4</sup>.</p>- +</li></ul><h4>Variant anatomy</h4><p>The risorius muscle is commonly absent. Occasionally the risorius muscle is duplicated or markedly larger than normal. The fibres of risorius may be merged into the <a href="/articles/platysma-muscle">platysma muscle</a> <sup>2</sup> or fused with the <a href="/articles/transversus-nuchae-muscle">transversus nuchae muscle</a> <sup>5</sup>.</p><h4>History and etymology</h4><p><strong>Giovanni Domenico Santorini</strong> (1681-1737), described the risorius muscle, hence its historical name, muscle of Santorini <sup>6</sup>. The German born, naturalised Dutch, anatomist <strong>Bernhard Siegfried Albinus</strong> (1697-1770), wrote a detailed treatise on the risorius muscle, such that it was also called the muscle of Albinus in the past <sup>7</sup>.</p>
References changed:
- 6. Kleinerman R, John A, Etienne D et al. Giovanni Domenico Santorini (1681-1737): a prominent physician and meticulous anatomist. Clin Anat. 2014;27(4):545-7. <a href="https://doi.org/10.1002/ca.22294">doi:10.1002/ca.22294</a>
- 7. Bernard Siegfried Albinus (1697-1770), German-Dutch anatomist. JAMA. 1966;196(10):910. <a href="https://www.ncbi.nlm.nih.gov/pubmed/5327733">PMID 5327733</a>
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