Risorius muscle
Musculus risorius
- Eponym: Muscle of Albinus; Santorini's muscle
- Related terms: Risorius
Definition
Risorius muscle | |
Origin | Parotid and masseter fascia |
Insertion | Modiolus, anguli oris |
Artery | Facial artery |
Innervation | Facial nerve (buccal branch) |
Action | Draws back angle of mouth |
The risorius is a thin, highly variable muscle of facial expression located in the superficial layer of the cheek. it contributes to smiling by retracting the angle of the mouth laterally — producing a horizontal or closed-mouth smile.
Anatomical details
1. Origin
From the fascia overlying the masseter muscle and the parotid gland (parotid–masseteric fascia).
2. Insertion
Into the skin at the angle (corner) of the mouth, blending with fibres of the orbicularis oris at the modiolus.
Innervation
Buccal branch of facial nerve.
Blood supply
Facial artery (superior labial branch).
Actions
Risorius retracts the angle of the mouth laterally. It acts synergistically with zygomaticus major (to retract the mouth corner upward and laterally in smiling).
Relations
Superiorly lies Zygomaticus major
Inferiorly lies depressor anguli oris
It is superficial to the buccal fat pad and buccinator muscle
References
Gray, H. (2016) Gray’s Anatomy: The Anatomical Basis of Clinical Practice. 41st edn. Edited by S. Standring. New York: Elsevier. Chapter 30: Face and Scalp, p. 489-496.
