Muscle details :-
The risorius begins around the parotid gland, a salivary gland in the back of the jaw, and wraps around the platysma muscle, a muscle located in the chest and neck. … Smiling and frowning are two of the facial expressions that are created by all of the facial muscles working together.
The risorius originates from the masseteric fascia.
The risorius inserts into the skin of the angle of the mouth.
Nerve supply :-
Buccal branch of the facial nerve.
Upon activation the risorius pulls the angle of the mouth laterally.The risorius retracts the angle of the mouth to produce a smile, albeit an insincere-looking one that does not involve the skin around the eyes. Compare with a real smile, which raises the lips with the action of zygomaticus major and zygomaticus minor muscles and causes “crow’s feet” around the eyes using the orbicularis oculi muscles.
Related pathology :-
In Bell’s palsy risorius muscle commonly paralysis .