It receives motor innervation from branches of facial nerve (CN VII).

[1] The risorius receives motor innervation from the buccal branch of the facial nerve (CN VII).

[1] Because it partially overlies the masseter muscle, it may be unintentionally affected during botox injections, resulting in unnatural facial expressions.

[3] It has been suggested that the risorius muscle is only found in Homininae (African great apes and humans).

[5] This article incorporates text in the public domain from page 385 of the 20th edition of Gray's Anatomy (1918)