Depressor anguli oris muscle

The depressor anguli oris muscle of the angle of the mouth is understood, in man, from the lower part of the chin to the corner of the lips, which it pulls down. In domestic mammals, the platysma also extends evidently to the corner of the lips, after crossing the ventral edge of the mandible.

Conformation: Located immediately under the skin, it covers a small part of the buccinator and orbicularis oris muscles as well as the depressor labii inferioris muscle.

Insertions: It originates from the mental tubercle and inserts into the mandible in continuity with the platysma muscle. At the angle of the mouth, in man, its termination unites with the risorius muscle. In domestic mammals, the two muscles are confused.

Functions: In humans it contributes to the lowering of the mouth, in domestic mammals it contributes more to its retraction, action particularly visible in carnivores and pigs.

Vessels and nerves: The depressor anguli oris muscle is vascularized by the inferior labial artery and innervated by the cervical branch of the facial nerve.

In equines, the depressor anguli oris muscle is weak and pale in horses and wider in donkeys and mules.