Depressor anguli oris

The depressor anguli oris is a facial expression muscle of the lower lip and chin region. It depresses the angle (corner) of the mouth.

Anatomical details

1. Origin

Long linear origin from the oblique line of the mandible, extending from below the first molar, premolar, and canine to the tubercle of mandible. It is continuous below with the fibres of the platysma muscle.

2. Insertion

Its fibres converge onto the angle (corner) of the mouth where they blend with the fibres of the orbicularis oris, risorius, and even levator anguli oris and zygomaticus major muscles.

• Transverse menti muscle: Some of the fibres of the depressor anguli oris from its origin, may pass below the mental tubercle to connect with their counterparts from the other side. These transversely oriented fibres are called the Transverse menti muscle.

Innervation

• Marginal mandibular branch of the facial nerve (cranial nerve VII).

• Buccal branch of facial nerve

Blood supply

• Inferior labial branch of the facial artery and the mental branch of the maxillary artery.

Actions

Acts synergistically with the platysma and depressor labii inferioris in lowering the corners of the mouth.