What is depressor labii inferioris?

Depressor labii inferioris is a muscle located in the lower area of the mouth. It originates from the mandible and inserts into the lower lip. Its main function is to depress and pull the lower lip downwards. It also assists in a variety of facial expressions such as pouting and frowning. This muscle is innervated by the mandibular branch of the facial nerve (CN VII). Dysfunction of this muscle can occur due to facial nerve damage, leading to difficulty in performing certain facial expressions or speaking.