The auricularis posterior is a small, thin muscle located in the back of the ear. It consists of two parts: a superficial part and a deep part. The superficial part of the auricularis posterior muscle arises from the mastoid process, a bony projection behind the ear, and inserts into the cartilage of the ear. It is responsible for pulling the ear backward and helping to maintain the position of the ear. The deep part of the auricularis posterior muscle is located beneath the superficial part and arises from the mastoid process and the posterior border of the sternocleidomastoid muscle. It inserts into the cartilage of the ear and is responsible for pulling the ear backward and downward. The auricularis posterior muscle is innervated by the posterior auricular branch of the facial nerve (cranial nerve VII) and works in conjunction with other muscles of the ear to produce various movements, such as lifting or lowering the ear. Dysfunction or weakness of the auricularis posterior muscle can lead to difficulty in maintaining the position of the ear and may contribute to deformities or asymmetries of the ear.