Location
The anterior auricular muscle, also known as the frontalis muscle, is located in the forehead region of the face. It is a long, thin muscle that extends from the eyebrows to the top of the head.
Structure
The anterior auricular muscle originates from the galea aponeurotica, a tough fibrous sheet that spans across the top of the head. It inserts into the skin of the forehead and eyebrow region. The muscle is innervated by the temporal and frontal branches of the facial nerve (CN VII).
The anterior auricular muscle is composed of long, thin muscle fibers that run horizontally across the forehead. It is located just beneath the skin, making it easily visible when it contracts. The muscle is surrounded by a thin layer of connective tissue called the epicranial aponeurosis, which helps to anchor it in place.
Function
The main function of the anterior auricular muscle is to move the skin of the forehead and eyebrows. When the muscle contracts, it causes the eyebrows to lift and the forehead to wrinkle. This movement is essential for expressing a range of emotions, including surprise, disgust, and anger.
The anterior auricular muscle also plays a role in keeping sweat and other substances out of the eyes. When the eyebrows are lifted, the sweat glands on the forehead are exposed, allowing sweat to evaporate and evaporative cooling to occur. This helps to regulate body temperature and keep the forehead and eyes dry.
Clinical Significance
Dysfunction of the anterior auricular muscle can lead to a variety of clinical issues. For example, weakness or paralysis of the muscle can cause the eyebrows to droop, leading to a lack of facial expression and difficulty with facial communication.
In some cases, the anterior auricular muscle may become overactive, leading to excessive wrinkling of the forehead and eyebrows. This condition, known as hyperfunctional lines, can be treated with a variety of therapies, including botulinum toxin injections and facial fillers.
