Depressor anguli oris muscle, also known as the depressor labii inferioris muscle, is a small, thin muscle located in the lower face. It is one of several muscles that help to control facial expressions and movements of the mouth.
What is Depressor anguli oris muscle?
The depressor anguli oris muscle is a small, triangular muscle located in the lower face, just below the mouth. It is a skeletal muscle, meaning that it is under voluntary control and can be consciously moved by the person. The depressor anguli oris muscle is one of several muscles that help to control facial expressions and movements of the mouth.
Location
The depressor anguli oris muscle is located in the lower face, just below the mouth. It originates from the lower jawbone (mandible) and inserts into the skin and connective tissue of the lower lip. The muscle is situated in the region of the angle of the mouth, which is why it is also known as the depressor anguli oris muscle.
Structure
The depressor anguli oris muscle is a thin, triangular muscle with a narrow base and a broad apex. It is located in the subcutaneous tissue of the lower face, just below the skin. The muscle is composed of long, slender fibers that run parallel to each other.
The depressor anguli oris muscle has two main attachments: the origin and the insertion. The origin of the muscle is located on the mandible, near the angle of the jaw. The insertion of the muscle is located on the skin and connective tissue of the lower lip.
The depressor anguli oris muscle is innervated by the mandibular branch of the facial nerve (CN VII). This nerve supplies the muscle with the necessary signals for contraction and relaxation.
Function
The primary function of the depressor anguli oris muscle is to pull the lower lip downward and outward, creating a downward curvature of the mouth. This action is responsible for the facial expression known as “frowning.”
The depressor anguli oris muscle also plays a role in speech and eating. When the muscle contracts, it helps to open the mouth slightly and facilitate the movement of the lower jaw. This is important for activities such as speaking and eating.
In addition to its role in facial expressions and speech, the depressor anguli oris muscle also helps to protect the teeth and mouth from injury. When the muscle contracts, it helps to keep the lower lip away from the teeth, which can reduce the risk of biting or damaging the lip.
Clinical significance
There are several conditions that can affect the function of the depressor anguli oris muscle, including facial nerve disorders, muscle imbalances, and trauma.
Facial nerve disorders, such as Bell’s palsy, can cause paralysis of the depressor anguli oris muscle and other facial muscles. This can lead to difficulty in controlling facial expressions and may cause the mouth to droop or appear asymmetrical.
Muscle imbalances can also affect the function of the depressor anguli oris muscle. If the muscle is overly weak or too strong, it can cause problems with facial expressions and speech. In some cases, muscle imbalances may be corrected through physical therapy or other rehabilitation techniques.
Trauma to the face, such as a facial injury or surgery, can also affect the function of the depressor anguli oris muscle. In these cases, the muscle may become weak or paralyzed, which can cause problems with facial expressions and speech. Treatment may involve physical therapy or other rehabilitation techniques to help restore function to the muscle.
In some cases, the depressor anguli oris muscle may be injected with Botox, a neurotoxic protein that temporarily paralyzes the muscle. This treatment is often used for cosmetic purposes to reduce the appearance of wrinkles and fine lines around the mouth. While the effects of Botox are temporary, repeated injections may be necessary to maintain the desired result.
