Digastric Muscle: Structure, Function & Diseases

The digastric muscle, as part of the head, specifically the upper tongue muscles, is responsible for mouth and jaw joint mobility. In addition, it influences swallowing, speaking, and yawning and voice production. If the digastric muscle is tense, mild to even severe complaints can occur over the body, which are not always directly assigned to it. This can cause massive health problems for those affected due to a lack of diagnosis for targeted treatment.

What is the digastric muscle?

The musculus digastricus, in German two-bellied muscle (skeletal muscle) and formerly also called musculus biventer mandibulae, is part of the head, specifically the upper tongue muscles. The muscle is involved in mouth opening (jaw joint mobility to open and close), yawning and speaking (vocal cord tension). If tension occurs, serious upper cervical asymmetry can result, almost always extending to the entire body with many physiological limitations. The digastric muscle must therefore always be considered in a holistic focus beyond its actual tasks mentioned above. Even or especially when complaints such as ear pain occur without a pathological diagnosis regarding this organ by the ENT doctor, orthopedist, etc.

Anatomy and structure

The digastric muscle consists of two fleshy bellies, which are innervated by two cranial nerves. This innervation originates from the mandibular nerve in the anterior belly and from the ramus digastricus in the anterior belly. The two bellies are connected by a tendon. The anterior belly (venter anterior) starts at the inner side of the mandible. The posterior belly (venter posterior) begins at the temporal bone, specifically at the incisura mastoidea (3). The muscle is located on both sides of the head (i.e., in pairs). Both muscle heads meet in the middle and form the common intermediate tendon, through which they are thus connected as already mentioned. This intermediate tendon is attached to the hyoid body by a connective tissue loop. Thus, it belongs to the suprahyal musculature (skeletal muscles coming from cranial, starting at the hyoid bone and thus located above the hyoid bone). With this structure, the digastric muscle is not only responsible for many central processes, but unfortunately also for many complaints that are not always directly assigned to it. More on this in the next sections.

Function and tasks

One of the most important tasks of the digastric muscle is its part in the swallowing process. It raises the hyoid bone or fixes it in place. In addition, this muscle is involved in jaw opening. Two distinctions must be made:

The venter posterior, the posterior venter, is responsible for hyoid elevation. The venter anterior, the anterior belly, on the other hand, is responsible for opening the jaw. In addition, the digastric muscle is thus responsible for yawning, speaking as well as swallowing. Thus, it is considered the antagonist of the masticatory muscles. The suprahyoidal musculature does not only form the floor of the mouth. Rather, it is the part responsible for chewing and swallowing as well as speaking. Together with the infrahyoid muscles, they are also responsible for positioning the hyoid bone as correctly as possible. In detail, the hyoid bone is lifted by the digastric and stylohyoid muscles during swallowing. At the same time, support is provided during mouth opening. During swallowing, the hyoid bone is moved forward by the geniohyoideus. This supports the opening but also the lateral movement of the lower jaw. The mylohyoid is different. It mainly causes the tightening and lifting of the floor of the mouth. However, it can also support the opening of the jaw and the chewing movement. Due to the support during chewing, the suprahyoid muscles are then also called the masseter muscles.

Diseases

Ear complaints, irritable cough and irritable rales as well as lump in the throat (globus sensation) but also swallowing difficulties (dysphagia) and voice disorders (dysphonia) can originate from the hyoid muscles. However, this can only be diagnosed by examining the muscles and fascia. If this is not done, the patient does not receive any physical findings. The symptoms of irritable cough and irritable rales are then often dismissed as psychological.During sensorimotor body therapy according to Dr. Pohl, the fasciae and neck muscles are loosened. In most cases, the symptoms are resolved. The swallowing problems occur because the process of swallowing is affected by the asymmetrical digastricus muscle. The hyoid bone with the pharynx, which is located underneath, is raised laterally differently by the muscle. Persistent swallowing difficulties may result. The voice pitch and the voice strength (the so-called vocal cord tension) are also determined by the muscles above the hyoid bone. If there are serious changes (worsening) here without a cold, there may be upper cervical asymmetry involving the digastric muscle. The lump in the throat is not infrequently accompanied by swallowing and breathing disorders, as well as nausea in the throat, nausea and retching. Tension often results in a lowered and thus increasingly tense head posture, with the chin closer to the neck. With this head posture, an accompanying obstruction of breathing is always mentioned on the part of the affected person. The presentations of complaints such as shortness of breath and anxiety in the throat emphasize these symptoms and make it clear how much everyday life can be affected.