As Musculi epicranii is a muscle group is known, which is attributed to the mimic muscles and fits closely to the skull. The approach of the muscle group lies at the Galea aponeurotica. Different muscles belong to the epicranial muscles, for example the frontalis muscle and the occipital muscle. The former is a skin muscle.
Together with the occipitalis muscle, it is called the occipitofrontalis muscle or, in the German translation, the occipital forehead muscle. The two muscles are innervated by the facial nerve, which controls the entire musculature of facial expressions. The two bellies of the occipitofrontalis muscle are located on opposite skull poles. The Galea aponeurotica establishes the connection between the two parts. Synonyms for the two muscle bellies of the occipitofrontalis are the expressions Venter frontalis and Venter occipitalis.
The Venter frontalis takes its origin from the Margo supraorbitalis of the frontal bone and near the Glabella. The muscle radiates fibers into the mimic musculature of the immediate neighborhood, thus communicating with the muscles procerus, corrugator supercilii and orbicularis oculi.
The antipolar muscle belly of the Occipitofrontalis Occipitalis takes its origin from the linea nuchae suprema of the occipital bone and partly from the temporal bone. Both muscle pylons send their fibers vertically in the cranial direction to radiate into the tendon plate of the skullcap. At this Galea aponeurotica they find common approach. Each of the muscle bellies has an almost quadrangular floor plan. However, the venter frontalis gets more pronounced and shows longer fiber tracts.
Like all skin muscles, the frontalis muscle is located between the fascia and the skin. Motorically, the venter frontalis is innervated by the temporal rami of the facial nerve. In the Venter occipitalis the Nervus auricularis posterior of the Nervus Facialis takes over the Innervation.
Like all mimic muscles, the occipitofrontalis muscle is involved in human facial expressions. Mimic has the expressive and communicative value for humans. Compared with linguistic communication, mimic communication corresponds to a more original and relatively comprehensive form of communication.
Even infants are capable of interpreting mimic signals. This connection confirms the genetically deep roots of mimic communication. Long before language existed, man was already capable of self-expression thanks to the mimic form of expression. In addition, the mimic expression is characterized by far less cultural differences than the language expression. During verbal communication, people receive clues to the actual emotional state of their interlocutor through minute movements of facial expressions. Many mimic movements are almost automatic and 'betray' verbally withheld.
Like any mimic muscle, the occipitofrontalis muscle thus assumes communicative and expressive functions. The contraction frontalis muscle frowns and raises the eyebrows. Thus, the muscle is involved in the mimic expression of doubt or misunderstanding. The contraction of the occipital muscle smoothes the wrinkled forehead and lowers the eyebrows. As the occipitofrontalis muscle are thus summarized two antagonistic muscles of facial expression. While one of the muscle tensions spans, the other must relax. The simultaneous contraction of both muscles is impossible.
Since the occipitofrontalis muscle releases individual fibers into other muscles of facial expression, it is in the broadest sense involved in further movements of facial expressions. Due to the involvement in the procerus muscle, individual fibers of the occipitofrontalis muscle, for example, include the expression of wrath in the form of an angry fold. In addition, fibers of the muscle in the orbicularis oculi muscle are involved in the distribution of the tear fluid. As a skin muscle, the occipitofrontalis muscle is called because its contraction ultimately moves the forehead skin.
Like all other muscles, the occipitofrontalis muscle forms a neuromuscular unit with its supplying nerve. This nerve corresponds to several parts of the facial nerve, which distributes contraction commands from the central nervous system in the form of bioelectric excitation to the two individual muscles.
Damage to the nerve may interfere with the occipitofrontal muscle and all other muscles of the facial muscles in their work. Paralysis of the facial nerve may be preceded by innate but also acquired causes such as fractures of the skull. Also inflammatory causes such as the middle ear inflammation, chronic meningitis or Lyme disease are conceivable as a cause. In addition, tumors of the cerebellopontine angle and immunological processes such as Guillain-Barré syndrome, Heerfordt syndrome or Melkersson-Rosenthal syndrome cause facial paralysis.
Mild facial paralysis shows only discrete symptoms. More severe paralysis causes changes in facial expression, often with a raised or diminished frown, incomplete eyelid closure, and drooping corners of the mouth. Because the facial nerve sensibly innervates the tongue, taste disorders may also occur. Isolated paralysis of the occipital muscles has less effect on the facial expression than isolated paresis of the frontalis muscle.
An isolated paralysis of a single muscle belly occurs with locally limited damage to the facial nerve, as can be caused mainly by inflammation. Like any other muscle, the occipitofrontalis muscle may be affected by typical muscle diseases such as myopathy or atrophy. Muscle fiber tears and related phenomena are extremely rare in the mimic muscles.Tags: