The facial muscles are a complex structure that performs important tasks and is an expression of both physical and mental well-being.
What are facial muscles?
Facial muscles include all 26 muscles located in the area of the human face. In medical terminology, facial muscles are referred to as the mimic muscles. Because they do not need to mobilize any joints, unlike skeletal muscles, they are directly connected to and radiate into the skin overlying them. They control the physical display of emotions, so they are primarily responsible for human facial expressions.
Anatomy and structure
The majority of facial muscles, unlike large portions of skeletal muscle, do not have any fascia. The transmission and processing of facial muscle stimuli occurs via the 7th cranial nerve, the facial nerve. Since the human face is generally axisymmetric, almost each of the facial muscles exists twice. The facial muscles themselves are divided into five distinct areas: The nasal musculature, the ear musculature, the mouth musculature, the palpebral fissure musculature, and the cranial roof musculature. The nasal musculature is composed of three muscles:
- The nasalis muscle is located above the nostrils and has the task of pulling them down and back, respectively.
- The procerus muscle runs from the bridge of the nose up to the forehead. It serves to lift the side of the eyebrows facing the nose.
- The third nasal muscle is called Musculus levator labii superioris alaeque nasi and moves the nostril and upper lip upward. When contracted on both sides, it also lifts the tip of the nose.
The ear is moved by three muscles, the auricularis anterior, posterior and superior muscles. In theory, they serve to move the auricle to all sides. However, not all people are able to actively contract them to wiggle their ears. By far the most facial muscles are located at the mouth. No less than four muscles are responsible for moving the lip. The orbicularis oris muscle runs along the mouth, closing the oral fissure and pursing the lips at maximum contraction. The levator labii superioris muscle serves to raise the upper lip, and the depressor labii inferioris muscle serves to pull down the lower lip. The musculi zygomatici major and minor raise the corners of the mouth. Another four muscles control the movement of the corners of the mouth. The depressor anguli oris muscle pulls them downward, and the levator anguli oris muscle pulls them upward. The risorius muscle, colloquially known as the smile muscle, enables the lateral movement of the corners of the mouth. One of the most important muscles of the mouth is the buccinator muscle. This is what makes blowing, spitting, sucking and whistling possible. The muscles of the cranial vault are often referred to as one muscle, the musculus epicranius. They raise the eyebrows and frown and smooth the forehead. Finally, the palpebral fissure muscle, the orbicularis oculi muscle, which snakes around almost the entire eye, is responsible for opening and closing the eyes and pulling down the eyebrows.
Function and tasks
Through their contraction, the facial muscles are responsible for the movement of the facial skin and thus for human facial expressions, although actually only eight are responsible for facial expressions per se. The remaining muscles of the face are also capable of contraction and movement, but these are not visible from the outside. As a result, the facial muscles fulfill an enormously important role in nonverbal human communication, which is made possible in the first place by the various facial expressions. The expression of numerous emotions also runs through the contraction of the facial muscles. Feelings such as joy, sorrow, sadness or hate are transported to the outside world through various facial expressions. In addition, the facial muscles also perform important physical functions such as opening and closing the eyes or mouth, without which elementary bodily functions such as seeing or eating would hardly be possible.
Diseases and disorders
Complaints of facial muscles often occur as a symptom of severe diseases of the central nervous system.For example, in the course of amyotrophic lateral sclerosis (ALS disease), a weakening and progressive atrophy of the facial muscles develops, resulting over time in a slow loss of facial expression. Weakness of the facial muscles also develops in myotonic dystrophy (DM), which can manifest itself in drooping eyelids, an inability to laugh broadly, and, due to weakness of the mouth muscles, a progressive speech disorder. In addition, strokes also carry the risk of a facial paralysis, in most cases hemifacial paralysis, if the area in the brain responsible for it has been affected by the stroke. Facial paralysis can also occur suddenly and for no apparent reason. In this case, the affected person loses control of their facial muscles from one moment to the next and can no longer laugh, wrinkle their nose or control their facial expressions. The muscles then hang limply, usually on only one half of the face. The upside to this form of facial paralysis is that with proper treatment, it can be cured in most cases and the symptoms completely eliminated.
