Introduction
The facial musculature (mimic muscles) is a group of 26 muscles in humans, which is not only necessary for opening and closing the eyes or mouth, but also moves the skin of the face and thereby controls facial expressions. The muscles of the face are divided into the ear muscles, the nose muscles, the mouth muscles, the muscles of the lid fissure and the muscles in the area of the cranial roof. Unlike other muscles of the body, the mimic muscles do not have to move joints.
For this reason, they do not attach to bones, but lie directly under the skin. They are usually named after their function and location and are all innervated by the facial nerve (7th cranial nerve). Due to the axial symmetry of the face, almost all mimic muscles occur twice.
The orbicualris oculi muscle lies around the eye, but does not form a closed ring. It is divided into three parts: The muscle corrugator supercilii also belongs to the eyelid cleft muscles. This muscle pulls the eyebrows down and towards the middle and raises a longitudinal fold in the middle of the forehead.
- The pars orbitalis is responsible for the closure of the eyelid and the firm squeezing of the eye.
- The pars palpebralis for the lid closure reflex and
- The pars lacrimalis acts on the lacrimal sac.
- The Musculus nasalis can pull the nostrils down or backwards.
- The procerus muscle originates from the bridge of the nose and radiates into the skin of the forehead. It lifts the parts of the eyebrows that lie towards the nose, creating a transverse furrow above the root of the nose.
- The Musculus levator labii superioris aleque nasi pulls the upper lip and the nostrils upwards. When both sides contract, it raises the tip of the nose.
- The musculus orbicularis oris apparently encloses the entire mouth and closes the oral fissure.
At maximum contraction it shortens the lips.
- The Musculus levator labii superioris lifts the upper lip,
- The musculus depressor labii inferioris pulls the lower lip downwards.
- The Musculus depressor anguli oris moves the corners of the mouth downwards.
- The buccinator muscle is an almost square muscle and lies below the strong masticatory muscle (Musculus masseter). It pulls the corners of the mouth outwards. In addition, it enables the blowing of air, whistling, spitting and sucking.
- The Musculus levator anguli oris pulls the corners of the mouth upwards,
- The Musculus mentalis pulls in the skin in the area of the chin and thereby forms the chin-lip furrow.
- The laugh muscle is called the risorius muscle.
It moves the corners of the mouth to the side, thereby raising the nasolabial folds.
- The Musculi zygomatici major and minor move the upper lip and the corners of the mouth upwards.
The ear has three muscles, the auricularis anterior, posterior and superior muscles. These move the auricle forwards/backwards/upwards. However, not all people can actively contract these muscles and thus “wiggle their ears”.
There are also mimic muscles in the area of the cranial roof. They are often summarized as Musculus epicranius and are loosely connected to the periosteum, but firmly connected to the cranial roof. The occipitofrontalis muscle lifts the eyebrows and wrinkles the forehead with its front part (Venter anterior), and smoothes the forehead with its rear part (Venter posterior).
The galea aponeurotica is stretched in a transverse direction by the temporoparietalis muscle. This taut tendon plate covers the cranial roof and serves as a starting point for some mimic muscle fibers.
