Also called expression muscle, it is the skin muscle of the face. The facial muscle starts from the skull and ends at the facial skin. When this muscle contracts, the face will appear wrinkles to change the shape of mouth crack and eye crack, so as to express various feelings such as joy, anger, sadness and joy, and participate in activities such as language and chewing. Facial muscles are mainly distributed around the eyes, nose and mouth in circular or radial shape. The circular muscles have the function of closing the fissure, and the radial muscles have the function of opening the fissure. The muscles include frontalis, temporalis, buccinator, occipital, orbicularis oris, orbicularis oculi, etc. Facial muscle is innervated by facial nerve, so facial nerve paralysis occurs after facial nerve injury, in which peripheral paralysis is different from central paralysis.
Facial muscles include cranial parietal muscle, nasal muscle, descending nasal septum muscle, orbicularis oculi muscle, corrugator brow muscle, descending eyebrow muscle, anterior auricular muscle, superior auricular muscle, posterior auricular muscle, orbicularis oris muscle, angle depressor, transverse genius muscle, laughing muscle, zygomaticus major muscle, zygomaticus minor muscle, levator labii superioris muscle, levator labii nasalis muscle, levator labii inferioris muscle, levator buccinator muscle, genius muscle and buccinator muscle; They, latissimus and several deep muscles all occur in the protomuscular mass of the lingual arch, and each receives the distribution of nearby blood vessels. The blood circulation is rich, and they are all dominated by the branches of the facial nerve. The development degree of facial muscles varies from person to person, and there are also some fusions between the muscles. Facial muscles mostly start from bone and end at the skin. When contracting, they can open and close eyes, open and close mouth, or affect the skin.
Parietal muscle The main muscles of the right and left occipitofrontal muscles are paired. It has two flat muscle abdomens, which are connected by a cap aponeurosis in the middle and cover the skull top. The occipital abdomen starts from 2/3 of the outer side of the supracervical line of the occipital bone; The forehead and abdomen attach to the eyebrow skin and fuse with the muscle bundle of orbicularis oculi muscle; The superficial surface of the cap like aponeurosis is connected to the scalp by dense subcutaneous tissue, and the deep surface is connected to the periosteal septum of the skull by honeycomb tissue. Function: lift eyebrows, make forehead wrinkle horizontally, and make scalp move forward and backward. Orbicularis oculi muscle : The orbicularis oculi muscle is circular around the ocular fissure, attached to the medial canthal ligament and its adjacent bone surface, and is divided into three parts: ① the eyelid is weak, located under the skin of the upper and lower eyelids; ② The orbit is relatively developed, surrounding the orbital margin, and the muscle bundle of its lateral branch is often connected with the muscle bundle of zygomaticus minor muscle; ③ The lacrimal part is connected with the eyelid and located in the deep side of the lacrimal sac. Function: gently close the eyelid; The eye socket and the lacrimal part tightly close the eyelid, and tighten the lacrimal fascia to expand the lacrimal sac. The orbicularis oris muscle has a complex structure around the oral fissure, and it is interlaced with other facial muscle bundles. ① At the corner of the mouth, it is interlaced with the muscles of zygomaticus major, zygomaticus minor, laughing, buccinator and levator; ② On the upper lip, the muscle bundles of the levator labii superioris, levator labii alaris superioris, and zygomaticus minor muscles are all mixed with the orbicularis oris muscle; ③ In the lower lip, the muscle bundles of the lower lip depressor and buccinator also participate in this muscle; ④ There are muscle bundles in the lip that run obliquely from the skin to the lip mucosa. Function: close the mouth, press the lips against the teeth, make the upper and lower lips protrude forward, thus playing an important role in language, drinking, eating, chewing and various expressions.
Buccinator muscle The buccinator muscle is located outside the buccal mucosa, attached to the alveolar part of the maxilla and mandible, directly facing the third molar and the bone surface after it; The muscle bundles tend to the corners of the mouth. The upper and lower branches of the muscle bundles are crossed and mixed with the orbicularis oris muscle and the muscles of the upper and lower lips. Function: Keep buccal mucosa tight when opening and closing mouth; When chewing, this muscle and the tongue together push food between the upper and lower teeth; When blowing or playing an instrument, compress the gas in the mouth. ① Parietal muscle
The cranial parietal muscle is wide and thin, with one occipitofrontal muscle on the left and one on the right. It is composed of two muscle abdomens and a cap like aponeurosis in the middle. The front muscle belly is located under the skin of the forehead, called frontal belly; The posterior muscle belly is located under the occipital skin, called occipital belly. The cap like aponeurosis is very tough, connected to the belly of two muscles, and closely connected to the scalp, while it is separated from the deep periosteum by loose connective tissue. The occipital abdomen starts from the occipital bone, and the frontal abdomen ends at the eyebrow skin. The occipital abdomen can pull the cap like aponeurosis backward. When the forehead abdomen contracts, it can lift the eyebrows and wrinkle the forehead skin.
② Orbicularis oculi muscle
The orbicularis oculi muscle is located around the eyes and is oblate. It can close the eyes. Since a small amount of muscle bundles attach to the back of the lacrimal sac, when the eyes are closed, the lacrimal sac can be expanded at the same time to promote the flow of tears through the nasolacrimal duct to the nasal cavity.
③ Perioral muscle
The perioral muscles are located around the oral fissure, including radial muscles and circular muscles. The radial muscles are located above and below the lip, which can lift the upper lip, lower the lip or pull the mouth angle upward, downward or outward. There is a pair of cheek muscles in the deep part of the cheek. These muscles are close to the side wall of the mouth, which can make the lips and cheeks close to the teeth, helping to chew and suck; It can also be used for external corners. The annular muscle surrounding the oral fissure is called orbicularis oris muscle, which closes the oral fissure (shut up) when contracting.
④ Nasal muscle
The nasal muscles are not developed, and they are several small flat muscles distributed around the nostrils, which can enlarge or narrow the nostrils.
