Muscles on the forehead
The frontalis muscle (frontal belly) is the muscle on the forehead. It is a thin, quadrilateral form. There is a pair of them. There are no bony attachments. The medial fibers are going downwards and connected with the muscle fibers below including the Procerus; the corrugator and the orbicularis oculi. They attach to the skin of eyebrow. Its lateral fibers also mix with the latter muscle over the zygomatic process of the frontal bone. The muscle fibers move up and join the galea aponeurotica (tough fiber layer on the head). The frontalis muscles lift eyebrows when looking up and wrinkle the forehead horizontally by pulling the scalp back. The muscle is innervated by facial nerve. The antagonist muscle is orbicularis oculi muscle.
Procerus muscles and corrugators
The procerus muscle arises from the nasal bone and inserts into the skin over the lower part of the forehead between the two eyebrows. Its fibers blend in with those of the frontalis muscles. Its contraction pulls the skin between the eyebrows downwards producing horizontal wrinkles between the eyes over the bridge of the nose.
The corrugators supercilli muscle is a small muscle at the medial end of the eyebrow. It originates from the medial end of the superciliary arch and its fibers pass upward and laterally and end at the deep surface of the skin above the middle of the orbital arch. It is beneath the frontalis muscle and above the orbicularis oculi muscle. Contracting of this muscle draws the eyebrow downward and medially creating the deep vertical wrinkles between the eyebrows. It is known as frowning muscle.
Muscles surrounding the eyes
The orbicularis oculi muscle is the ring like muscle surrounding the eye. It originates from the nasal part of the bone and goes all the way laterally surrounding the border of the orbit forming a broad and thin layer. It spread over the eyelids, temple and down to the cheek. The orbital orbicularis is the orbital portion of the muscle. It forms a complete circle without interruption. The upper part blends in with the frontalis and corrugators muscles. Palpebral orbicularis is the palpebral portion of the muscles responsible for the involuntary eye blink. Contraction of this muscle causes the eye to close or blink. The orbital portion can be consciously controlled. Contraction of the muscle also causes the wrinkles at the out corner of the eye which are known as crow feet. For example, as under the sun, the skin of the forehead, temple, and cheek is drawn toward the medial angle of the orbit, and the eyelids are firmly closed. The skin is folded especially radiating from the lateral angle of the eyelids. The antagonist of this muscle is the levator palpebrae superioris muscle.
Muscles in the cheek
There are four muscles on the cheek: They are lying in the cheek from middle to lateral, from cheek bone to the upper lip: They are the levator labii superioris alaeque nasi, the levator labii superioris muscle, the zygomaticus minor, the zygomaticus major. They form the nasolabial groove, from the side of the nose to the upper lip. This line is deepened in expressions of sadness. These muscles draw the angle of the mouth upward and backward in smiling. These muscles’s contraction creates tension on the cheek, deep nasolabial groove, gummy smile and wrinkles the cheek.
Levator anguli oris is a deep facial expression muscle on the cheek. It originates from the canine fossa of maxilla, inferior to the infraorbital foramen. It elevates the angle of the mouth and deepens the nasolabial lines and facilitates smiling.
There are two muscles on the cheek by the mouth.
The risorius muscle arises in the fascia over the parotid gland and, passing horizontally forward, inserts onto the skin at the angle of the mouth. It is a narrow bundle of fibers, broadest at its origin lying superficial to the platysma. It is known as the ‘smiling muscle’ as its contraction draws the angle of the mouth outward and produces a smile.
The buccinator muscle is a thin quadrilateral facial muscle by the mouth. It originates from maxilla and mandible bones and fibrous band behind the third molar. It is the main muscle of the cheek, that provides it with structure and tightness. The muscle goes towards and inserts to the angle of the mouth. It contributes to smiling and chewing.
Muscles on the nose
Nasalis is a paired muscle that covers the dorsum of the nose. It originates from the maxilla crawls upwards on the back of the nose and ends there and blends in each other from the opposite side at the back of the nose. This muscle dilates the nostrils, depresses the nostril wings and wrinkles the nasal skin.
Muscles surrounding the mouth
There are a few groups of muscles around the mouth.
The orbicularis oris muscle is the muscle encircling the mouth and it lies between the skin and the mucous membranes of the lips. The orbicularis oris muscle is a complex of muscles in the lips that encloses the mouth. It consists of four independent quadrants that connects each other which gives it a look of circular. It blended in with other expression muscles on the face. When it contracts, it closes the mouth and puckers the lips creating vertical wrinkles around the mouth.
Muscles below the mouth draw the corner of the mouth down.
The depressor anguli oris is a muscle that originates from the mandible and inserts on angles of the mouth to depress the angle of the mouth.
The depressor labii inferioris muscle is a muscle of the face that draws the lower lip down and slightly laterally.
The mentalis muscle elevates and protrudes the lower lip and wrinkles the skin of the chin.
The platysma muscle is a broad sheet of muscle originated from the the fascia covering the upper parts of the pectoralis major and deltoid going upwards to lower cheek and blend in with the muscle around the mouth. It draws the lower lip and corner of the mouth outward and downward.
Muscles lift up the upper lip. Muscles in the cheek involves in lifting upper lip. These muscles include the levator labii superioris alaeque nasi, the levator labii superioris muscle, the zygomaticus minor, the zygomaticus major and Levator anguli oris. They originate from cheek bone and all end in upper lip.
The risorius muscle and the buccinator muscle pull corner of the mouth outwards.
The Platysma muscle is thin like a flat sheet situated within the subcutaneous tissue of the neck. It originates from the fascia that covers the clavicle, the acromial region and the superior portions of the pectoralis major and deltoid muscles. It arises across the neck up to the lower face. It inserts onto the lower border of the mandible or the skin of the lower lip and attaches to the skin and subcutaneous tissue of the perioral region, and to the muscles surrounding the mouth. The platysma blends with the depressor anguli oris and depressor labi inferioris muscles and reinforces their actions. It also contributes to the formation of the orbicularis oris complex and the formation of the modiolus.