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.
Platysma Muscles
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.
