The human head can be divided into many different muscles groups differing in functions and actions. We will be examining the two main muscles of the head, the muscles of the face which are primarily responsible for our facial expressions and the muscles of mastication which are responsible for chewing. There are other important muscles located on or in the head such as the muscles of the tongue and throat and the extrinsic muscles of the eyes responsible for controlling the movement of our eyes, which we will not be discussing here.
The muscles of facial expression are extremely important muscles as they are chiefly responsible for communication between humans. You can generally see just from looking at from someone’s face whether they are feeling happy, surprised, angry, fearful, sad as well as many other emotions. These muscles of facial expression are extremely important in non-verbal communication and are countlessly relied upon through out the day.
These muscles of facial expression are uniques as they generally originate from the skull, however unlike most skeletal muscles which insert to another bone, the muscles of facial expression insert into the superficial fascia and dermis of the skin and as a result when they contract, the skin moves. In the following we will detail the different facial expression muscles and their associated actions.
Frontalis and the Occipital Muscles
The Frontalis and Occipital muscles are part of the epicranius and primarily responsible to create the expressions of surprise and fright by tightening the entire scalp. The frontalis muscles as the name suggests in located in the anterior part of the epicanius. Its Origin point is out of muscles that are over the bridge of the nose and it’s insertion point is the posterior edge of the galea aponeruotica. The galea aponeurotica travels over the top of the skull until it meets the occipital muscle which is located near the rear or base of the scull. It’s origin point is along the superior nuchal line at the base of the occipital bone of the skull and courses upward to an insertion point at the posterior edge of the galea.
Muscles for Frowning
Corrugator Supercilii and Procerus Muscles
The Corrugator Supercilii and Procerus muscles are located where the top nose meets the forehead and are responsible for the expression of frowning. They have the same origin points at the frontalis muscle and insertion points just above the root of the nose.
Palperbral Levator Superioris Muscle
The palpebral levitator superior muscle or more commonly known as the levitator for short is the the muscle which lifts the upper eye lid in the second part of the blinking action and maintains the correct level of the upper lid when the eye is open. It has an origin point from the small wing of the sphenoid bone, at the apex of its orbit. The levitator ends as many tiny fiber-like attachments and has an insertion point at the inner surface of the skin of the upper eye lids forming the lid crease.
Orbicularis Oculi Muscle
The orbicular Oculi muscle is the muscle responsible for closing your eyelids when blinking and allowing you to squint or wink your eyes. It is made up of two portions the palpebral portion and the orbital portion. The Palpebral portion of the muscle is a thin layer which is essentially part of the eyelid and has an origin point from the frontal and maillary bones and the medial palpebral ligament, and forms a series of concentric curves around the eyeball and has an insertion point into the lateral palpebral raphia at the outer canthus of the eye. This portion of the muscle is primarily responsible for opening the eyelids. The orbital portion is the muscle that encircle the entire eye above and below with it’s fibers forming a complete ellipse around the eyeball with the upper fibers of the orbital portion blending with the Frontalis and Corrugator muscles.
Muscles for flaring your nose
Nasalis Muscle
The nasalis muscle is the muscle which is responsible for flaring your nostrils. It consists of two parts the Transverse part and the Altar part. The transverse part has an origin point from he maxilla above and lateral to the incisive fossa and an insertion point at the aponeurosis on the bridge of the nose. The altar part has its origin point at greater altar cartilage and an insertion point at thin aponeurosis on the bridge of the nose.
Depressor Septi Muscle
The depressor septi muscle is a small muscle responsible for drawing the nose downward. It has an origin point from the maxilla, just under the nose, and an insertion point at the septum of the nose.
Muscles of the mouth
Orbicularis Oris Muscle
The Orbicularis Oris is the muscle responsible for closing your mouth, kissing and pouting. As the name suggests the fibbers of the orbicular oris muscle encircle the mouth is a sphincter muscle. It has an origin points at the maxilla and the the mandible the lips and the buccinator muscles and it’s insertion points encircle the mouth.
Buccinator Muscle
The buccinator is the muscle of the cheek and assists in chewing motion by holding the cheek close to the teeth. It is also the muscle used for blowing such as playing a trumpet. It has origin points at the maxilla, the mandible, and the superior constrictor pharyngis muscle. The insertion points are the orbicularis oris and the modiolus, beneath the risorius muscle.
Levator Anguli Oris Muscle
The Levator Anguli muscle assist the naso-labial fold in the cheek. It lifts the upper lip to expose the teeth when smiling. The origin point is on the maxilla just below the infraorbital foramrn and has an insertion point at the modiolus.
Zygomaticus Major Muscles
The zygomaticus major muscle works with the risorious muscle to assist laughing and smiling by lifting the corners of the mouth. It’s origin point id from the Zygomatic bone and has insertion points at the orbicularis at the modiolus.
Zygomaticus Minor Muscle
The zygomaticus minor muscle also works with the risorius muscle lifting the lip to assist laughing and smiling. It’s origin points from the malar surface of the zygomatic bone and has insertion points on the orbicularis oris just next to and above the zygomaticus major .
Levator Labii Superior Muscle
The levator labii superioris muscle is one of the muscles responsible for lifting the upper lip. It has origin points on the cheek bone near where it meets the bones of the nose and insertion points into the skin of the nose and skin of the lip.
Levator Anguli Muscle
The name of the levator anguli oris muscle lifts the mouth at corners. It has origin points just outside and beneath the orbital rim and insertion points at the modiolus. It lies beneath them, coursing under the levator labii superioris, then arising just outside of and beneath the orbital rim.
Levator Labii Superior Alawque Nasi Muscle
The levator labii superioris alaeque nasi muscle is responsible for the facial expression allowing you to sneer. It has an origin point from the upper frontal process of the maxilla and insertion points at the skin of the lateral part of the nostril and upper lip
Depressor Anguli Oris Muscle
The depressor anguli oris muscle is located on the lower lip and aids in drawing the lower lip downward. It has origin points out of the fibers of the platysma muscle and has insertion points at the modiolus, mingling its fibers with the risiorious and the orbicularis oris,
Depressor Labii Inferior Muscle
The deppressor labii inferioris muscle is primarily responsible for depressing or drawing down muscle of the lower lip. It’s origin point is from the mental region of the lower mandible and has an insertion points on the orbicular oris.
Risorious Muscle
The risorious muscle is primarily responsible for the facial expressions of laughing and smiling. It’s origin point is in the fascia of the cheek and has insertion points into the orbicular oris.
