Did you know facial muscles link facial skin to the skull? Originating from the skull (fascia), these striated muscles insert into the skin for individual facial movements. The two types of muscles on the face are facial muscles, also called craniofacial muscles, and mastication muscles.
This guide breaks down the anatomy and function of facial expression muscles and mastication muscles.
Muscles of Facial Expression
Craniofacial muscles are positioned around the eyes, ears, nose, and mouth and work together to make facial expressions. They are innervated by the facial nerve and are categorized into orbital, oral, and nasal groups.
1. Oral Group
Oral group muscles consist of 11 muscles that control the movements of the lips, mouth, and jaw. They are:
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Orbicularis Oris
The orbicularis oris muscle is the circular muscle around the lips that closes the lips and mouth, also known as the kissing muscle. Bilateral contraction closes the lips, whereas isolated contraction produces lip pouting and puckering. It also facilitates speech.
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Buccinator
The buccinator muscle sits between the maxilla and mandible. It consists of the superior, inferior, and posterior parts that meet at the angle of the mouth. This muscle constricts the cheek when whistling, sucking, blowing, and chewing.
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Depressor Anguli Oris
Found on either side of the chin, this muscle allows the downward movement of the corners of the mouth. Contraction of this muscle makes the frowning expression.
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Levator Anguli Oris
This muscle raises the corners of the mouth, meaning it is the direct opposite of the depressor anguli oris muscle. It produces a smile and works alongside the zygomaticus major and minor, and risorius muscles.
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Risorius
It originates from the parotid fascia and is responsible for producing smiles. The muscle pulls the corners of the mouth backward to create a smile.
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Zygomaticus Major and Minor
Both muscles originate from the zygomatic bone, are found on the cheek, and produce a smile. The Zygomaticus major elevates the angle of the mouth, while the zygomaticus minor elevates the upper lip.
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Levator Labii Superioris
This muscle elevates and everts the upper lip to expose nasolabial lines and the teeth. The facial expressions associated with it are grins, smiles, and contempt.
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Levator Labii Superioris Alaeque Nasi
This muscle is responsible for two functions: elevate the upper lip and widen the nostrils. It originates from the frontal process of the maxilla and receives nerves from the zygomatic and buccal branches of the facial nerve.
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Depressor Labii Inferioris
Present in the chin area, the depressor labii inferioris is the muscle responsible for sulking as it depresses the bottom lip down when it contracts.
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Mentalis
This muscle is located at the tip of the chin and helps make the chin wrinkle and shape the lips while drinking. It acts by elevating and thrusting the lower lip.
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Platysma
The role of the platysma muscle is to wrinkle the skin of the neck, pull the corners of the mouth downwards, and depress the lower jaw.
The muscles above are responsible for chin, lips, mouth, and jaw movements. And if you’d love to transform your jawline, try the mewing.coach app.
2. Nasal Group
Nasal facial muscles move the nose and the skin around it. The three muscles in the nasal group are:
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Nasalis
Nasalis is located on each side of the nose and consists of the alar and transverse sections. The muscle compresses the nasal cartilage and depresses the tip of the nose and nostrils.
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Procerus
These muscles are located in the small area between the eyebrows. They depress the eyebrows to make transverse wrinkles over the glabella associated with frowning.
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Depressor Septi Nasi
The depressor septi nasi originates from the maxilla, right above the central incisor. Its role involves constricting and widening the nasal aperture when taking deep breaths.
3. Orbital Group
These facial muscles around the eye sockets control eyelid movements to protect the cornea. The muscles in the orbital group are:
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Orbicularis Oculi
This sphincter-like muscle consists of the orbital, palpebral, and lacrimal parts. The palpebral part has gentle control of the eyelids, say when blinking or sleeping, whereas the orbital part is more protective and tightly shuts the eyes in case of danger. The lacrimal part allows the flow of tears.
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Corrugator Supercilii
This small triangular muscle is located above the eyes at the medial end of the eyebrows. Upon contraction, the muscle produces a frowning expression with vertical wrinkles over the forehead. It also draws the eyebrows downwards to protect the eyes from bright light. The muscle’s innervation is the temporal branches of the facial nerve.
Muscles of Mastication
Mastication muscles are responsible for jaw movement and are innervated by the trigeminal nerve’s mandibular branch (CNV3). This group contains the following four muscles:
1. Temporalis
This muscle is distinct for its fan shape, and upon contraction, it elevates and retracts the mandible and aids grinding movement.
2. Masseter
The masseter muscle consists of three layers: the superficial, intermediate, and deep layers. This muscle elevates the mandible for powerful jaw closure and stabilizes the temporomandibular joint (TMJ).
3. Medial Pterygoid
The medial pterygoid muscle aids the protrusion and elevation of the mandible and side-by-side motion when grinding and chewing food.
4. Lateral Pterygoid
The lateral pterygoid muscle moves the mandible downwards during bilateral contraction. Furthermore, it works alongside the medial pterygoid for alternate side-by-side chewing motions.
Other muscles that support mastication are:
- Suprahyoid Muscles: They depress the mandible to open the jaw.
- Infrahyoid Muscles: They pull down the hyoid bone and help during swallowing.
- Buccinator Muscles: This facial expression muscle ensures food stays within the oral cavity during chewing.
Disorders Affecting the Facial Muscles
All the above facial muscles receive signals from the facial nerve to function. When there is a problem with the nerve signals, specific parts of your face or the whole face may experience partial paralysis. You may have difficulty speaking, chewing, moving, and feeling parts of the face. If your face feels droopy, saggy, or paralyzed, seek medical help.
Final Thoughts
Now you understand what makes up the facial muscles. Facial muscles are either muscles of mastication or muscles of facial expression. Regardless of their category, both groups support each other’s actions.
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