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Facial Muscles are striated muscles that attach to the bones of the skull to perform important functions for daily life including mastication and facial expressions. These muscles are located medially to the ears, superior to the mandible, and inferior to the coronal suture of the skull. Deficits in these muscles can lead to significant impairment of daily function.
Structure and Function of Facial Muscles
The facial muscles serve 2 major functions for the body: mastication and facial expressions. The muscles of mastication include the temporalis, medial pterygoid, lateral pterygoid, and the masseter (buccinator muscle is an important accessory of chewing). Another important function is facial expression. The majority of the facial muscles contribute to exhibiting expressions. These muscles include the orbicularis oculi, nasalis, levator labii superioris alaeque nasi, depressor labii inferioris, procerus, auriculars, zygomaticus major, zygomaticus minor, buccinator, occipitofrontalis, corrugator supercilii, risorius, depressor anguli oris, orbicularis oris, and mentalis. The orbicularis oculi is responsible for blinking the eye or closing of the eyelid. The nasalis and labii superioris alaeque nasi function by elevating the sides of the nose or “snarling.” The depressor labii inferioris depresses the nose. The procerus and corrugator supercilii muscles attach to the frontalis muscle in between the eyebrows and functions in crinkling the eyebrows together. The auriculars function in moving the ears anteriorly and posteriorly from the face. The zygomaticus major and minor run over the zygomatic bone and function in helping to smile by pulling the muscles upward. The risorius muscles are found at the edges of the mouth and also function in smiling. The buccinator allows an individual to chew without biting the cheeks and to blow air outward. The occipitofrontalis, with 2 communicating bellies, acts to raise the eyebrows on the face. The depressor anguli fibres functions in depressing the sides of the mouth in frowning. The orbicularis oris functions in pursing the upper and lower lips. The mentalis muscles is a primary muscle of the lower lip and function in lowering the inferior lip.
The superficial facial muscles affect the health of the skin and mucous membranes. Facial muscles can influence distant anatomical areas. To give an example, the occipitofrontalis muscle has an anatomical continuity with the eyelid elevator and the Tenon capsule, anteriorly, and a posterior continuity with the sub-occipital muscles. From a clinical point of view, an abnormal tension of this myofascial continuum could negatively affect the position of the neck, the relationship between the gaze and the posture of the head.
The facial muscles intervene in the speech and strongly affect the social relationship through facial expression.
Muscles of Facial Muscles
These are the muscles located on the face.
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Occipitofrontalis muscle
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Temporalis muscle
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Procerus muscle
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Nasalis muscle
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Depressor septi nasi muscle
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Orbicularis oculi muscle
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Corrugator supercilii muscle
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Depressor supercilii muscle
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Auricular muscles (anterior, superior and posterior)
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Orbicularis oris muscle
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Depressor anguli oris muscle
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Risorius muscle
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Zygomaticus major muscle
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Zygomaticus minor muscle
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Levator labii superioris muscle
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Levator labii superioris alaeque nasi muscle
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Depressor labii inferioris muscle
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Levator anguli oris muscle
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Buccinator muscle
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Mentalis muscle
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Platysma muscle
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Masseter muscle
Most of these muscles receive innervation from the facial nerve and participate in facial expression except for the masseter muscle. The innervation of the masseter muscle is via the trigeminal nerve, and this muscle participates in mastication.
Muscles located in the cheek region
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Orbicularis oculi muscle (lower border)
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Levator labii superioris muscle
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Levator labii superioris alaeque nasi muscle
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Risorius muscle
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Levator anguli oris muscle
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Zygomaticus major and minor muscles
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Buccinator muscle
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Masseter muscle
Nerves of Facial Muscles
The innervation for the facial muscles is from 2 major nerves.
- The facial nerve, or cranial nerve VII, serves as the main motor component. The facial nerve arises from beneath the parotid gland and radiates across the face.
- The facial nerve innervates the muscles of expression allowing a person to move their face accordingly. The trigeminal nerve, or cranial nerve V, serves as the sensory component of the face and scalp.
- Cranial nerve V has 3 major branches that supply different regions of the face. The ophthalmic branch, or V1, supplies the forehead region and exits the skull superiorly to the orbits.
- The maxillary branch, or V2, innervates the maxilla bone region inferior to the orbit. The mandibular branch, or V3, supplies innervation to the mandible bone region inferior to the nose.
- This V3 branch can contribute to both sensory and motor innervation of the face. The motor component of V3 innervates the muscles of mastication. \All 3 branches of the trigeminal nerve provide general somatic afferent fibers that contribute to the sensory innervation of the face.
- Cervical spinal nerves contribute to the cutaneous sensation of the face as well, but the trigeminal nerve is the main innervation.
Surgical Considerations
Anatomy of the face is essential when it comes to surgeries in the face. The face is highly vascularized and heavily innervated by nerves. The knowledge of the anatomy of the face can guide clinicians in the avoidance of damage to crucial structures in the face during surgeries and injections in the face.
- Forehead lift – also known as a brow lift, is a surgical procedure that some individuals receive to decrease the appearance of wrinkles across the forehead, bridge of the nose, and between the eyes. A plastic surgeon usually performs this surgery. The procedure consists of removing segments of excess skin and fat to reduce the appearance of wrinkles.[rx]
- Cheek augmentation – is a cosmetic procedure that enhances the appearance of the cheeks by adding volume, removing sagginess, or removing wrinkles. The augmentation of the cheeks can be done by implantation of cheek implants or the injection of fillers to add volume to the cheeks. The addition of implants or injected fillers will increase the volume of the cheeks, usually resulting in less sagging and wrinkling of the cheeks.
- Otoplasty – is a surgical procedure done to correct or alter the ear. This surgery is done to improve the proportions and position of the ear to make a face appear more desirable to the patients.[rx]
- Rhytidectomy – is also known as a facelift. This procedure reduces the appearance of the wrinkles and sagging skin from aging. In a facelift, the surgeon may remove excess fat pad and resect excess sagging skin to create a tighter and more defined face.[rx]
- Lower rhytidectomy – is also known as a neck lift. This procedure targets the platysma muscle. The resection and tightening of the skin on the neck make the neck appear more desirable and hides the features of aging in some individuals.[rx]
- Buccal fat removal – is a procedure where the buccal fat pad is removed to create the illusion of dimpling and a more defined cheekbone.[rx]
- Mentoplasty – is a procedure done to enhance the appearance of the chin by implants or resection of the chin. The decision to resect or to add chin implants is decided by the patient on what would make them appear more natural or enhanced.
- Blepharoplasty – is a procedure done to alter the appearance of the eyelids. This procedure can reduce the appearance of bags under the eyes, eye puffiness, wrinkles due to excess skin, or reduction of excess skin that is obstructing vision.
- Facial implants – are done to enhance the appearance of the cheeks, chin, or jaw by the placement of implants. Implants are done to enhance and make the various regions appear fuller with less wrinkling.
- Rhinoplasty – is also known as a nose job. Rhinoplasties are done to alter the appearance of the nose to make it appear more proportionate to the dimensions of the face.
All of these procedures are also useful in conjunction with facial trauma repairs. In facial traumas, the surgeons operate to repair and restore the appearance of the patient’s face. Sometimes the cosmetic procedures are done as adjunctive in facial trauma repairs to optimize the surgical approach to the restoration of the face.
Reflexes
The facial motor nucleus receives afferent information from several origins and participates in a number of reflexes:
- The corneal reflex – is tested by stimulating the cornea with a wisp of cotton. It results in the reflex closure of both eyelids. The afferent limb of this reflex is mediated by the trigeminal nerve, and the efferent limb is mediated by the facial nerve.
- Orbicularis oculi reflex – can be evoked by various stimuli such as stimulation of the supraorbital nerve, light, and sound. The afferent limb of this reflex is mediated by the trigeminal, optic, and vestibulocochlear nerves respectively. The efferent limb is mediated by the facial nerve and produces bilateral eye blink.
- Orbicularis oris reflex – also known as snout reflex, is produced by percussion on the upper lip or the side of the nose and results in ipsilateral elevation of the angle of the mouth. The trigeminal nerve stands for the afferent limb and the facial nerve for the efferent limb of the reflex. Orbicularis oris reflex can be evoked in infants and disappears later in life. It can recur in the setting of the supranuclear facial nerve ulcer. সহজ বাংলা: শরীরের অস্বাভাবিক দাগ, ক্ষত বা ফোলা অংশ।" data-rx-term="lesion" data-rx-definition="A lesion is an abnormal area of tissue such as a spot, wound, patch, lump, or ulcer. সহজ বাংলা: শরীরের অস্বাভাবিক দাগ, ক্ষত বা ফোলা অংশ।">lesion and extrapyramidal diseases like Parkinson disease.[rx]
