Facial Muscle

Muscles of mouth, nose, cranium, neck, external ear, and eyelid - Anatomy, functions, common conditions, and disorders.

Facial Muscle

Muscles of mouth, nose, cranium, neck, external ear, and eyelid - Anatomy, functions, common conditions, and disorders.

Introduction

The facial muscles are also called craniofacial muscles.
These muscles produce expressions (like smiling, frowning, etc.); therefore, they are also known as muscles of facial expression or mimetic muscles.
These expressions are possible due to these muscles' specific location and attachment. As they contract, they uniquely pull on facial skin and exhibit expressions.
They are 20 skeletal muscles located within the subcutaneous tissue of the face.
These muscles originate from bone or fascia and insert onto the skin.
All of them are supplied by the facial nerve (CN VII) and vascularized by the facial artery.
These muscles are categorized into five groups:

Muscles of the mouth (buccolabial group).
Muscles of the nose (nasal group)
Muscles of the eyelid (orbital group)
Muscles of the cranium and neck (epicranial group)
Muscles of the external ear (auricular group)

Anatomy and Function

Muscles of the mouth (buccolabial group)

It is a broad group of muscles that controls the shape and movements of the mouth and lips.
They are required to sing and whistle and add emphasis to vocal communication.
The group consists of the

Orbicularis Oris,
Buccinator, and
Various smaller muscles.

Orbicularis Oris

It is the complex, multilayered sphincter muscle of the lips located around the circumference of the mouth.

Attachments

Action

Insertion

Intervention

Blood Supply

Arises from the maxilla and the other cheek muscles.

It inserts onto the skin and mucous membrane of the lips.

Closes the lip to narrow the oral opening.

The skin surrounding the lips.

Buccal branches of the facial nerve.

The superior and inferior labial branches of the facial artery.

Buccinator

It is a thin, square-shaped muscle.
It forms the cheek's anterior aspect and the oral cavity's lateral aspect.
Several structures penetrate the buccinators, including the parotid duct, the cheeks' molar glands, and the mandibular nerve's buccal branch.

Attachments

Action

Insertion

Intervention

Blood Supply

Originates from the maxilla and mandible.

The fibers run in an inferomedial direction, blending with the orbicularis oris muscle and the skin of the lips.

Pull the cheek inwards against the teeth, preventing the accumulation of food in that area.

The orbicularis oris muscle and modiolus act as the insertion site for this muscle.

Buccal branches of the facial nerve.

The buccal branch of the maxillary artery.

Minor Oral Muscles

Other minor muscles act on the lips and mouth.
They can be divided into lower and upper groups.

Lower Group

Muscle	Origin	Action	Insertion	Intervention	Blood Supply
Depressor anguli oris	The mental tubercle of the mandible.	Contraction of this muscle causes depression of the angle of the mouth, which contributes to frowning.	The modiolus and angle of the mouth	The buccal and mandibular branches of the facial nerve.	The inferior labial branch of the facial artery and mental branch of the maxillary artery.
Depressor Labii Inferioris	The mandible (specifically between the mental foramen and the symphysis).	Contraction of this muscle depresses the lower lip.	The skin of the lower lip. The fiber blend with the fiber of the orbicularis oris muscle at the insertion point.	The mandibular branch of the facial nerve.	The inferior labial branch of the facial artery and the mental branch of the maxillary artery.
The Mentalis	The anterior aspect of the mandible.	Contraction of this muscle causes protrusion of the lower lip, as well as elevation and wrinkling of the skin of the chin.	The skin of the chin.	The mandibular branch of the facial nerve.	The inferior labial branch of the facial artery and the mental branch of the maxillary artery.
Platysma	The skin and fascia of the infraclavicular and supraclavicular regions.	Draws the corners of the mouth downwards, which assists in creating the expression of melancholy. Tenses the skin of the neck when the teeth are clenched. Depresses the lower jaw.	The base of the mandible, skin of the cheek and lower lip, mouth angle, orbicularis oris muscle.	The cervical branch of the facial nerve.	Branches of the submental and suprascapular arteries.

Upper Group

Muscle	Origin	Action	Insertion	Intervention	Blood Supply
Levator anguli oris	The canine fossa of the maxilla.	Contraction of this muscle elevates the angle of the mouth contributing to smiling.	The modiolus and angle of the mouth.	The zygomatic and buccal branches of the facial nerve.	The superior labial branch of the facial artery and the infraorbital branch of the maxillary artery.
Risorius	The parotid fascia.	This muscle draws the angle of the mouth backwards.	The modiolus of the mouth.	The buccal branch of the facial nerve.	The superior labial branch of the facial artery.
Zygomaticus major	The zygomatic bone.	This muscle helps to facilitate smiling by pulling the angles of the mouth superiorly and laterally.	The modiolus of the mouth.	The zygomatic and buccal branches of the facial nerve.	The superior labial branch of the facial artery.
Zygomaticus minor	The zygomatic bone.	Contraction of this muscle aids in the elevation of the upper lip .	This muscle inserts into the skin of the lateral upper lip.	The zygomatic and buccal branches of the facial nerve.	The superior labial branch of the facial artery.
Levator labii superioris	The maxilla and zygomatic bone superior to infraorbital foramen.	Contraction causes elevation of the upper lip.	This muscle inserts into the skin and muscle of the upper lip.	The zygomatic and buccal branches of the facial nerve.	The facial artery and the infraorbital branch of the maxillary artery.
Levator labii superioris alaeque nasi	The frontal process of the maxilla.	This muscle facilitates the expression of ‘snarling’ by causing dilation of the nostrils, as well as elevation of the wings of the nose and upper lip.	Skin of the alar cartilage of nose and skin of the upper lip.	The zygomatic and buccal branches of the facial nerve.	The facial artery and the infraorbital branch of the maxillary artery.

Muscles of the nose (nasal group)

These muscles are primarily responsible for creating facial expressions, but they also contribute to respiration.
Three main muscles comprise this group:

Nasalis,
Procerus, and
Depressor septi nasi.

Muscle	Attachments	Action	Insertion	Intervention	Blood Supply
Nasalis 1. Largest of the nasal muscles. 2. Comprises two parts: Transverse and Alar.	Transverse part – originates from the maxilla, immediately lateral to the nose. It attaches to an aponeurosis across the dorsum of the nose. Alar part – originates from the maxilla overlying the lateral incisor. It attaches to the alar cartilage of the nasal skeleton.	Transverse part – compresses the nasal opening. Alar part – widens the nasal opening.	At an aponeurosis over the bridge of the nose and at the skin around the alar part of the nose.	Buccal branches of the facial nerve.	The superior labial branch of the facial artery and the infraorbital branch of the maxillary artery. .
Procerus	Originates from the nasal bone and inserts onto the skin of the lower medial forehead.	Pulls the eyebrows downward to produce transverse wrinkles over the nose.	The inferior skin of the forehead is on either side of the midline between the eyebrows.	Buccal branches of the facial nerve.	The angular and lateral nasal branches of the facial artery.
Depressor septi nasi	Originates from the maxilla (above the medial incisor tooth) and inserts onto the nasal septum.	Pulls the nasal septum inferiorly to widen the nasal opening.	The nasalis muscle and nasal septum.	Buccal branches of the facial nerve.	The superior labial branch of the facial artery.

Muscles of the eyelid (orbital group)

They control the movements of the eyelids
Two muscles comprise this group:

Orbicularis oculi, and
Corrugator supercilii.

Muscle	Attachments	Action	Insertion	Intervention	Blood Supply
Orbicularis Oculi 1. Surrounds the eye socket and extends into the eyelid. 2. Comprises three parts: Palpebral, Lacrimal, and Orbital.	Originates from the medial orbital margin, the medial palpebral ligament, and the lacrimal bone. It inserts into the skin around the margin of the orbit as well as the tarsal plates of the eyelid.	Palpebral part – gently closes the eyelids. Lacrimal part – involved in the drainage of tears. Orbital part – tightly closes the eyelids.	The skin overlying the circumference of the orbit, The orbital septum, The temporal aspect of the orbit, and Inferiorly towards the cheek.	Temporal and zygomatic branches of the facial nerve.	Branches of the facial, superficial temporal, maxillary, and ophthalmic arteries. .
Procerus	Originates from the medial aspect of the superciliary arch and inserts onto the skin of the eyebrow.	Draws the eyebrows together, creating vertical wrinkles on the bridge of the nose.	The skin of the forehead near the eyebrow acts as the insertion site for this muscle.	Temporal branches of the facial nerve.	The ophthalmic artery and branches from the superficial temporal artery.

Muscle of the cranium and neck (epicranial group)

Occipitofrontalis comprise of two main sections:

Occipital (located posteriorly), and
Frontal (located anteriorly) bellies.

Muscle	Attachments	Action	Insertion	Intervention	Blood Supply
Occipitofrontalis	The occipital belly originates from the occipital bone, and the mastoid process of the temporal bone. The frontal belly originates from the epicranial aponeurosis.	Contraction of this muscle raises the eyebrows and wrinkles the forehead.	The occipital part inserts into the epicranial aponeurosis. The frontal belly inserts into the fascia of the facial muscles surrounding the eyes and the skin above the eyes.	The temporal branch of the facial nerve innervates the frontalis and the posterior auricular branch of the facial nerve innervates the occipitalis.	The occipital belly is supplied by the occipital artery and The frontal belly is supplied by the supraorbital and supratrochlear arteries. .

Muscle of the external ear (auricular group)

The auricular muscles are thin, fan-shaped muscles that connect the auricle to the scalp.
These muscles include:

Auricularis anterior,
Auricularis posterior, and
Auricularis superior.

Muscle	Attachments	Action	Insertion	Intervention	Blood Supply
Auricularis anterior	It arises from the lateral border of the epicranial aponeurosis and attaches to the spine of the helix of the auricle.	Draws the auricle of the outer ear upwards and forwards.	Major Helix	Temporal branches of the facial nerve.	Derived from the posterior auricular artery. .
Auricularis posterior	It arises from the mastoid process of the temporal bone and inserts into the ponticulus on the eminentia conchae.	Draws the auricle backwards, usually a very slight effect.		Posterior auricular branch of the facial nerve.	Derived from the posterior auricular artery.
Auricularis superior	It arises from the epicranial aponeurosis and converges into a thin, flat tendon to insert onto the upper part of the auricle.	Draws the auricle upwards.		Temporal branches of the facial nerve.	Derived from the posterior auricular artery.

Common Conditions & Disorder

Paralysis to the Orbital Muscles

A damaged facial nerve leads to ceasing the function of the orbital muscles. It causes:

Exposure keratitis - the eye cannot shut and cause the cornea to dry out.
Ectropion, the lower eyelid droops
Lacrimal fluid pools in the lower eyelid and cannot be spread across the surface of the eye. This can fail to remove debris and ulceration of the corneal surface.

Paralysis to the Oral Muscles

Dysfunctional facial muscles can also lead to paralyzed oral muscles.
Difficulty in eating, food collection between the teeth and cheeks, sagging around the mouth, and tissue is drawn across to the opposite side while smiling are a few of the consequences.
Peripheral Facial Lesions, the facial muscles are completely paralyzed on the affected side. When trying to close the lids the eye rotates upwards exposing the sclera (Bell’s phenomenon).
Central Facial Lesions, patient can still wrinkle the forehead on both sides.
Additional disturbances of tear and saliva secretion, hearing, or taste could also be there depending upon the location of the lesion.
Damage to the facial nerve and problems with the facial muscles can be caused by

Autoimmune disease
Bell’s palsy
Head and neck cancer
Infection
Injury to the head or face
Stroke

References

Drake, R. L., Wayne Vogl, A., Mitchell, A. Gray’s anatomy for students second edition.
Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2014). Clinically Oriented Anatomy (7th ed.). Philadelphia, PA: Lippincott Williams & Wilkins.
Netter, F. (2019). Atlas of Human Anatomy (7th ed.). Philadelphia, PA: Saunders.
Gray’s Anatomy: The Anatomical Basis of Clinical Practice

DrDent_Notes

Facial Muscle

Muscles of mouth, nose, cranium, neck, external ear, and eyelid - Anatomy, functions, common conditions, and disorders.

Facial Muscle

Introduction

Anatomy and Function

Muscles of the mouth (buccolabial group)

Orbicularis Oris

Buccinator

Minor Oral Muscles

Muscles of the nose (nasal group)

Muscles of the eyelid (orbital group)

Muscle of the cranium and neck (epicranial group)

Muscle of the external ear (auricular group)

Common Conditions & Disorder

Paralysis to the Orbital Muscles

Paralysis to the Oral Muscles

References

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