Facial muscles

The facial muscles are a group of striated skeletal muscles supplied by the facial nerve (cranial nerve VII) that, among other things, control facial expression. These muscles are also called mimetic muscles. They are only found in mammals, although they derive from neural crest cells found in all vertebrates. They are the only muscles that attach to the dermis.[1]

Facial muscles
Head
Lateral head anatomy
Details
Nervefacial nerve
Identifiers
Latinmusculi faciei
MeSHD005152
TA98A04.1.03.001
TA22060
FMA71288
Anatomical terms of muscle

Structure

The facial muscles are just under the skin (subcutaneous) muscles that control facial expression. They generally originate from the surface of the skull bone (rarely the fascia), and insert on the skin of the face. When they contract, the skin moves. These muscles also cause wrinkles at right angles to the muscles’ action line.[2]

Nerve supply

The facial muscles are supplied by the facial nerve (cranial nerve VII), with each nerve serving one side of the face.[2] In contrast, the nearby masticatory muscles are supplied by the mandibular nerve, a branch of the trigeminal nerve (cranial nerve V).

List of muscles

The facial muscles include:[3]

The platysma is supplied by the facial nerve. Although it is mostly in the neck and can be grouped with the neck muscles by location, it can be considered a muscle of facial expression due to its common nerve supply.

The stylohyoid muscle, stapedius and posterior belly of the digastric muscle are also supplied by the facial nerve, but are not considered muscles of facial expression.

Facial muscles by type of movement
Movement[4]TargetTarget motion or directionPrime moverOriginInsertion
Raising eyebrows (e.g., showing surprise)Skin of scalpAnteriorOccipitofrontalis frontal bellyEpicraneal aponeurosisUnderneath skin of forehead
Tensing and retracting scalpSkin of scalpPosteriorOccipitofrontalis, occipital bellyOccipital bone; mastoid process (temporal bone)Epicraneal aponeurosis
Lowering eyebrows (e.g., scowling, frowning)Skin underneath eyebrowsInferiorCorrugator superciliiFrontal boneSkin underneath eyebrow
Flaring nostrilsNasal cartilage (pushes nostrils open when cartilage is compressed)Inferior compression; posterior compressionNasalisMaxillaNasal bone
Raising upper lipUpper lipElevationLevator labii superiorisMaxillaUnderneath skin at corners of the mouth; orbicularis oris
Lowering lower lipLower lipDepressionDepressor labii inferiorisMandibleUnderneath skin of lower lip
Opening mouth and sliding lower jaw left and rightLower jawDepression, lateralDepressor angulus orisMandibleUnderneath skin at corners of mouth
SmilingCorners of mouthLateral elevationZygomaticus majorZygomatic boneUnderneath skin at corners of mouth (dimple area), orbicularis oris
Shaping of lips (as during speech)LipsMultipleOrbicularis orisTissue surrounding lipsUnderneath skin at corners of the mouth
Lateral movement of cheeks (e.g., sucking on a straw; also used to compress air in mouth while blowing)CheeksLateralBuccinatorMaxilla, mandible; sphenoid bone (via pterygomandibular raphae)Orbicularis oris
Pursing of lips by straightening them laterallyCorners of mouthLateralRisoriusFascia of parotid salivary glandUnderneath the skin at corners of the mouth
Protrusion of lower lip (e.g., pouting expression)Lower lip and skin of chinProtractionMentalisMandibleUnderneath skin of chin

Development

The facial muscles are derived from the second branchial/pharyngeal arch. They, like the branchial arches, originally derive from neural crest cells. In humans, they typically begin forming around the eighth week of embryonic development.[1]

Clinical significance

An inability to form facial expressions on one side of the face may be the first sign of damage to the nerve of these muscles. Damage to the facial nerve results in facial paralysis of the muscles of facial expression on the involved side. Paralysis is the loss of voluntary muscle action; the facial nerve has become damaged permanently or temporarily. This damage can occur with a stroke, Bell palsy, or parotid salivary gland cancer (malignant neoplasm) because the facial nerve travels through the gland. The parotid gland can also be damaged permanently by surgery or temporarily by trauma. These situations of paralysis not only inhibit facial expression but also seriously impair the patient’s ability to speak, either permanently or temporarily.[2]

See also
This article uses anatomical terminology.

References
  1. Wilkins, Adam S. (2017). "History of the Face I". Making Faces. Belknap Press. p. 169. ISBN 9780674725522.
  2. Illustrated Anatomy of the Head and Neck, Fehrenbach and Herring, Elsevier, 2012, page 89
  3. Kyung Won, PhD. Chung (2005). Gross Anatomy (Board Review). Hagerstown, MD: Lippincott Williams & Wilkins. p. 364. ISBN 0-7817-5309-0.
  4.  This article incorporates text available under the CC BY 4.0 license. Betts, J Gordon; Desaix, Peter; Johnson, Eddie; Johnson, Jody E; Korol, Oksana; Kruse, Dean; Poe, Brandon; Wise, James; Womble, Mark D; Young, Kelly A (June 8, 2023). Anatomy & Physiology. Houston: OpenStax CNX. 11.3 Axial muscles of the head, neck and back. ISBN 978-1-947172-04-3.
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