Muscles of Facial Expression

Chapter 4

Muscles of Facial Expression

• Muscles of facial expression are paired muscles and allow for a wide variety of facial expressions

How Many Muscles Does It Take to Smile and Frown?

• Smile- 17 muscles
• Frown- 43 muscles

Origin and Insertion

• The origins and insertions of these muscles vary
• They are grouped according to their location in the scalp, eye, or mouth region

Action

• During facial expressions the muscles of facial expression act in various combinations to vary the appearance of the face

Innervation

• All muscles of facial expression are innervated by the seventh cranial (VII) or facial nerve

Anterior View of Most of The Muscles of Facial Expression

Lateral View of Most of the Muscles of Facial Expression

Muscles of the Facial Expression in the Scalp Region

• The epicranial muscle is located in the scalp region
• It has two bellies, frontal and occipital bellies, which are separated by a large spread-out scalpel tendon

Muscles of the Facial Expression in the Scalp Region

Epicranial Muscle

• Frontal belly origin- epicranial aponeurosis

• Frontal belly insertion- skin tissue of the eyebrow and root of the nose

   

• Occipital belly origin- occipital bone and mastoid process of the temporal bone

• Occipital belly insertion- epicranial aponeurosis

• Epicranial muscle- raises the eyebrows and scalp, as when a person shows surprise

  

Muscles of the Facial Expression in the Eye Region

• The muscle of the facial expression located in the eye region include the orbicularis oculi and ***corrugator supercilii ***muscles

  

Orbicularis Oculli Muscle

• Orbicularis oculi muscle closes the eyelids

Corrugator Supercilii Muscle

• Corrugator supercilii origin- frontal bone in the supraorbital region

• Corrugator supercilii insertion- skin tissue of the eyebrow

  

• The corrugator supercilli muscle is responsible for frowning

• Horizontal wrinkles in bridge of nose

  

Muscles of Facial Expression in the Mouth Region

• The largest group of facial muscles is associated with the mouth
• These muscles include the orbicularis oris, buccinator, risorius, levator labii superioris alaeque nasi, zygomaticus major, zygomaticus minor, levor anguli oris, depressor anguli oris, depressor labii inferioris, mentalis, and platysma muscles

Orbicularis Oris Muscle

• This muscle encircles the mouth

• It’s origin is the facial modiolus and it inserts into the skin tissue at the angle of the mouth

• Action: Closing and tightening the lips, rolling lips inward (grimacing),thrusting lip outward (pouting & kissing)

  

  

Buccinator Muscle

• The buccinator muscle forms the anterior portion of the cheek or the lateral wall of the oral cavity

• It originates from the maxilla, mandible, and pterygomandibular raphe & inserts into the angle of the mouth

• Action: Pulls the corners of the mouth back and compresses the cheek; plays a role in mastication by compressing the cheeks against the teeth; assists in whistling

  

Risorius Muscle

• The risorius muscle is a thin muscle of facial expression in the mouth region

• The risorius muscle originates from the fascia superficial to the mass enter muscle and inserts at the angle of the mouth

• Action: Stretching the lips

  

Levator Labii Superioris Muscle

• This muscle is a broad, flat muscle which originates in the maxilla and inserts into the upper lip

• Action: Elevates the upper lip

  

Levator Labii Superioris Alaeque Nasi Muscle

• This muscle originates from the maxilla and inserts into the ala of nose and upper lip

• Action: Raises the upper lip and dilates the nostrils, as in a sneering expression

  

Zygomaticus Major Muscle

• This muscle originates in the zygomatic bone and inserts into the angle of the mouth

• Action: Elevates the angle of the upper lip and pulls it laterally, as when a person smiles

  

Zygomaticus Minor Muscle

• Runs parallel to the Zygomaticus major muscle

• This muscle originates on the zygomatic bone and inserts into the upper lip (commissure)

• Action: Elevates the upper lip, assisting in smile

  

Levator Anguli Oris Muscle

• In between the Zygomaticus major and minor muscles

• This muscle originates on the canine fossa of the maxilla and inserts at the angle of the mouth

• Action: Elevates the angle of the mouth, as when a person smiles

  

Depressor Anguli Oris Muscle

• This muscle originates from the lower order of the mandible and inserts at the angle of the mouth

• Action: Depresses the angle of the mouth, as when a person frowns

  

Depressor Labii Inferioris Muscle

• This muscle originates from the lower border of the mandible and inserts in the lower lip

• Action: Depresses the lower lip, exposing the mandibular incisor teeth

  

Mentalis Muscle

• This muscle originates on the mandible near the midline and inserts in the chin

• Action: Raising the chin and protruding the lower lip

  

Platysma Muscle

• This muscle runs from the neck all the way to the mouth

• It originates in the clavicle and shoulder and inserts on the mandible and the muscles surrounding the mouth

• Action: Raising the neck skin and pulling the corners of the mouth down

  

Clinical Considerations With Muscles of Facial Expression Pathology

• Damage to the facial nerve results in ***facial paralysis ***of the muscles of facial expression on the involved side
• Paralysis- loss of voluntary muscle action; can be temporary or permanent
• Facial paralysis can occur with a stroke, Bell’s Palsy, or possible with parotid salivary gland cancer