Muscles of facial expression

INTRODUCTION:
  • The facial muscles are a group of striated skeletal muscles innervated by the facial nerve (cranial nerve VII) which control facial expression.
  • These muscles are also called mimetic muscles.
  • Develop from mesoderm
  • The facial musculature is fairly unique.
  • They include the only somatic muscles in the body attached on one side to bone and the other to skin; thus facial movements are specialized for expression.
  • They also act as sphincters and dilators of the orifices of the face
  • Facial muscles develop from second pharyngeal arch except levator palpebrae superioris
  • The face is also one of the few places in the body where some muscles are not attached to any bone at all (e.g., orbicularis oculi, the muscle surrounding the eyes; orbicularis oris, the muscle in the lips). 
GROUPS:
  • For logical understanding, they are grouped as:
Orbicular Group
  • Orbicularis Oculi: Closes and squints the eye. Wink, concern, perplexion.It's lacrimal part is k/as Horner's muscle
  • Levator Palpebrae Superioris: Elevates the upper eyelid & dilate palpebral aperture. Surprise, fear 
  • Corrugator Supercilii: Draws the eyebrow inferomedially and shows anger, concern 
Nasal Group
  • Nasalis: Maxilla to the cartilage of the nose and the opposite­side nasalis muscle. Compresses the nares. 
  • Procerus: Fascia and skin medial to the eyebrow to the fascia and skin over the nasal bone (disdain look) 
  • Depressor Septi Nasi: From medial fiber of dilator naris muscle to mobile part of nasal septum. Depresses septum and narrows nostril
Oral Group
  • Levator labii superioris :Infraorbital head & zygomatic head to upper lip. Raises upper lip; helps form naso -labial furrow. Disgust, smugness 
  • Levator labii superioris alaeque nasi : Frontal nasal process to one to ala & other to orbicularis oris.Raises upper lip and opens Nostril. anger, contempt Levator anguli oris : Maxilla below infraorbital foramen & canine fossa to angle of mouth. Elevates the angle of the mouth. smile, sneer, “Dracula” expression
  • Zygomaticus major: From zygomatic bone & arch to angle of mouth. Draws the corner of the mouth upward and laterally. Smile, laugh 
  • Zygomaticus minor: From zygomatic bone & medial to zygomatic major to nasolabial groove. Draws the upper lip upward. Smile & Smugness. 
  • Risorius: From superficial fascia over parotid to skin & mucosa on angle of lip. Retracts corner of mouth. Grin, smile, laugh 
  • Depressor anguli oris / triangularis: From oblique line of mandible to angle of mouth. Draws corner of mouth down and laterally. 
  • Depressor labii inferioris : From base of mandible to skin n mucosa of lower lip. Draws lower lip downward and laterally. Sadness, uncertainty, dislike 
  • Mentalis : From mandible below lower incisors to skin of chin. Raises and protrudes lower lip as it wrinkles skin on chin. doubt, pout, disdain 
  • Orbicularis Oris: From buccinator muscle to angle of mouth (upper lip) and mandible (lower lip). Closes lips; protrudes lips.puckering, whistling 
  • Buccinator : From alveolar process of max. and mand. In region of molars & pterygomandibular ligament. Presses the cheek against teeth;Compresses distended cheeks. pucker, exertion, sigh 
  • Platysma : From skin and superficial fascia of pectoral and deltoid region to lower border of mandible. Draws up the skin of the superior chest and neck. Creature from Black Lagoon.expression
Other muscles or groups
  • Occipitofrontalis :
  • Frontal Belly:From ant. Part of Galea aponeurotica to Skin on lower part of forehead. Wrinkles forehead; Raises eyebrows 
  • Occipital belly:From lateral 2/3rd of Superior nuchal line To post. Part of galea Aponeurotica. Draws scalp backward 
  • Anterior auricular: Draws ear upward and forward 
  • Superior auricular : Elevates ear
  • Posterior Auricular: Draws ear upward and backward
NERVE INNERVATION OF FACIAL MUSCLES:

All Facial muscles are supplied by facial nerve except levator palpaberal superioris which is supplied by occulomotor nerve by following branches :
  1. Temporal branch – Innervates the frontalis, orbicularis oculi and corrugator supercilii
  2. Zygomatic branch – Innervates the orbicularis oculi.
  3. Buccal branch – Innervates the orbicularis oris, buccinator and zygomaticus muscles.
  4. Marginal Mandibular branch – Innervates the mentalis muscle.
  5. Cervical branch – Innervates the platysma.
Exam Question
  • Facial muscles develops from mesoderm
  • Act as sphincter & dilator of orifice of face
  • Develops from 2nd pharyngeal arch except levator palpebrae superioris
  • Some muscles are not attached to any bone eg. orbicularis oris, orbicularis oculi, muscles surrounding eye and muscles in lips
  • Lacrimal part of orbicularis oculi is k/as Horner's muscle
  • Levator Palpebrae superioris dilate palpebral aperture
  • Facial muscles are supplied by Facial nerve
  • Only Facial muscle not supplied my facial nerve is levator palpeberae superioris

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