Muscles of the Face

Summary

  • There are two types of muscles in the face
    1. Mimetic Muscles 
      • These are the muscles of facial expression
      • Innervate by CNVII (facial nerve)
    2. Muscles of Mastication 
      • These are used in mastication (i.e. chewing)
      • Innervated by CNV (trigeminal nerve)

Mimetic Muscles

  • These muscles act to manipulate skin/muscle
    • Therefore attach from bone to skin/fascia
  • Collectively, they have a sphincter-like activity in two key areas:
    1. Around the mouth
      • Orbicularis oris
      • Buccinator – also puffs out the cheeks
      • Risorius
      • Levators/depressorsthere are several of these
    2. Around the eyes
      • Occipito-frontalis
      •  Orbicularis oculi – 3 parts
        1. Orbital part (squeezes eye shut)
        2. Palpebral part (gentle eye closure)
        3. Lacrimal part (tear release)
      • Levator palpebrae superioris
        • CNIII
        • Positioned in the upper eyelid
      • Procerus
        • Used in frowning
      • Summary of muscles and nerves of the face. Taken from Clinically Oriented Anatomy, Moore & Dalley.
  • Modiolus  – this is a chiasma of several muscles (seen as dimples)
  • Innervation of the mimetic muscle is done by the five branches of CNVII (Ten Zulus Brought My Cat)
    • Trochlear
    • Zygomatic
    • Buccal
    • Mandibular
    • Cervical
Branches of CNVII.
An easy method of approximating the distribution of the 5 branches of CNVII.

Muscles of Mastication

  • There are 5 muscles of mastication
    • All five are supplied by the three branches of CNV (trigeminal nerve)

      The four main muscles of mastication
  1. Masseter
    • Attachments: from angle + ramus of mandible => zygomatic arch
    • Function: Elevation
    • Origin Insertion

  2. Temporalis
    • Attachments: Temporal fossa => Coronoid process
    • Function: Elevation + retraction
    • ) rigin Inserti

  3. Medial Pterygoid
    • Attachments:Medial angle of mandible => Medial aspect of Lateral Pterygoid Plate (LPP)
    • Function: Elevation + side-to-side movement
  4. Lateral Pterygoid
    • Attachments: Condyle of mandible => Lateral aspect of LPP
    • Function: Depression + protraction
    • asul

  5. Digastric (anterior belly) – sometimes considered separate to the MofM
    • Attachments: Digastric belly => Mastoid notch of the temporal bone
    • Function: Depression along with infrahyoids

Actions of the muscles of mastication
  1. Elevation
    • Masseter
    • Temporalis
    • Medial pterygoid
  2. Depression
    • Gravity
    • Suprahyoid
    • Infrahyoid
  3. Protrusion (moving the mandible forward)
    • Lateral Pterygoid
    • (Medial pterygoid)
  4. Retrusion (moving the mandible back and bringing lower teeth in front of upper teeth)
    • Posterior Temporalis
    • Masseter
  5. Grinding (side-to-side)
    ○ Unilateral action of pterygoid muscles

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