muscles of the face

Question 1

What are muscle groups of the face?

Answer 1

• Together they are collectively known as the muscles of facial expression or mimetic muscles
  
  • They are all skeletal muscles therefore they are striated and under ‘voluntary control’
  • Have 2nd brachial arch origins
  • Are classified as branchio-motor not somatic
  • Receives innervation from the brachial motor region of the brachial arch
  • Cranial nerve 7 is the motor division on the brachial arch
  • All the muscles receive efferent or motor innervation form a common cranial nerve source
  • Special visceral efferent= motor division of CNVII
  • Sensory information/ pain is processed by the sensory nuclear complex of CNV
  • Most CN7 information is processed by CN5

Question 2

What are the functional groups of muscles of the face?

Answer 2

• Divisible into two groups
  
  • Sphincter muscles which are circular muscles that contact to open (open eyelids and oral cavity
  • Muscles of facial expression proper: alter facial expression

Question 3

Where do the muscles in the face attach?

Answer 3

• Have deep attachments-some attach to bone only and some attach to other muscles e.g. orbital muscles of the face/sphincter muscles
  
  • Have superficial attachments-attachments to the SAMS, they all attach directly to the skin
  • Some have bone attachments or attachments to other muscles
  • E.g. some muscles attach to orbicularis sphincter muscles (damage to one would cause problem in both)
  • Neurological conditions can affect motor tone of muscles of facial expression can also lead to expressionless faces-e.g. parkinsonian face

Question 4

Give me an overview of CNVII

Answer 4

• Has is a mixed nerve with 3 branches that carry signals sub-serving the following functional modalities: branchiomotor (facial nerve), general sensory and autonomic
  
  • General sensation is very limited
  • May also have special sensory
  • Depending on where there is damage in the face it make take out 1/2 or all 3 modalities of CN7
  • Need to know the anatomy of CNVII
  • CN7 is not the facial verve
  • The motor Davison of CN7 is the facial nerve

Question 5

What are the Modalities for CNVII?

Answer 5

• Branchio-motor (Special Visceral Efferent)
  Only motor nerve
  ○ Also known as The Facial Nerve
  ○ muscles of facial expression, posterior belly of the digastric, stylohyoid and stapedius muscles
  
  • Special Sensory (Afferent)
    ○ Also known as Nervus Intermedius or ‘Intermediate Nerve’
    ○ Taste Sensation via Chorda Tympani (Anterior 2/3rds of the tongue)
    ○ Called Chandra Tympani because it looks like a string
    ○ provides special taste sensation to the anterior 2/3 of the tongue via the chorda tympani
  • General Sensory (Afferent)
    ○ Nervus Intermedius for negligible sensation of skin of the outer ear
    ○ Very small section/part of the nerve for general sensation for a small amount of external, auditory canal and a bit of the ear
    ○ a small area around the concha of the external ear.
  • Autonomic Efferent
    ○ Also known as the Greater Petrosal Nerve
    ○ Pre ganglionic parasympathetic fibres
    ○ Has relation to petrosal bone
  • Parasympathetic
    ○ supplies many of the glands of the head and neck, including:
    § Submandibular and sublingual salivary glands.
    § Nasal, palatine and pharyngeal mucous glands.
    § Lacrimal glands.

Question 6

What are the branches of CNVII?

Answer 6

• It is effectively a mixture of 3 separate nerves, namely: Facial Nerve, Nervus Intermedius and Greater Petrosal Nerve
  
  • Facial coli clips if the loop of axons if the facial nucleus in the brain stem
  • Pterygopalatine ganglion is at the level where the facial and cranial skeletons meet
  • It is the nerve that is known as the facial nerve and is one of the most important cranial nerves in the body
  • The Facial Nerve is a branchiomotor nerve
  • It originates from the Facial Motor Nucleus in the Pons
  • It has 5 terminal branches
    ○ Temporal (To)
    ○ Zygomatic (Zanzibar)
    ○ Buccal (By)
    ○ Mandibular (Motor)
    ○ Cervical (Car)

Question 7

What are the nervus intermedius branch of CNVII?

Answer 7

• It is the sensory branch of Cranial Nerve VII
  
  • Nervus Intermedius is only formed by axons that emerge from the geniculate ganglion
  • Nervus Intermedius carries axons of neurones with:
    ○ Cell bodies in the geniculate ganglion
    § These are sensory neurones of CNVII
  • Axons of nervus intermedius exit the cranial cavity via the internal auditory meatus to join those of the motor root of CNVII
    ○ This is the Chorda Tympani nerve
    ○ The geniculate ganglion sits in the temporal bone between the cochlear and tympanic cavity

Question 8

What is the greater petrosal branches of CNVII?

Answer 8

• When nerves pass though the geniculate ganglion then will be called the greater personal branch
  
  • This is the Pre-ganglionic Parasympathetic Fibres of the autonomic branch of Cranial Nerve VII (CNVII)
  • axons of the superior salivatory nucleus of the brainstem make up pre-ganglionic parasympathetic fibres that pass through the geniculate ganglion without synapsing in it
  • When these pre-ganglionic fibres exit the geniculate ganglion, they are known as the greater petrosal nerve
  • Axons of the greater petrosal nerve terminate in the
    ○ Pterygopalatine Ganglion
    ○ Submandibular Ganglion

Question 9

What is the motor division of the CNVII?

Answer 9

• motor division’ of CNVII is Also known as the Facial Nerve
  
  • The facial nerve supplies efferent or motor innervation to all muscles of facial expression
  • Embryology of CNVII & Muscles of Facial Expression

Question 10

What is the basic terminology of the facial muscles?

Answer 10

Levator. . .” – i.e. Raises
* “Depressor. . .” – i.e. Lowers
* “Major” – i.e. the larger
* “Minor” – i.e. the smaller
* “Superioris” – superior
* “Inferiorioris” – inferior
* “Orbicularis” - encircles

Question 11

What are sphincter muscles?

Answer 11

• Classified as orbital muscles-therefore known as orbicularis
  
  • Circular muscles which Surround the mouth and eyes
  • When they contract the open the eyes and oral cavity (orifices)
  • Muscles can be attached to the sphincter muscles this means that if the sphincteric muscle is damaged/paralyzed then the attached muscle will also be damaged/paralyzed
    ○ This will also occur the other way around
  • Orbicularis oculi (eye)
    ○ Has 2 parts: orbital portion and palpebral portion
    ○ Closes the eyelid when contracted/changes the size of the fissure
  • Orbicularis oris (oral)
    ○ When contracted closes mouth and also can purse lips
    ○ Sie of attachment of other facial muscles e.g. risorius
    ○ Coeses the mouth/changes the size of the fissure

Question 12

What is the risorius?

Answer 12

Used to smile widely