UNIT 5: Muscles of Facial Expression Flashcards
most muscles of facial expression act on the
mouth
muscles of facial expression act _____ to create facial expressions
together
muscles of facial expression are unique bc
no discrete fascial sheath encasing the muscle
insert directly into the skin (w/o a tendon)
1 muscle of the scalp w two bellies
epicranius
frontalis and occipitalis bellies
frontalis belly of epicranius: O, I, A, Inn
O = epicranial aponeurosis
I = skin of eyebrows and root of nose
A= raises eyebrows w aponeurosis fixed, wrinkles forehead
I = CN VII, temporal branch
Occipitalis belly of epicranius: O, I, A, Inn
O = occipital and temporal bones
I = epicranial aponeurosis
A = fixes apponeurosis, pulls scalp posteriorly
Inn = CN VII, posterior auricular branch
two muscles of the eyes
orbicularis oclui and corrugator supercilli
orbicularis oculi: O, I, A, Inn
O = frontal and maxillary bones
I = lateral palpebral raphe
A= closes eye, tight closure can also draw eyebrows downward
Inn = CN VII, temporal and zygomatic branches
Corrugator supercilli: O, I, A, Inn
O = arch of frontal bone above nasal bones
I = skin of eyebrow
A = draws eyebrows together and wrinkles forehead vertically
Inn = CN VII, Temporal branch
4 muscles of the nose
procerus
depressor septi nasi
nasalis, compressor naris
nasalis, dilator naris
procerus: O, I, A, Inn
O = nasal bone and lateral nasal cartilage
I = skin over the glabella (bw eye brows)
A = wrinkles nose
Inn = CN VII, temporal and zygomatic branches
depressor septi nasi: O, I, A, Inn
O = maxillary incisive fossa
I = nasal septum and alar cartilage
A = contricts nostrils
Inn = CN, VII, zygomatic and buccal branches
nasalis, compressor naris: O, I, A, Inn
O = maxilla
I = bridge of nose
A= compresses back of the nose
Inn = CN VII, Zygomatic and buccal branches
nasalis, dilator naris: O, I, A, Inn
O = nasal notch of maxilla
I = alar cartilage
A = dilates nostrils
Inn = CN VII, zygomatic and buccal branches
what is the orbicularis oris - how is it intrinsic and extrinsic?
muscle of the mouth
deep unpaired oval ring of muscle fibres (intrinsic)
superficial fibres from other muscles that insert into lips (extrinsic)
orbicularis oris: O, I, A, Inn
O = facial midline (maxilla and mandible)
I = inserts into muscles and ski at angles of the mouth (modiolus)
A= closes and protrudes lips; compresses lips for bilabial sounds
Inn = buccal and mandibular branches of VII
what are the three categories of extrinsic muscles that converge on the lip
transverse
angular
vertical
transverse extrinsic muscles
course horizontally from origin to insert into the corner of the mouth and orbicularis oris
angular extrinsic muscles
approach corners of mouth obliquely from above and below
vertical extrinsic muscles
enter lip directly from above and below
modiolus
central axis located at the corners of the mouth
region where fibres from extrinsic lip muscles converge to intermingle w intrinsic orbicularis fibres
damage to modiolus has….
major effect bc it interferes w cross over of muscle fibres
levator labii superioris alaeque nasi: O, I, A, Inn
O = frontal process of maxilla
I = alar cartilage and upper lip
A= elevates upper lip; flares nostril
Inn = zygomatic and buccal branches of VII
levator labii superioris: O, I, A, Inn
O = infraoribital margin
I = upper lip lateral to alaeque nasi
A = elevates and everts upper lip
Inn = zygomatic and buccal branches of VII
Levator anguli oris: O, I ,A, Inn
O = canine fossa below infraorbital margin
I = fibres converge to modiolus
A= pulls corners of lips superiorly; deepens nasolabial fold (smiling/laughing)
Inn = zygomatic and buccal branches of VII
zygomaticus minor (medial): O, I, A, Inn
O= zygomatico-maxillary suture
I = converge to modiolus (run inferiorly and medially)
A = elevates upper lip and deepens nasolabial fold
Inn = zygomatic and buccal branches of VII
zygomaticus major (lateral): O, I, A, Inn
O = body of zygomatic bone
I = converge to modiolus
A = pulls lateral corners of the mouth superiorly and laterally (smiling/laughing)
Inn = zygomatic and buccal branches of VII
Risorius: O, I, A, Inn
O = fascia of masseter
I = modiolus
A = retracts corner of mouth, pulls lips toward teeth
Inn = zygomatic and buccal branches of VII
deepest facial muscle
buccinator
buccinator: O, I, A, Inn
O = maxilla, alveolar margin; mandible, oblique line; pterygomandibular raphe (meets superior constrictor muscle)
I = modiolus
A = compresses lips and draws them toward teeth; compresses the cheeks; relaxed - cheeks puff up “bugler’s muscle”
Inn: buccal branch of VII
depressor anglui oris: O, I, A, Inn
O = oblique line of mandible
I = fibres pass thru modiolus to deeper layers
A = draws corners of mouth downward and laterally
Inn = mandibular and buccal branches of VII
depresor labii inferioris: O, I, A, Inn
O = arises deep to DAO along oblique line
I = lower lip
A = depresses lower lip as in pouting
Inn = mandibular and buccal branches of VII
mentalis: O, I, A, Inn
O = mental symphysis of mandible
I = passes thru DLI to insert in skin inferior to orbicularis oris
A = protrudes and everts lower lip and wrinkles chin
Inn = mandibular branch of VII
Platysma is …
a neck muscle, very thin, superficial, wide and flat
aka shaving muscle
platysma: O, I, A, Inn
O = fascia overlying petoralis major and deltoid
I = corner of mouth (modiolus), cheeks and muscles of mouth
A = lowers jaw, pulls lower lip down and back, tenses skin of neck
Inn = cervical branch of VII
what 4 fibre types does the facial nerve have?
special visceral efferent
general visceral efferent
special visceral afferent
general somatic afferent
SVE of CN VII innervate…
muscles of facial expression (and auricular muscles around the ear), plus stapedius, stylohyoid, and the posterior belly of digastric
all of these muscles are derived from the 2nd branchial arch
GVE of CN VII innervate…
the lacrimal gland, submandibular and sublingual salivary glands, mucous membranes of nose and hard and soft palate
SVA of CN VII are for
taste sensation from the anterior 2/3 of the tongue
GSA of CN VII are for
sensations from skin of concha of the external ear, skin behind ear, external auditory meastus, external tympanic membrane
in CN VII, ____ fibres which are majority of the nerve are separated from the rest of the nerve…. remaining fibres, ____, ____, ____ are bound in a fascial sheath and called _____ ______
SVE
GVE, SVA, GSA
Nervus intermedius
describe the course of the facial nerve (generally)
all CN VII fibres emerge at lower border of pons
enter the petrous temporal bone via internal acoustic meatus
fibres travel thru petrous bone, there is a swelling of the nervus intermedius: geniculate ganglion
other fibres continue in facial canal
SVE and GSA fibres leave skull thru stylomastoid foramen
in the course of the facial nerve there is a swelling in the petrous bone that fibers pass thru, it is called the
geniculate ganglion
in the course of the facial nerve, the geniculate ganglion is where …
the greater petrosal nerve branches off - which are GVE fibres to glands in the upper head
in the course of the facial nerve, some fibres continue in facial canal, one branch of SVE fibres leaves to…
innervate the stapedius m in the middle ear
in the course of the facial nerve, some fibres continue in facial canal: _____ _____ (SVA fibres) branches from nervus intermedius and passes through the middle ear cavity and exits thru the ____ ______, which travels to….
chorda tympani
petrotympanic fissure
travels to the tongue, oral cavity to support taste and salivary secretion
SVE of CN VII have 3 major functions
facial expressions
acoustic reflex (stapedius)
elevating an retracting hyoid bone (stylohyoid and posterior belly of digastric)
lower motor neuron of CN VII SVE has cell bodies in _______ in the _____
facila motor nucleus
pons
the facial motor nucleus for CN VII SVE, receives _____ info from the cortex for facial muscles above the eye, and receives _____ info only for muscles below the eye
bilateral (contralateral and ipsilateral)
contralateral
describe the intracranial pathway for CN VII SVE
the fibres bend around abducens nucleus
axons leave the caudal border of the pons –> enter internal acoustic meatus w nerve intermedius and CN VII
passes by geniculate ganglion –> travels w/i facial canal of petrous bone
branches to stapedius muscle –> remaining fibres emerge thru stylomastoid foramen
describe the extra-cranial pathway of CN VII SVE
after passing thru stylomastoid foramen –> posterior auricular nerve (to occuputalis m and auricular m) and muscular branch (nerve to posterior belly of digastric, nerve to stylohyoid m)
remaining SVE fibres travel thru the parotid salivary gland (from surface to deep) = parotid plexus …. divides into 5 branches that innervate muscles of facial expression
what are the 5 branches of the parotid plexus of CN VII SVE?
temporal nerve
zygomatic nerve
buccal nerve
mandibular nerve
cervical nerve
tumour in the _____, _____, or ______ will usually result in CN VI and CN VII abnormalities such as
4th ventricl, pons, cerebellopontine angle
stabismus (inward eye turn), loss of facial expression bw the eye on the same side
CN VII and CN VIII abnormalities suggest pathology in _____, bc…
internal auditory meatus
they travel together in the temporal bone
muscles of the upper face receive _____ innervation, muscles of the lower face only receive ______ innervation
bilateral, contralateral
upper motor neuron lesion affects muscles of facial expression ____ to eye muscles contralateral to lesion
inferior
lower motor neuron lesion affects _____ muscles of facial expression ipsilateral to the lesion
all
UMN lesion ex. is…. what would you see?
stroke in one hemisphere
drooping of lower face but able to raise eyebrows
LMN lesion ex….. what would you see?
bells palsy
drooping of whole face
CN VII GVE provides… it does not innervate the ______ gland…. its major functions are…..
parasympathetic innervation of glands (secretomotor) in the head
parotid gland
major functions:
crying/tearing
runny nose
salivary flow (at rest)
describe the intracranial course of CN VII GVE
cell bodies in superior salivatory nucleus in the pons
receives input from hypothalamus + CNs
fibres exit pons to nervus intermedius portion of CN VII
at geniculate ganglion, divides into 2 fibres: greater petrosal nerve + chorda tympani
describe the extra-cranial course of CN VII GVE
greater petrosal nerve - exits skull via foramen lacerum - supplies lacrimal/nasal glands, hard/soft palate
chorda tympani - travels thru middle ear space, exits skull via petrotympanic fissure; joins lingual notch to get to floor of mouth - supplies submandibular and sublingual salivary glands
CN VII SVA provides…
taste sensation from anterior 2/3 of tongue and palate
extra-cranial course of CN VII SVA
chorda tympani - travels w lingual nerve of V3… also contains visceral motor fibres for submandibular and sublingual salivary glands
intra-cranial course of CN VII SVA
enter cranium thru the petrotympanic fissure –> cell bodies for taste lie in geniculate ganglion
first order sensory neurons synapse w/i rostral part of nucleus tractus solitarius, called the gustatory nucleus
fibres project to thalamus bilaterally, then to inferior part of postcentral gyrus bilaterally, the gustatory cortex (in insula)
CN VII GSA provide…
sensations from skin of the concha of outer ear, skin behind the ear, external auditory meatus, external tympanic membrane
extra-cranial course CN VII GSA
primary neuron enters cranium thru stylomastoid foramen, joins nervus intermedius
intra-cranial course CN VII of GSA
cell bodies are contained in geniculate ganglion in temporal bone
primary neurons synapse on cell bodies of secondary neuron in nucleus of the spinal tract of CN V –> project to contralateral thalamus –> sensory cortex (post central gyrus)
Bell’s Palsy
form of facial paralysis resulting from damage to/inflamation of CN VII (peripheral nerve)
Bell’s palsy is more common …
pregnant females, and persons w diabetes, upper respiratory infection
what are the signs of bell’s palsy
hemi facial paralysis - corner of the mouth sags, drooling, lower eyelid droops (SVE)
dependent on location of nerve damage - eye constantly drips tears (GVE), hypersensitivity to sound in the affected ear (SVE), taste impairment (SVA)
what is the likely cause of bells palsy
herpes simplex virus (HSV), trauma
bells palsy usually clears up ______ and often improves within _____ weeks, recovery almost always ________
untreated
2-6
complete
how do you clinically test CN VII facial musculature
symmetry at rest
symmetry w motion, alternating motion (smiling, lip rounding, pouting, blinking, raising eyebrows); UMN vs LMN
range of motion and strength (lips, eyes)
