UNIT 6: Mandibular sys and Trigeminal Nerve (CN V) Flashcards
The ramus of the mandible is _____ in shape; projects _____ from the _____ aspect of the body
quadrangular
upward
posterior
the angle of the mandible is where the ____ and ____ meet
body and ramus
the body of the mandible: ____ surface is modified into alveolar process/margin
upper
the mandibular notch of the mandible is a ____ separating _____ and ______
depression
coronoid
condyle
the condyle of the mandible is the ___ of the mandible and articulates w the _____
head
cranium
the mandibular foramen of the mandible is in the _____ of the medial surface of the ramus, through which the _____ nerve enters
centre
trigeminal
the coronoid process of the mandible is where the ____ muscle attaches
temporalis
dental alveoli are
small sacs in which the teeth sit and are on the upper surface of the alveolar margin
the alveolar margin …
bears lower teeth
mental symphysis develops because
right and left halves fuse during dev and ossifies during 1st year of life
mental foramen is where
trigeminal nerve exits
mental protuberance is a
midline elevation
mental spines are the site of
muscles attachment
teeth are ____ components of the _____ mechanism
vital
speech
teeth provide ______ _____ for speech sounds
articulatory surface
the integrity of dentition is important for speech bc
minor deficits may arise as a result of dental abnormalities
teeth provide the mechanism for
mastication
______ of teeth is key to effective mastication
orientation
jaws and teeth are important contributors to an indv’s characteristic _____ _____
facial structure
edentulous elderly experience the
resorption of alveolar bone
3 parts of the tooth
root
crown
neck
the root is hidden beneath
the gingival line
crown is the
visible 1/3 above gingival line
neck is the juncture bw
crown and root
enamel covers the
crown and overlays dentin
pulp contains
the nerve supplying the tooth
cementum is a
thin layer of bone holding tooth in alveolus along w the periodontal ligament
periodontal ligament holds the
teeth together
5 types of teeth
central incisors
lateral incisors
cuspids
bicuspids
molars
central incisors are ____ shaped and contain ___ root
chisel shaped
one root
mandibular central incisors are _____ than maxillary central incisors
smaller
lower central incisors are
overlapped by uppers
lateral incisors are ___ than centrals and have ____ roots than centrals
smaller
shorter
cuspids are ____ to lateral incisors
lateral
cuspids are
large, have a single point, good solid root
upper cuspids are ____ than lower cuspids
larger
bicuspids aka premolars are the
first and second bicuspids
bicuspids are only found in the
adult arch
bicuspids have
2 cusps
may have one or two roots
the largest of all the teeth are the
molars
there are ____ molars in the permanent arch
12
molars have
large, rectangular crowns
the first molar is the _____, the third molar (wisdom tooth) is the ____
largest
smallest
upper molars are ____ than lowers
smaller
upper and lower dental arch contain the ______ number of teeth
same
each dental arch can be divided in …
half by a midline
each tooth has ___ surfaces that can be described, which are….
5
occlusal
medial (mesial)
distal
buccal/labial
lingual
occlusal surface is where
the teeth touch on their upper surface - touch the teeth above them
lingual surface is
the surface closest to your tongue
buccal surface is the
surface closest to lip/cheek
mesial surface is
the surface closest to midline
distal surface is the
surface farthest from midline
there are ___ deciduous teeth, ___ on each arch
20
10
for deciduous teeth on each 1/2 arch there is ….
1 central incisors
1 lateral incisor
1 cuspid
2 molars
there are ____ permanent teeth, with ___ on each arch
32
16
each 1/2 arch of permanent teeth contains…
1 central incisor
1 lateral incisor
1 cuspid
2 premolars/bicuspids
3 molars
relationship of arches to each other is important for
mastication
3 types of dental occulsions
class I neutral occlusion
class II malocclusion
class III malocclusion
class I neutral occlusion is where the
1st mandibular molar is 1/2 tooth advanced of 1st maxillary molar
class II malocclusion is where the
1st mandibular molars are retracted from 1st maxillary molars - aka overbite
sometimes accompanied by micrognathia which is a small mandible
class III malocclusion is where the
1st mandibular molars are advanced greater than 1 tooth beyond 1st maxillary molars (underbite)
torsiversion is
rotation of tooth along axis
labioversion/buccoversion is
tooth tilts towards lips/cheek
linguaversion is
tooth tilts toward tongue
distoversion is
tooth tilts away from midline
mesioversion is
tooth tilts toward midline - toward mesial surface
infraversion is
tooth has not sufficient erupted to meet its partner on the other arch - aka too low
supraversion is
the tooth has erupted too far
the jaw moves in 3 dimensions
superior/inferior
anterior/posterior
laterally
muscles of the jaw need to make 5 movements
depress the jaw
elevate the jaw
retract the ja
protrude the jaw
swing the jaw laterally
muscles that depress the jaw do what
open the mouth
muscles that elevate the jaw do what
close the mouth
anterior belly of digastric: O, I, A, Inn
O = Internal surface of mandible
I= Intermediate tendon at hyoid
A= Depresses mandible (or elevates hyoid)
Inn = mandibular branch of CN V
geniohyoid: O, I, A, Inn
O= Inferior mental spine on mandible
I = Anterior surface of the body of they hyoid
A = Depresses mandible (pulls hyoid anteriorly)
Inn = 1st cervical spine nerve of CN XII
mylohyoid: O, I, A, Inn
O = Mylohyoid line on mandible
I = Hyoid and midline raphe
A = Depresses mandible (pulls hyoid anteriorly and sueperiorly)
Inn = mandibular branch of CN V
anterior b of digastric, geniohyoid, mylohyoid all do what
depress the mandible
temporalis is a
large fan shaped muscles with anterior and posterior fibres
temporalis: O, I, A, Inn
O = greater wing of sphenoid, frontal, parietal, temporal bones
I = medial surface of coronoid process of mandible via a tendon deep to zygomatic arch
A = anterior fibres elevate mandible, posterior fibres retract the jaw
Inn = mandibular branch of CN V
the only jaw retractor muscle is the
temporalis
masseter is a
thick, flat, powerful
most superficial muscle of mastication
masseter: O, I, A, Inn
O = zygomatic arch (inferior and deep surfaces)
I= external surface of angle and ramus of mandible, coronoid process of mandible
A= elevates mandible (major role in chewing)
Inn = mandibular branch of CN V
massester has a major role in
chewing
the lateral pterygoid is ___ to the masseter, and ____ to medial pterygoid m
deep
superior
lateral pterygoid: O, I, A, Inn
O= greater wing of sphenoid, lateral pterygoid plate of sphenoid
I= condyle of mandible, capsule of the TMJ
A= inferior compartment depresses the jaw, bilateral contraction protrudes the jaw, unilateral contraction moves jaw laterally (to opp side)
Inn= mandibular branch of CN V
medial pterygoid: O, I, A, Inn
O = medial surface of lateral pterygoid plate, pterygoid fossa, tubercle of the palatine bone
I = medial surface of angle of mandible and ramus
A = bilateral contraction elevates jaw, protrudes jaw w lateral pterygoid, unilateral contraction moves jaw laterally (toward opp side)
Inn = mandibular branch of CN V
medial pterygoid is ____ to lateral pterygoid, runs along _____ surface of mandible
deep
internal
describe the masticatory cycle aka how the jaw moves in a looping pattern…. what does it result in?
lower incisor swings away from the working side during jaw opening
then crosses midline and moves toward working side during jaw closing
looping pattern results in grinding motion across the surfaces of the premolar and molar teeth
what is the central pattern generator?
a network of neurons that sets the basic chewing rhythm
for the CPG, alternating activity in antagonistic muscles is generated by activity of …
isolated groups of neurons
the CPG is modulated by inputs from
peripheral sensory organs (proprioception, somatosensation, taste from muscles of mastication/oral cavity)
CPG may be triggered by
peripheral afferent inputs or inputs from higher brain centres (cortex) - ex. knowing that a food you had before required more chewing
CPG is located in _________ it is ________ and interconnected
reticular formation of the pons
bilateral - aka one on left and one on right and they communicate
temporomandibular joint - TMJ is _____ joint with ____ ligament support
synovial joint
weak
the TMJ is maintained mainly by
muscles of mastication acting on the joint and the mandible
integrity of the TMJ is important for
speech
major movements in the TMJ occur during
chewing and yawning
TMJ disorders occur in ____ % of the population and is associated with _____
5%
bruxism aka teeth grinding
TMJ is comprised of 3 things, held together by ….
condyle
mandibular fossa
articular tubercle/eminence
held together by a lax joint capsule
the lax joint capsule of the TMJ has a lateral thickening called the _______ ______, also receive support from 2 other ligaments
temporomandibular ligament
stylomandibular ligament
sphenomandibular ligament
TMJ has an _________ which divides the synovial cavity into superior and inferior compartments
articular disc
the superior and inferior compartments of TMJ allow for 2 types of jaw movement
lower compartment = permits the condyle to make hinge-like jaw opening/closing aka speech
upper compartment = permits the condyle to glide anteriorly and sit under the articular tubercle when the mouth is opened widely
in the TMJ, the _____ is braced against the articular tubercle preventing the mandible from crushing thru the thin mandibular fossa during _____
condyle
biting of hard food
in speech the mandible provides …. what if the tongue is weak?
a moving platform for the tongue
if the tongue is weak, the mandible may compensate w exaggerated movement in attempts to retain adequate constriction of the vocal tract
in mastication the mandible brings…
the jaw into occlusion thru repeated rotary lateral motion
in deglutition the mandible provides…
a stable platform for the tongue
two types of fibers in CN V
special visceral efferent
general somatic afferent
SVE of CN V ….
supply muscles of mastication, tensor tympani, tensor palatini, mylohyoid, anterior belly of digastric
innervates muscles arising from 1st branchial arch
GSA of CN V….
mainly sensory
sensations of the face, scalp, eye, mucous membranes of the nasal and oral cavities, tongue, teeth, part of the external aspect of tympanic membrane, meninges of anterior and middle cranial fossa
intracranial course of SVE of CN V
LMN - cells bodies in trigeminal motor nucleus in the pons
Axons leave pons, exit skull at foramen ovale in sphenoid bone
extracranial course of SVE of CN V
Pass thru foramen ovale w sensory fibres of V3 forming the mandibular nerve
Nerve branches supply muscles of mastication
the trigeminal motor nucleus receives input from 3 things
CN V sensory signals relating to conditions in the oral cavity and stretch receptors in muscles of mastication
CN VIII sensory input for control of tension of tympanic membrane
bilateral inputs from the cortex to mediate movements of jaw in speech and voluntary mastication
extracranial course of GSA of CN V - 3 major divisions
carry sensory info from various regions of the face and head
ophthalmic - V1
Maxillary - V2
Mandibular - V3
what is innervated by V1 of GSA CN V?
sensations from forehead, scalp bridge of nose, and medial upper eyelid
Sensations from upper eyelid, conjunctiva, and lacrimal gland
Sensations from medial lower eyelid, side of nose, nasal septum, and lateral wall of nasal cavity
what is innervated by V2 of CN V GSA
Sensations from side of forehead, cheek
Sensations from upper lip, medial cheek, side of nose
Sensations from upper teeth - mostly pain
Sensations from hard and soft palates, nasopharynx
What is innervated by V3 of GSA CN V?
Mandibular, V3 →
Sensations from mucous membranes of cheek, and upper gingiva
Sensations from anterior ⅔ of tongue (lingual nerve)
Sensations from side of head, scalp, external auditory meatus and tympanic membrane,TMJ
intracranial course of V1 of GSA CN V
Enters cranium thru the superior orbital fissure and has its cell bodies in the trigeminal ganglion sitting in the trigeminal impression of the petrous bone
intracranial course of V2 of GSA CN V
Enters cranium thru foramen rotundum and has cell bodies in the trigeminal ganglion
intracranial course of V3 of GSA CN V
Enters cranium thru foramen ovale and then has cell bodies in the trigeminal ganglion
after V1, V2, V3’s primary neurons enter the cranium, where are the cell bodies of the secondary neurons?
Cell bodies of secondary neurons are located in trigeminal nuclei
the trigeminal sensory nuclei contains 3 subnuclei
mesencephalic n
principal sensory n
nucleus of spinal tract
mesencephalic n is for…. and is located in….
nerves that carry stretch info (proprioception) from muscles of mastication, in midbrain
principal sensory n is for…. and is located in….
nerves that carry touch sensation, in the pons
nucleus of spinal tract is for… and is located in
nerves carrying pain and temp sensation, in medulla
what are the two ways the extra cranial course of the peripheral nerve can be damaged?
injury to the head
herpes zoster virus aka shingles
injury to the head can damage the extra cranial course of the peripheral nerve because…
bc the trigeminal nerve is pretty superficial, not rly covered by any muscles
ex. trauma to the chin can lead to sensory loss from lower lip ad chin; injection of anesthetic into the inferior alveolar nerve by the dentist
herpes zoster virus aka shingles can…
lie dormant in the trigeminal gnaglion
when active it travels along the peripheral nerve, leads to irritation at the outbreak, pain following resolution
what are the two ways the trigeminal nerve can be damaged w/i the middle cranial fossa
peripheral nerve can be damaged by compression as nerve passes thru MCF, or by a schwannoma of the nerve
acoustic neuroma (schwannoma of CN VIII) can compress trigeminal nerve (cerebellopontine angle syndrome, where is here the nerve travels thru)
for the CN V, damage in the medulla causes
primarily loss of pain and temp sensation on ipsilateral side of face
for CN V, damage to the pons causes
loss of discriminative touch ipsilaterally; may also be a LMN lesion (affecting ipsilateral muscles of mastication)
for CN V, damage above the brainstem leads to
all modalities contralateral to affected hemisphere are affected - no notable UMN damage bc m of mastication are bilaterally innervated, and drive mostly by sensory input w/i the pons
3 ways the sensory component CN V can be tested
discriminative touch (touch skin w sharp end of pointed object)
simple touch (w cotton swab -not at midline of face, corneal reflex)
pain/temp (warm or cool objects against skin)
how to test jaw closure for CN V
at rest, palpate massester and temporalis on both sides, ask to clench jaws together tightly
w jaw closed examiner tries to depress it
how to test jaw opening for CN V
client opens mouth, jaw will deviate toward weak side (side of LMN damage)
w jaw open examiner tries t close it
how to test lateral jaw motion for CN V
client moves jaw to one side, examiner tries to push it back to midline
have client move jaw back and forth
how to test jaw jerk (neurological exam) for CN V
tap middle of chin w reflex hammer while jaw is slightly open - no movement or slight closing constitutes normal reflex
the mandibular system contributes to
speech, mastication, swallowing, and one’s facial appearance
