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56 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What is the purpose of muscle?
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The purpose of muscle is to provide force
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What are the three types of force muscle can provide?
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Pulling force
Tension force Contraction force |
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What are the structural components of muscle?
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Motor unit
Motor endplate |
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What is a motor unit?
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The number of fibers innervated by a single neuron
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If a neuron innervates many fibers, the movement is gross (masseter)
If a neuron innverates very few fibers, the movement is intricate (Inf Lat Pterygoid) |
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Type 1 vs Type 2 muscle fibers
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Type 1 are slow muscle fibers while Type 2 are fast muscle fibers
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Properties of Type 1
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high concentration of myoglobin
deep red color slow, sustained contractions rely on aerobic metabolism resistant to fatigue 80% of lat pterygoid is Type 1 |
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Properties of Type 2
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white color
quick contractions rely on anaerobic metabolism fatigue rapidly Masseter and Temporalis |
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Muscles Stuff
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Go to notebook
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The TMJ has bilateral articulation, what does that mean?
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It means that each joint cannot function separately
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What makes the articular surface of the TMJ unique for a synovial joint?
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It is made of dense fibrous connective tissue which makes it less susceptible to DJD and better for repair and regeneration
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The TMJ is a compound joint. What are the compartments?
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Inferior and superior compartments
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What are the properties of the Inferior compartment?
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-consists of the tissues that surround the inferior synovial cavity
-can only do rotational movement (ginglymoid) -Condye-disc complex |
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What are the properties of the Superior compartment?
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-consist of tissues that surround the superior synovial cavity
-disk-eminence complex -free sliding movement (arythmoidal) |
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What is the function of the disk?
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-Acts as non-ossified bone
-divides the two compartments -isolates synovial fluid -determines joint movement |
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What maintains the joint's stability?
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Since there are no attachments and the joint is in constant contact with its articulating surface, it is maintained by muscle activity (resting tonus)
-the superior retrodiscal lamina and the superior lateral pterygoid also play siginificant roles in stability |
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What is IAP?
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-pressure between the surfaces caused by muscle activity
-less space equals more activity equals more pressure |
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What allows for disc movement in a stable joint?
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Superior retrodiscal lamina
Inferior retrodiscal lamina Superior lateral pterygoid Anterior capsular ligament |
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Properites of the Superior Retrodiscal Lamina
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-made of elastic fibers
-ONLY STRUCTURE THAT CAN RETRACT THE DISC POSTERIORLY ON CONDYLE |
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Superior Lateral Pterygoid
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-draws disc forward
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Anterior capsular and Inferior Retrodiscal
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only passively restrict extreme border movements
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What happens when in resting closed position?
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-condye in contact with intermediate and posterior zones of disc
-tonus of SLP exceeds retraction force of SRL |
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What happens when condyle moves forward?
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force of SRL exceeds SLP tonus which causes the disc to rotate posteriorly
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What happens during power stroke?
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-IAP is decreased on biting side due to food being used as a fulcrum
-IAP is increased in opposite side -SLP is active and rotates disc forward to maintain contact (STABILITY) |
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What happens as food is chewed?
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-disc moves posteriorly on condyle
-SLP returns to tonus |
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Actions of Ligaments
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-Ligaments DO NOT stretch
-they restrict some movements while allowing others -elongated ligaments are not good and compromise function |
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What does the term Arcon mean for an articulator?
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It means the condylar guidance is in the upper member and condyle is on the lower member
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What is condylar guidance?
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rotates on the horizontal axis to mimic anatomy from +60 to -20 degrees
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What is bennet calibration?
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medial-lateral adjustment that goes from 0-20 degrees
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What does the centric lock do?
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It allows for no movements except hing movements
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What is an orbitale indicator?
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provides vertical orientation for maxillary arch
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What three points are used to measure spatial position with a facebow?
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bite plane, orbitale pointer, and the earpieces
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What adjustments can be made on our semi-adjustable articulator?
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condylar inclination, lateral translational movement, condylar distance, anterior guidance
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What does the incisal guidance represent?
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lingual surface of upper anterior teeth
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tilting one side of the table effects
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canine guidance
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What is "centric relation occlusion" or simply "centric occlusion"?
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If centric relation and maximal intercuspation occur at the same time, it can be referred to as centric occlusion.
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What is Habitual Maximum intercuspation or musculoskeletay stable position?
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This is when maximal intercuspation does not occur at centric relation. (90% of people)
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Properties of Class I occlusion
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-Most typical relationship (75%)
-MB cusp of mandibular 1st molar in the embrasure between max 1st molar and max 2nd premolar -Lower canines mesial to uppers |
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Properties of Class II occlusion
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-Disto or retrognathic occlusion (20%)
-MB cusp of mandibular 1st molar in CF of maxillary 1st molar -MB of lower is in CF and aligned with buccal groove |
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Properties of Class III occlusion
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-Mesio or prognathic occlusion (5%)
-Buccal cusp of maxillary 2nd premolar in buccal groove of 1st mandibular molar -incisors edge to edge or even behind -posterior teeth crossbite -MB cusp of 1st molar in embrasure between first and second maxillary premolars -DB of 1st molar in embrasure between 1st molar and second maxillary premolar -ML of upper 1st molar occludes in mesial fossa of 2nd molar |
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Posterior crossbite
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When the buccal cusps of mandibular teeth are outside of the buccal cusps of maxillary teeth
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Open Bite
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opposing teeth lack contact usually caused by tongue habits
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What do the incisal edges of the lowers contact?
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lingual surfaces of the uppers
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Which cusps are centric cusps?
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Buccal of lower and lingual of upper
-Centric cusps contact fossa of opposing teeth |
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Which cusps are guiding cusps?
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Lingual of lower and buccal of upper
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Summary of Centric contacts
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ML of uppers and DB of lowers occlude in CF
DL of uppers and MB of lowers occlude in embrasures |
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Summary of Premolar centric contacts
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L of upper in distal fossa of lower
B of lower in embrasure of upper |
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Summary of Anterior central contacts
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incisal edge of lowers occlude on marginal ridges of uppers
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Eccentric movements
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any movement of mandible from ICP that results in tooth contact
Ideally, this only refers to anterior teeth, but posterior teeth could contact resulting in occlusal interference. |
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Retrusive movements
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posterior movement from ICP
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Protrusive movements
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forward movement from ICP
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Laterotrusive or Mediotrusive movements
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left or right movements from ICP
working-condyle rotates non-working: down, forward, medial Laterotrusive is the side it moves to (working side) Mediotrusive is the opposite (non-working side) |
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Anterior guidance
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present in protrusive movement
helps in incising during eating and articulation of sound |
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Horizontal overlap is known as
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overjet
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Vertical overlap is known as
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overbite
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Balanced occlusion
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indicated for complete dentures and means simultaneous posterior and anterior contacts during lateral and protrusive movements
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Group function
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canine rise does not take all other teeth out of occlusion
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