Mastication and occlusion: anatomical factors Flashcards
5 functions of mastication
- enables food bolus to be swallowed easily
- enhances digestibility of food (maybe. increase SA for enzymes & reflex stimulation of digestive juices)
- mixes food with saliva and salivary amylase
- prevents irritation of GI tract by large food masses
- ensures healthy growth and development of oral tissues
muscles of mastication table
6 components of craniomandibular articulation for mastication
- bones (1 mandible, 2 temporals)
- synovial joint (fibrocartilaginous) + capsules + disc (ginglymo-arthroidal = sliding hinge joint)
- muscles of mastication
- ligaments
- innervation
- teeth
where does TMJ sit in skull
glenoid fossa
5 types of movement made by the jaw muscles
elevation depression retraction protrusion lateral excursion
the muscles for which movement are v weak?
depressors
which muscles run through infratemporal fossa
medial and lateral pterygoid muscles
what limits range of movement of muscles 3
COL
- contour of bony surfaces
- occlusal surfaces of teeth
- ligaments
name/explain 4 ligaments (label on diagram)
- temporomandibular (thickening of lateral side of capsule)
- pterygomandibular(raphe. where buccinator muscle meets mm going to pharynx)
- sphenomandibular (sphenoid bone - lingula
- stylomandibular (thickening of investing layer of deep cervical fascia)
where/ how is tmj innervated
disc itself and fibrous tissue lack blood/ nerve supply
–> posterior capsule and periphery innervated by auriculo-temporal nerve and branch to masseter
5 elements of inflammation
rubor (red) calor (heat) dolor (pain) tumor (swelling) loss of function
explain why tmj problems often seem like ear problems
auriculo-temporal nerve supplies skin of temple, EAM, tympanic membrane
4 parts of ideal occlusion
- teeth aligned so masticatory loads are within physiological range and act through long axes of as many teeth as possible
- lateral jaw movements occur without undue mechanical interference
- in rest position the freeway space is comfortable functional for the individual concerned
- tooth alignment is aesthetically pleasing to pt
what is the relationship of the cusps in ideal occlusion
functional cusps overlap:
Palatal upper cusps in to lower fossae
Buccal lower cusps in to upper fossae
explain BULL rule
when adjusting dentures, only adjust non-functional cusps:
buccal cusp of uppers
lingual cusp of lowers
explain curve of spee
from SIDE:
curve that allows there to still be occlusion during protrusion of mandible
explain curve of wilson/ sphere of monson
curve laterally- so teeth stay in occlusion during lateral excursion
what is the neutral zone
spaces around teeth which teeth can be forced in to by excessive force by muscles eg tongue/ cheeks
what are occlusal stops
points on teeth which stop excess movement of teeth
3 locations of occlusal stops
centric
protrusive
lateral excursion
what is used to measure freeway space
willis gauge
*draw and label TMJ* attachments of TMJ capsule: a. superior b. inferior c. anterior d. posterior
a. superior: temporal bone
b. inferior: condyle
c. anterior: articular eminence (temporal bone)
d. posterior: squamotympanic fissure
where do all parts of the capsule attach to?
glenoid fossa (temporal bone)
which parts of tmj capsule attach to the disc
medially, laterally and posteriorly (NOT anteriorly- superior part of lat pterygoid muscle attaches here)
describe attachment between capsule and surrounding areas
villi filled with synovial fluid
