Posselt's Envelope of Movement Flashcards
REFERENCE POSITIONS (3)
- CENTRIC RELATION
- MAXIMUM INTERCUSPAL POSITION
- POSTURAL POSITION
CENTRIC RELATION
the position of the mandible in which the condyles are in the most superior and anterior position in the articular fossa, resting against the posterior slopes of the articular eminences with the articular discs interposed
CENTRIC RELATION (CR) --- DETERMINED POSITION
CONDYLE
CR is (3)
repeatable
reproducible
recordable
when the mandible is in CR, the condyles can rotate around a horizontal axis up to an opening of — measured at the central incisors
20-25 mm
if the opening of the mandible continues beyond 20-25 mm, then — of the mandible occurs
translation
pure rotational movement is also referred to as — movement and the axis is referred to as —
hinge movement
terminal hinge axis
MAXIMAL INTERCUSPAL POSITION
OR MAXIMUM INTERCUSPATION
— determined position
tooth
MAXIMAL INTERCUSPAL POSITION
OR MAXIMUM INTERCUSPATION
does not provide any info about the
TMJ
in most people, MIP does not coincide with
CR
in MUP The condole-disc assembly is
anterior inferior and/or medial or lateral or a combo of the above compared to the position in CR
usually, the condyle disc assemblies are
anterior and inferior
when is MI used
clinically if the patient needs minimal restorations
position restorations are made in
MI
postural position
the habitual postural of the mandible when the patient is resting comfortably in the upright position and the condyles are in the neutral unstrained position in the glenoid fossa
in PP< there is an equilibrium between the
forces acting on the mandible
in the PP, the muscles are not totally
relaxed
there is a degree of electromyographic activity
PP is determined by the
muscles and the forces of gravity
PP does not give us information about the
condyles or the teeth
in PP, the condyles are usually
anterior and inferior compared to their CR position
PP can be – and is — for the patient
sustained
comfortable
in PP, the teeth are
apart and there is a wedge space between the teeth
the wedge shaped space is called the
interocclusal space
interocclusal space is usually –mm between the incisors, –mm between the premolar, and –mm between the molars
2-3
2
3/4-1
there is a -:- ratio from anterior to posterior
1:3
PP is clinically used to determine the
OVD in edentulous patients or in patients with severely worn dentition
the OVD is the distance measure between two points when the
occluding members are in contact
the vertical dimension at rest (in PRP) is usually — greater than the occlusal vertical dimension
2-3mm
type of movement (3)
rrotation
translation
combo
the mandibular movements are limited by the (3)
ligaments,
the articular surfaces of the TMJ,
and the morphology and alignment of the teeth
the outer range of movement is reproducible and called
border movements
when do functional movements occur
during functional activity of the mandible
functional movements are confused within the
border movements
functional movements begin and end in the
MI position
BORDER AND FUNCTIONAL MOVEMENTS
IN THE SAGITAL PLANE
Posselt’s Envelope of Movemet
movement components in sagittal plane (4)
posterior opening border
anterior opening border
superior contact border
functional movements
envelope of motion is –
3D
envelope of movement is a combo of borer movements in all three planes:
sagital
horizontal
frontal
the envelope differs from person to person but it has the same
characteristic shape
during opening of the mouth the condyles will move
forward and down the articular eminence
maximum opening is reached when
capsular ligaments prevent further movement
anterior opening border movement represents the
movement from max opening to max protrusion
the max protrusion is determined partly by the
sytlomandibular ligaments
the condyles are in the most anterior position
superior contact border movement:
the initial tooth contact occurs between the – inclines of the max teeth and the – inclines of the mand teeth
mesial
distal
superior contact border movement:
the mandible will then move
superioanteriorly (shift) until the max intercuspation occurs. there may also be a lateral component to the shift
the average distance between CR MIP in 90% of the population is
1.25 +/- 1 mm
superior contact border movement:
the mandible moves forward from MIP to edge to edge. this is determined by the
lingual surface of the max anterior teeth. the pathway inclines inferiorly
superior contact border movement:
from edge to edge the mandible can move
further horizontally for the width of the incisal edges
superior contact border movement:
continued forward movement of the mandible. with the anterior teeth in contact, results in
superior movement guided by the lingual surfaces of mandibular anterior teeth
superior contact border movement:
continued forward movement of the mandible is guided by the
posterior teeth until the mandible reaches max protrusion
the chewing stroke
starts at the MIP and drops downwards and forwards to the position of desired opening
the chewing stroke returns in a
straighter pathway slightly posterior
BORDER AND FUNCTIONAL MOVEMENTS IN
THE HORIZONTAL PLANE:
pattern
rhomboid shaped
BORDER AND FUNCTIONAL MOVEMENTS IN
THE HORIZONTAL PLANE:
four movement components
left lateral border
continued left lateral border with protrusion
right lateral border
continued right lateral border with protrusion and functional movements
contraction of the right inferior lateral pterygoid causes the right condyle to move
anteriorly and medially
the left inferior lateral pterygoid relaxes
left lateral border movement:
left condyle
rotating or working condyle
left lateral border movement:
right condyle
orbiting or non working
left lateral border with protrusion:
from the left lateral the left inferior lateral pterygoid starts to contract (right stays contracted) and causes the left condyle to move
anteriorly and to the right to max protrusion
right lateral border movement:
the exact opposite to the left lateral border movement occurs
right lateral border with protrusion:
the exact opposite to the left lateral border with protrusion occurs
functional movements occur near
MIP
functional movements:
the outer range of movement is greater in
early stages of mastication
functional movements:
the outer range of movement is smaller in the
late stages of mastication
BORDER AND FUNCTIONAL MOVEMENTS IN THE
FRONTAL PLANE:
pattern
shield shaped
BORDER AND FUNCTIONAL MOVEMENTS IN THE
FRONTAL PLANE:
four distinct movement components
left lateral superior border
left lateral opening border
right lateral superior border
right lateral opening border and functional movements
left lateral superior border:
from MIP the mandible moves to the
left
left lateral superior border:
the path is determined primarily bu the
morphology and inter arch relationship of the teeth
left lateral superior border:
the max lateral border position is determined by the
ligaments of the rotating condyle
left lateral opening border:
path
lateral convex path
left lateral opening border:
as maximum opening approaches, ligaments
tighten and produce a medial shift
RIGHT LATERAL SUPERIOR BORDER
similar to the left lateral superior border
RIGHT LATERAL
OPENING BORDER
similar to the left lateral opening border
FUNCTIONAL MOVEMENTS:
occur near
MIP
FUNCTIONAL MOVEMENTS:
occur within the
outer range of the border movements
ENVELOPE OF MOTION:
the superior surface of the envelope is determined by the
tooth contacts
ENVELOPE OF MOTION:
the other borders are primarily determined by the
TMJ anatomy and the ligaments
