Cranial nerves and foramina

Topics: Temporomandibular joint, Medial pterygoid muscle, Teeth Pages: 12 (1628 words) Published: October 11, 2013

Occlusion

Intraarch—prox contact betw teeth
tooth inclination: inclined to receive closing force along axes
occlusal plane curvature (Curves of Spee & Wilson)
Spee— anteroposterior
mand canine→along buccal cusp tips
affects posterior cusp height
**protects against protrusive interferences

Wilson—translateral curve
lingual inclination of mand posteriors
**protects against lateral interferences

Interarch—arch length: max and mand arches the same
arch width: max slightly > mand

Centric cusps—i.e. functional cusps: mand=buccal
max=lingual
fnxn: vertical dimension of occlusion (VDO)
support of facial height
aligned with opposing for mastication

Non-centric cusps—i.e. non-functional cusps: mand=lingual
max=buccal
fnxn: ↓tissue impingement
maintain bolus of food on occlusal table
mand stability in MI (max intercuspation)

some rules: (remember we’re speaking about the functional cusps only!)

mand mesial cusp occludes w/: max marg ridge
mand distal cusp occludes w/: max fossa
max mesial cusp occludes w/: mand central fossa
max distal cusp occludes w/: mand distal marg ridge

mand tooth# + max tooth # = 33 (to deduce which teeth are in occlusion)

mandibular movement pattern determined by: Anterior guidance & TMJ guidance

Groove rules:
1. Working grooves are at right angles to the central groove
2. Non-working grooves are usually oblique to the central groove
3. During protrusive mvmt, centric cusp usually moves parallel to central groove

Three axis of reference for mandibular mvmt:

1. Horizonal axis: occurs in sagittal plane
open/close
first 20-25 mm = pure rotation

2. Vertical axis: occurs in horizontal plane
lateral movements
doesn’t occur naturally

3. Sagittal axis: occurs in frontal plane
lateral movements
doesn’t occur naturally

2 types of condylar mvmt:

Rotational mvmt—first stage of opening
first 20-25 mm
occurs w/in inferior cavity of TMJ
fully or semi-adjustable articulator using facebow + CR interocclusal record

Tranlational mvmt—2nd stage of opening
moves down articular eminence while opening to max limit
occurs w/in superior cavity of TMJ
fully or semi adjustable articulator using a protrusive interocclusal record

*usually both mvmts occur simultaneously

TMJ—Fixed factor
influences movement of the post mandible
pathology & trauma can alter

Anterior guidance—Variable factor
influences mvmt of anterior mandible
altered by: pathology, trauma, and dental procedures
determined by exact positioning of anterior teeth

1. Vertical Overlap (VO): sagittal plane
↑ vertical overlap ↑longer post cusps may be
↓ vertical overlap ↓shorter post cusps must be
2. Horizontal Overlap (FHO): sagittal plane
.005-.5 mm = post cusps may be long
> .5 mm = post cusps must be short

Condylar guidance—eminentia angle: Fixed Factor
glenoid fossa anatomy: medial, superior, posterior walls
medial wall determines inward mvmt of orbiting condyle during lateral excursion
orbiting condyle: on non-working side
rotating condyle: on working side

↑divergence of two planes = post cusps may be longer
↑parallel the two planes = post cusps must be shorter

mandibular lateral translation (aka Bennett Movement)
if no well positioned canines, working & non working groove may be positioned as simple arcs with an apex in central groove, if no immediate side shift
if no well positioned canines, working & non working groove must be positioned more distally in the max arch and the central groove must be wider if no immediate side shift

Primary...
Continue Reading

Please join StudyMode to read the full document

You May Also Find These Documents Helpful

  • Essay about Cranial Nerve Palsy and the Sixth Cranial Nerve Palsy
  • The Brain and Cranial Nerves Essay
  • Cranial Nerve Labanswers Research Paper
  • cranial nerves Essay
  • Cranial Nerves Essay
  • Cranial nerves Essay
  • Cranial Nerves Essay
  • Essay about Brain and Cranial Nerves

Become a StudyMode Member

Sign Up - It's Free