Post on 04-Jun-2018
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FUNCTION OF
TONGUE INSTOMATOGNATHIC
SYSTEM
:P
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The function of tongue in mastication
and deglutition
Preparatory stage- the tongue is at resting
position, dorsum upwards, trough shaped to
collect food on its dorsum
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Throwing stage- after food is collected, the
anterior half of tongue twists to one side
(dorsum to lingual), throwing ingesta onto
lower teeth
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Guarding stage- tongue retains twisted position
and dorsum presses on medial side of grinding
teeth to prevent food from slipping mediallyinto buccal cavity, for food grinding, with
assistance of buccal muscles
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Sorting-out stage- chewing is complete and
buccinators muscles drives cheek medially that it
pushes food into buccal cavity and tongue. Thetongue is preparing to resume resting position and
trough shape. Uncrushed food in placed on middle
trough of tongue to be deposited on teeth, while
crushed food is more lateral on the tongue. The
movement is repeated until all food is crushed.
Bolus formation stage- overlaps with previous
stage. The tongue alreternates side to sideschurning movements to mix crushed food with
saliva, mucus coat it, and ready it for swallowing
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First dilution stage- the tip of tongue is pressed
against front teeth and anterior hard palate, to
close off mouth and pharynx. For fluids a deepgutter shape is formed.
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Slide preparation stage- The hyoid bone ispulled upwards and anteriorly, the posteriortongue is depressed towards hyoid bone. Thetongue now slopes obliquely downwards andbackwards- tip against teeth and hard palate,root against hyoid bone. Side to side it is
concave; anterioposteriorly, there is a smoothslope from mouth to oropharynx
Pressure stage- bolus forces by pressurebetween tongue and hard palate to move
backwards towards isthmus and enters thepharynx.
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Function of tongue in speech
The tongue is an articulator and can be moved
in many different places and shapes. There is
the tip, blade, front, back and root of tongue.
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Tongue height can be changed by moving the
tongue up and down, or by movement of the
lower jaw to produce: A vertical distance between upper surface of
tongue and palate
And the part of tongue between the front andback which is raised the highest
These allows us to sound different vowels
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Front vowels: front of
tongue at highest point
ae,i:
Back vowel: back oftongue at highest point u:,
a:
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Respiratory system
The tongue does not play any function in the
respiratory system.