23. tmj jaw bones

7/31/2019 23. TMJ Jaw Bones

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The Temporomandibular Joint

& Jaw Bones


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TMJ

Type:ginglymoarthrodial synovial

joint

Ginglymus:

Arthrodial:

1st movement:

2nd movement:


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Articulations:

Head of mandibular condyle

Ant. Part of Mandibular fossa

Of?

&

Articular tubercle

of ?

*articular surfaces

fibrocartilage


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Supporting Ligaments

Main (Intrinsic)Articular fibrous capsule

surrounds the J.

attached

sup.:

inf.:

Lat. (TM) Lig.:

runs downwards backwards

between?

prevents?

protects?


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Accessory (Extrinsic)

Stylomandibular lig.:extends between?

thickened part of ?

Sphenomandibular lig.:

lies on medial side &

extends between?

3. Is there any other lig.??

*define the extents of

Mandibular movements


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The Articular Disc

Oval plate of fibrocartilage that is located between articularsurfaces of TMJ

Ant. & post. Bands

Attachments

periphery:

ant.: ? &?

post.:

* The disc divides the Jointcavity into 2 compartments:

Sup. & Inf.


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Movements

1. Depression of mand.

(mouth opening)

3 muscle groups ?

* Main mover ?

2. Elevation:

(mouth closing)

3 muscles?


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3. Protrusion:

(forwards)

3 muscles?

main one?

4. Retrusion, Retraction:

(backwards)by ??

5. Lat. Movement to the sides:

by ??


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Movements of Mouth Opening

Involves 2 kinds of movement:

1. Rotation:

condyle & lower surface of

articular disc ( compartment) 20o (hinge)

2. Translation:

condyle & disc

articular tubercle

until ?? (gliding)


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Relations of TMJ

Ant.:

masseteric a. & n.(from?)

Post.:

glenoid process of ?

tympanic plate of EAM

& ??

Lat.:

parotid gland

Med.:

max. Vessels &auriculotemp. N.


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Dislocation of TMJ

The head of the mandible moves ant. To the articular tubercle

mandible is depressed & the pt. cannot close his mouth

Cause:

excessive contraction of lat. Pterygoid m.

as in: taking a large biteover opening for the dentist

Rx.:pressure the mandible inf. Then post.

by grasping the mandible with your thumbs over lowerdentition


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Clicking of TMJ

When the post. Band of articular disc is anteriorly displaced

(in front of mand. Condyle)

*As the pt. opens his mouth:

the displaced disc, at a certain point, returns to its normalposition

producing the click sound in the joint

Ant. Displacement with reduction


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Anterior Displacement WithoutReduction

The disc remains anteriorly displaced as the mouth is opening

- the pt. cannot fully open his mouth

- Grinding sounds are present

- sometimes perforation of the disc may happened


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The Jaw Bones


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Maxilla

Body & 4 Processes

Body

pyramidal

hollow inside (max. sinus)

Upper surface: ?

Anterolateral surface: ?

Posterolateral surface: ?

Medial surface: ?


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Maxillary Processes

Zygomatic:

projects lat.,

ant. zyg. Arch

Frontal:

sup.,

lat. to nasal bones

Alveolar:

inf.,

contains upper teeth

Palatine:

post.,

ant. 2/3 of hard palate


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Maxillary Foramina

2 foramina:

Infraorbital F.

ant. wall, infraorbital n. & a.

Incisive Foramen:

between palatine processes

post. to central incisors

incisive n. (nasopalatine n.)


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Largest & strongest facial bone

Only movable skull bone beside

The ear ossicles

Horizontal part:

Body

Vertical Parts:

Rami (ramus)

Jxn.:

Angle

Mandible


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Body:

mental foramen

alveolar process

mental protuberance

sup. & inf. Mental spines

mylohyoid line

Ramus:

mandibular notch

coronoid process

condylar process:

head & neck

lingula & mand. foramen


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Mention 8 muscles attached to the mandible ?

23. tmj jaw bones

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