11. muscles of ma stication.ppt

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1. Temporal & infratemporal fossae
Temporal fossa:extends
above by the sup.temporal
lineand below by
zygomatic arch.
Infratemporal fossa:lies
beneath the base of the
skull, between the pharynx
(medially) & ramus of
mandible (laterally).
or the space lying below
the temporal fossa and
behind the maxilla.

2. Muscles of mastication:1-Temporalis
It lies in the temporal fossa.
Origin:floor of temporal fossa
& temporal fascia.
Insertion:by a tendon into the
coronoid processof the mandible.
N.supply: deep temporal
nervesfrom the ant.division of
mandibular N.
Action: anterior fibers---
elevate the mandible.
posterior fibers---retract the
mandible.

3. Muscles of mastication
2-Masseter muscle :
Origin :lower border&
inner surface of zygomatic
arch.
Insertion:lateral (outer)
surface of ramus of the
mandible.
N.supply:masseteric N.
from anterior division of
mandibular N.
Action :raises the mandible.

4. Muscles of Mastication attached to
mandible :
Lateral Surface
Medial Surface

5. Contents of the temporal fossa
1-Temporalis muscle.
2-Temporal fascia----
covers temporalis muscle,
attached above to sup.temporal
lineand below to upper border
of zygomatic arch.
3-Deep temporal nerves:
from the ant. division of
mandibularN.,emerge from
upper border of lateral
pterygoid, enter the deep
surface of temporalis .

6. Contents of the temporal fossa
4-Auriculotemporal
nerve:arise from the
posterior division of
mandibular N.It emergesfrom
upper border of parotid gland ,
It liesbehind superficial
temporal artery & TMJ,
in frontof the auricle.
It suppliesskin of auricle ,
ext.auditory meatus and the
scalpe over the temporal region.

7. Contents of the temporal fossa
5-Superficial temporal
artery :it is a terminal
branch of ext.carotid artery.
It Emergesfrom upper
border of parotid gland,
behind T.M.J.
It crossesroot of zygomatic
arch in frontof auriculo-
temporal N. & auricle ,here
its pulsation can be easily felt.

8. Contents of Infratemporal fossa
Lateral & medial
pterygoid muscles
(muscles of mastication)
Branches of the
mandibular N.
Otic ganglion.
Chorda tympani.
Maxillary artery.
Pterygoid venous plexus.

9. Lateral pterygoid
Origin :upper head----from the
infratemporal surface of the greater wing of
sphenoid.Lower head----from the lateral
surface of lateral pterygoid plate.
Insertion :neck of mandible(pterygoid
fovea) & articular disc of T.M.J.
N.supply :anterior division.of mandibular
N.
Action:
1-Pulls the neck of mandible forward with the
articular disc to depress mandibleduring
opening of mouth.
2-Acting with medial pterygoid of the same
side during movement of chewing.
3-Acting with medial pterygoid to protrude
the mandible.

10. Medial pterygoid
Origin:superficial head-----
from the tuberosity of the
maxilla.Deep head-----from
the medial surface of the lateral
pterygoid plate.
Insertion: angle of
mandible (medial surface).
N.supply: main trunkof
mandibular N.
Action :
1-elevates the mandible.
2-Acting with lateral pterygoid
duringmovement of chewing.

11. Tempromandibular joint (TMJ)
Articlation :betweenthe
articular tubercle & mandibular
fossa of temporal bone, andthe
head of mandible(condyloid
process).
Type :condyloid synovial
joint.
Capsule :it surrounds the
joint.
Synovial membrane---lines
the capsule in upper & lower
cavities.

12. Ligaments of Temperomandibular
joint : Lateral temporomandibular
ligament :lies on the lateral side
of joint ,between the tubercleand
lateral surface of the neck of
mandible.
Sphenomandibular ligament :
lies on the medial sideof the joint
,it connects the spine ofsphenoid
to the lingula of mandibular
foramen.
Stylomandibular ligamentbehind&
medial .to the joint.it is a band of
thickened deep cervical fascia,
from apex of styloid processto angle
of mandibule.

13. Intracapsular articular disc
It is a plate offibro-cartilage,
it divides the joint into upper
& lower cavities.
It is attached in frontto the
tendon of lat. pterygoid,and
by fibrous bands to head of
mandible.
Its upper surfaceis concavo-
convexto fit the articular tubercle
& mandibular fossa, while
its lower surface is concave to fit
the head of mandible.

14. N.supply-auriculotemporal & masseteric branches ofmandibular N.
Movements:
Depression of mandibule :
by lat.pterygoid, helped by
digastric,geniohyoid& mylohyoid
muscles.
Elevation:by temporalis,
masseter, and medial pterygoid.
Protrusion :by lateral +
medial pterygoids of both sides.
Retraction :by post.fibers of
temporalis .
Lateral chewing movement:
by lat.& med. Pterygoidsof both sides
acting alternately.

15. Relation of the Temporomandibular
joint (TMJ) :
Anteriorly :mandibular notch
and masseteric N. & artery
(structures passing through
mandibular notch).
Posteriorly :ext.auditory
meatus, glenoid process of
parotid gland., auriculotemporal
N., & superficial temporal artery.
Laterally :parotid gland, fascia
& skin.
Medially :maxillary vessels.

16. Clinical significance of the TMJ :
The great strength of the Lat.TM ligament
prevents head of mandible from passing backward
to cause fracture of the tympanic platein case of
severe blow on the chin.
The articular disc
may be partially detached
causing noisy & audible
click,during movements
of the joint.

17. Dislocation of the TMJ
Sometimes occurs when the
mandible is depressed.
In case of minor blow on chinor
sudden contraction of lateral
pterygoids as in yawning, leads to
pull the head of mandible &
articular disc forward beyond the
summit of tubercle.
Reduction of disloction: by
pressingthe thumbs downward
onthe lower molar teeth and
pushing the jaw backward.