Uploaded by Humza Mumtaz Baloch

11. muscles of mastication (1)

Temporal & infratemporal fossae
Temporal fossa :extends
above by the sup.temporal
line and 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.
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 process of the mandible.
N.supply : deep temporal
nerves from the ant.division of
mandibular N.
Action : anterior fibers --elevate the mandible.
posterior fibers--- retract the
Muscles of mastication
2-Masseter muscle :
Origin : lower border &
inner surface of zygomatic
Insertion : lateral (outer)
surface of ramus of the
N.supply : masseteric N.
from anterior division of
mandibular N.
Action : raises the mandible.
Muscles of Mastication attached to
mandible :
Lateral Surface
Medial Surface
Contents of the temporal fossa
1-Temporalis muscle.
2-Temporal fascia---covers temporalis muscle,
attached above to sup.temporal
line and below to upper border
of zygomatic arch.
3-Deep temporal nerves :
from the ant. division of
mandibular N., emerge from
upper border of lateral
pterygoid, enter the deep
surface of temporalis .
Contents of the temporal fossa
nerve : arise from the
posterior division of
mandibular N. It emerges from
upper border of parotid gland ,
It lies behind superficial
temporal artery & TMJ,
in front of the auricle.
It supplies skin of auricle ,
ext.auditory meatus and the
scalpe over the temporal region.
Contents of the temporal fossa
5-Superficial temporal
artery : it is a terminal
branch of ext.carotid artery.
It Emerges from upper
border of parotid gland,
behind T.M.J.
It crosses root of zygomatic
arch in front of auriculotemporal N. & auricle ,here
its pulsation can be easily felt.
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.
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
1-Pulls the neck of mandible forward with the
articular disc to depress mandible during
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.
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 trunk of
mandibular N.
Action :
1-elevates the mandible.
2-Acting with lateral pterygoid
during movement of chewing.
Tempromandibular joint (TMJ)
Articlation : between the
articular tubercle & mandibular
fossa of temporal bone, and the
head of mandible (condyloid
Type :condyloid synovial
Capsule :it surrounds the
Synovial membrane--- lines
the capsule in upper & lower
Ligaments of Temperomandibular
Lateral temporomandibular
joint :
ligament : lies on the lateral side
of joint ,between the tubercle and
lateral surface of the neck of
Sphenomandibular ligament :
lies on the medial side of the joint
,it connects the spine of sphenoid
to the lingula of mandibular
Stylomandibular ligament behind &
medial .to the joint. it is a band of
thickened deep cervical fascia,
from apex of styloid process to angle
of mandibule.
Intracapsular articular disc
It is a plate of fibro-cartilage,
it divides the joint into upper
& lower cavities.
It is attached in front to the
tendon of lat. pterygoid , and
by fibrous bands to head of
Its upper surface is concavoconvex to fit the articular tubercle
& mandibular fossa , while
its lower surface is concave to fit
the head of mandible.
N.supply-auriculotemporal & masseteric branches of mandibular N.
Depression of mandibule :
by lat.pterygoid, helped by
digastric, geniohyoid & mylohyoid
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. Pterygoids of both sides
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.
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 plate in case of
severe blow on the chin.
 The articular disc
may be partially detached
causing noisy & audible
click, during movements
of the joint.
Dislocation of the TMJ
Sometimes occurs when the
mandible is depressed.
In case of minor blow on chin or
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
pressing the thumbs downward
on the lower molar teeth and
pushing the jaw backward.