Tmj Muscles Flashcards
Muscles Of Mastication
• Masseter
• Temporalis
• Lateral Pterygoid
Medial Pterygold
contains medial and lateral pterygold and the tendon of temporalis.
Infratemporal fossa
• lies on the face, on the lateral surface of the ramus of the mandible
quadrilateral muscle
consists of three layers that blend anteriorly.
• Superficial layer
•Middle layer
Deep layer
Masseter muscle
Masseter consist of three layer that blend anteriorly
Superficial layer
•Middle layer
Deep layer
is the largest layer of Masseter
Arises by a thick aponeurosis from the
• maxillary process of the zygomatic bone
Anterior two-thirds of the inferior border of the zygomatic arch.
Superficial layer
It’s fibers pass downwards and backwards
insert into the angle and lower posterior half of the lateral surface of the mandibulor ramus.
Superficial layer
angled approximately 10°
from the vertical, as is visible in lean individuals.
• in the coronal (frontal) plane, the muscle forms a 10° angle with the mandibular ramus.
intramuscular tendinous septa in this layer are responsible for the ridges on the surface of the ramus.
Superficial layer
Arises from the:
medial aspect of the anterior two-thirds of the
zygomatic arch
lower border of the posterior third of the
zygomatic arch.
Middle layer
Insert into the central part of the ramus of the mandible.
Middle layer
Arises from the deep surface of the zygomatic arch
inserts into the upper part of the mandibular ramus
and into its coronoid process.
Deep layer
deep fibers run vertically and are evident just anterior to the temporomandibular joint, where they are not covered by the more superficial layers.
Deep layer
The anterior margin of masseter is:
separated from buccinator and the buccal branch of the mandibular nerve by a buccal pad of fat
crossed by the facial vein.
Overlapped by the parotid gland
Posterior margin of muscle
reach the deep surtace of masseter by passing over the mandibular incisure (mandibular notch).
The masseteric nerve and artery
Vascular supply
masseteric branch of the maxillary artery
•facial artery
transverse facial branch of the
superficial temporal artery.
Masseter action
elevates the mandible to occlude the teeth in mastication
• has a small effect in side-to-side movements. protraction and retraction.
Its electrical activity in the resting position of the mandible is minimal.
OLe
Action Masseter
elevates the mandible to occlude the teeth in mastication
• has a small effect in side-to-side movements. protraction and retraction.
Its electrical activity in the resting position of the mandible is minimal.
Arises from the
whole of the temporal fossa up to the inferior temporal line - except the part formed by the zygomatic bone
• deep surface of the temporal fascia.
Temporalis muscle
its fibers converge and descend into a tendon that passes through the gap between the zygomatic arch and the side of the skull.
Attached to the medial surface, apex, anterior and posterior borders of the coronoid process and
to the anterior border of the mandibular ramus almost up to the third molar tooth.
Temporalis muscle
•anterior fibers are orientated vertically.
• the most posterior fibers almost horizontally
• the intervening fibres with intermediate degrees of obliquity. in the manner of a fan.
Temporalis muscle
may occasionally gain attachment to the articular disc.
Fibers of Temporalis
•supplied by deep temporal branches from the second part of the moxillary artery, which enter on its deep aspect, and middle temporal branches from the superficial temporal artery, which enter on its lateral aspect.
• The anterior deep temporal artery supplies 20% of the muscle anteriorly:
Vascular supply
•the posterior deep temporal artery, entering the mid-portion of the muscle, supples 40% of the muscle in the mid-region; and the middle temporal artery, entering the muscle posteriorly, supplies 40% of the muscle in its posterior region.
• Considerable vascular anaslomoses are present within the muscle
Vascular supply
Innervation vascular supply
•anterior, middle and posterior deep temporal branches of the anterior trunk of the mandibular nerve.
Actions vascular supply
elevates the mandible and so closes the mouth and approximates the leeth.
• IThis movement requires both the upward pull of the anterior fibers and the backward pull of the posterior fibers because the head of the mandibular condyle rests on the articular eminence when the mouth is open.)
•also contributes to side to-side grinding movements.
“the posterior fibers retraci the mandible after it has been protruded.
• The posterior fibers of temporalis, which are almost horizontal, are the only source of mandibular retrusion.
Actions vascular supply
are the two deep pairs of the muscles of mastication.
they attach to the lateral and medial sides of the Lateral pterygold plates of the sphenoid bone respectively.
Lateral and Medial pterygoid muscles
• thick triangular muscle
• fibers are oriented HORIZONTALLY
• like the medial pterygoid muscle has two heads
Lateral pterygoid muscle
Upperhead lateral pterygoid muscle
originates from the roof of the infra-temporal fossa lateral to the foramen ovale and foramen spinosum.
(Infratemporal fossa - Inferior surface of the greater wing of the sphenoid and the infratemporal crest)
is larger than the upper head
originates from the lateral surface of the lateral plate of the pterygoid process,
•the inferior part insinuates Itself between the cranial attachments of the two heads of the medial pterygoid.
Lower head lateral pterygoid muscle
The fibers from both heads of the lateral pterygoid muscle converge to insert
Into the pterygold fovea of the neck of the mandible and
into the capsule of the temporo-mandibular joint in the region where the capsule is attached internally to the articular disc.
Oriented vertically pterygoid muscle
Muscle oriented vertically
Medial pterygoid
pterygoid muscle oriented almost horizontally.
Lateral pterygoid
contracts it pulls the articular disc and head of the mandible forward onto the articular tubercle and is therefore the
MAJOR PROTRUDER of the lower jaw.
Lateral pterygoid
•When the lateral and medial pterygoids contract on only one side.
The chin moves to the opposite side
When opposite movements at the two temporomandibular joints are coordinated,
A chewing movement results
assumed a specialized role in mandibular opening that is medialed by its horizontally onenfated fibres.
Lateral pterygoid
When left and right muscles of lateral pterygoid contract together,
the condyle is pulled forwards and slighily downwards.
main jaw opening muscles
Digastric and geniohyoid
