Temporomandibular joint and Muscles of Mastication Flashcards
- one of the most complex joints in our body
- area where the mandible articulates
with the temporal bone of the
cranium - only freely movable joint between skull bones
Temporomandibular joint
temporomandibular joint is considered as a __________ joint
ginglymoarthrodial
temporomandibular joint is the _______ _______ of the mandible and mandibular ______ and _______ ______ of temporal bone
condylar process
fossa
articular tubercle
Since the articular surface of the joint is nonvascular, it acts as a medium for providing metabolic requirements to these tissues. it also serves as a lubricant between articular surfaces during friction.
Synovial fluid
What are the anatomical components of TMJ?
- Articular disc
- Articular capsule
- Lateral ligament
- Sphenomandibular ligament
- Stylomandibular ligament
it is a fibrocartilage that separates the synovial cavity: superior and inferior compartment
Articular disc
Thin, fairly loose envelope around the circumference of the joint
Articular capsule
Known to be 2 short bands in the lateral surface of the articular surface. Extended inferiorly and posteriorly from the inferior border and tubercle of the zygomatic process
Lateral Ligament
this band extends inferiorly and anteriorly from the spine of the sphenoid bone to the ramus of the mandible. it does not contribute significantly to the strength of the joint
Sphenomandibular ligament
from the styloid process of the temporal bone to the inferior and posterior border of the ramus of the mandible
Stylomandibular ligament
What are the movement of the Mandible?
- Hinge
- Condyloid
- Sliding/ Arthrodial
It is a movement of the mandible which function in a hinge-like fashion during elevation and depression.
Hinge
A movement of the mandible which glides slightly forward when the jaw is in protrusion and retrusion
Condyloid
A movement of the mandible which glides side to side during chewing
Sliding/ Arthrodial
Movement of each compartment:
Inferior Compartment:
Superior Compartment:
- depression/ elevation
- protraction/ retraction, lateral displacement, slight rotation
What are the muscles of mastication?
- Masseter
- Temporalis
- Lateral Pterygoid
- Medial Pterygoid
Muscles of Mastication:
Blood supply:
Innervated by:
- maxillary artery
- mandibular nerve (V3 Trigeminal Nerve)
What are the functions of Muscles of Mastication?
- to move the mandible
- to secure then stabilize the mandibular positions
- to determine the direction of mandibular movements
Muscles of Mastication
- a small quadrilateral muscle that covers most of the lateral aspect of the ramus of the mandible
- superficial to this muscle is a portion of the parotid gland, parotid duct, facial artery, and the various branches of the facial nerve
Masseter
Muscles of Mastication
- an almost a
mirror-like image of
the masseter muslce. - it is rhomboidal and
runs practically in the
same direction on the
inner surface of the
mandible.
Medial Pterygoid
Muscles of Mastication
- fan-shaped, with the
periphery of the fan
attached to the side of
the skull and the handle
of the fan attached to
the coronoid process of
the mandible - covered by a strong
membranous sheet of
fascia, which attaches
superiorly to the
superior temporal line - below, the fascia splits
to attach to the medial
and lateral aspects of
the zygomatic arch.
Temporalis
Muscles of Mastication
- almost triangular in
shape with two distinct
heads, inferior and
superior head, each
with contrasting
functions - only muslces of the four
muscles of mastication
to occupy primarily a
horizontal position.
Lateral Pterygoid
Muscles of Mastication
- the occupants of the infratemporal fossa
Medial and Lateral Pterygoid
Actions of the Muscle
Masseter- superfical head
- elevation
- Ipsilateral excursion
- protrusion
Actions of the Muscle
Masseter- deep head
- retrussion
Actions of the Muscle
temporalis
- elevation
- ipsilateral excursion
- retrusion
Actions of the Muscle
medial pterygoid
- elevation
- protrusion
- contralateral excursion
Actions of the Muscle
lateral pterygoid- inferior head
- depression
- protrussion
- contralateral excursion
Actions of the Muscle
- elevation: particularly during power stroke
-
- suprahyoid muscle
- infrahyoid muscle
Muscles involved in the Action of MoM
Depression
1.
2.
3.
- inferior head of the right and left lateral pterygoid muscles
- right ad left suprahyoid muscles of the neck
- right and left infrahyoid muscles of the neck
Muscles involved in the Action of MoM
Protrusion
1.
2.
3.
- right and left lateral pterygoid muscles
- right and left medial pterygoid
- right and left superficial heads of the masseter muscles
Muscles involved in the Action of MoM
Retrusion
1.
2.
- posterior fibers of the right and left temporalis muscles
- deep heads of the right and left masseter muscles
Muscles involved in the Action of MoM
right lateral excursion
1.
2.
3.
4.
- right masseter
- right temporalis
- right medial pterygoid
4.right lateral pterygoid
Muscles involved in the Action of MoM
left lateral excursion
1.
2.
3.
4.
- left masseter
- left temporalis
- right medial pterygoid
.4. right lateral pterygoid
