Temporomandibular joint is a modified hinge type of synovial joint formed by articulation of the mandible and the temporal bone of the cranium.

1. Temporomandibular joint

2. What is tmj??
 Temporomandibular joint is a modified hinge type of synovial joint formed
by articulation of the mandible and the temporal bone of the cranium
 Location : Anterior to the tragus of the ear on the lateral aspect of the face

3. Articulating surfaces
 The tmj consists of articulations between three 3 surfaces
 Superiorly :
1. Mandibular fossa of the temporal bone
2. Articular tubercle of the temporal bone
 Inferiorly :
1. Head of the condylar process of the mandible
• The articulating surfaces are covered by fibrocartilage and not hyaline
cartilage

5.  JOINT CAPSULE :
The loose fibrous layer of the joint capsule attaches to the :
•margins of the articular cartilage on the temporal bone
•around the neck of the mandible
 ARTICULAR DISC :
The articular surfaces of the bones never come into contact with one
another
The two bony articular surfaces are completely separated by intervening
fibrocartilage , the articular disc of the tmj
Attached at its periphery to the internal aspect of the fibrous (Joint) capsule

7.  SYNOVIAL JOINT CAVITIES:
The presence of articular disc splits the joint into two synovial joint cavities or
compartments :
1. Superior articular cavity (between the temporal bone & articular disc)
2. Inferior articular cavity (between articular disc & head of mandible)
These cavities are lined by separate
1. Superior synovial membrane
2. Inferior synovial membrane

8. LIGAMENTS OF TMJ
 Two types of ligaments:
1. Intrinsic ligament
•lateral ligament of tmj
1. Extrinsic ligaments
•Stylomandibular
•Sphenomandibular

9.  Lateral ligament of the TMJ :
•Thickened part of the joint capsule
•runs from the beginning of the articular tubercle to the mandibular neck
•Functions:
1. Strengthens the joint laterally
2. Acts to prevent posterior dislocation of the joint with the “Postglenoid tubercle”
3. Connects the mandible to the cranium with two extrinsic ligaments
 Stylomandibular ligament :
•thickening of the fibrous capsule of the parotid gland
•runs from the styloid process of the temporal bone to angle of the mandible
•Does not contribute significantly to the strength of the joint
 Sphenomandibular ligament
•runs from the spine of sphenoid to the lingula of the mandible
•primary passive support of the mandible
•serves as a swinging hinge for the mandible, serving both as a fulcrum and as a check
ligament for the movements of mandible at the TMJs

10. MOVEMENTS OF TMJ
 Movements at tmj are produced by:
•Muscles of mastication
•hyoid muscles
 2 Types of movements occur at tmj
1. Gliding / Translational movements → occurs in superior articular cavity
•protrusion
•retrusion
2. Rotational / Pivoting / Hinge Movements → occurs in inf articular cavity
•Flexion (elevation)
•Extension (depression)

12. NEUROVASCULAR SUPPLY OF TMJ
 Arterial supply:
 External carotid branches:
1. Superficial temporal
2. Ascending Pharyngeal
3. Maxillary Artery (deep auricular)
 Innervation:
1. Mandibular Nerve :
a. Auriculotemporal
b. Masseteric branches

13. MUSCLES OF MASTICATION (TMJ)
 Associated with movements of the jaw (tmj)
 One of the major muscle groups of the head
 Four :
1. Masseter
2. Temporalis
3. Lateral pterygoid
4. Medial pterygoid
 MOM develop from first pharyngeal arch
 All are innervated by mandibular branch (V3) of the trigeminal nerve

14. MASSETER
 Quadrangule Muscle
 2 parts : Deep & Superficial
 Origin :
•Superficial part → inferior border and medial surface of
Maxillary process of zygomatic bone
•Deep part → zygomatic arch
 Insertion :
. Angle of the mandible + lateral surface of ramus of the mandible
 Innervation : mandibular branch V3 (Masseteric nerve)
 Action :
1. Elevates mandible , closing jaws
2. Protrusion of the mandible
3. Retrusion

15. TEMPORALIS
 Triangular muscle
 Origin :
Floor of the temporal fossa
 Insertion :
Condenses into a tendon which inserts onto the tip &
Medial surface of Coronoid process of the mandible
+ Anterior border of ramus of mandible
 Innervation:
Mandibular nerve (V3) (deep temporal branches)
 Action :
Elevates the mandible, closing jaws
Retrusion

16. MEDIAL PTERYGOID
 Quadrangular shape
 Two heads : Deep & superficial
 Origin :
•superficial → tuberosity of maxilla
•deep → medial surface of lateral pterygoid
Process of sphenoid bone + pyramidal process of
Temporal bone
 Insertion :
Medial surface of ramus of mandible (Mirror image of ipsilateral
masseter)
 Innervation : mandibular nerve (V3) (medial pterygoid nerve)
 Action :
Elevate mandible + protrusion

17. LATERAL PTERYGOID
 Triangular muscle
 Two heads : superior & inferior
 Origin :
•superior → crest of greater wing of sphenoid
•inferior → lateral surface of lateral pterygoid plate of
sphenoid
 Insertion :
Joint capsule + neck of condylar process of the mandible
 Innervation : Mandibular nerve V3 (lateral pterygoid
nerve)
 Action : protrusion + Depresses mandible