Type of joint articular disc ligamnets relations blood and nerve supply movements applied anatomy

1. Dr VidyaLakshmi
BDS,MScmedicalAnatomy

2.  It is the articulation of the base of the skull with
the mandible
 It is a bicondylar variety of the synovial joint
 Articular surfaces of both bones are covered by
white fibrocartilage
 Joint cavity is divided into upper menisco
temporal & lower menisco mandibular
compartments by articular disc

4. Bones forming the joint
 Above :
Articular tubercle at the root of the zygoma &
anterior part of the mandibular fossa of the
temporal bone
 Below :
Head of the mandible

6. Articular disc
 It is an oval plate of fibrocartilage
 Caps the head of the mandible
 Divides the joint completely into two
compartments
Attachment of the disc
 Attached to the inner aspect of fibrous capsule
 Blends in front with insertion of lateral pterygoid
muscle
 Splits into two lamellae posteriorly- getting
attached to squamotympanic fissure and posterior
surface of neck of mandible

7. Ligaments of the T-M Joint
 Capsular ligament with synovial membrane
 Articular disc
 Lateral temporomandibular ligament
 Accessory ligaments- Stylomandibular ligament
Sphenomandibular ligament

9. 1. Capsular ligament
 Envelops the joint
Attachments
Above :
 Articular tubercle –in front
 Squamotympanic fissure -behind
 Articular fossa –at the periphery
Below :
 Attached around the neck of mandible
In front :
 Blends with insertion of lateral pterygoid muscle
 Above the disc capsule is loose, below it is taut

11. 2. Lateral temporomandibular
ligament
 Blends with lateral part of fibrous capsule
 Extends from the root of the zygoma to lateral
surface and posterior margin of neck of mandible

12. 3. Sphenomandibular ligament
 Situated medial to the capsule
Attachments
Above
 Spine of the sphenoid
Below
 Lingula of the mandible
4. Stylomandibular ligament
 Extends from the tip of the styloid process to the
angle of the mandible

13. Relations of the joint
 In front- lateral ptertgoid ,temporalis muscle,
masseteric nerves & vessels
 Behind – Parotid gland, auriculotemporal nerve,
superficial temporal vesslels,external acoustic
meatus
 Lateral –subcutaneous
 Medial – ,spine of sphenoid, middle meningeal
artery, roots of auriculotemporal nerve
 Above- floor of the middle cranial fossa separated
by thin plate of bone

14. Arterial supply
 Superficial temporal & maxillary artery
Nerve supply
 Auriculotemporal nerve
 Masseteric nerve

17. Movements taking place in the joint
 Protrusion /Protraction
 Retraction
 Elevation
 Depression
 Side to side movements

19. Muscles producing movement
Protrusion (protraction )
 Both the pterygoid muscles
 Movement occurs in upper compatment
Retraction
 Posterior fibres of temporalis
 Forceful retraction is assisted by middle and
deep fibres of masseter, digastric , geniohyoid

22. Depression
 Lateral pterygoid muscle, geniohyoid,
mylohyoid, digastric-
 Gravity
Elevation
 Masseter,temporalis, medial pterygoid,
Side to side movement
 Both pterygoids acting alternatively

26. Mechanism of depression
 At first there is forward rotation of mandibular condyle in
lower compartment so that condyle come in contact with
intermediate area of articular disc
 At second stage head of the mandible and articular disc
glides forward in the upper compartment with the pull of
lateral pterygoid muscle
 At the end ,head of mandible rotates forward till it comes to
lie below articular tubercle with the pull of suprahyoid
muscles
 Movement is initiated in the lower compartment by the
rotation of mandibular head
 Forward gliding is further prevented in the upper
compartment by posterior fibres of temporalis and articular
disc, therefore the movement is completed by the lower
compartment

27. Factors maintaining the stability of the
joint
 Bones
Articular tubercle – prevents forward dislocation
Post glenoid tubercle-prevents backward dislocation
 Ligaments
 Muscles
Protraction – Temporalis fibres
Retraction – Lateral pterygoid
 Position of the mandible

28. Clinical anatomy
Dislocation of the joint
 Forward dislocation is most common
 Mandible is displaced from articular tubercle to
infratemporal fossa
 Cause is sudden spasm of lateral pterygoid while
opening the jaw
 Reduction is done by traction on mandible to relieve
spasm of masseter followed by elevation of
mandible to throw back head into the articular fossa

32. Deatchment of articular disc from fibrous
capsule results in derangement of joint
 Movement becomes painful & clicking sound
appears during movement of the joint
Degenerative changes can take place in the joint
Injury to auriculotemporal nerve close to the
joint result in laxity of the joint

33. TMJ Examination

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