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‫بسم هللا الرحمن الرحيم‬
Tempromandibular joint
Bilateral synovial joint
• It is the articulation of the condyle
with the articular fossa and articular
eminence of the temporal bone.
TMJ is consisted of:
1-Bones of the joint
*Mandibular condyle
*Temporal bone……
articular fossa & articular
eminence
• 2-Articular disc
• 3-Capsular ligament
• 4-Joint cavity ( synovial membrane)
Bones of the joint
• It consists of two bones:
* The condyle
*The articular eminence and articular fossa of
the temporal bone.
Compact bone
A- The condyle
Spongy
bone
• Composed of spongy bone
covered by thin layer of compact
bone.
• The trabeculae are grouped in
such a way that they radiate from
the neck of the condyle and reach
cortex at right angle. This give
maximum strength to the
condyle.
The fibrous covering of the condyle
(fibrocartilage)
• Its superficial layer consists of:
Network of strong collagenous f. & very occasionally
elastic fibers and fibroblasts. Cartilage cells
(chondrocytes) may be present that increase in number
by age.
The deeper layer consists of:
UMC as long as hyaline cartilage is present.
* By E/M a lamina splendens layer was detected
which is about (1-2 microns thick). It separates the
collagen from the joint cavity (Synovial cavity).
Joint cavity
During the period of growth
• Underneath the fibrous covering……… There is a
layer of hyaline cartilage which serves as an active
growth center till the age of 20 years
Fibrocartilage
Layer (fibrous
covering)
B-temporal bone
• Articular eminence
• Articular (glenoid) fossa
• The articular eminence is
composed of spongy bone that is
covered by a thin layer of
compact bone.
• The glenoid fossa is formed
only of thin layer of compact
bone.
• The fibrous covering layer is
thin in the g.fossa and thickened
rapidly on the posterior slope of
the articular eminence.
The articular
em.
The disc
The condyle
• In this region (post. slope of
art.em.) the fibrous tissue is
arranged in 3 zones:
• inner layer - collagen
fibers perpendicular to the
surface
• Intermediate transitional
layer-fibers run in complex
fashion
• outer layer - fibers parallel
to the surface.
•Fibroblasts & chondrocytes (single or gathered in
groups) form a type of fibrocartilage.
•This fibrocartilage become thin toward the glenoid
fossa……it disappears at the depth of the glenoid
fossa, here a layer of fibrous layer only is present.
Articular disc
• The articular disc:
• Is Oval
• Fused with the capsule
• Separates the cavity into
two compartments
• -Upper surface is concavoconvex ( to fit AE &
GF)
• -Lower surface is concave ( to fit head of the
condyle)
Histologically
Formed of dense avascular fibrous tissue that is
formed of:
-Tight collagen fs + some elastic fs + fibroblasts +
some chondrocytes.
-The collagen fiber is of type I and form 80% of the
disc weight and about 5% is glucosaminoglycans
(chondritine sulphate that withstands compressive
forces).
-The fibers are curled and wavy in shape to share in the
biomechanical properties of the disc so allow the disc
to stretch during compression.
The disc is divided into three bands:
Posterior band
Anterior
Band
Intermediate band
• Anterior band – split into 2 lamellae
• -Upper lamella attached to articular eminence
• -Lower lamella attached to anterior surface of the
condylar head
• fibers of superior head of the lateral pterygoid
muscle inserted in-between
Upper lamella
Anterior
Lower lamella
Intermediate band:
• Thinnest central region which is avascular and has
no innervation.
• This zone is composed of fibrous connective tissue
and is devoid of cells .
Posterior band:
• This region attaches posteriorly by:
• Upper lamella (retrodiscal pad)
-attaches to the capsular ligament
-highly vascular and innervated.
(loose CT ,elastic fs., BV., nerves)
• Lower lamella
-attaches to the posterior aspect of the neck of the condyle.
-consists mainly of collagenous fibers with no elastic
fibers.
Upper lamella
Posterior
Lower lamella
Fibrous
capsule
Anatomy
•It is a fibrous non-elastic membrane attached above
to the squamotympanic fissure, the margin of the
Glenoid fossa, and the articular eminence.
•Inferiorly, the capsule is attached to the neck of the
condyle.
•The lateral aspect of the capsule is thickened to
form a fan shaped ligament known as the tempromandibular ligament.
• The capsular ligament is attached :
Superiorly………to the temporal bone
• Inferiorly………..to the neck of condyle
Histology
• The capsule consists of :
• Outer fibrous layer
-dense fibrous collagenous connective tissue.
• Inner synovial layer (synovial membrane)
- lines the inner aspect of the capsule facing the two
synovial spaces and has synovial villi.
Synovial membrane:
• 1-cellular intima
• Fiber free matrix
• -fibroblast-like
cells (type B)
• -macrophage-like
cells (type A)
• -intermediate cells
•
•
•
•
2-vascular subintima
Loose C.T.
-fibroblast,macrophage,mast cells,fat cells
-blood ves.
The joint
cavity
Synovial fluid is viscous and consists
of plasma ,protein ,mucin.
• Functions
• 1-To lubricate the joint surfaces;
2-As a source of nutrition for tissues lining
cavity
3-To remove material (debris) from joint
this is done by macrophages present in
the synovial membrane adjacent to joint
cavity.
Innervation and
blood supply
• Sensory innervation :
• branches of the mandibular division of the
trigeminal nerve
• 1-auriculotemporal nerve
• 2- masseteric nerve.
• 3-posterior deep temporal nerve.
Blood supply
• Internal maxillary artery:
• -deep auricular
• -superficial temporal
• --Pterygoid plexus
Movements of the joint
• Hinge - rotatory action
Between condyle and articular disk
Inferior synovial (joint) cavity
• Gliding - translatory action
Between disk and articular eminence
Superior synovial (joint) cavity