General AnatomyDr Muhammad Ressam Nazir

6.2 Classification of Joints

Fibrous joints

Cartilaginous joints

Synovial joints

6.3 Structures comprising a Synovial Joint

6.4 Movements of Joint

6.8 Factors stabilizing a joint

H.M.USMAN ASLAM

Different Classifications of Synovial Joint

1. Depending upon the shape of articulating surfaces:

Homomorphic

Two articular surfaces are in plane e.g. Plane joint, Saddle joint

Hetromorphic

Both articulating surfaces have varied appearance. E.g. Ball & Socket joint

2. Depending upon complexity of organization:

Simple

Cromio-clavicular joint

Shoulder joint

Compound

Elbow joint

Knee joint

Complex (Intra articular discs or menisci are involved)

Temporomandibular joint

3. Depending upon axis of movement

Uniaxial

Elbow joint

Biaxial

Wrist joint

Polyaxial

Shoulder joint

Hip joint

4. Depending upon type of movements

Gliding

Plane joint (Intermetatarsal joint)

Angular

Temporomandibular joint

Rotatory

Superior radio-ulnar joint

Circumductory

Ball and socket joint

5. Architectural or structural classification

i. Plane joints

Articulation of two flat surfaces.

a) Intermetatarsal joints

b) Some Inter carpal joints

ii. Hinge joints

Resembles the hinges of a door

Uniaxial type

a) Elbow joints

b) Interphalangeal joints

iii. Pivot joints

Uniaxial type

Composed of a pivot surrounded by Osteo-ligamentous ring.

a) Proximal radio-ulnar joints

b) Atlanto-axial joints

iv. Condylar or condyloid joints

Two condyles are articulating with two concave surfaces.

Main movement is in one plane only.

Limited amount of rotation is also possible

a) Knee Joint

b) Temporo-mandibular joint

v. Ellipsoid joint

Biaxial joint (Flexion/Extension, Abduction/Adduction)

Articulation of oval, convex surface with elliptical concave surface.

a) Radio carpal joint

b) Meta carpo phalengeal joints

vi. Saddle joint

Bi axial (Pri movements at 2 planes, accompanied be a degree of axial rotation)

a) Carpometacarpal joint of thumb

vii. Ball and socket joint

Poly axial

a) Shoulder joint

b) Hip joint

Movement of Joints

Gliding movements

Angular movements

Flexion

Extension

Abduction

Adduction

Rotation

Circumduction

1) Gliding movements

Simplest kind

One surface crawls over the others w/o angular or rotatory.

1) Intercarpal joints

2) Intertarsal joints

2) Rotation

A form of movement in which the bone move around some longitudinal axis.

1) Supination and Pronation of forearm (at superior radio-ulnar joint).

2) Inversion and Eversion of the foot.

Axis of rotation may lie…

Separate bone e.g. rotation of atlas (1st cervical vertebra) around axis (2nd cervical vertebra)

Same bone e.g. rotation of humerus at shoulder joint

Two bones oblique axis

3) Angular movements

Decrease or Increase in angle between two articulating bones.

Four types…

1. Flexion Occurs along a transverse axis

Result in approximation of two morphologically ventral surfaces

Exceptions Carpo-metacarpal joint of the thumb>>>>Axis is anterior posterior

and not transverse axis.

2. Extension Transverse axis

Approximation of morphologically dorsal surfaces

3. Adduction At antero-posterior axis

Approximation towards the median plane of the body.

Exceptions

1. Carpo-metacarpal joint of the thumb>>>>Axis is anterior posterior and not transverse axis.

4. Abduction At antero-posterior axis

Approximation towards the median plane of the body.

Exceptions

1. Carpo-metacarpal joint of the thumb>>>>Axis is anterior posterior and not transverse axis.

4. Circumduction

Elements of flexion, extension, adduction and abduction are compunded. 1. Shoulder joint

2. Hip joint

3. Carpo-metacarpal joint of the thumb

Miscellaneous movements

Pronation

Rotation

Inversion

Eversion

Opposition

Protraction

Retraction

Blood Supply

Supplied by Periarticular plexus of arteries

From this plexus, various branches pierce the articular capsule and form another plexus in subintimal tissue of synovial membrane.

Plexus send minute branches which supply the intima (part of synovial layer)

Lymph drainage

Lymph vessels also form a plexus in subintimal tissue.

Lymph from this plexus is drained into deep lymph nodes on the flexor surface of joint.

Factors stabilizing a synovial joint.

1. Tension of muscles crossing the joint. Shoulder joint

2. Tension of ligaments Knee joint

3. Tendons Biceps brachii muscle preventing upward dislocation of shoulder

joint.

4. Nature of articular surface Hip joint

5. Articular discs Knee joint

Temporo-mandibular joint

6. Force of cohesion

7. Atmospheric pressure

8. Apposition of soft parts Limits the movements thus helps in stability.

Limitation of the movements at a joint

1. Apposition of soft parts

2. Locking of the articular surfaces

3. Tension in surrounding muscles

4. Tightness of the ligament

The End – Any Questions?