Dr. R. S. Daisy

Joint

Articulation or junction

between two bones

or

Articulation or junction

between more than two

bones

orArticulation or junction

between parts of a bone of

Skeleton

Movement :

• A joint may not move or

• A joint may move in a limited amount

or

• wide range of movement may occur in a joint

Joint : Features:

BONE+ MATERIALS CONNECTED BONE

+BONE

=JOINT

JOINT

Joints are 3 types: According to type of material by which bones are articulate/connected

Classification of joint

1.FIBROUS JOINTS

2.CARTILAGINOUS JOINT

3.SYNOVIAL JOINT

FIBROUS JOINT=BONE+FIBROUS TISSUE+BONE

Two important features of it :

1. Bones are separated only by connective tissue

2. No movement / negligible.

Fibrous joints:

1. Suture : this joint unite the bones of the vault of the skull. ex: sagital suture, coronal suture etc.

2. Gomphosis : dentoalveolar joint

3. Syndesmosis: radio-ulnar joint

Classification of fibrous joint

Suture Sagital SutureCoronal suture

Inter-osseous membrane

( a connective tissue membrane) articulates two bones. Exa:

• Middle radio ulnar joint

• Middle and inferior tibio fibular joint

Syndesmosis

Middle radio ulnar joint

Radius

Inter osseous membrane

Ulna

• Tooth • Fibrous tissue • Socket ( present in

alveolar process of maxilla & mandible)

Gomphosis

Bone

Bone

Cartilaginous joint =

Bone +cartilage+bone

2. Secondary cartilaginous joint= Bone+ hyaline cartilage+fibrocartilage +hyaline

cartilage+bone

Classification of cartilaginous jointare two types:

1. Primary cartilaginous joint=Bone+ hyaline cartilage+bone

Primary cartilaginous jointfeatures:

• All primary cartilaginous joint are strong and immobile

• These are temporary joint (in adult,

it is replace by bone)

Primary cartilaginous jointExamples:

• all epiphyses are primary cartilaginous joint

• head of humerus + hyaline cartilage + shaft of humerus

= Primary cartilaginous joint

Primary cartilaginous joint

Black line is cartilage

Primary cartilaginous joint is temporaryThe cartilage is replace by bone

Black line is cartilageThe primary cartilaginous joint

No black line in between head & shaft of humerusNo Primary cartilaginous joint

Adult Children

Secondary Cartilaginous joints

Articular surface of bone is covered by thin plate of hyaline cartilage

Fibrocartilage

Bone Bone

Secondary cartilaginous joint

• It is a union between bones whose articular surfaces are covered with a thin lamina of hyaline cartilage.

• The hyaline laminae are united by fibrocartilage,

but it is never lined with synovial membrane and it contains only tissue fluid

• A limited amount of movement is possible in this joint

• Usually situated in the midline of body

• Examples : pubic symphysis inter-vertebral

joint

2nd cartilaginous joint

Hyaline cartilage

Fibro cartilage cartilage

Synovial joint

Two bones are separated by a joint cavity

Red colour : articular surface of bones

Blue colour: articular surfaces of bones are covered by articular cartilage(hyaline cartilage)

Articular capsule has two layer outer fibrous layer(brown colour)

Articular capsule has two layer outer fibrous layer (brown colour) & inner synovial membrane (green colour)

Joint cavity the most unique feature of synovial joint is filled by synovial fluid (the secretion of

synovial membrane)

Synovial joint freely move due to presence of joint cavity

Plane x-ray of synovial joint

Articular capsule

Menisci

Articular cartilage

Typical synovial joint :Features:

1. Contains a joint cavity which is filled with synovial fluid

2. The articular surfaces of bones are covered by articular cartilages

3. The joint cavity is enveloped by a complete articular capsule, which consists of

outer fibrous capsule and inner synovial membrane • The articulating bones are connected by a

number of ligaments • Sometimes, the joint cavity is divided

completely or incompletely by articular disc or meniscus, which is composed of fibro-cartilage.

Classification of synovial jointit can be classify according to different logic

1. According to the number of articulating bones

2. According to the shape of articular surfaces of bones

3. According to axis of movement

Simple joint :Two bones separated by single joint cavity

Compound jointMore than two bones are separated by single

joint cavity

Complex joint :Articular disc( fibrocartilage) divide the

joint cavity into two compartment

Articular disc

According to the axis of movements

• Uni-axial• Bi-axial• Multi-axial

Uni-axial joint

Bi-axial joint

Multi axial joint

According to the axis of movements

• Uni-axial: pivot plane hinge • Bi-axial: saddle condyloid ellipsoid • Multi-axial: ball and socket

According to the shape of articular surfaces

1. pivot 2. plane 3. hinge4. saddle 5. condyloid 6. ellipsoid 7. ball and socket

Pivot

• A round process of bone that fits into a bony ligamentous socket

• Movement is rotation around one axis

• Rotation of radius during pronation and supination

Pivot joint

• Distal radio ulnar joint

Pivot joint

Articular discLooks black in xray

Hinge• Convex cylinder applied to a concave

bone • Movement in one plane, it permit flexion

and extension only

Plane

• Two flat surfaces approximately equal in size

• Movement gliding or slightly twisting

Saddle• Two concavo-convex surfaces are

applied to each other • Permit movement in two different

plane

Condyloid(bi-condylar joint) • It has two convex

condyles which articulate with concave or flat surfaces

• It is biaxial but movement is greater in one plane than in the other

Ellipsoid

• It consists of oval convex surfaces apposed to an elliptical concavity

• They are bi-axial joint • Movement flexion

extension abduction adduction and circumduction

Ball and socket• Round head fitting into a round

depression • Wide range of movement

Articular discLooks black in xray

• Articular disc:

is a thin, oval plate of

fibrocartilage present in

several joints which

separates synovial

cavities. This separation

of the cavity space

allows for separate

movements to occur in

each space.

Bursa • A bursa (plural bursae or bursas)

is a small fluid-filled sac lined by synovial membrane.

• It provides a cushion between bones and tendons and/or muscles around a joint.

• This helps to reduce friction between the bones and allows free movement.

• Bursae are filled with synovial fluid and are found around most major joints of the body.

Homework

1.Identify the joint.

ABCD

A

BC

D

2. Questions

• What do you mean by very similar terms:

1. Articular surface

2. Articular cartilage

3. Articular capsule

4. Articular disc

3. Questions

1. Which type of joint is most common in our body?

2. Which type of joint is temporary?

3. Which type of joint can’t move?

4. Which type of joint is situated in the midline?

5. Which type of joint has great range of movement?