articular sustem

Joints

Contact of 2 or more bone

Classification

Fibrous cartilagenous and synovial

Fibrous :and it’s types

Bones are connected by fibrous tissue and it’s a fixed immobile joints suture gomphosis syndesmosis

Sutures

In skull.

-Bones are connected by

fibrous tissue (sutural ligament).

-Obliterated in old ag

Gomophosis

In teeth.

-Roots of teeth are

connected to sockets in

mandible & maxilla by

fibrous tissue

(periodontal ligament

Syndesmosis

inf. tibio-fibular joint.

-Lower ends of tibia &

fibula are connected by

fibrous tissue

(interosseous ligam

Cartilagenous joints

Connected y cartilage tissue into primary secondary

Primary ex site type ossification and mobility

Epiphyseal plate Intervertebral discs.

Site:

At ends of growing long

bones between epiphysis

& diaphysis.

Hyaline. Midline.

Type:

White fibrocartilage disc (articulating surfaces are

covered by thin hyaline cartilage). It is strengthened

by ligaments which do not fuse to form complete

capsule.

Permanent.

Ossification:

Temporary, disappears by

ossification.

Immobile.

Secondary ex site type ossification and mobility

Intervertebral discs.

Midline.

White fibrocartilage disc (articulating surfaces are covered by thin hyaline cartilage). It is strengthened by ligaments which do not fuse to form complete capsule.

Permanent.

Limited mobility (facilitated by white fibrocartilage elasticity).

Synovial

Free mobile and present in most limbs

Characters

Fibrous capsule particular cartilage joint cavity synovial membrane synovial fluid ligaments

Fibrous capsule

*Joint is surrounded by strong fibrous capsule, which is lined by synovial membrane & supported by strong ligaments.

Particular cartilage

	Articular cartilage	Joint	Synovial membrane	Synovial fluid	Ligaments	Structures inside cavity of some synovial joints
*Joint is surrounded by strong fibrous capsule, which is lined by synovial membrane & supported by strong ligaments. (	*Articular surfaces are covered by hyaline cartilage, which is smooth & lubricated by synovial fluid. *It has no blood vessels or nerves (nutrition is from synovial fluid). *In old age it shows irregularities due to erosion (eroded areas donot repair).

Joint cavity

Potential cavity, containing thin film of synovial fluid. It becomes manifest if fluid, blood or pus collect in it.

Synovial membrane and synovial fluid

*Thin, moist & glistening, covers all structures inside joint except articular surfaces & lines capsule. *It secretes & absorbs synovial fluid.

Pale yellow viscus similar to egg albumin (containing synovial cells, macrophages & lymphocytes). *It lubricates, helps in nutrition & reduces erosion of articular cartilage.

Ligaments and structure inside cavity of synovial joint

Ligaments

Structures inside cavity of some synovial joints

Capsular, extra & intra capsular ligaments, support & strengthen the joint.

• Articular fibro-cartilagenous disc: Temporo-mandibular joint (divides joint cavity into upper & lower compartments).

• Menisci: Knee joint (semilunar plates of fibro-cartilage).

• Ligaments: Cruciate ligaments in knee joint.

• Tendon: Tendon long head biceps in shoulder

Factors affecting stability of synovial joints

Shape & fitting of articulating surfaces 3-Position & strength of ligaments 2-Thickness & elasticity of capsule.

4-Strength of surrounding mus

Range of movement

Tension of surrounding ligaments 3-Approximation & contact of soft tissues around joint.

2-Contraction of antagonistic muscles

Nerve supply of synovial joints

Hilton’s lawHiltons law: N. supply to a muscle acting on specific joint, gives branch to joint

& another branch to skin covering joint.

N.B.: Nerves supplying joint (articular nerves) end in fibrous capsule & related

ligaments. They are sensitive to pain, position & movement of joint.

Movement flexion extension abduction addiction corcuumdunction rotation supination pronation inversion eversion opposition gliding

-Flexion: Bending (approximation of 2 ventral aspects).	-Extension: Straightening (2 ventral aspects move away from each other).
-Abduction: Movement of limb away from midline (middle finger in hand, second toe in foot).	-Adduction: Movement of limb towards midline (middle finger in hand, second toe in foot).
-Circumduction: Combination of all above movements.	-Rotation: Medially or laterally around a vertical axis.
-Supination: Lateral rotation forearm	-Pronation: Medial rotation forearm.
-Inversion: Sole directed inwards.	-Eversion: Sole directed outwards.
-Opposition: Thumb comes in contact with other 4 fingers.	-Gliding: Non axial movement.

Why would a cavity swell

Fluid pus or bloody collection

In dislocation

Separation of articular surfaces is called dislocation.

Basis

Types of synovial joins

According to number and axis of movement and shape of articular surface

Number

A- According to the number of articulating bones:

1. Simple joints: Between 2 bones ; shoulder.

2. Compound joints: Between more than two bones ; elbow.

3. Complex joints: Contain intra-articular structures ; kne

Uniaxial joints single axis such

Hinge joint

The convex articular surface is trochlea-

like; elbow joint. The movement is only

flexion and extension around a transverse

axis due to strong collateral ligaments.

B- Pivot joint

Articulating surfaces consist of a central

bony axis surrounded by a fibro-osseous ring;

superior radio-ulnar joint. The movement is

rotation around a longitudinal axis

Biaxial joint condylar

A-Condylar joint

2 separate convex surfaces (condyles)

which articulate with 2 concave surfaces,

; knee joint (bicondylar) or 1 condyle

articulating with 1 concave surface ;

temporomandibular joint (unicondylar

Ellip