JOINTS

BY DR SIKANDER KHAN

dr.sikander05@gmail.com

Allah has bestowed human beings with a wide variety of joints.

`A'ishah (R.A) narrated that the Prophet (S.A.W) said: "Everyone has been created with three hundred and

sixty joints.

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DEFINITION

• The point where two or more bones meet is called a joint.

• The other name of joints is arthroses.

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Different joints in body

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FUNCTIONS

• Give the skeleton mobility.

• Hold the skeleton together.

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Classification of joints

1) On the basis of structure

2) On the basis of function

3) On the basis of movement

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1)Classification on the basis of structure:

I. Solid joints: the joints without a cavity .

II. Synovial joints: the joints with a cavity between them.

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Types of solid joints

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I. Solid joints1) Fibrous joints: the bones are held together by

fibrous connective tissue that is rich in collagen fibers. No synovial cavity

a. Sutures– Skull only

– Bony fusion

– Bound by dense fibrous connective tissue– TYPES:• Serrate edges are saw-like• Denticulate: tooth like processes • Squamous suture: bone margins overlap • Plane suture: apposition of flat surfaces

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Fibrous joints……………continued

b.Gomphosis– Teeth to

gums– Peg and

socket joint

c.Syndesmoses– bones

connected by ligaments

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Types of solid joints....continued

2)Cartilaginous joints: The bones are held together

by cartilage.

a. Synchondroses/primary cartilaginous joints

– On completion of growth hyaline cartilage is replaced by bone

e.g– epiphyseal cartilage

of long bones– between

vertebrosternal ribs and sternum

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Types of cartilagenous joints…continued

b. Symphyses/ secondary cartilaginous joints

– bones separated by fibro cartilage

– Mostly permanent

e.g.– pubic symphysis

– Intervertebral discs

– Some joints e.g. between sacrum and coccyx undergo partial or complete synostosis

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II. Synovial joints

– more movement– within articular capsules

• lined with synovial membrane

• where synovial fluid is found

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Accessory structures of synovial joint…continued

• Articular/Hyaline CartilageSmooth cartilage at the end of bones at joint

• Two-Layered Joint CapsuleOuter Layer – Tough fibrous capsule

Inner Layer – Synovial Membrane

• Synovial FluidSlippery fluid in joint capsule

• LigamentA band of strong fibrous tissue

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Accessory structures of synovial joint…continued

• Articular/Hyaline Cartilage

Prevent friction between articulating bones

• Two-Layered Joint Capsule

Outer Layer – Strengthen joint

Inner Layer – To secrete synovial fluid

• Synovial Fluid

Reduce friction between articular cartilages

Nourish articular cartilage

• Ligament

To connect one bone to another

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Accessory structures of synovial joint…continued

• Tendons– Strong connective tissue that attaches muscle to bone.

Connect muscle to muscle.

• BursaFluid filled sacs

Cushion the joint and act as shock absorbers• Meniscus White fibrocartilage

Improves the fit between bone ends Increases joint stabilityReduces wear and tear at joint

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SYNOVIAL JOINT

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Types of synovial joints

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Types of synovial joints…continued

• Plane joints :the articulating surfaces are flat or slightly curved.

• e.g are intercarpal joints, intertarsal joints, sternoclavicular joints, acromioclavicular joints, sternocostal joints, vertebrocostal joints.etc.

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Examples of plane joint

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Types of synovial joints…continued

• Hinge Joints-the convex surface of one fits into the concave surface of another.

• e.g. elbow joint, ankle joint, interphalangeal joints,etc.

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Types of synovial joints…continued

• Pivot Joints-here the rounded or pointed surface of one bone articulates with a ring formed partly by another bone and partly by a ligament.

• e.g atlanto-axial joint, radioulnar joint etc.

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Types of synovial joints…continued

• Condyloid Joints-also called ellipsoidal joint. The convex oval-shaped projection of one fits into the oval-shaped depression of another

• e.g metacarpophalangeal joints.

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Types of synovial joints…continued

• Saddle Joints-here the articular surface of one bone is saddle-shaped and the articular surface of the other fits into the “saddle”.

• e.g. Carpometacarpal joint.

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Types of synovial joints…continued

• Ball-and-Socket Joints- this consists of the ball-like surface of one bone fitting into a cuplike depression of another bone

• e.g Shoulder and hip joints.

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2)Classification on the basis of function

• Functionally, joints are classified as one of the following:– Synarthrosis: an immovable

joint.

– Amphiarthrosis: a slightly movable joint. Most amphiarthrosis joints are cartilaginous.

– Diarthrosis: a freely movable joint. All diarthroses are synovial joints.

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3)CLASSIFICATION ON THE BASIS OF MOVEMENT • Uniaxial joints e.g.

the elbow joint

• Biaxial joints e.g. the wrist joint

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CLASSIFICATION ON THE BASIS OF MOVEMENT…continued

• Multiaxial joints: e.g. shoulder joint

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Factors affecting at Synovial Joints• Structure or shape of

the articulating bones• Strength and tension

of ligaments.• Arrangement and

tension of muscles• Apposition of soft

parts• Hormones• use

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Vasculature of joints

• Articular arteries from vessels around joints

• Often these arteries form anastamoses around joints

• Articular veins accompany arteries

• Articular veins like articular arteries, are located inside a joint capsule, mostly in the synovial membranes

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Innervation

• Rich nerve supply• Most articular nerves are

branches of cutaneous nerves supplying the muscles that cross and move the joint( obey Hiltons law)

• In distal parts of limbs( hands and feet) articular nerves are branches of cutaneous nerves supplying the overlying skin

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Innervation ……………continued

• Joints transmit a sensation called proprioception

• Synovial membrane is relatively insensitive

• Pain fibers are numerous in fibrous layer and associated ligaments causing pain when joints are injured

• Sensory nerve endings respond to twisting and stretching that occur during sport activities

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Joints of new born

• The bones of the calvarium (skullcap) of a new born infant do not make full contact with each other

• At these sites, the sutures form wide areas of fibrous tissue called fontanelles

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DEGENERATIVE JOINT DISEASES

• Risk factors include age ,heredity, injury and obesity

• Particularly those of hip, knee, vertebral column and hands

• Some destruction is inevitable during such activities as jogging, which wears away the articular cartilages and sometimes erodes the underlying articular surfaces

• Trauma to a joint may be followed by arthritis ,inflammation of joint and septicemia

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Degenerative joint diseases………..continued

Most common is osteoarthritis, which is often accompanied by stiffness, discomfort and pain.

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Degenerative joint diseases………..continued

• Rheumatoid arthritis– Chronic

inflammatory disorder

– Marked by flare-ups

– Autoimmune disease.

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Degenerative joint diseases………..continued

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Examination of joint

1. Clinical examination

2. Imaging( MRI/CT)

3. Arthroscopy• A cannula and

arthroscope is inserted in joint cavity

• For abnormalities such as torn articular discs

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