Chapter 8Joints of the Skeletal System

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• Joint- site where two bones come together• Articulation – functional junctions between bones

FUNCTIONS OF JOINTS:• Articulations• Junctions between bones• Binds parts of skeletal system together• Makes bone growth possible• Permit parts of the skeleton to change shape during

childbirth• Enable body to move in response to skeletal muscle

contraction

Classification of Joints

• Fibrous Joints• Bones held together by connective tissues• between bones in close contact• skull sutures and teeth• no joint cavity

• Cartilaginous Joints• Bones held together by cartilage• pubic symphysis and invertebral discs• no joint cavity

• Synovial Joints• Bones separated by a joint cavity • most complex• allow free movement• hip, knee, shoulder

• SynarthroticSynarthrotic• immovable

• AmphiarthroticAmphiarthrotic• slightly movable

• DiarthroticDiarthrotic• freely movable

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Structural ClassificationStructural Classification

Functional ClassificationFunctional Classification

Fibrous Joints

3 Types• Syndesmosis• Suture• Gomphosis

Syndesmosis• long fibers connect bones• amphiarthrotic• distal ends of tibia and fibula

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Fibrous Joints

Suture• between flat bones• synarthrotic• thin layer of connective tissue connects bones

Gomphosis• cone-shaped bony process in a socket• tooth in jawbone• synarthrotic

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Cartilaginous Joints

2 Types• Synchondrosis• Symphysis

Synchondrosis• bands of hyaline cartilage unite bones• epiphyseal plate (temporary)• between manubrium and first rib• synarthrotic

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Cartilaginous Joints

Symphysis• pad of fibrocartilage between bones• pubis symphysis• joint between bodies of vertebrae• amphiarthrotic

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Synovial Joints

Diarthrotic – move freely

• joint cavity

• joint capsule

• articular cartilage– Osteoarthritis

• synovial fluid

• reinforcing ligaments

• fatty pads

• menisci

• bursae – flattened fibrous sacs that prevent friction 8-8

• A lubrication fluid within the joint cavity

Functions of SF:

1. Reduces friction between cartilages of 2 bones

2. Nourishes cartilage of the joint

3. Contains phagocytes

4. Provides “weeping lubrication”

Synovial fluid

Types of Synovial Joints

Ball-and-Socket Joint• all angular movement• hip• shoulder

Condyloid (ellipsoid) Joint• permit all angular movement, except rotation •between metacarpals and phalanges• knee

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Types of Synovial Joints

Gliding (plane) Joint• cartilaginous joints • intervertebral discs• between carpals and tarsals

Hinge Joint• permit flexion and extension only •elbow• between phalanges

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Types of Synovial Joints

Pivot Joint• permit rotation •between proximal ends of radius and ulna

Saddle Joint• between carpal and metacarpal of thumb

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1. Gliding movementsGliding movements – when flat bones surfaces glide or slide over one another

2. Angular movementsAngular movements – changes in angles between bones (synovial joints)

3. Special MovementsSpecial Movements – at special joints

General Types of Movements

• Occur at cartilaginous joints

• Examples:– Intervertebral disc– Sternoclavicular joint

Gliding Movements

Angular Movements

• abduction/adduction• dorsiflexion/plantarflexion• flexion/extension/hyperextension

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Angular Movements

• rotation/circumduction

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Special Movements• eversion/inversion• protraction/retraction• elevation/depression• supination/pronation

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Shoulder Joint

• ball-and-socket• head of humerus• glenoid cavity of scapula• loose joint capsule• bursae• ligaments prevent displacement• very wide range of movement

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Shoulder Joint

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Elbow Joint

• hinge joint• trochlea of humerus• trochlear notch of ulna

• gliding joint• capitulum of humerus• head of radius

• flexion and extension• many reinforcing ligaments• stable joint

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Elbow Joint

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Hip Joint

• ball-and-socket joint• head of femur• acetabulum• heavy joint capsule• many reinforcing ligaments• less freedom of movement than shoulder joint

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Hip Joint

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Knee Joint

• largest joint• most complex• medial and lateral condyles of distal end of femur• medial and lateral condyles of proximal end of tibia• femur articulates anteriorly with patella• modified hinge joint• flexion/extension/little rotation• strengthened by many ligaments and tendons• menisci separate femur and tibia• bursae

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Knee Joint

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Life-Span Changes

• Joint stiffness is an early sign of aging (next slide)• Regular exercise can prevent stiffness• Fibrous joints first to strengthen over a lifetime.

Sutures during infancy• Ligaments lose their elasticity and become tightly

crossed linked. • Changes in symphysis joints of vertebral column

diminish flexibility and decrease height • Synovial joints start to lose elasticity in 30’s. Affects

range of motion and can upset balance, contributing to more falls later in life.

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Joint Disorders

Sprains• damage to cartilage, ligaments, or tendons associated with joints• forceful twisting of joint (slide)

Bursitis• inflammation of a bursa• overuse of a joint

Arthritis• inflamed, swollen, painful joints• over 100 types of arthritis • involves cartilage, bone, muscles, tendons, ligaments, and nerves• 10% of the population• no cure

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Types of Arthritis

Rheumatoid Arthritis – the synovial membranes of the joints and connective tissues grow abnormally to form a layer in the joint capsule. - this layer grows into the articular surface, destroying cartilage and fusing bones of the joint.

Osteoarthritis – degenerative joint disease, occurs in people in their 70’s. - more common in overweight people- exercise can prevent this disease

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