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Chapter 8Joints of the Skeletal System

• Articulations• Functional junctions between bones• Bind parts of skeletal system together• Make bone growth possible• Permit parts of the skeleton to change shape during childbirth• Enable body to move in response to skeletal muscle contraction

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Classification of Joints

• Fibrous Joints• dense connective tissues connect bones• between bones in close contact

• Cartilaginous Joints• hyaline cartilage or fibrocartilage connect bones

• Synovial Joints• most complex• allow free movement

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• Synarthrotic (Synarthroses)• immovable

• Processes are interlocked

• Between skull bones• Amphiarthrotic (amphiarthroses)

• slightly movable• Pubis Symphysis

• Diarthrotic (diarthroses)• freely movable• Most joints in body

Classification of Joints

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Fibrous Joints

3 Types• Syndesmosis• Suture• Gomphosis

Syndesmosis •a sheet or bundle of fibrous tissue connects bones• amphiarthrotic• lies between 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 adjacent vertebrae• amphiarthrotic

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Synovial Joints• Diarthrotic• End of long bone covered in hyaline cartilage• Joint cavity

• filled with Synovial fluid•Reduces friction•Synovial membrane

• Joint capsule•Fibrous tissue

• Bursae

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Ball-and-Socket Joint• Angular

movement in all directions

• Rounded head of one bone lies in a cup like cavity of another

• Hip• Shoulder

Types of Synovial Joints

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Condyloid Joint• Allow movement in

2 directions• Oval-shape condyle

of one bone fits into a cavity or fossa of the other

• Capable of circumduction, flexion, abduction and adduction

• Between metacarpals and phalanges

Types of Synovial Joints

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Types of Synovial Joints

Gliding Joint• Ends of bones glide over each other

• Articular surfaces are almost flat

• between carpals• between tarsals

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Hinge Joint

• Allow angular motion in ONE direction

• Convex surface of one bone fits into concave surface of the other

• Allows for flexion, extension, and sometimes hyperextension

• elbow, knee• between phalanges

Types of Synovial Joints

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Types of Synovial Joints

Pivot Joint•Pointed process of one bone turns within a ring formed•Partly by another bone and partly by a ligament•Allows for rotation• atlas and axis

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Saddle Joint• Allow movement in 2

directions

• between trapezium and metacarpal of thumb

Types of Synovial Joints

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• Abduction• drawn away

from the midline of the body

• Adduction• bring toward

the midline of the body

Types of Joint Movements

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• Dorsiflexion• Flexing your foot

• Plantarflexion• Pointing your toes

Types of Joint Movements

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• Flexion

• Decrease in the angle between the bones

• Extension

• Angle is increased

• Hyperextension

• Over-extending joint beyond healthy range

Types of Joint Movements

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• Supination

• turns the palm anterior

• Pronation

• turns the palm posterior

Types of Joint Movements

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• Rotation• Bone moves around a

central axis

• Circumduction• The distal end of a

bone moves around a circle while the proximal end remains stationary

• The bone outlines a cone in the air

Types of Joint Movements

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• Eversion• sole of the foot

turns away from the midline

• Inversion

• sole of the foot turns toward the midline

Types of Joint Movements

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• Protraction

• moves forward on a plane parallel to the ground

• Retraction

• move backward

Types of Joint Movements

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• Elevation• Raising the

shoulders

• Depression

• Lowering the shoulders

Types of Joint Movements

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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 of coxa• 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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• Patellar ligament• Central portion of insertion for the quadriceps

muscles• Strengthens anterior surface

• Popliteal ligaments • Criss-cross ligaments on the posterior surface

• Medial (tibial) collateral– provides lateral support and is easily injured

• Lateral (fibular) collateral

Knee Joint

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• Intra articular ligaments• Posterior cruciate

• keeps tibia from sliding backward (back part of X)

• Anterior cruciate• keeps tibia from sliding forward (anterior part of X)

• Meniscus• fibrocartilage that may tear and the loose parts may

impede movement

• Bursae• sac of synovial fluid found at the friction points of

your body

Knee Joint

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• Clinical Application• Terrible triad

• Tear in the medial collateral, anterior cruciate and medial meniscus

• Causes• sports or accidents

• Treatment• surgery with intense rehabilitation

Knee Joint

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Clinical Application

Joint Disorders

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

Bursitis• inflammation of a bursa• overuse of a joint

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Arthritis• inflamed, swollen, painful joints

• Rheumatoid Arthritis• Autoimmune disease • body attacks its own tissue--cartilage and joint linings• inflammation of the synovial membrane• Treatments aimed to reduce pain and inflammation

while preserving strength and mobility (rest, aspirin, steroids, exercise, etc.)

• bilateral• small joints 1st

Clinical Application

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• Osteoarthritis• More common and less damaging • Deterioration of articular cartilage and formation of

bone in the joint (bone spurs)• Non-inflammatory, progressive disorder• Bone spurs decrease articular cavity and restrict

movement• Affects large weight-bearing joints• Results from combination of age, irritation of the

joint, and normal wear and tear• Treatments are similar to Rheumatoid Arthritis

Clinical Application

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• Gouty Arthritis• Body produces excess amounts and/or is not

able to excrete normal amounts of uric acid• waste produced when nucleic acid is metabolized

• Excess uric acid reacts with sodium to form a salt called sodium urate

• Sodium urate crystals are deposited into soft tissues (articular kidneys, ears)

Clinical Application

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• Gouty Arthritis• Crystals irritate and wear down the cartilage

eventually destroying all joint and wearing down bones

• If not treated bones might fuse and become immovable

• Affects primarily middle to older males• Treatment can be successful (other two types

cannot be fully treated) by controlling the uric acid production

Clinical Application