Joints. Articulations of bones Functions of joints Hold bones together Allow for mobility Ways...

SKELETAL SYSTEMJoints

Joints

Articulations of bones Functions of joints

Hold bones together Allow for mobility

Ways joints are classified Functionally Structurally

Functional Classification of Joints

Synarthroses Immoveable joints

Amphiarthroses Slightly moveable joints

Diarthroses Freely moveable joints

Structural Classification of Joints

Fibrous joints Generally immoveable

Cartilaginous joints Immoveable or slightly moveable

Synovial joints Freely moveable

Summary of Joint Classes

Fibrous Joints:Joints made of fibrous tissue

Lies between tibia and fibula (interosseous membrane)

Fibrous joint

TibiaFibula

Fibrous Joints:Joints made of fibrous tissue

• Suture:• Between flat bones• Teeth-like projections• Thin layer of connective tissue connects bones• Skull

Cartilaginous Joints:Joints composed of cartilage

• There are two (2) types of cartilaginous joints (amphiarthroses):• Synchondrosis - plate of hyaline

cart.• Symphysis - pad or plate of

fibrocartilage

Cartilaginous Joints:Joints composed of cartilage

• Synchondrosis:• Bands of hyaline cartilage unite bones• Epiphyseal plate (temporary)• Between manubrium and the first rib (costal

cartilages)

Costal cartilage

Cartilaginous Joints:Joints composed of cartilage

• Symphysis:• Pad of fibrocartilage between bones• Pubic symphysis• Joint between bodies of adjacent vertebrae

Pubis

Fibrocartilage disc of

symphysis pubis

Band offibrocartilage

General Structure of a Synovial Joint

• Synovial joints are freely moveable (diarthroses)

• There are six (6) types of diarthroses• There are specific parts of a diarthroses:

• Articular cartilage• Joint cavity• Joint capsule• Synovial membrane • Synovial Bursae

Joint cavity filledwith synovialfluid

Spongybone

JointcapsuleArticularcartilage

Synovialmembrane

General Structure of a Synovial Joint

Articular cartilage – hyaline cartilage covers the surface of each bone

Joint capsule – double layered capsule surrounding cavity

Synovial cavity – space filled w/ synovial fluid Synovial fluid – viscous lubricating fluid Reinforcing ligaments – ligaments that

strengthen joint - ligament - joins a bone to another bone

General Structure of a Synovial Joint

Other joint features:1. Fatty pad (hips & knee)

2. Menisci or articular discs – separate cavity into 2 compartments (ex. Knee, jaw, sternoclavicular)

3. Bursa – flattened fibrous sacs w/ synovial membrane and fluid that act as “ball bearings” to prevent friction on adjacent structures during joint activity.

a. Cushion movement of one body part over anotherb. Located between skin and bone (where skin rubs over bone) and between muscle, tendons, ligaments and bone

General Structure of a Synovial Joint

Types of Synovial Joints

• Uniaxial• Hinge joint - elbow & knee • Pivot joint - articulation of atlas and axis of cervical

vertebra

• Biaxial• Saddle joint - thumb• Condylar joint - wrists & knuckles

• Multiaxial• Ball and socket joint - hip & shoulder• Gliding joint - intervertebral discs and between

carpals and tarsals

Uniaxial Synovial Joints

• Hinge Joint• Elbow joint• Between phalanges

• Pivot Joint• Between atlas (C1) and the dens of axis (C2)

Hinge joint Pivot joint

humerus

radius

atlas

axis

dens

Transverseligament

Biaxial Synovial Joints

• Saddle Joint• Between carpal and 1st metacarpal (of thumb)

• Condylar Joint• Between metacarpals and phalanges• Between radius and carpals

Saddle joint Condylar joint

Multiaxial Synovial Joints• Ball-and-Socket Joint

• Hip joint• Shoulder joint

• Gliding Joint• Between carpals• Between tarsals• Between facets of adjacent vertebrae

Ball and Socket Joint Gliding Joint

Examples of Synovial Joints

The shoulder, elbow, and knee are large, freely moveable joints.

Shoulder Joint

• Ball-and-socket• Head of humerus and glenoid cavity of scapula• Loose joint capsule• Bursae• Ligaments prevent displacement• Very wide range of movement (circumduction)

• Gliding joint• Between acromion process and clavicle

clavicle

acromionprocess

humerus

scapula

Joint capsule

subdeltoid bursa

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

humerus

radius

ulna

trochlea

Joint capsuleJoint cavity

Knee Joint

• Largest joint• Most complex – 3 joints

• Medial and lateral condyles of distal end of femur and

• Medial and lateral condyles of proximal end of tibia and

• Femur articulates anteriorly with patella

• Strengthened by many ligaments and tendons

• Menisci separate femur and tibia

• Bursae

femur

tibia

jointcavity

patella

menisci

prepatellarbursa

joint capsule

synovial membrane

Lifespan Changes

• Joint stiffness is an early sign of aging• Fibrous joints first to change; can

strengthen however over a lifetime• Changes in symphysis joints of vertebral

column diminish flexibility and decrease height (remember water loss from the IVDs)

• Synovial joints lose elasticity• Disuse hampers the blood supply• Activity and exercise can keep joints

functional longer