Joints

 Articulations of bones  Functions of joints  Hold bones together  Allow for mobility  Ways joints are classified  Functionally  Structurally

 Synarthroses  Immoveable joints  Amphiarthroses  Slightly moveable joints  Diarthroses  Freely moveable joints

 Fibrous joints  Generally immoveable  Cartilaginous joints  Immoveable or slightly moveable  Synovial joints  Freely moveable

 Lies between tibia and fibula (interosseous membrane) Fibrous joint Tibia Fibula

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

There are two (2) types of cartilaginous joints (amphiarthroses): Synchondrosis - plate of hyaline cart. Symphysis - pad or plate of fibrocartilage

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

Symphysis: Pad of fibrocartilage between bones Pubic symphysis Joint between bodies of adjacent vertebrae Pubis Fibrocartilage disc of symphysis pubis Band of fibrocartilage

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 filled with synovial fluid Spongy bone Joint capsule Articular cartilage Synovial membrane

 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

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 another b. Located between skin and bone (where skin rubs over bone) and between muscle, tendons, ligaments and bone

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

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 Transverse ligament

Saddle Joint Between carpal and 1 st metacarpal (of thumb) Condylar Joint Between metacarpals and phalanges Between radius and carpals Saddle joint Condylar joint

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

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

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 acromion process humerus scapula Joint capsule subdeltoid bursa

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 capsule Joint cavity

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 joint cavity patella menisci prepatellar bursa joint capsule synovial membrane

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