SKELETAL SYSTEM Joints Joints Articulations of bones Functions

SKELETAL SYSTEM Joints

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 � Amphiarthroses � Slightly � joints 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) Fibula Tibia Fibrous joint

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 of fibrocartilage

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

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 another b. 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 • • • Biaxial • • • Hinge joint - elbow & knee Pivot joint - articulation of atlas and axis of cervical vertebra 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 (C 1) and the dens of axis (C 2) dens atlas humerus radius axis Hinge joint Transverse ligament Pivot joint

Biaxial Synovial Joints • • Saddle Joint • Between carpal and 1 st 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 scapula subdeltoid bursa acromion process humerus Joint capsule

Elbow Joint • Hinge joint • • • humerus Gliding joint • • Trochlea of humerus Trochlear notch of ulna Joint capsule Capitulum of humerus Head of radius Joint cavity radius Flexion and extension Many reinforcing trochlea ligaments Stable joint ulna

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 synovial membrane joint cavity prepatellar bursa patella menisci joint capsule tibia

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