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~ HUMAN JOINTS ~. PSE 4U: Exercise Science Westdale Secondary School. No PAIN! No GAIN!. Emergency Rooms across North America tallied more than 4 million sports and recreation-related injuries last year. See how your favourite pastime rates to the E.R.-o-meter:
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~ HUMANJOINTS~ PSE 4U: Exercise Science Westdale Secondary School
No PAIN! No GAIN! • Emergency Rooms across North America tallied more than 4 million sportsand recreation-related injuries last year. See how your favourite pastime rates to the E.R.-o-meter: • Basketball 213,847 • Bicycling 147,140 • Lifting/Running 88,532 • Football 61,353 • Softball 50,824 • Fishing 17,798 • Golf 8,469 OUCH!
Introduction to the Articular System • Bones are too rigid to bend without being damaged. Fortunately, flexible connective tissues form joints that hold bones together while still permitting some degree of movement, in most cases. • Most movements of the body occur at joints, you can appreciate their importance if you imagine how a cast over the knee joint makes walking difficult or how a splint on a finger limits the ability to manipulate small objects. The scientific study of joints is referred to arthrology. The study of motion of the human body is called kinesiology.
Joint Classification • A joint consists of cartilage and fibrous connective tissue. • A joint in the human body is defined as the point at which two or more bones join together. • An articulation (joint) is a point of contact between bones, between cartilage and bones, or between teeth and bones. When we say one bone articulates with another bone, we mean that one bone forms a joint with another bone.
Synovial Joint • Freely movable (DIARTHRODIAL) • Space between the articular surface of the bones forming the joint • A synovial membrane surrounds the joints and secretes a lubricating fluid called synovial fluid • Example – Shoulder, Knee, Hip • Classified by the number of axis about which they rotate (e.g., uniaxial, biaxial)
Cartilaginous Joint • Stable joint • Also called AMPHIARTHRODIAL • Somewhat moveable • Example – Intervertebral discs • Can be divided into two groups: • Syndesmosis – held together by strong ligaments which allow for minimal movements between the bones • Synchondrosis – joint separated by a fibrocartilage that allows for slight movement between the bones (Example of the joints betweenthe Ribs and Sternum)
Fibrous or Sutured Joint • Very stable • Also called SYNARTHRODIAL • No movement • Example – Sutures in the Skull
JOINT TYPES • There are a number of joints found within the human body: • HINGE JOINT • GLIDING JOINT • BALL and SOCKET JOINT • PIVOT JOINT • SADDLE JOINT • IMMOVABLE JOINT
HINGE JOINT • Bones that fit together like two part of a hinge – convex surface of one bone fits into the concave surface of another bone • Examples include ankle, elbow, phalanges • 1 axis..Usually flexion, extension, and hyperextension
GLIDING JOINT • The gliding surfaces are flat and the surfaces merely slide across one another • Limited movement; only side to side and back and forth movements are permitted • 0 axis; twisting and rotating are usually prohibited by attached ligaments or adjacent bones • Example include the carpals
BALL & SOCKET JOINT • The ball shape of one bone fits into the socket shape of the other (movement is multi- axial) • 3 axes; they allow three types of movements including flexion/extension, abduction/adduction, and rotation / circumduction • Examples include the shoulder and hip
PIVOT JOINT • One bone rotates around another, movement is only in one axis • Movement is permitted in only one plane, usually rotation • Examples include atlas/axis
SADDLE JOINT • Freely moving joint that resembles a saddle in two axes (oval head into shallow cavity); the articular surface of one bone is saddle-shaped and the articular surface of another bone is shaped like a rider sitting in the saddle • This joint is biaxial; movements are side to side, back and forth and sometimes circumduction • Ball and socket movement without rotation • Example include the 1st metacarpal and carpal at base of the thumb
IMMOVABLE JOINT • Bones that join but do not move • No axes • Examples include the cranium and teeth sutures
JOINT CHARACTERISTICS • A joint is the articulation of two or more connecting bones. The joint either provides stability or mobility. • Uniaxial - Move about one axis i.e.. Hinge • Biaxial - Movement about two axes i.e.. Ellipsoid • Triaxial - Movement about three exes i.e.. Ball & Socket • Nonaxial - Sliding motion rather than rotating i.e.. Wrist/Hand
RELATED JOINT STRUCTURES • LIGAMENTS • Strong connective tissues that run from bone to bone and help to maintain stability in a joint • Ligaments are not elastic and can lose their ability to perform correctly when stretched • They are NOT highly elastic and lost their ability to perform correctly when stretched • Prevents dislocation of bones – if they are repeatedly stretched or torn, survey may be necessary
RELATED JOINT STRUCTURES • Fibrocartilage • Occupies the space between certain bones to form the articular surface and can take on many sizes and shapes • Fibrocartilage is round and are known as disks (e.g., those between the vertebrae of the spine) while others may be flat or circular in shape (e.g., knee) • Resilient and functions as the shock absorber • It has no blood supply of its own and relies on synovial fluid for nourishment
RELATED JOINT STRUCTURES • Synovial Membrane • A synovial membrane is a thin tissue that surrounds most freely moving joints • The membrane secretes synovial fluid which provides nourishment for cartilaginous disks, lubrication, and hydrostatic cushioning
RELATED JOINT STRUCTURES • Bursae • Bursae is a liquid filled membrane that protects soft tissues as they pass by bony projections
RELATED JOINT STRUCTURES • Joint Capsule • A joint capsule is a tough fibrous sheet that surrounds many joints and functions to protect them and to provide stability • Surrounds the bony ends to form a joint cavity • Secretes synovial fluid to lubricate the area inside the joint capsule
RELATED JOINT STRUCTURES • Hyaline Cartilage • Covers bone ends to grease joint surface for smooth, friction-free movement • Most abundant in the human body