Joints or Articulations • A joint, or articulation, is the place of union between two or more bones.
Classification of joints Based on movement • Synarthroses • Amphiarthroses • diarthroses Based on the structure • Fibrous Joints • Cartilaginous Joints • Synovial Joints
Synarthroses • Immovable Joints
Amphiarthroses Slightly Movable joints • articulations between the bodies of the vertebrae. • the sternocostal joint.
Diarthrosis • Types of joints which allow free movement • Few examples • Shoulder joint • Elbow joint • Wrist joint • Knee joint
Fibrous Joints The fibrous joints are further divided into three types: Sutures Syndesmosis Gomphosis
Sutures Sutures Connected by dense regular connective tissue. Synarthrotic joints. • Eg:bones of the skull. In fetal skulls the sutures are wide to allow slight movement during birth. They later become rigid.
Syndesmosis Syndesmosis Unlike other fibrous joints, syndesmoses are moveable (amphiarthrodial), albeit not to such degree as synovial joints. Connected by interosseous ligaments • Eg: radius and ulna in forearm and the fibula and tibia in leg.
Gomphosis • Gomphosis is a joint between the root of a tooth and the sockets in the maxilla or mandible. • Held together by strong fibres • Synarthrotic joint
Cartilagenous joints • Cartilaginous joints are connected entirely by cartilage (fibrocartilage or hyaline) Classified into • Symphysis • Synchondrosis
Symphsis Symphsis • have a thick, fairly compressible pad of fibrocartilage between articulating bones • Amphiarthrotic • Eg: manubriosternal joint (between the manubrium and the sternum)intervertebral discs, and the pubic symphysis.
Synchondrosis • Synchondrosis • Bone segments seperated by hyaline cartilage • Synarthrotic joint • Eg: the hyaline cartilage occurring between ossification centers
Synovial Joint • The main structural differences between synovial and fibrous joints is the • existence of capsules surrounding the articulating surfaces of a synovial joint and • the presence of lubricating synovial fluid within that capsule (synovial cavity). All for allowing the easy movement of the two bones with ease
Synovial Joint • All synovial joints are diarthrotic
Synovial Joint • Ligaments • Articular capsule(fibrous capsule+synovialmembrane+articular cartilage) • Synovial membrane: makes synovial fluid
Hinge Joints • These joints occur where the convex surface of one bone fits into the concave surface of another bone, so making movement possible in one plane only • Allows only flexion and extension • Elbow joint and Knee joint
Pivot • Permits rotational movements along the single axis • the joint between the atlas and the axis (first and second cervical vertebrae), which allows for turning of the head from side to side. • Between radius and ulna bringing about supinationa and pronation
Gliding/plane joint • Plane joints permit sliding or gliding(side to side) movements in the plane of articular surfaces. The opposed surfaces of the bones are flat or almost flat • The eight carpal bones in the wrist (arranged in two adjacent rows of 4 carpals) form an example of a gliding joint, the mid-carpal joint.
Condyloid • an ovoid articular surface, or condyle, is received into an elliptical cavity. • This permits movement in two planes, allowing flexion, extension, adduction, abduction, and circumduction. • Eg:the movement of the fingers
Saddle joint • In a saddle joint (sellar joint, articulation by reciprocal reception) the opposing surfaces are reciprocally concave-convex. • The best example of is carpometacarpal joint of the thumb.
Ball and socket joint • Ball like spherical part of one bone fits into socket of other bone • Provides greatest range of movement in all axis • Permits flexion,extension, abduction,adduction and circumduction • Glenohumeral shoulder joint • Hip joint