Joints or Articulations

A joint, or articulation, is the place of union between two or more bones.

Classification of joints Based on movement 1.Synarthroses 2.Amphiarthroses 3.diarthroses Based on the structure 1.Fibrous Joints 2.Cartilaginous Joints 3.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 1.Shoulder joint 2.Elbow joint 3.Wrist joint 4.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 (amphiarthrodia l), 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 1.Symphysis 2.Synchondrosis

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 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 1.existence of capsules surrounding the articulating surfaces of a synovial joint and 2.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 A.Ligaments B.Articular capsule(fibrous capsule+synovial membrane+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.head 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

Movements in the ball socket glenohumeral shoulder joint