JOINTS Types of Joints Joints n Functional junctions

JOINTS

Types of Joints

Joints n Functional junctions between bones n Vary in structure and function n Classified according to the degree of movement they make possible (immovable, slightly movable, freely movable) n Grouped by type of tissue (fibrous, cartilaginous, or synovial)

Fibrous Joints n Lie between bones that closely contact one another n Thin layer of fibrous connective tissue joins the bones at such joints (pair of flat bones of the skull) n No appreciable movement in fibrous joints

Cartilaginous Joints n Disks of fibrocartilage or hyaline cartilage connect the bones of cartilaginous joints. n For example: Joints of this type separate the vertebrae of the vertebral column. n Intervertebral disks absorb shocks and helps equalize pressures between adjacent vertebrae. n They allow limited movement (the back is bent forward or to the side)

Cartilaginous Joints 2 60 × 280

Synovial Joints n Most joints within the skeletal system n Allow free movement n More complex structurally than fibrous or cartilaginous joints. n Joint Capsule- Articular ends of the bones are covered with hyaline cartilages and a surrounding dense fibrous tissue covering holds them together. n Joint capsule is composed of ligaments and synovial membrane.

Synovial Joint 722 × 704

Synovial continued: Menisci and Bursae n Some synovial joints have flattened, shock absorbing pads of fibrocartilage called menisci n Menisci are between articulating surfaces of the bone called bursae. n Each bursa is lined with synovial membrane which may be continuous with the synovial membrane of a near by joint cavity. n Bursae are commonly located between the skin and underlying bony prominences and aid in movement of the tendons.

Bursa and Meniscus

Classifications of synovial joints n Ball- and- socket joint n Condyloid joint n Gliding joints n Hinge Joint n Pivot Joint n Saddle Joint

Ball and Socket Joints n consists of a bone with a ball shaped head that articulates with a cup- shaped cavity of another bone. n These joints allow for a wider range of movement n Allows for movement on all planes and rotational movement around a central axis n Ex. : Shoulder and hip

Condyloid joint 1116 × 651 n An oval shaped condyle of one bone fits into an elliptical cavity of another bone n This joint permits a variety of movemnts in different planes. Rotational movement is impossible. n Ex. : Joints between metacarpals and phalanges

Gliding Joints n The articulating surfaces of gliding joints are nearly flat of slightly curved. n These joints allow sliding and twisting movements. n Ex. : Most joints within wrist, ankle, those adjacent to the vertebrae, sacroiliac joint, and the joints formed by ribs connecting with the sternum are also gliding.

Hinge Joint n A convex surface of one bone fits into the concave surface of another n This joint is like a door and permits movement in only one plane. n Ex. : Elbow and joints of phalanges 432 × 356

1339 × 808 n The cylindrical surface on one 1600 × bone rotates within a ring formed of bone and fibrous tissue. n Movement is limited to the rotation around a central axis. n Ex. : Joint between the proximal ends of the radius and the ulna, skull and top vertebrae 1350 Pivot Joint

Saddle joint n These joints form between bones whose articulating surfaces have both concave and convex regions. n The surface of one bone fits the complementary surface of the other. n Ex. : The joint between the carpal and metacarpal of the thumb.