Joints and Their Classification Arthrology = study of the joints Kinesiology = study of musculoskeletal movement Classified how adjacent bones are joined Fibrous – by fibrous connective tissue with no space between Cartilaginous – by pad or bridge of cartilage Synovial – bones separated by fluid- filled cavity covered by connective tissue Classified by freedom of movement Synarthrosis (little or no movement) – fibrous or cartilaginous Amphiarthrosis (slightly movable) – fibrous or cartilaginous Diarthrosis (freely movable) – always synovial 7-1

Synarthroses - immobile joints 1. Synostosis - Bony Joint Gap between two bones ossifies frontal and mandibular bones in infants cranial sutures in elderly attachment of first rib and sternum Can occur in either fibrous or cartilaginous joint 7-2

Synarthroses -Fibrous Joints Collagen fibers span the space between bones 1. Sutures - bind skull bones together Serrate - interlocking lines coronal, sagittal and lambdoid sutures Lap - overlapping beveled edges temporal and parietal bones Plane - straight, non-overlapping edges palatine processes of the maxillae 2. Gomphosis Attachment of a tooth to its socket Held in place by fibrous periodontal ligament collagen fibers attach tooth to jawbone Some movement while chewing 7-3

Synarthroses -Cartilaginous Joint Synchondrosis Bones are joined by hyaline cartilage rib attachment to sternum epiphyseal plate in children binds epiphysis and diaphysis 7-4

Amphiarthroses - fibrous joint Syndesmosis Two bones bound by ligament only interosseus membrane Most movable of fibrous joints Interosseus membranes unite radius to ulna and tibia to fibula 7-5

Amphiarthroses - cartilaginous joint Symphysis 2 bones joined by fibrocartilage pubic symphysis and intervertebral discs Only slight amount of movement is possible 7-6

Diarthrosis - Synovial Joint Joint in which two bones are separated by a space called a joint cavity Most are freely movable 7-7

General Anatomy Articular cartilage = hyaline cartilage covering the joint surfaces Synovial cavity Articular capsule encloses joint cavity continuous with periosteum lined by synovial membrane Synovial fluid = slippery fluid; feeds cartilages Articular discs and menisci jaw, wrist, sternoclavicular and knee joints absorbs shock, guides bone movements and distributes forces Tendon attaches muscle to bone Ligament attaches bone to bone 7-8

Tendon Sheaths and Bursae Bursa = saclike extension of joint capsule between nearby structures so slide more easily past each other Synovial tendon sheaths = cylinders of connective tissue lined with synovial membrane and wrapped around a tendon 7-9

Range of Motion Degrees through which a joint can move Nonaxial – vertebrocostal, sacroiliac Monoaxial – elbow, knee,ankle, interphalangeal Biaxial – radiocarpal Triaxial (multiaxial) – sholder, hip Determined by structure of the articular surfaces strength and tautness of ligaments, tendons and capsule stretching of ligaments increases range of motion double-jointed people have long or slack ligaments action of the muscles and tendons nervous system monitors joint position and muscle tone 7-10

Types of Synovial Joints 7-11