The Articular System Joint Connection between two bones

The Articular System

Joint �Connection between two bones �Joints allow motion �Bear body weight �Provides stability

Types of Joints �Fibrous �Cartilaginous �Synovial

Fibrous joint Has thin layer of periosteum between the bones e. g. – sutures of skull

� 3 types of fibrous joints: �Synarthrosis thin layer of fibrous periosteum between two bones no motion between bones �Syndesmosis great deal of fibrous tissue small amount of twisting or stretching e. g. - distal tibiofibular jint distal radio ulnar joint �Gomphosis between tooth & wall of its dental socket in mandible & maxilla

Cartilaginous joint �Hyaline or fibrocartilage is present between bone surfaces Vertebral joints: disc of fibro cartilage directly connect bones 1 st sternocostal joint: direct connection made by hyaline cartilage

Synovial (diarthrodial) joint �No direct union between bone ends �Joint surfaces covered with hyaline (articular) cartilage �Outer layer of capsule by strong fobrous tissue

Diarthroidal Joint Classification �Nonaxial �Uniaxial �Biaxial �Triaxial

Nonaxial �Linear movement �Flat surfaces of bone glide over each other

Uniaxial Angular movement (hinge) One plane around one axis

Biaxial Movement in 2 different directions allowed

Triaxial(multiaxial) Motion occurs at 3 axes

Joint Structure Bone Ligament- bands of fibrous tissue Hold ends of bones together Flexible, but not elastic

Joint Capsule Surrounds Protects 2 layers: Outer fibrous layer Inner layer Synovial membrane Synovial fluid http: //www. allaboutmydoc. com/surgeonweb/surgeon. Id. 2729/clinic. Id. 1432/theme 3/country. US/language. en/page. article/doc. Id. 20262

Cartilage – 3 Types Hyaline (articular) cartilage Fibrocartilage Meniscus Intervertebral discs Labrum Elastic cartilage Ear

Tendon Connects muscle to bone Tendon sheaths Aponeurosis Flat tendinous sheet Linea alba

Bursa Fluid filled sac Located in areas of friction Lined with synovial membrane Natural vs. Acquired

PLANES of the BODY �Sagittal plane �Divides body into left and right halves �Flexion/extension �Frontal plane �Divides body into front and back halves �Adduction/abduction �Transverse (Horizontal) plane �Divides body into top and bottom halves �Rotation �Cardinal Planes – divide the body equally

Axis �Point through center of joint around which the body part rotates �Movement Occurs In a Plane, Around an Axis

Sagittal axis Frontal axis Vertical axis

Degrees of Freedom �Number of planes in which a joint can move �Uniaxial joint – one degree of freedom, motion at one axis �Biaxial joint – 2 degrees of freedom, motion at 2 axes �Triaxial joint – 3 degrees of freedom, motion at 3 axes

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