Chapter 8 Joints J.F. Thompson, Ph.D. & J.R. Schiller, Ph.D. & G. Pitts, Ph.D.

Classification of Joints òTable Summary of Joint Classes òStructural l Fibrous - bones joined by fibrous connective tissue; no joint cavity l Cartilaginous - bones joined by cartilage; no joint cavity l Synovial - bones separated by fluid filled cavity òFunctional l Synarthroses - non-movable l Amphiarthroses - slightly movable l Diarthroses - freely movable

Fibrous Joints òSuture - wavy border with dense fibrous connective tissue which penetrates into both bone òSyndesmosis - connected by a ligament òGomphosis - peg in a socket (teeth)

Cartilaginous Joints òSynchondroses l hyaline cartilage l epiphyseal plate most limb bones l most ribs to sternum òSymphyses l fibrocartilage l pelvis, vertebrae

Synovial Joints òGeneral Structure l articular cartilage l synovial (joint) cavity l articular capsule l synovial fluid l reinforcing ligaments l meniscus – a fibrocartilage pad, e.g., at the tempero-mandibular joint (TMJ) and at the tibio-femoral (knee) joint

Synovial Joints òBursae - flattened sacs filled with synovial fluid òTendon sheath - elongated bursa which wraps around a tendon

Synovial Joints òGliding (plane) joint l flat planes gliding over each other l intercarpal and intertarsal joints

Synovial Joints òHinge l cylindrical projection fits into a notch l ulna and humerus l tibia and femur l interphalangeal joints

Synovial Joints òPivot l rounded end of one bone protrudes into sleeve or ring of bone or ligaments l atlas (C1) and dens of the axis (C2) l proximal radio-ulnar joint

Synovial Joints òCondyloid l rounded (convex) articulating surface of one bone fits into concave depression on the other bone l radio-carpal joints l metacarpal-phalangeal joints

Synovial Joints òSaddle l each articular surface has both convex and concave areas l carpo-metacarpal joint of the thumb l special case of a condyloid joint

Synovial Joints òBall and Socket l spherical or hemispherical head of one bone articulates with cuplike socket l provides greatest rotational flexibility l shoulder l hip l special case of a condyloid joint which is capable of circumduction

Know the Terminology for Types of Motions in Your Lab Guide Gliding Rotation Flexion/Extension Abduction/Adduction Circumduction Special Movements Reviewed in lab

Factors Influencing Joint Stability òArticular surfaces – shape and condition are important for smooth functioning of the joint òLigaments – dense regular fibrous connective tissue which will only stretch ~6% before tearing òMuscle Tone l most important l tone - resting activity – some minimal level of contraction operating at all times l muscles, tendons, and ligaments are supplied with sensory nerve endings for feedback control of limb and body position and posture

Sagittal View of Knee Joint

òThe knee joint is a classic site for repeated injuries. òSince cartilage does not repair well, the cumulative effect of multiple traumas is to permanently weaken the joint. òAnterior view.

Knee joint relationships with some associated muscles Ligaments and tendons contribute to joint stability. Physical therapists and practitioners of sports medicine must become expert in the anatomy of the musculoskeletal system.

A common knee injury A blow from the side forces the bones to move in a direction incompatible with the joint’s design. Ligaments are not flexible so they tear. They can repair with time. Cartilage repair will be minimal.

Anterior Cruciate Ligament (ACL) Injury ACL torn above → & repaired below; screws stabilize the repair. 

Arthritis  More than 100 different types of inflammatory or degenerative joint diseases  Most common crippling diseases in the U.S.  Symptoms – pain, stiffness, and swelling of joint(s)  Acute forms are caused by bacteria and are treated with antibiotics  Chronic forms include osteoarthritis (OA), rheumatoid arthritis, and gouty arthritis

After the End of Chapter 8, You Will Find Some Additional Slides with More Detailed Information on Certain Topics for Your Review

End Chapter 8

Gliding Movement Figure 8.5a

Angular Movement

Rotational Movement

ò Special Movements

Ligaments and Tendons of Knee all contribute to stability many contribute to fibrous capsule

Sprains  The ligaments reinforcing a joint are stretched or torn  Partially torn ligaments slowly repair themselves  Completely torn ligaments require prompt surgical repair

Cartilage Injuries  The snap and pop of overstressed cartilage  Common aerobics injury  Repaired with arthroscopic surgery

Dislocations  Occur when bones are forced out of alignment  Usually accompanied by sprains, inflammation, and joint immobilization  Caused by serious falls and are common sports injuries  Subluxation – partial dislocation of a joint

Inflammatory and Degenerative Conditions  Bursitis  An inflammation of a bursa, usually caused by a blow or friction  Symptoms are pain and swelling  Treated with anti-inflammatory drugs; excessive fluid may be aspirated  Tendonitis  Inflammation of tendon sheaths typically caused by overuse  Symptoms and treatment are similar to bursitis

Developmental Aspects of Joints òBy embryonic week 8, synovial joints resemble adult joints òFew problems occur until late middle age òAdvancing years take their toll on joints: l Ligaments and tendons shorten and weaken l Intervertebral discs become more likely to herniate l Most people in their 70s have some degree of OA òPrudent exercise (especially swimming) that coaxes joints through their full range of motion is key to postponing joint problems

End Chapter 8 End of extra review slides