Chapter 8

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

Ph.D.

Classification of JointsTable 8.1 - Summary of Joint ClassesStructural

Fibrous - bones joined by fibrous connective tissue; no joint cavity

Cartilaginous - bones joined by cartilage; no joint cavity

Synovial - bones separated by fluid filled cavity

Functional Synarthroses - non-movable Amphiarthroses - slightly movable Diarthroses - freely movable

Fibrous JointsSuture - wavy

border with dense fibrous connective tissue which penetrates into both bone

Syndesmosis - connected by a ligament

Gomphosis - peg in a socket (teeth)

Cartilaginous JointsSynchondroses

hyaline cartilage epiphyseal plate

• most limb bones most ribs to sternum

Symphyses fibrocartilage pelvis, vertebrae

Synovial JointsGeneral Structure

articular cartilage synovial (joint) cavity articular capsule synovial fluid reinforcing ligaments

meniscus – a fibrocartilage pad, e.g., at the tempero-mandibular joint (TMJ) and at the tibio-femoral (knee) joint

Synovial JointsBursae - flattened sacs filled with synovial fluidTendon sheath - elongated bursa which wraps

around a tendon

Synovial JointsGliding (plane)

joint

flat planes gliding over each other

intercarpal and intertarsal joints

Synovial JointsHinge

cylindrical projection fits into a notch

ulna and humerus

tibia and femur

interphalangeal joints

Synovial JointsPivot

rounded end of one bone protrudes into sleeve or ring of bone or ligaments

atlas (C1) and dens of the axis (C2)

proximal radio-ulnar joint

Synovial JointsCondyloid

rounded (convex) articulating surface of one bone fits into concave depression on the other bone

radio-carpal joints

metacarpal-phalangeal joints

Synovial JointsSaddle

each articular surface has both convex and concave areas

carpo-metacarpal joint of the thumb

special case of a condyloid joint

Synovial JointsBall and Socket

spherical or hemispherical head of one bone articulates with cuplike socket

provides greatest rotational flexibility

shoulder hip special case of a

condyloid joint which is capable of circumduction

Know the Terminology for Types of Motions in Your Lab Guide

GlidingRotationFlexion/ExtensionAbduction/AdductionCircumductionSpecial Movements

Reviewed in lab

Factors Influencing Joint StabilityArticular surfaces – shape and condition

are important for smooth functioning of the joint

Ligaments – dense regular fibrous connective tissue which will only stretch ~6% before tearing

Muscle Tone most important tone - resting activity – some minimal level of

contraction operating at all times 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

The knee joint is a classic site for repeated injuries.

Since cartilage does not repair well, the cumulative effect of multiple traumas is to permanently weaken the joint.

Anterior 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 stabilizethe repair.

ArthritisMore than 100 different types of

inflammatory or degenerative joint diseasesMost 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

Special Movements

Ligaments and Tendons of Kneeall contribute to

stability

many contribute to fibrous capsule

SprainsThe 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

By embryonic week 8, synovial joints resemble adult joints

Few problems occur until late middle age

Advancing years take their toll on joints: Ligaments and tendons shorten and weaken Intervertebral discs become more likely to

herniate Most people in their 70s have some degree of

OA

Prudent 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