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Joints   (download here)

Joints (Articulations)

•      Weakest parts of the skeleton

•      Articulation – site where two or more bones meet

•      Functions

•    Give the skeleton mobility

•    Hold the skeleton together

Classification of Joints: Structural

•      Structural classification focuses on the material binding bones together and whether or not a joint cavity is present

•      The three structural classifications are:

•    Fibrous

•    Cartilaginous

•    Synovial

Classification of Joints: Functional

•      Functional classification is based on the amount of movement allowed by the joint

•      The three functional class of joints are:

•    Synarthroses – immovable

•    Amphiarthroses – slightly movable

•    Diarthroses – freely movable

Fibrous Structural Joints

•      The bones are jointed by fibrous tissues

•      There is no joint cavity

•      Most are immovable

•      There are three 
types – sutures, 
syndesmoses, 
and gomphoses

Fibrous Structural Joints: Sutures

•      Occur between the bones of the skull

•      Comprised of interlocking junctions completely filled with CT fibers

•      Bind bones tightly together, but allow for growth during youth

•      In middle age, skull bones fuse and are called synostoses

Fibrous Structural Joints: Syndesmoses

•      Bones are connected by a fibrous tissue ligament

•      Movement varies from immovable to slightly variable

•      Examples include the connection between the tibia and fibula, and the radius and ulna

Fibrous Structural Joints: Gomphoses

•      The peg-in-socket fibrous joint between a tooth and its alveolar socket

•      The fibrous connection is the periodontal ligament

Cartilaginous Joints

•      Articulating bones are united by cartilage

•      Lack a joint cavity

•      Two types – synchondroses and symphyses

Cartilaginous Joints: Synchondroses

•      A bar or plate of hyaline cartilage unites the bones

•      All synchondroses are synarthrotic

•      Examples include:

•    Epiphyseal plates of children

•    Joint between the costal cartilage of the first rib and the sternum

Cartilaginous Joints: Symphyses

•      Hyaline cartilage covers the articulating surface of the bone and is fused to an intervening pad of fibrocartilage

•      Amphiarthrotic joints designed for strength and flexibility

•      Examples include intervertebral joints and the pubic symphysis of the pelvis

 

Synovial Joints

 

•      Those joints in which the articulating bones are separated by a fluid-containing joint cavity

•      All are freely movable diarthroses

•      Examples – all limb joints, and most joints of the body

Synovial Joints: General Structure

•      Synovial joints all have the following:

•    Articular cartilage

•    Joint (synovial) cavity

•    Articular capsule

•    Synovial fluid

•    Reinforcing ligaments

Synovial Joints: Friction-Reducing Structures

•      Bursae – flattened, fibrous sacs lined with synovial membranes and containing synovial fluid

•      Common where ligaments, muscles, skin, tendons, or bones rub together

•      Tendon sheath – elongated bursa that wraps completely around a tendon

Synovial Joints: Stability

•      Stability is determined by:

•    Articular surfaces – shape determines what movements are possible

•    Ligaments – unite bones and prevent excessive or undesirable motion

•      Muscle tone is accomplished by:

•    Muscle tendons across joints are the most important stabilizing factor

•    Tendons are kept tight at all times by muscle tone

Synovial Joints: Movement

•      Muscle attachment across a joint

•    Origin – attachment to the immovable bone

•    Insertion – attachment to the movable bone

•      Described as movement along transverse, frontal, or sagittal planes

Synovial Joints: Range of Motion

•      Nonaxial – slipping movements only

•      Uniaxial – movement in one plane

•      Biaxial – movement in two planes

•      Multiaxial – movement in or around all three planes

Gliding Movements

•      One flat bone surface glides or slips over another similar surface

•      Examples – intercarpal and intertarsal joints, and between the flat articular processes of the vertebrae

Angular Movement

•      Flexion

•      Extension

•      Dorsiflexion and plantar flexion of the foot

•      Abduction

•      Adduction

•      Circumduction

Rotation

•      The turning of a bone around its own long axis

•      Examples:

•    Between first two vertebrae

•    Hip and shoulder joints

Special Movements

•      Supination and pronation

•      Inversion and eversion

•      Protraction and retraction

•      Elevation and depression

•      Opposition

Types of Synovial Joints

•      Plane joints

•    Articular surfaces are essentially flat

•    Allow only slipping or gliding movements

•    Only examples of nonaxial joints

•      Hinge joints

•    Cylindrical projections of one bone fits into a trough-shaped surface on another

•    Motion is along a single plane

•    Uniaxial joints permit flexion and extension only

•    Examples: elbow and interphalangeal joints

 

Pivot Joints

•      Rounded end of one bone protrudes into a “sleeve,” or ring, composed of bone (and possibly ligaments) of another

•      Only uniaxial movement allowed

•      Examples: joint between the axis and the dens, and the proximal radioulnar joint

Condyloid, or Ellipsoidal, Joints

•      Oval articular surface of one bone fits into a complementary depression in another

•      Both articular surfaces are oval

•      Biaxial joints permit all angular motions

•      Examples: radiocarpal (wrist) joints, and metacarpophalangeal (knuckle) joints

Saddle Joints

•      Similar to condyloid joints but with greater movement

•      Each articular surface has both a concave and a convex surface

•      Example: carpometacarpal joint of the thumb

Ball-and-Socket Joints

•      A spherical or hemispherical head of one bone articulates with a cuplike socket of another

•      Multiaxial joints permit the most freely moving synovial joints

•      Examples: shoulder and hip joints

Synovial Joints: Shoulder (Glenohumeral)

•      Ball-and-socket joint in which stability is sacrificed to obtain greater freedom of movement

•      Head of humerus articulates with the glenoid fossa of the scapula

Synovial Joints: Shoulder Stability

•      Weak stability is maintained by:

•    Thin, loose joint capsule

•    Four ligaments – coracohumeral, and three glenohumeral

•    Tendon of the long head of biceps, which travels through the intertubercular groove and secures the humerus to the glenoid cavity

•    Rotator cuff (four tendons) encircles the shoulder joint and blends with the articular capsule

Synovial Joints: Knee

•      Largest and most complex joint of the body

•      Allow flexion, extension, and some rotation

•      Three joints in one surrounded by a single joint cavity

•    Femoropatellar

•    Lateral and medial tibiofemoral joints

Synovial Joints: Major Ligaments and Tendons – Anterior View

•      Tendon of the quadriceps femoris muscle

•      Lateral and medial patellar retinacula

•      Fibular collateral ligament

•      Tibial collateral ligament

•      Patellar ligament

Synovial Joints: Knee – 
Other Supporting Structures

•      Anterior cruciate ligament

•      Posterior cruciate ligament

•      Medial meniscus (semilunar cartilage)

•      Lateral meniscus

Synovial Joints: Knee – Posterior Superficial View

•      Adductor magnus tendon

•      Articular capsule

•      Oblique popliteal ligament

•      Arcuate popliteal ligament

•      Semimembranosus tendon

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

Arthritis

•      More than 100 different types of inflammatory or degenerative diseases that damage the joints

•      Most widespread crippling disease in the U.S.

•      Symptoms – pain, stiffness, and swelling of a joint

•      Acute forms are caused by bacteria and are treated with antibiotics

•      Chronic forms include osteoarthritis, rheumatoid arthritis, and gouty arthritis

Osteoarthritis (OA)

•      Most common chronic arthritis; often called “wear-and-tear” arthritis

•      Affects women more than men

•      85% of all Americans develop OA

•      More prevalent in the aged, and is probably related to the normal aging process

Osteoarthritis: Course

•      OA reflects the years of abrasion and compression causing increased production of metalloproteinase enzymes that break down cartilage

•      As one ages, cartilage is destroyed more quickly than it is replaced

•      The exposed bone ends thicken, enlarge, form bone spurs, and restrict movement

•      Joints most affected are the cervical and lumbar spine, fingers, knuckles, knees, and hips

Osteoarthritis: Treatments

•      OA is slow and irreversible

•      Treatments include:

•    Mild pain relievers, along with moderate activity

•    Magnetic therapy

•    Glucosamine sulfate decreases pain and inflammation

•    SAM-e (s-adenosylmethionine) builds up cartilage matrix and regenerates tissue

Rheumatoid Arthritis (RA)

•      Chronic, inflammatory, autoimmune disease of unknown cause, with an insidious onset

•      Usually arises between the ages of 40 to 50, but may occur at any age

•      Signs and symptoms include joint tenderness, anemia, osteoporosis, muscle atrophy, and cardiovascular problems

•      The course of RA is marked with exacerbations and remissions

Rheumatoid Arthritis: Course

•      RA begins with synovitis of the affected joint

•      Inflammatory blood cells migrate to the joint, causing swelling

•      Inflamed synovial membrane thickens into a pannus

•      Pannus erodes cartilage, scar tissue forms, articulating bone ends connect

•      The end result, ankylosis, produces bent, deformed fingers

Rheumatoid Arthritis: Treatment

•      Conservative therapy – aspirin, long-term use of antibiotics, and physical therapy

•      Progressive treatment – anti-inflammatory drugs or immunosuppressants

•      The drug Embrel, a biological response modifier, removes cells that promote inflammation

Gouty Arthritis

•      Deposition of uric acid crystals in joints and soft tissues, followed by an inflammation response

•      Typically, gouty arthritis affects the joint at the base of the great toe

•      In untreated gouty arthritis, the bone ends fuse and immobilize the joint

•      Treatment – colchicine, nonsteroidal anti-inflammatory drugs, and glucocorticoids

 

 

 
Joints

What you need to know:

  1. Functions of Joints
  2. Structural and functional classifications of joints
  3. Where the various joints are located
  4. Structures of joints
  5. Details of the hip, shoulder and knee joints  special download here
  6. All joint movements (flexion, extension etc.)

 

 

Brief Notes:

Articulationΰjoint, where two bones interact

3 functional categories of joints

    1. synarthorsis – immovable joint
    2. Amphiarthrosis – slightly movable joint
    3. Diarthrosis – freely movable

 Synarthrosis:

  • a.      suture – between bones of skull; bound by dense connective tissue

  • b.      Periodontal ligament – binds tooth to bony sockets (fibrous); articulation = gomphosis (bolting together)

  • c.      Synostosis – fusion of two separate bones forming a rigid immovable joint

 Ampphiarthrosis:

Maybe connected by collagen fibers in cartilage

  1. syndismosis – articulation bones are connected by ligaments (tibia & fibula)
  2. symphysis -  bones are separated by a wedge or pad of fibro-cartilage ( pubic symphysis, invertebrate discs
  3. Diarthrosis – Synovial joint
  • -          permits a wide range of movement

  • -          found at ends of long bones

  • -          articulation surfaces covered by cartilage

  • -          surround by a capsule- dense connective tissue

 Synovial membrane line joint & produce Synovial fluid

  • -          provide lubrication

  • -          nourish the chondrocyte

  • -          act as shock absorber

Accessory structures:

  1. pads of cartilage or fatsΰ provides protection, fills spaces when bines move
  2. ligamentsΰstrengthen or reinforce joint capsule
  3. tendonsΰ pass across & over 7& around the joint
  4. bursaeΰ (purse) small fluid filled sacs of connective tissue

Articular form & function:

-          Possible movement of bone at articulation

    1. linear motion
    2. angular motion
    3. rotation

 joints classified on the number of axes they allow movement

-          monaxialΰ joint (back/forth)

-          biaxialΰ back/forth & left/right

-          triaxialΰ rotation, angular motion, in multiple planes 

types of movement:

  1. gliding
  2. angular motion
  • -          abductionΰ away from the longitudinal axis of the body

  • -          adductionΰ back to longitudinal axis of the body

  • -          flexionΰ reduces the angle between articulation elements

  • -          extensionΰ increase the angle between articulation elements

  • -          hyperextensionΰ further than articulations position

  • -          circumductionΰ

 Rotation – left & right

  • -          pronation

  • -          supination 

Special movements:

  • -          eversion/inversion (foot)

  • -          plantar flexion & dorsiflexion (foot)

  • -          lateral flexion

  • -          protraction/retraction; movement in a horizontal plane (movement of mouth back & forth)

  • -          opposition; allow to grasp with a thumb

  • -          elevation/depression (mouth: open & close) 

Structural classification of Synovial joints:

  • -   gliding jointsΰ flattened surfaces; slide across one another ( found at ends of clavicles; between carpals & tarsals; between facets of adjoining vertebrae); classified as monaxialθ permits small sliding movement; multiaxialθ slides in any directions

  • -   hinge jointΰ permits angular movement in a single pane monaxial ( elbow & knee)

  • -   pivot jointsΰ permit only rotation (monaxialθ axis, atlas, head rotation)

  • -   ellipsoidal jointΰoval artic surface nestled in a depression; angular motion in 2 planes ( biaxialθ connection of fingers & toes with metatarsals & metacarpals)

  • -   saddle jointsΰ concave on one axis & convex on the other; allows angular motion w/o rotation ; base of thumb allowing twiddle (biaxial)

  • -   Ball & socket  jointΰ round head of bones rest w/in a cup shape of another; triaxialθ all combination of movements (shoulder & hip)