Articulations (Joints) Martini Chapter 9 Bio 103 Feb 11, 2008.

Articulations (Joints)

Martini

Chapter 9

Bio 103

Feb 11, 2008

Joint Classifications

1. Functional Classification• based on range of motion

2. Anatomical (structural) Classification• based on material in joint

Structural vs. Functional Joint Classifications

• structural categories do have some relationship with the functional categories (structure function)

Structural Joint Categories

1. Fibrous• no joint cavity• held together with fibrous connective tissue



2. Cartilaginous• no joint cavity• held together with cartilage



2. Cartilaginous• no joint cavity• held together with cartilage

3. Synovial• has a joint cavity• articular capsule and ligaments join bones

Functional Joint Classification

3 Functional Classifications

1. Synarthrosis (together + joint)

– no movement– structural type:

• fibrous, cartilaginous, or bony fusion

4 Types of Synarthrotic Joints

1. Suture (sewn together)

• fibrous• bound by dense fibrous connective tissue• found only in skull


2. Gomphosis (bolted together)

• fibrous• binds teeth to bony sockets (maxillary bone and

mandible) • fibrous connection between tooth and socket is

called periodontal ligament

4 Types of Synarthrotic Joints3. Synchondrosis (together + cartilage)

• cartilaginous• rigid bridge between 2 bones

– epiphyseal cartilage of long bones – Between ribs and sternum


4. Synostosis • totally rigid fused bones (bony fusion)• epiphyseal lines of mature long bones• metopic suture in frontal bone (doesn’t always fuse!)

Craniosynostosis

• when skull sutures fuse prematurely


2. Amphiarthrosis (both sides + joint)

– little movement– structural type:

• fibrous or cartilaginous

2 Types of Amphiarthroses

1. Syndesmosis (desmos = ligament)

– bones connected by ligaments• example between tibia and fibula

2 Types of Amphiarthroses

2. Symphysis– bones separated by a wedge or pad of fibrocartilage

• intervertebral discs• connection between pubic bones


3. Diarthrosis (through + joint)

– more movement– articular cartilage + synovial fluid +

accessory structures

Diarthrosis (Synovial) Joints

• freely moveable joints• catagorized by movement type• typically located in appendicular skeleton, at

connections of long bones

The shoulder joint is the most freely moving joint in the body.

Synovial Joint Structure• articular capsule

– unites 2 bone ends



– outer layer • fibrous, dense irregular connective

tissue that blends with the periostea of the two bones to form ligaments



– outer layer • fibrous, dense irregular connective

tissue that blends with the periostea of the two bones to form ligaments

– inner layer (synovial membrane) • composed of areolar tissue and

epithelial tissue

Synovial Joint Structure• articular cartilage

– like hyaline cartilage, but• no perichondrium• matrix more watery

Synovial Joint Structure• synovial fluid

– thin film between articular cartilage• creates smooth gliding surface

Synovial Joint Structure• synovial fluid

– thin film between articular cartilage• creates smooth gliding surface

– similar to interstitial fluid with high concentration of proteoglycans• consistency of molasses

Functions of Synovial fluid

• Lubrication– cartilage sucks up fluid like sponge

and releases when compressed to reduce friction




• Nutrient Distribution– fluid circulates bringing nutrients

and removing wastes for chondrocytes




• Nutrient Distribution– fluid circulates bringing nutrients

and removing wastes for chondrocytes

• Shock absorption– lessens shock by distributing

pressure evenly across articular surface

Synovial Joint Accessory Structures

• Cartilages

– meniscus (crescent)

• aka articular disc

• pad of fibrocartilage that sits between 2 bones


• Fat pads

– covered by synovial membrane

– protect articular cartilages • act as packing material for joint,

filling in spaces left as joint cavity changes shape


• Ligaments– attach bone to bone– support and strengthen joints


• Ligaments– Intrinsic (capsular)

ligaments• thickening of joint capsule


• Ligaments

– Extrinsic ligaments• separate from joint capsule

1. intracapsular (inside capsule)– e.g., ACL, PCL

2. extracapsular (outside capsule)– patellar ligament

Sprains

• ligament collagen stretched/torn

• more likely to break bone than tear ligament


• Tendons– attach to muscles around

joint, but not a part of articulation

– pass through/around joint and can affect joint movement


• Bursae (pouch) – pockets of synovial fluid

that cushion areas where tendons or ligaments rub against other tissue

– synovial tendon sheaths• tubular bursae that surround

tendons where they cross bone

Bursitis

• inflammation of bursae causing pain during motion

• caused by:

– overuse– pressure

• bunion

– chemicals/infection

Stabilization of Joints

• movement beyond range causes joint damage



• greater range of motion = greater chance for injury




• To reduce chance of injury joints are stabilized by:




• To reduce chance of injury joints are stabilized by:

1. collagen fibers of capsule and ligaments

2. shape of articulating surfaces and menisci might prevent

movement in certain directions

3. presence of other bones, muscles, fat pads around joint

4. tension in tendons encourages movement in specific direction

Describing Dynamic Motion

3 possible movements

1. linear (gliding)

2. angular (circumduction)

3. rotation

Types of Movements at Synovial Joints


• Linear Motion (Gliding)

– 2 opposing surfaces slide past one another

between tarsal bonesbetween carpal bones clavicle and sternum


• Flexion/Extension– movement in anterior/posterior

plane• flexion reduces the angle• extension increases the angle

• in the anatomical position, all major joints (except ankle) are at full extension.

• extension past the anatomical position is called hyperextension• example is bending your neck backwards

to look at the sky

http://davisplus.fadavis.com/wilkinson/animations.cfm


• Abduction/Adduction– angular movement in frontal

plane• abduction moves away from the

longitudinal axis of the body• adduction moving towards the

longitudinal axis of the body



• Circumduction– angular motion,

without rotation



• Rotation– Left or right rotation

– Medial rotation (inward rotation) • rotates toward axis

– Lateral rotation (outward rotation) • rotates away from axis



• Rotation of the forearm– Pronation:

• rotates forearm, radius over ulna

– Supination:• forearm in anatomical position


Special Movements

• Inversion/Eversion– twisting motion of the foot that turns sole

inward (inversion) or outward (eversion)


Special Movements

• Dorsiflexion/Plantar flexion– flexion at ankle joint

• dorsiflexion elevates sole• plantar flexion elevates heel

NOTE: it is acceptable

to use the terms flexion and

extension for these

movements of the ankle.

Special Movements

• Opposition– thumb movement toward fingers or palm (grasping)

• only primates and a few other species have opposable thumbs• humans can move their thumbs farther across their hand than any other primate


Special Movements

• Protraction– moves anteriorly– in the horizontal plane (pushing forward)

• Retraction– opposite of protraction– moving anteriorly (pulling back)

Special Movements

• Elevation– moves in superior direction (up)

• Depression– moves in inferior direction (down)

shoulder shrug

Special Movements

• Lateral Flexion– bends vertebral column from side to side


Synovial Joint Types

Classified by:1. Movement Type

2. Structure Type

Synovial Joint Classification Based on Movement


1. Nonaxial (Gliding) • gliding movements only

• carpals, tarsals, sacroiliac (sacrum to ilium)

between carpal bones


2. Uniaxial (monoaxial)• angular movement in one plane

• hinge joints (temporomandibular joint)• pivot joints (atlas to axis and proximal radioulnar)


3. Biaxial • angular movement in two planes

• forward/backward and left/right• occipital condyles to atlas


4. Triaxial • angular and rotational movement

• ball and socket (shoulder joint)

Synovial Joint Classification Based on Structure


1. Gliding (planar)

2. Pivot

3. Hinge

4. Ellipsoidal (condyloid)

5. Saddle (sellaris)

6. Ball & socket

http://www.argosymedical.com/flash/synovial_joints/landing.html


• Gliding (planar) Joint – Articular surfaces are essentially flat– Allow only slipping or gliding movements– nonaxial joints

• intercarpel, intertarsel, claviculosternal, joints

http://www.bbc.co.uk/science/humanbody/body/factfiles/joints/saddle_joint.shtml


• Hinge Joints – Cylindrical projections of one bone fits into a

trough-shaped surface on another– Motion is along a single plane (uniaxial)

• permit flexion and extension only

• elbow, knee, interphalangeal joints



• Pivot Joint– bone protrudes into a sleeve or

ring, composed of bone and possibly ligaments

– only uniaxial movement allowed

• joint between the atlas and axis• proximal radioulnar joint



• Ellipsoidal (condyloid) Joints – oval articular surface of

one bone fits into a complementary depression in another

– biaxial joint (motion in 2 planes)• radiocarpal (wrist) joints, • metacarpophalangeal

(knuckle) joints



• Saddle Joints– Similar to ellipsoidal joints but allow greater

movement– articular surface has both a concave and a

convex surface

• 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

• shoulder and hip joints


Specific Articulations

1. Intervertebral Articulations

2. Knee Joint

3. Shoulder Joint (maybe)

Intervertebral Articulations

• Synovial gliding joints– Between superior and

inferior articular processes of adjacent vertebrae

– Flexion and rotation of vertebral column


Intervertebral Articulations

• Symphyseal joints– Vertebrae are separated

by pads of fibrocartilage called intervertebral discs

– Not found between C1-C2

– Not found in sacrum/coccyx where bones are fused

The Intervertebral Discs

• Anulus fibrosus:– tough outer layer that attaches

disc to vertebrae

• Nucleus pulposus:– elastic, gelatinous core that

absorbs shocks

Discs account for ¼ of height and as we age, water in nucleus pulposus decreases leading to reduction in height

6 Intervertebral Ligaments 1. Anterior longitudinal ligament

– connects anterior surface of vertebral bodies

2. Posterior longitudinal ligament– connects posterior surfaces of

vertebral bodies

3. Ligamentum flavum– connects laminae

4. Interspinous ligament – connects spinous processes

5. Supraspinous ligament– connects tips of spinous

processes (C7 to sacrum)

6. Ligamentum nuchae– continues supraspinous ligament

(C7 to skull)

Damage to Intervertebral Discs

• Slipped disc– bulge in anulus fibrosus – invades vertebral canal

• Herniated disc– nucleus pulposus breaks through anulus fibrosus– presses on spinal cord or nerves

Articulation of the Vertebral Column

The Knee Joint

The Knee Joint

• 2 femur–tibia articulations:– 1 at medial and lateral condyles– 1 between patella and patellar surface of femur

Medial and lateral menisci

• fibrocartilage pads – at femur–tibia articulations to cushion and

stabilize joint and give lateral support

7 Ligaments of the Knee Joint• patellar ligament

– reinforce anterior surface• 2 popliteal ligaments

– reinforce posterior surface• anterior cruciate and posterior

cruciate– ACL & PCL found inside capsule– cruciate means cross– ensure alignment of tibia and femur

• tibial collateral ligament – reinforce the medial surface

• fibular collateral ligament– reinforce the lateral surface

Sprains and Strains• Sprains:

– The ligaments reinforcing a joint are stretched or torn

– Partially torn ligaments slowly repair themselves

– Completely torn ligaments require prompt surgical repair

• Strains– The muscles or tendons are stretched or torn– Healing generally better than with a sprain,

however it depends on the location of the strain with relationship of the joint

Mallet Finger

Bursitis and Tendonitis

• 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

Dislocation (luxation)

• common in acromioclavicular joint

• subluxation– partially

dislocated

Rheumatism

• general term to describe pain/stiffness of the skeletal and/or muscular systems

• There are more than 100 different types of inflammatory or degenerative diseases that damage the joints

– Arthritis is a rheumatism of the synovial joints

Osteoarthritis (OA)

• Most common chronic arthritis– aka “wear-and-tear” arthritis– aka degenerative joint disease (DJD)

• affects women more than men• affects older population

– as one ages, cartilage is destroyed more quickly than it is replaced

– results in bone ends thicken, enlarge, form bone spurs, and restrict movement

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

Rheumatoid Arthritis (RA)

• Chronic, inflammatory, autoimmune disease

• Typical onset between the ages of 40 to 50

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

Gouty Arthritis (Gout)

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

• More common in men

• 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

The Shoulder Joint(glenohumeral)

• Greatest range of motion• Greatest risk of dislocation

The Shoulder Joint(glenohumeral)

• Ball and socket joint

• Articulation at head of humerus and glenoid cavity of scapula

• Glenoid labrum is a fibrocartilage that deepens the socket

• Articular capsule is large and loose permitting a large range of motion

Ligaments of the Shoulder Joint

1. Glenohumeral

2. Coracohumeral

3. Coracoacromial

4. Coracoclavicular

5. Acrominoclavicular

• Shoulder separation is common injury involving partial or complete dislocation of the acromioclavicular joint

Muscles and Tendons of the Shoulder Joint

• Muscle and tendons of the rotator cuff support the shoulder and limit movement:– Supraspinatus– Infraspinatus– Subscapularis– Teres minor

• Many bursae are present to reduce friction between large muscles/tendons and shoulder capsule

Articulations (Joints) Martini Chapter 9 Bio 103 Feb 11, 2008.

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