Chapter #8- Joints

Joints

Areas where two or more bones join together

aka- articulations

function of joints

give skeleton mobility and hold skeleton together

2 classifications of joints

structure and function

3 structural classifications of joints

1. Fibrous

2. Cartilaginous

3. Synovial

3 functional classifications of joints

synarthroses, amphiarthroses, diarthroses

3 types of fibrous joints

sutures, syndesmoses, gomphoses

Syntharoses joints

immovable joints

amiphiarthroses joints

slightly movable joints

Diarthroses

freely movable joints

Fibrous Joints: Sutures

Rigid, interlocking joints

Immovable joints for protection of brain

Contain short connective tissue fibers

Allow for growth during youth

In middle age, sutures ossify and fuse

Called Synostoses

fibrous joints: syndesmoses

Bones connected by ligaments (bands of fibrous tissue)

Movement varies from immovable to slightly movable

Fibrous Joint: Gomphoses

attachment of a tooth to its socket

cartilaginous joints

allow only slight movement and consist of bones connected entirely by cartilage

2 types of cartilaginous joints

synchondroses and symphyses

Cartilaginous Joints: Synchondroses

A bar or plate of hyaline cartilage unites the bones

All are synarthrotic

EX: epiphyseal plate, joint between rib and sternum

Cartilaginous Joints: Symphyses

Fibrocartilage unites bone

Hyaline cartilage present as articular cartilage

Strong, flexible amphiarthroses

EX: intervertebral joints, pubic symphysis

synovial joints

freely movable joints

-bones that separated by fluid-filled joint cavities

-all are diarrhetic

-include almost all limb joints

5 characteristics of synovial joints

1. have six general features

2. have bursae and tendon sheaths

3. stability is influenced by three factors

4. allow several movements

5. classified into six different types

6 features of synovial joints

1. articular cartilage

2. joint cavity

3. articular capsule

4. synovial fluid

5. reinforcing ligaments

6. nerves and blood vessels

articular cartilage

Hyaline cartilage attached to articular bone surfaces

prevents crushing of bones

joint cavity

the space between two connecting bones

fluid-filled space that is unique to the synovial joint

articular capsule

2 layers thick

-external fibrous layer: dense irregular connective tissue

-inner synovial membrane: loose connective tissue that makes synovial fluid

synovial fluid

Viscous, slippery filtrate of plasma and hyaluronic acid

-Lubricates and nourishes articular cartilage

-Contains phagocytic cells to remove microbes and debris

3 types of reinforcing ligaments

capsular, extracapsular, intracapsular

capsular

thickened part of fibrous layer of synovial joints

extracapsular ligaments

outside the capsule

intracapsular ligaments

stabilizing ligaments located inside joint capsule

nerve and blood vessels

-detect pain; monitor joint position and stretch

-capillary beds supply filtrate for synovial fluid

Fats pads

cushioning between fibrous layer of capsule and synovial membrane or bone

articular discs

fibrocartilage that separates articular surfaces of bones and minimizes wear and tear

Bursae

reduce friction where ligaments, muscle, skin, tendons or bones rub together

Tendon sheaths

Elongated bursa wrapped completely around tendon subjected to friction

3 factors of synovial joint stability

1. shape of articular surface (shallow surface less stable than ball-and-socket)

2. ligament number and location (more ligaments=more strength)

3. muscle tone(keeps tendons taut as they cross joints)

origin

attachment of a muscle that remains relatively fixed during muscular contraction

Insertion

attached to the movable bone

4 ranges of motion

nonaxial, uniaxial, biaxial, multiaxial

Non-axial motion

slipping movement

uniaxial motion

movement in one plane

biaxial motion

movement in two planes (metacarpophalangeal joint, occipital condyles to atlas)

multiaxial motion

movement in or around all three planes

3 movements of synovial joints

1. Gliding

2. Angular

3. Rotation

gliding movement

one flat bone surface glides or slips over another similar surface

EX: inter carpal joints, intertarsal joints,

angular movements

increase or decrease the angle between two bones

movement along side the sagittal plane

3 types of angular movements

flexion, extension, hyperextension,

Flexion

decrease in the angle between articulating bones

extension

increases the angle of a joint

Hyperextension

extension beyond anatomical position

Abduction

Movement away from the midline of the body

Adduction

Movement toward the midline of the body

Circumduction

circular movement of a limb at the far end

Rotation

Turning around an axis or center point.

medial and lateral rotation

Supination

movement that turns the palm up

Pronation

turning the palm downward

Dorsiflexion

bending of the foot or the toes upward

plantar flexion

bending of the sole of the foot by curling the toes toward the ground

Inversion

Turning the sole of the foot inward

Eversion

turning the sole of the foot outward

2 types of movement in lateral plane

protraction and retraction

Protraction

mandible juts out

Retraction

mandible is pulled toward neck

Elevation

lifting a body part superiorly

Depression

lowering a body part

oppoisition

movement of thumb

EX: touching thumb to tip of fingers on the same hand... grasping movements

6 types of synovial joints

1. plane

2. hinge,

3. pivot

4. condyloid

5. saddle

6. ball and socket

plane joint

Non-axial The flat surface of one bone slides in many directions along the flat surface of another bone.

hinge joint

uniaxial, flexion and extension

pivot joint

rotating bone turns around an axis; i.e. connection between radius/ulna and humerus

uniaxial

condylar joint

a shallow ball-and-socket joint with limited mobility

biaxial

saddle joint

type of joint found at the base of each thumb; allows grasping and rotation

biaxial

ball and socket joint

hip and shoulder joints

Main synovial joints

knee, shoulder, elbow, hip, jaw

temporomandibular joint

jaw joint; modified hinge joint

-mandibular condyle articulates with temporal bone

-posterior temporal bone forms mandibular fossa, while anterior portion forms articular tubercle

-articular capsule thickens into strong lateral ligament

shoulder joint

-mostly freely moving joint in the body

-stability is sacrificed for freedom of movement

-ball-and socket joint

Reinforcement of shoulder joint

gelnoid labrum: fibrocartilaginous rim around glenoid cavity, adds depth to shallow cavity

coracohumeral ligament: helps support weight of the upper limbs

3 glenohumeral ligaments: strengthen anterior capsule, but are weal support

4 rotator cuff tendons

1. subscapularis

2. supraspinatus

3. infraspinatus

4. teres minor

shoulder dislocations

-common due to mobility in shoulder

-structures reinforcing this joint are weakest anteriorly and inferiorly

-head of humerus can easily dislocate forwards and downward

-glenoid cavity provides poor support when humerus is rotated laterally and abducted

elbow joint

hinge joint formed by humerus, ulna, and radius

allows flexion and extension only

3 elbow ligaments

1. Radial collateral

2. anular ligament

3. Ulnar collateral

hip joint

-ball and socket joint

-large, spherical head of the femur articulates with deep cup-shaped acetabulum

-allows good range of motion, but is limited by deep socket

acetabular labrum

rim of fibrocartilage that enhances depth of socket (hip dislocations are rare)

4 hip ligaments

1. iliofemoral

2. pubofemoral

3. ischiofemoral

4. ligaments of the head of the femur

knee joint

-largest, most complex join of the body

hinge joint that allows flexion, extension, and some rotation when it is partly flexed

Three joints of the knee joint

- all three are within a single synovial cavity

1. Laterally: a tibiofemoral joint - a modified hinge joint

2. Medially: a second tibiofemoral joint - also a modified hinge joint.

3. An intermediate patellofemoral joint - a planar joint.

3 broad ligaments of knee joint

- patellar ligament

- Lateral and medial patellar retinaculum

joint capsule ligaments of knee

-capsular, extra capsular or intracapsular ligaments (stabilize knee joint)

-capsular & extracapsular ligaments (prevent hyperextension)

-fibular and tibial collateral ligaments

-fibular and tibial collateral ligaments (prevent rotation when knee is extended)

-oblique popliteal ligament (stabilizes posterior knee joint)

-arcuate popliteal ligament (reinforce joint capsule posteriorly)

intracapsular ligaments joints of knee

-within capsule but outside synovial cavity

-prevent anterior posterior displacement

Anterior Cruciate Ligament (ACL)

A ligament in the knee that attaches to the anterior aspect of the tibial plateau. restricting anterior movement of the tibia on the femur... stops hyperextension

Posterior Cruciate Ligament (PCL)

A ligament in the knee that attaches to the posterior aspect of the tibial plateau, restricting posterior movement of the tibia on the femur

3 C's of knee injuries

1. collateral ligaments

2. cruciate ligaments

3. cartilages (menisci)

cartilage tears

Caused by compression and shear stress (especially of menisci); rarely repairs itself

-fragments may lead to locking or binding of joint

-requires arthroscopic surgery

Sprains

ligaments reinforcing a joint are stretched or torn

-poorly vascularized therefor recovery is very slow

3 options of completely sprain

1. end of ligament is sewn together

2. replaced with graft

3. allow time and mobilization for healing

Dislocation

displacement of a bone from its joint

aka... luxations

7 Inflammatory and Degenerative Conditions

1. bursitis

2. tendonitis

3. arthritis

4. osteoarthritis

5. rheumatoid arthritis

6. gouty arthritis

7. lyme disease

burstisis

inflammation of bursa, usually caused by blow or friction

treatment: ice, and anti0inflammatory drugs

Tendonitis

inflammation of tendon sheaths typically caused by overuse

arthritis

-inflammatory or degenerative disease that damages the joints

symptoms: pain, stiffness, swelling of joint

acute form: caused by bacteria, treated with antibiotics

chronic forms: osteoarthiritis, rheumatoid arthritis and gouty arthritis

Osteoarthritis (OA)

-Most common type of arthritis

-Irreversible, degenerative ("wear-and-tear") arthritis

-May reflect excessive release of enzymes that break down articular cartilage

-Cartilage is broken down faster than it is replaced

-Bone spurs (osteophytes) may form from thickened ends of bones

-By age 85, half of Americans develop OA, more women than men

rheumatoid arthritis (RA)

Chronic, inflammatory, autoimmune disease of unknown cause

-inflimation of synovial membrane of affected joints, blood cells migrate to the joint and release inflammatory chemicals that destroy tissues

-synovial fluid accumulates, causing swelling

treatments: steroids, NSAID, immunosuppressants

gouty arthitis (gout)

-deposition of uric acid crystals in joints followed by inflammation

-affects base of big toe

-if untreated bone ends fuse and immobilize joints

treatment: drugs, water, avoidance of alcohol and foods high in purines (liver, kidney, sardines...)