A&P 1: Chapter 8-Joints

Joints are also called

articulations

Two classifications of joints

Structural

• fibrous

• cartilaginous

• synovial

Functional Classifications

• synarthroses - immovable

• amphiarthroses - slightly moveable

• diarthroses - freely moveable

3 Types of Fibrous Joints

1. Suture- joints held together by very short interconnecting fibers, and bone edges interlock (only found in skull)

2. Syndesmoses- joints held together by a ligament, fibrous tissue can vary in length but longer in sutures

3. Gomphoses- “peg in socket” fibrous joint (periodontal ligament holds tooth in socket)

2 Types of Cartilaginous Joints

1. Synchondroses- bones united by hyaline cartilage (sternum and epiphyseal plate)

2. Symphyses- bones united by fibrocartilage (body of vertebra, pubic symphysis)

Types of Synovial Joints

• plane (gliding- intercarpal joints)

• hinge (flexion and extension- elbow joint)

• pivot (rotation- proximal radioulnar joints)

• ball-and-socket (flexion and extension/ abduction and adduction/ rotation- hip and shoulder joint)

• condylar (flexion and extension/ abduction and adduction- knuckle)

• saddle (flexion and extension/ abduction and adduction- carpometacarpal joints of thumb

Tendon Sheath

an elongated fluid-filled sac that wraps around a tendon to decrease tension

Bursa

a fluid-filled sac that decreases friction where a ligament (or other structure) would rub against a bone

Origin

attachment to immovable bone

Insertion

attachment to movable bone

Special Body Movements

pronation

supination

dorsiflexion

plantar flexion

inversion

eversion

protraction

retraction

elevation

depression

opposition

Characteristics of Synovial Joints

• have 6 general features

• have bursae and tendon sheaths associated with them

• stability influenced by 3 factors

• allows several types of movements

• classified into 6 different types

• fatty pads

  • for cushioning between fibrous layers of capsule and synovial membrane or bone

• articular discs (menisci)

  • fibrocartilage separates articular surfaces to improve “fit” of bone ends, stabilize joint, and reduce wear and tear

Angular Movements

flexion

extension

abduction

adduction

circumduction

Three General types of movements allowed by synovial joints are

gliding

angular movements

rotation

Five main synovial joints are

• jaw (temporomandibular joints)

• shoulder

• elbow

• hip

• knee

Organization of Muscle

muscle → fascicle → muscle fiber → myofibril

Sacromere

z-disc to z-disc

M-line

hold thick filaments in place

A-band

beginning of thick filaments to the end of the same filament

I-band

end of one thick filament to the beginning of another thick filament

H Zone

end of a thin filament to the beginning of a thin filament

5 Main Synovial Joints

• jaw (temporomandibular joint)

• shoulder

• elbow

• hip

• knee

Cartilage tears

• due to compression and shear stress

• repaired with arthroscopic surgery

• fragments may cause joint to lock or bind

Sprains

reinforcing ligaments are stretched or torn

Dislocations

• aka luxations

• bones forced out of alignment

• accompanied by sprains, inflammation, and difficulty moving

• must be reduced to treat

Subluxation

partial dislocation of a joint

Bursitis

• inflammation of bursa, usually caused by blow or friction

• treated with rest and ice, if severe, anti-inflammatory drugs

Tendonitis

• inflammation of tendon sheaths, typically caused by overuse

• symptoms and treatment similar to bursitis

Arthrisits

• more than 100 different types of inflammatory or degenerative disease

• most widespread crippling disease in the U.S.

• symptoms: pain, stiffness, and swelling of joints

• Acute forms are caused by bacteria and treated with antibiotics

• chronic forms: osteoarthritis, rheumatoid arthritis, and gouty arthritis

Osteoarthritis

• most common type of arthritis

• may reflect excessive release of enzymes that break down articular cartilage

• by 85, half of Americans develop OA, more women than men

• treatment: moderate activity, mild pain relievers, capsaicin creams

Rheumatoid arthritis

• chronic, inflammatory, autoimmune disease of unknown cause

• signs and symptoms include joint pain and swelling, anemia, osteoporosis, muscle weakness, and cardiovascular problems

Gouty arthritis

• deposition of uric acid crystals in joints and soft tissues, followed by inflammation

• treatment: drugs, plenty of water, avoidance of alcohol and foods high in purines (like liver, kidneys, and sardines)

Lyme disease

• caused by bacteria transmitted by tick bite4s

• symptoms: skin rash, flu-like symptoms, and foggy thinking

• may lead to joint pain and arthritis

• treatment- long course of antibiotics

What is the key to postponing joint problems

full-range-of-motion exercises

When do embryonic joints resemble synovial adult joints?

at embryonic week 8

Flexion

decreasing the angle between 2 bones

Dorsiflexion

pointing toes upward

Plantar flexion

pointed toes

Extension

increasing the angle between 2 bones

Hyperextension

increasing the angle greater then 180 degrees (standing back in your knees)

Abduction

moving a LIMB away from the midline

Adduction

moving a LIMB toward the midline

Circumduction

moving a LIMB in a cone-shaped manner

Rotation

turning movement of a bone along its axis

Supination

palm up (movement between the radius and ulna at the proximal radioulnar joint)

Pronation

palm down (movement between the radius and ulna at the proximal radioulnar joint)

Inversion

sole of foot inward

Eversion

sole of foot outward

Elevation

shoulder shrug

Depression

mandible when you open your mouth

Protraction

thrust/move forward

Retraction

move back

General Structure of a Synovial Joint

1. articular cartilage

2. joint cavity

3. articular capsule

4. synovial fluid

5. reinforcing ligaments

6. fatty pads, menisci (articular discs), and bursa