A&P Chapter 9: Joints

Joints definition

Site where 2 or more bones meet

Function of a joint

Give mobility and hold the skeleton together

Arthology definition

study of joints

Orthopedics definition

branch of medicine concerned with prevention/correction of injuries to bones, muscles, ligaments, and joints

Kinesiology definition

study of musculoskeletal movement

Joints are named by

the bones involved

Joints are classified by

structure and function

4 types of Joints

Bony, fibrous, cartilaginous, and synovial

Bony joints is AKA

Synostosis

Bony joints characteristics

immobile joints; form when 2 bones ossify together and become a single bone

Fibrous Joints are connected by

Fibrous CT

Fibrous joints are AKA

synarthrosis or synarthrodial joints

In fibrous joints bones connect via

collagen fibers

3 kinds of fibrous joints

sutures, gomphosis, and syndesmosis

Example and movement of sutures

cranial bones; immobile

Example and movement of gomphosis

periodontal ligament; slightly mobile

Example and movement of syndesmosis

radius and ulna; mobile

Cartilaginous joints is AKA

amphiarthrosis or amphiarthrodial joint

In cartilaginous joints, bones connect via

cartilage

2 types of cartilaginous joints

Synchondrosis and symphysis

Synchondrosis example and characteristics

epiphyseal plate; connected by hyaline cartilage and immobile

Symphysis example and characteristics

intervertebral discs; connected by fibrocartilage

Synovial joints are AKA

diarthrosis or diarthrodial joints

Synovial joint charaacteristics

freely mobile; most complex joint anatomically

In synovial joints, bones are capped with

articular cartilage

Synovial joint cavity is filled with

synovial fluid

Joint capsule has 2 parts

Outer fibrous capsule and inner synovial membrane

Outer fibrous capsule characteristics

gives structure; made of fibrous CT

Inner synovial membrane characteristics

fibroblast-like cells secrete synovial fluid; macrophages remove debris

Why is fibrocartilage important in synovial joints?

It separates articular surfaces of bones and minimizes wear and tear

4 accessory structures of synovial joints

tendons, ligaments, bursae, and tendon sheath

Bursae characteristics

fibrous sac filled with synovial fluid; cushions muscle, helps tendons slide over joints, and can modify direction of tendon’s pull

Tendon sheath characteristics

elongated bursae wrapped around a tendon

Joint flexibility is AKA

range of motion

ROM is determined by 3 things

1. structure of the articular surface, strength 2. tautness of ligaments and joint capsules 3. actions of muscles and tendons

Degree of freedom is = to

number of planes the joint can move through

Multiaxial definition and example

all 3 planes; shoulder

Biaxial definition and example

2 planes; metacarpophalangeal

Monaxial definition and example

1 plane; elbow

Ball and Socket

shoulder and hip joints; multiaxial

Example of ball and socket joint

humeroscapular joint

Condyler Joint

Oval convex surface fits into complementary depression on other bone; biaxial

Example of condyler joint

metacarpophalangeal

Saddle joint

convex and concave connections between bones; biaxial

Example of saddle joint

trapeziometacarpal

Plane joints

flat surfaces; biaxial

example of plane joint

intercarpal

Hinge joint

acts like a hinge on a door; monaxial

Example of hinge joint

humeroulnar

Pivot joint

rotational movements along the longitudial axis of the bone; monaxial

Flexion

decreases joint angle

Extension

Increases joint angle

Abduction

movement away from midline

Adduction

movement toward the midline

Circumduction

combination movement

Protraction

movement anteriorly in the transverse plane

Retraction

posterior movement in the transverse plane

Elevation

increases frontal plane

Depression

decreases frontal plane

internal and external rotation

medial and lateral rotation; bone must rotate along its long axis

Pronation

hand is down

Supination

Hand is up

Inversion

foot is moved medially

eversion

foot turns laterally

Opposition

finger to thumb movement

Luxation

dislocation of bones from normal position

Arthritis

inflammatory or degenerative disease of joints

Osteoarthritis

“wear and tear”; articular cartilage wears away

Rheumatoid Arthritis

autoimmune disorder where the immune system causes inflammation in the joints

Ligaments heal slowly due to poor

blood supply

Bursitis

inflammation of a bursa, usually due to overextension of a joint

dislocation

displacement of a bone

Gout

hereditary disease; most common in men, in which uric acid crystals accumulate in the joints and irritate the articular cartilage and synovial membrane

Rheumatism

broad term for any pain in the supportive and locomotory organs of the body, including bones, ligaments, tendons, and muscles

Sprain

torn ligament or tendon

Strain

painful overstretching of a tendon or muscle without serious tissue damage

Synovitis

inflammation of a joint capsule

Tendinitis

a form of bursitis in which a tendon sheath is inflamed