Ch09 Joints Edited

Chapter 9

Joints

Joints

Points where bones meet

Classifications

Structurally: by their anatomy

Fibrous, cartilaginous, or synovial

Functionally: by the degree of movement they

permit

Immovable, slightly movable, and freely movable

Structural Classification

Based on what is between bones:

Space (or not)

Type of connective tissue present

Types

Fibrous joints - no cavity, just dense irregular

connective tissue

Cartilaginous joints - no cavity, bones held

together by cartilage

Synovial joints - have synovial cavity, dense

irregular tissue of articular capsule, and often

ligaments

Functional Classification

Based on degree of movement they permit

Types

Synarthrosis: immovable

Pelvis, sutures, teeth

Amphiarthrosis: slightly movable

Epiphyseal plate, tibia-fibula, vertebrae, pelvic symphysis

Diarthrosis: freely movable

Most joints of the body

All diarthrotic joints are synovial

Fibrous Joints

Suture (synarthrosis)

Joined by thin layer of dense fibrous connective tissue

Example: between bones of skull

Syndesmosis

Greater distance between bones and greater amount of dense irregular connective tissue

Examples Distal tibia to distal fibula (amphiarthrosis)

Gomphosis (synarthrosis): tooth root in socket (alveolar process) of mandible or maxilla

Fibrous Joints

Interosseous membrane (amphiarthrosis)

Has greater amount of dense irregular connective tissue

Examples: extensive membranes between shafts of some long bones Radius-ulna

Tibia-fibula

Fibrous Joints

Cartilaginous Joints

Synchondrosis (synarthrosis)

Cartilage connects two areas of bone

Example

Epiphyseal (growth) plate connecting epiphysis and

diaphysis of long bone (synarthrosis)

Symphysis (amphiarthrosis)

Cartilage connects two bones, but a broad disc of

fibrocartilage is present also

Examples: pubic symphysis and intervertebral

discs

Cartilaginous Joints

Synovial Joints: Structure

Synovial cavity: space containing fluid

Articular cartilage

Covers ends of bones, absorbs shock

Articular capsule

Inner layer: synovial membrane that secretes

synovial fluid (reduces friction, supplies nutrients)

Outer layer: dense, irregular connective tissue


In some cases synovial joints include:

Ligaments (either inside or outside of joint cavity)

Menisci (cartilage discs)

Labrum

Articular fat pads

Bursae

Sacs made of synovial membranes containing fluid

Located where friction can occur

Examples: between skin-bone, tendons-bones,

muscles-bones, ligaments-bones

Knee Joint

Types of Movements at Synovial Joints

Gliding

Flat bone surfaces moving across each other

Flexion

Decrease in angle between articulating bones

Extension

Increase in angle between articulating bones

In anatomical position the body is in full extension

Hyperextension

Bending beyond 180o degrees, such as moving humerus backwards behind anatomical position

Movements

Abduction

Movement of bone away from midline

Adduction

Movement of bone toward midline

Circumduction

Movement of distal end in a circle

Rotation

Bone revolves around its own longitudinal axis

Special Movements

Elevation

Movement upward

Depression

Movement downward

Protraction

Movement forward

Retraction

Movement backward into anatomical position

Special Movements at Synovial Joints

Special Movements

Inversion

Move soles medially

Eversion

Move soles laterally

Dorsiflexion

Bend foot toward dorsum (stand on heels)

Plantar flexion

Bend foot toward plantar surface (stand on toes)

Supination

Movement of forearm so palms face forward or

upward

Pronation

Movement of forearm so palms face backward or

downward


Six Types of Synovial Joints

Planar joints

Articulating surfaces flat or slightly curved

Examples: between carpals, tarsals, sternum-

clavicle, scapula-clavicle

Movements: gliding

Hinge joints (ginglymus joints)

Convex-to-concave surfaces

Examples: elbow, knee, ankle, interphalangeal

Movements: flexion (F) and extension (E) only

Types of Synovial Joints Pivot joints (trochoid)

Rounded surface with ring formed by bone and

ligament

Examples: atlantoaxial joint (to turn head to say

no) and radius-ulna for pronation-supination

Movement: rotation (ROT)

Condyloid joints

Convex oval surface to concave oval surface

Examples: wrist, metacarpophalangeal-2 to -5

joints

Movements F, E, ABD, ADD

Types of Synovial Joints

Saddle joints

One side of saddle-shaped, other like a rider

astride it

Example: trapezium (carpal) to metacarpal-1

(thumb)

Movements: triaxial (F, E, ABD, ADD, ROT)

Ball-and-socket joints

Ball-like surface into cuplike socket surface

Example: shoulder, hip

Movements: triaxial (F, E, ABD, ADD, CIR, ROT)

Types of Synovial Joints

Details of a Synovial Joint: Knee Joint

See slides 10a-d

Ligaments

Tibial and fibular collateral ligaments

Anterior cruciate ligament (ACL): 70 % of knee injuries

Posterior cruciate ligament (PCL)

Menisci (medial and lateral)

Fibrocartilage discs that increase stability of knee joint

Bursae

Arthroplasty

Knee replacement: total or partial

Aging of Joints

Decrease in production of synovial fluid

Thinning of articular cartilage

Ligaments shorten and lose flexibility

Influenced by genetic factors

Common Disorders of Joints

Common joint injuries

Rotator cuff injury

Separated shoulder

Tennis elbow (lateral epicondylitis)

Dislocation of the radial head

Knee injuries: swollen knee, rupture of tibial

collateral ligaments, dislocated knee

Rheumatism: rheumatoid arthritis, osteoarthritis

Ligaments shorten and lose flexibility

Influenced by genetic factors

COVERAGE OF PRELIM EXAM

INTRODUCTION TO THE HUMAN BODY

CHEMICAL LEVEL OF ORGANIZATION

CELLULAR LEVEL OF ORGANIZATION

TISSUE LEVEL OF ORGANIZATION

INTEGUMENTARY SYSTEM

SKELETAL SYSTEM

AXIAL & APPENDICULAR SKELETON

JOINTS

Ch09 Joints Edited

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