Articulations and Joints

Muse lecture #9 6/7/10

JointsChapter 9

Joint Classifications Fibrous Joints Cartilaginous Joints Synovial Joints Types of Movements at Synovial Joints Types of Synovial Joints Factors Affecting Contact and Range of Motion at

Synovial Joints Selected Joints of the Body Aging and Joints Arthroplasty

Muse Lecture #6

An Introduction to Articulations

Articulations Body movement occurs at joints

(articulations) where two bones connect

Joint Structure Determines direction and distance of

movement (range of motion) Joint strength decreases as mobility increases

Classification of Joints

Two methods of classification

Functional classification is based on range

of motion of the joint

Structural classification relies on the

anatomical organization of the joint

Classification of Joints

Functional Classifications Synarthrosis (immovable joint)

No movement Fibrous or cartilaginous connections May fuse over time

Amphiarthrosis (slightly movable joint) Little movement Fibrous or cartilaginous connections

Diarthrosis (freely movable joint) More movement Also called synovial joints Subdivided by type of motion

Party on Arth!

Classification of Joints

Classification of Joints

Classification of Joints

Structural Classifications

Bony

Fibrous

Cartilaginous

Synovial (capsulated)

Classification of Joints

Classification of Joints

Functional Classifications Synarthroses (immovable joints)

Are very strong Edges of bones may touch or interlock Four types of synarthrotic joints:

– suture

– gomphosis

– synchondrosis

– synostosis

Classification of Joints

Synarthrotic Joints

Suture Bones interlocked

Are bound by dense fibrous connective tissue

Are found only in skull

Gomphosis Fibrous connection (periodontal ligament)

Binds teeth to sockets

Yah can’t chomp without the gomph

Joints (Fibrous Joints) Sutures

Occur only between bones of the skull

Syndesmoses Permits slight movement Interosseous membrane

Between the tibia and fibula in the leg

Gomphoses Immovable joint Joint in which a cone-shaped

peg fits into a socket Articulations of the teeth with the

sockets of the maxillae and mandible

Figure 8.1b

Fibula

Tibia

Ligament

(b) Syndesmosis

Joint held together by a ligament.Fibrous tissue can vary in length, but

is longer than in sutures.

Joints (Fibrous Joints) Lack a synovial cavity The articulating bones are held very closely

together by dense irregular connective tissue Fibrous joints permit little or no movement Three types of fibrous joints

Sutures Syndesmoses Gomphoses

Classification of Joints

Synarthrotic Joints Synchondrosis

Is a rigid cartilaginous bridge between two bones:– epiphyseal cartilage of long bones– between vertebrosternal ribs and sternum

Synostosis Fused bones, immovable:

– metopic suture of skull– epiphyseal lines of long bones

Classification of Joints

Functional Classifications Amphiarthroses

More movable than synarthrosis

Stronger than freely movable joint

Two types of amphiarthroses

– syndesmosis:

» bones connected by ligaments

– symphysis:

» bones separated by fibrous cartilage

Classification of Joints

Functional Classifications

Synovial joints (diarthroses) Also called movable joints

At ends of long bones

Within articular capsules

Lined with synovial membrane

Synovial Joints

Components of Synovial Joints

Articular cartilages Pad articulating surfaces within articular

capsules:

– prevent bones from touching

Smooth surfaces lubricated by synovial fluid:

– reduce friction

Figure 8.3

Periosteum

Ligament

Fibrouscapsule

Synovialmembrane

Joint cavity(containssynovial fluid)

Articular (hyaline)cartilage

Articularcapsule

Synovial Joints

Components of Synovial Joints Synovial fluid

Contains slippery proteoglycans secreted by fibroblasts

Functions of synovial fluid:– lubrication

– nutrient distribution

– shock absorption

Synovial Joints Components of Synovial Joints

Accessory structures Cartilages:

– cushion the joint:» Fibrous cartilage pad called a meniscus

(articular disc) Fat pads:

– superficial to the joint capsule– protect articular cartilages

Ligaments:– support, strengthen joints – sprain: ligaments with torn collagen fibers

Synovial Joints

Components of Synovial Joints

Accessory structures Tendons:

– attach to muscles around joint

– help support joint

Bursae:

– pockets of synovial fluid

– cushion areas where tendons or ligaments rub

Figure 8.4b

Coracoacromialligament

Subacromialbursa

Cavity inbursa containingsynovial fluid

Bursa rollsand lessensfriction.

Humerus headrolls medially asarm abducts.

(b) Enlargement of (a), showing how a bursaeliminates friction where a ligament (or otherstructure) would rub against a bone

Humerusresting

Humerusmoving

Synovial Joints

Factors That Stabilize Synovial Joints

Prevent injury by limiting range of motion

Collagen fibers (joint capsule, ligaments)

Articulating surfaces and menisci

Other bones, muscles, or fat pads

Tendons of articulating bones

Synovial Joints

[INSERT FIG. 9.1a]

Figure 9–1a The Structure of a Synovial Joint.

Synovial Joints

Figure 9–1b The Structure of a Synovial Joint.

Synovial Joints

Injuries

Dislocation (luxation)

Articulating surfaces forced out of position

Damages articular cartilage, ligaments, joint capsule

Subluxation A partial dislocation

Movements

Types of Dynamic Motion Linear motion (gliding)

Angular motion

Rotation

Planes (Axes) of Dynamic Motion Monaxial (1 axis)

Biaxial (2 axes)

Triaxial (3 axes)

Movements

Figure 9–2 A Simple Model of Articular Motion.

Movements

Figure 9–2 A Simple Model of Articular Motion.

Movements

Types of Movements at Synovial Joints

Terms describe

Plane or direction of motion

Relationship between structures

Movements

Types of Movements at Synovial Joints

Linear motion

Also called gliding

Two surfaces slide past each other:

– between carpal or tarsal bones

Movements

Angular Motion Flexion

Angular motion Anterior–posterior plane Reduces angle between elements

Extension Angular motion Anterior–posterior plane Increases angle between elements

Movements

Angular Motion Hyperextension

Angular motion

Extension past anatomical position

Angular Movements

Movements

Figure 9–3a Angular Movements.

Movements

Angular Motion Abduction

Angular motion Frontal plane Moves away from longitudinal axis

Adduction Angular motion Frontal plane Moves toward longitudinal axis

Think adding

Think kidnapping

Movements

Figure 9–3 Angular Movements.

Movements

Figure 9–3 Angular Movements.

Movements

Angular Motion

Circumduction

Circular motion without rotation

Angular motion

Movements

Figure 9–3 Angular Movements.

Movements

Types of Movement at Synovial Joints Rotation

Direction of rotation from anatomical position Relative to longitudinal axis of body Left or right rotation Medial rotation (inward rotation):

– rotates toward axis

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

Movements

Figure 9–4a Rotational Movements.

Movements

Types of Movements at Synovial Joints

Rotation

Pronation:– rotates forearm, radius over ulna

Supination:– forearm in anatomical position

Movements

Figure 9–4b Rotational Movements.

Movements

Types of Movements at Synovial Joints Special movements

Inversion:– twists sole of foot medially

Eversion:– twists sole of foot laterally

Dorsiflexion: – flexion at ankle (lifting toes)

Plantar flexion:– extension at ankle (pointing toes)

Plant your feet

Movements

Special Movements at Synovial Joints Opposition

Thumb movement toward fingers or palm (grasping)

Protraction Moves anteriorly In the horizontal plane (pushing forward)

Retraction Opposite of protraction Moving anteriorly (pulling back)

Movements

Special Movements at Synovial Joints Elevation

Moves in superior direction (up)

Depression Moves in inferior direction (down)

Lateral flexion Bends vertebral column from side to side

Movements

Figure 9–5 Special Movements.

Movements

Figure 9–5 Special Movements.

Movements

Classification of Synovial Joints by Shape Gliding Hinge Pivot Ellipsoid Saddle Ball-and-socket

A Functional Classification of Synovial Joints

Movements

Gliding Joints Flattened or slightly curved faces

Limited motion (nonaxial)

Hinge Joints Angular motion in a single plane (monaxial)

Pivot Joints Rotation only (monaxial)

Movements

Figure 9–6 Movements at Synovial Joints.

Movements

Ellipsoid Joints Oval articular face within a depression Motion in two planes (biaxial)

Saddle Joints Two concave, straddled (biaxial)

Ball-and-Socket Joints Round articular face in a depression (triaxial)

Movements

Figure 9–6 Movements at Synovial Joints.

Movements

A joint cannot be both mobile and strong The greater the mobility, the weaker the

joint Mobile joints are supported by muscles

and ligaments, not bone-to-bone connections

Intervertebral Articulations

Intervertebral Articulations

C2 to L5 spinal vertebrae articulate

At inferior and superior articular processes (gliding

joints)

Between adjacent vertebral bodies (symphyseal

joints)

Intervertebral Articulations

Intervertebral Articulations C2 to L5 spinal vertebrae articulate

Intervertebral discs:– pads of fibrous cartilage– separate vertebral bodies– anulus fibrosus:

» tough outer layer» attaches disc to vertebrae

– nucleus pulposus:» elastic, gelatinous core » absorbs shocks

Intervertebral Articulations

Figure 9–7 Intervertebral Articulations.

Intervertebral Articulations

Vertebral Joints Also called symphyseal joints As vertebral column moves

Nucleus pulposus shifts

Disc shape conforms to motion

Intervertebral Ligaments Bind vertebrae together

Stabilize the vertebral column

Intervertebral Articulations

Six Intervertebral Ligaments Anterior longitudinal ligament

Connects anterior bodies

Posterior longitudinal ligament Connects posterior bodies

Ligamentum flavum Connects laminae

Intervertebral Articulations

Six Intervertebral Ligaments Interspinous ligament

Connects spinous processes

Supraspinous ligament Connects tips of spinous processes (C7 to sacrum)

Ligamentum nuchae Continues supraspinous ligament (C7 to skull)

Intervertebral Articulations

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

Intervertebral Articulations

Figure 9–8a Damage to the Intervertebral Discs.

Intervertebral Articulations

Figure 9–8b Damage to the Intervertebral Discs.

Intervertebral Articulations

Movements of the Vertebral Column Flexion

Bends anteriorly

Extension Bends posteriorly

Lateral flexion Bends laterally

Rotation Turning

Articulations of the Axial Skeleton

Articulations of the Axial Skeleton

Articulations of the Axial Skeleton

Joints (Selected Joints of the Body)

Temporomandibular Joint Combined hinge and planar joint formed by the

mandible and the temporal bone Only movable joint between skull bones Only the mandible moves

Figure 8.13c

Lateral excursion: lateral (side-to-side) movements of the mandible

Outline ofthe mandibularfossa

Superior view

Figure 8.13a

Zygomatic process

Mandibular fossaArticular tubercle

Infratemporal fossa

Externalacousticmeatus

Articularcapsule

Ramus ofmandible

Lateralligament

(a) Location of the joint in the skull

Figure 8.13b

Articularcapsule

Mandibularfossa

Articular discArticulartubercle

Superiorjointcavity

Inferior jointcavity

Mandibularcondyle

Ramus ofmandible

Synovialmembranes

(b) Enlargement of a sagittal section through the joint

The Shoulder Joint

Also called the glenohumeral joint

Allows more motion than any other joint

Is the least stable

Supported by skeletal muscles, tendons, ligaments

Ball-and-socket diarthrosis

Between head of humerus and glenoid cavity of

scapula

The Shoulder Joint

Socket of the Shoulder Joint Glenoid labrum

Deepens socket of glenoid cavity

Fibrous cartilage lining

Extends past the bone

Processes of the Shoulder Joint Acromion (clavicle) and coracoid process (scapula)

Project laterally, superior to the humerus

Help stabilize the joint

The Shoulder Joint

Shoulder Ligaments Glenohumeral Coracohumeral Coraco-acromial

Coracoclavicular Acromioclavicular

Shoulder Separation Dislocation of the shoulder joint

The Shoulder Joint

Shoulder Muscles (also called rotator cuff) Supraspinatus Infraspinatus Subscapularis Teres minor

Shoulder Bursae Subacromial Subcoracoid Subdeltoid Subscapular

The Shoulder Joint

Figure 9–9a The Shoulder Joint.

The Shoulder Joint

Figure 9–9b The Shoulder Joint.

The Elbow Joint

A stable hinge joint

With articulations involving humerus,

radius, and ulna

The Elbow Joint

Articulations of the Elbow

Humero-ulnar joint Largest articulation

Trochlea of humerus and trochlear notch of ulna

Limited movement

Humeroradial joint: Smaller articulation

Capitulum of humerus and head of radius

The Elbow Joint

Figure 9–10a The Elbow Joint.

The Elbow Joint

Supporting Structures of the Elbow Biceps brachii muscle

Attached to radial tuberosity Controls elbow motion

Elbow Ligaments Radial collateral Annular Ulnar collateral

The Elbow Joint

Figure 9–10b The Elbow Joint.

The Hip Joint

Also called coxal joint

Strong ball-and-socket diarthrosis

Wide range of motion

The Hip Joint Structures of the Hip Joint

Head of femur fits into it Socket of acetabulum Which is extended by fibrocartilaginous acetabular

labrum Ligaments of the Hip Joint

Iliofemoral Pubofemoral Ischiofemoral Transverse acetabular Ligamentum teres

The Hip Joint

Figure 9–11a The Hip Joint.

The Hip Joint

Figure 9–11b The Hip Joint.

The Hip Joint

Figure 9–11c The Hip Joint.

The Knee Joint

A complicated hinge joint

Transfers weight from femur to tibia

Articulations of the knee joint

Two femur–tibia articulations

At medial and lateral condyles

One between patella and patellar surface of femur

The Knee Joint

Menisci of the Knee Medial and lateral menisci

Fibrous cartilage pads At femur–tibia articulations Cushion and stabilize joint Give lateral support

Locking knees Standing with legs straight:

– “locks” knees by jamming lateral meniscus between tibia and femur

The Knee Joint

Seven Ligaments of the Knee Joint

Patellar ligament (anterior)

Two popliteal ligaments (posterior)

Anterior and posterior cruciate ligaments (inside joint

capsule)

Tibial collateral ligament (medial)

Fibular collateral ligament (lateral)

The Knee Joint

Figure 9–12a The Knee Joint.

The Knee Joint

Figure 9–12b The Knee Joint.

The Knee Joint

Figure 9–12c The Knee Joint.

The Knee Joint

Figure 9–12d The Knee Joint.

Figure 8.14

Tornmeniscus

The Knee Joint

The Knee Joint

Aging

Rheumatism A pain and stiffness of skeletal and muscular

systems Arthritis

All forms of rheumatism that damage articular cartilages of synovial joints

Osteoarthritis Caused by wear and tear of joint surfaces, or

genetic factors affecting collagen formation Generally in people over age 60

Developmental Aspects of Joints

By embryonic week 8, synovial joints resemble adult joints

A joint’s size, shape, and flexibility are modified by use

Advancing years take their toll on joints: Ligaments and tendons shorten and weaken Intervertebral discs become more likely to herniate Most people in their 70s have some degree of OA

Exercise that coaxes joints through their full range of motion is key to postponing joint problems

Aging

Rheumatoid Arthritis An inflammatory condition Caused by infection, allergy, or autoimmune

disease Involves the immune system

Gouty Arthritis Occurs when crystals (uric acid or calcium

salts) Form within synovial fluid Due to metabolic disorders

Rheumatoid Arthritis

RA begins with synovitis of the affected joint Inflammatory blood cells migrate to the

joint, release inflammatory chemicals Inflamed synovial membrane thickens into a

pannus Pannus erodes cartilage, scar tissue forms,

articulating bone ends connect (ankylosis)

Figure 8.15

Gouty Arthritis

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

More common in men Typically affects the joint at the base of the

great toe In untreated gouty arthritis, the bone ends

fuse and immobilize the joint Treatment: drugs, plenty of water,

avoidance of alcohol

Aging

Joint Immobilization Reduces flow of synovial fluid Can cause arthritis symptoms Treated by continuous passive motion

(therapy) Bones and Aging

Bone mass decreases Bones weaken Increases risk of hip fracture, hip dislocation,

or pelvic fracture

Joints (Arthroplasty)

Arthroplasty Joints may be replaced surgically with artificial joints Most commonly replaced are the hips, knees, and

shoulders Hip Replacements

Partial hip replacements involve only the femur Total hip replacements involve both the acetabulum and

head of the femur Knee Replacements

Actually a resurfacing of cartilage and may be partial or total

Potential complications of arthroplasty include infection, blood clots, loosening or dislocation of the replacement components, and nerve injury

Joints (Arthroplasty)

Joints (Arthroplasty)

Osteoarthritis (OA)

Common, irreversible, degenerative (“wear-and-tear”) arthritis

85% of all Americans develop OA, more women than men

Probably related to the normal aging process

Osteoarthritis (OA)

More cartilage is destroyed than replaced in badly aligned or overworked joints

Exposed bone ends thicken, enlarge, form bone spurs, and restrict movement

Treatment: moderate activity, mild pain relievers, capsaicin creams, glucosamine and chondroitin sulfate

Lyme Disease

Caused by bacteria transmitted by the bites of ticks

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

May lead to joint pain and arthritis Treatment: antibiotics

Integration with Other Systems

Bone Recycling Living bones maintain equilibrium between

Bone building (osteoblasts) And breakdown (osteoclasts)

Factors Affecting Bone Strength Age Physical stress Hormone levels Calcium and phosphorus uptake and excretion Genetic and environmental factors

Integration with Other Systems

Bones Support Body Systems The skeletal system

Supports and protects other systems Stores fat, calcium, and phosphorus Manufactures cells for immune system

Disorders in other body systems can cause Bone tumors Osteoporosis Arthritis Rickets (vitamin D deficiency)

Integration with Other Systems

Figure 9–13 Functional Relationships between the Skeletal System and Other Systems.

Integration with Other Systems

Figure 9–13 Functional Relationships between the Skeletal System and Other Systems.