the skeletal system:...

© 2012 Pearson Education, Inc.

8 The Skeletal System:

Articulations


Introduction

•The body cannot move without joints

•Movements are linked to the range of joint action

• Joints (arthroses) are connections between bones that may or may not permit movement

•Two bones may be in direct contact with each other or separated by:

• Cartilage

• Fluid

• Fibrous tissue


Introduction

• Joints are classified based on:

• Function

• Range of motion

• Structure

• Makeup of the joint


Classification of Joints

• Joints can be classified based on their

range of motion (function)

• Synarthrosis

• Immovable

• Amphiarthrosis

• Slightly movable

• Diarthrosis

• Freely movable



• Synarthrosis (immovable joint)

• Sutures (joints found only in the skull) • Bones are interlocked together

• Gomphosis (joint between teeth and jaw bones) • Periodontal ligaments of the teeth

• Synchondrosis (joint within epiphysis of bone) • Binds the diaphysis to the epiphysis

• Synostosis (joint between two fused bones) • Fusion of the three coxal bones


Classification of Joints (examples)

Synostosis



•Amphiarthroses (slightly movable joints)

• Syndesmosis (ligaments that connect two

bones but limit their motion)

• Between the radius and ulna

• Between the tibia and fibula

• Symphysis (bones are separated by a wedge

or pad of cartilage)

• Between the pubic bones of the two coxal bones


syndesmosis

symphysis




• Diarthroses (freely movable joints)

• Also called synovial joints

• Typically found at the ends of long bones

• Examples of diarthroses joints:

• Shoulder joint

• Elbow joint

• Knee joint

• TMJ


Classification of Joints • Synovial joints

• All synovial joints

have six basic

characteristics

• A joint capsule

(dense regular CT)

• The presence of

articular cartilages

• A joint cavity with

synovial fluid

• A synovial membrane

• Accessory structures

(cartilage, ligaments,

tendons, bursae sacs)

• Sensory nerves and

blood vessels




of synovial joints


are:

• Menisci (fibrous

cartilage)

• Ligaments

• Tendons

• Bursae sacs (fluid-

filled pockets)



• Joints can be classified based on their

makeup (structure)

• Bony fusion (fusion of the frontal bone)

• Fibrous joint (skull sutures)

• Cartilaginous joint (pubic symphysis)

• Synovial joint (ball and socket joints and hinge

joints)


Table 8.2 A Structural Classification of Articulations


Articular Form and Function

Types of movements:

•Linear movements

• Two bones gliding past each other

• carpal/carpal

• tarsal/tarsal

• clavicle/sternum

• Angular movements

• abduction/adduction

• flexion/extension


Figure 8.3ac Angular Movements

Abduction/adduction

Abduction

Abduction

Abduction

Adduction

Adduction

Adduction

Adduction Abduction

Adduction/abduction

Abduction Adduction

Away from midline Toward midline


Figure 8.3b Angular Movements

Flexion/extension

Flexion

Flexion

Flexion

Extension

Extension

Extension

Extension

Flexion

Decrease angle

Increase angle



• Rotational movements

• pronation/supination

• Special movements

• inversion/eversion

• dorsiflexion/plantar flexion

• lateral flexion

• protraction/retraction

• opposition

• depression/elevation


Figure 8.4 Rotational Movements

Head rotation

Right

rotation Left

rotation

Lateral

(external)

rotation Medial

(internal)

rotation

Supination Pronation

Pronation

Supination


Figure 8.5a Special Movements

Eversion/Inversion

Eversion Inversion


Figure 8.5b Special Movements

Dorsiflexion/plantar flexion

Dorsiflexion

Plantar flexion


Figure 8.5c Special Movements

Lateral flexion


Figure 8.5d Special Movements

Retraction/protraction

Retraction Protraction


Figure 8.5e Special Movements

Opposition


Figure 8.5f Special Movements

Depression/elevation

Depression Elevation



• Structural Classification of Joints

• Plane joints (gliding joints)

• Nonaxial (glides only in one direction)

• Multiaxial (glides in all directions)

• Ex. Carpal/carpal – Tarsal/tarsal – Vertebrae/vertebrae –

Clavicle/sternum

• Hinge joints

• Flexion and extension

• Ex. Elbow and knee

• Pivot joints

• Rotational movements

• Ex. Atlas/axis


Figure 8.6 A Structural Classification of Synovial Joints (Part 1 of 6)

Gliding Joint

Manubrium

Slight movement



Hinge Joint

Humerus

Ulna

Angular movement in a single plane



Pivot Joint

Atlas

Axis

rotation



• Structural Classification of Joints

• Condylar joints

• Oval articular surface on one bone articulates with a

depression on another bone

• Ex. Radius/capitulum – Radius/carpals –

Phalanges/metacarpals – Phalanges/metatarsals

• Saddle joints

• Biaxial joints that allow some circumduction

• Ex. Pollex/metacarpal

• Ball and socket joints

• Triaxial joints

• Ex. Shoulder joint – Hip joint



Condylar Joint

Scaphoid

Radius Ulna

Angular motion



Saddle Joint

Metacarpal

of thumb

Trapezium

III II

I

Extremely mobile



Ball-and-Socket Joint

Humerus

Scapula

All combination of movements


Aging and Articulations • As we age, joints are subjected to wear and

tear

• Rheumatism

• Pain and stiffness affecting the skeletal system,

muscular system, or both

• Arthritis

• Includes all rheumatic diseases that affect synovial

joints

• Damage to the articular cartilage


Bones and Muscles

• Musculoskeletal system

• The skeleton and muscles are structurally

and functionally interdependent

the skeletal system:...

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