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PowerPoint® Lecture Slides
prepared by Leslie Hendon,
University of Alabama,
Birmingham
9
HUMAN
ANATOMY
PART 1
Joints
fifth edition
MARIEB | MALLATT | WILHELM
Copyright © 2008 Pearson Education, Inc.,
publishing as Benjamin Cummings
Joints



Rigid elements of the skeleton meet at joints or
articulations
Greek root “arthro” means joint
Articulations can be
 Bone to bone
 Bone to cartilage
 Teeth in bony sockets

Structure of joints

Enables resistance to crushing, tearing, and other forces
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Classifications of Joints
 Joints can be classified by function or structure
 Functional classification – based on amount of movement

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Synarthroses – immovable; common in axial skeleton –
skull sutures
Amphiarthroses – slightly movable; common in axial
skeleton – pubic symphysis, intervertebral discs,
interrosseous membranes btwn. Radius/ulna, tibia/fibula
Diarthroses – freely movable; common in appendicular
skeleton (all synovial joints) arms, legs, hands and feet plus
the TMJ
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Classifications of Joints

Structural classification based on
 Material that binds bones together
 Presence or absence of a joint cavity
 Structural classifications include
 Fibrous – sutures, gomphosis (teeth in jaw), Fibrous
tissue ossifies in middle age and is called a
Synostoses – closed sutures
 Cartilaginous – pubic symphysis etc.
 Synovial - limbs, TMJ
 SYNDESMOSIS – radius/ulna, tibia/fibula
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Fibrous Joints
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Figure 9.1a, b
Gomphoses
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
Tooth in a socket
Connecting
ligament – the
periodontal
ligament
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Figure 9.1c
Synchondroses

Hyaline cartilage unites
bones
 Epiphyseal plates
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Figure 9.2a
Synchondroses

Joint between first rib and manubrium
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Figure 9.2b
Symphyses
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Hyaline cartilage – also present as articular
cartilage
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Figure 9.2c
Synovial Joints
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

Most movable type of joint
All are diarthroses
Each contains a fluid-filled joint cavity
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General Structure of Synovial Joints

Articular cartilage
 Ends of opposing bones are covered with hyaline
cartilage
 Absorbs compression

Joint cavity (synovial cavity)
 Unique to synovial joints
 Cavity is a potential space that holds a small
amount of synovial fluid
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General Structure of Synovial Joints

Articular capsule – joint cavity is enclosed in a
two-layered capsule
 Fibrous capsule – dense irregular connective
tissue, which strengthens joint
 Synovial membrane – loose connective tissue
 Lines joint capsule and covers internal joint surfaces
 Functions to make synovial fluid
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General Structure of Synovial Joints

Synovial fluid
 A viscous fluid similar to raw egg white
 A filtrate of blood with added lubricants
 Arises from capillaries in synovial membrane
 Contains glycoprotein molecules secreted by
fibroblasts
 Synovial joints are subject to compressive forces.
This acts like a “sponge”. When the pressure
releases, fluid is absorbed into the joint, then when
compressed again, it is squeezed out. This
mechanism is called “weeping lubrication”
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General Structure of Synovial Joints

Reinforcing ligaments
 Often are thickened parts of the fibrous capsule
 Sometimes are extracapsular ligaments – located
outside the capsule
 Sometimes are intracapsular ligaments – located
internal to the capsule
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A Typical Synovial Joint
continuous
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Figure 9.3a
General Structure of Synovial Joints

Richly supplied with sensory nerves
 Detect pain
 Most monitor how much the capsule is being
stretched
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Synovial Joints with Articular Discs

Some synovial joints
contain an articular
disc
 Occur in the
temporomandibular
joint and at the knee
joint
 Occur in joints whose
articulating bones have
somewhat different
shapes
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Figure 9.3c
Summary of Joint Classes
Don’t need to know
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Table 9.1 (1 of 2)
How Synovial Joints Function
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Synovial joints – lubricating devices
Friction could overheat and destroy joint tissue
Are subjected to compressive forces
 Fluid is squeezed out as opposing cartilages touch
 Cartilages ride on the slippery film
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Bursae and Tendon Sheaths
 Bursae and tendon sheaths are not synovial joints
 Closed bags of lubricant
 Reduce friction between body elements
 Bursa – a flattened fibrous sac lined by a synovial

membrane
Tendon sheath – an elongated bursa that wraps
around a tendon, it occurs in the carpal tunnel which is
subject to overuse and causing Carpal Tunnel
Syndrome
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Bursae and Tendon Sheaths
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Figure 9.4a, b
Factors Influencing Joint Stabililty

Articular surfaces – seldom play a major role in
joint stability
 The elbow, the knee and the hip do provide


stability
Ligaments – the more ligaments in a joint, the
stronger it is
Muscle tone – the most important factor in joint
stability
 Keeps tension on muscle tendons
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Gliding Joints – Types of Movement


Flat surfaces of two bones slip across
each other
Gliding occurs
between
 Carpals
 Articular
processes
of vertebrae
 Tarsals
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Figure 9.5a
Angular Movements


Increase or decrease angle between bones
Movements involve
 Flexion and extension
 Abduction and adduction
 Circumduction
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Angular Movements
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Figure 9.5b
Angular Movements
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Figure 9.5c
Angular Movements
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Figure 9.5d
Angular Movements
PLAY
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Movement of the
pectoral girdle (a)
Figure 9.5e
Rotation
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

Involves turning movement of a bone around its
long axis
The only movement allowed between atlas and
axis vertebrae
Occurs at the hip and shoulder joints
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Special Movements
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
Supination – forearm rotates laterally, palm faces
anteriorly
Pronation – forearm rotates medially, palm faces
posteriorly
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Special Movements
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Figure 9.6a
Special Movements
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Dorsiflexion – lifting the foot so the superior
surface approaches the shin
Plantar flexion – depressing the foot, pointing the
toes
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Special Movements
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
Inversion – turning the sole medially
Eversion – turning the sole laterally
PLAY
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Movement of the
ankle and foot (a)
Figure 9.6c
Special Movements
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Protraction – nonangular movement of jutting out
the jaw
Retraction – opposite movement to protraction
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Figure 9.6d
Special Movements
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Elevation – lifting a body superiorly
Depression – moving the elevated part inferiorly
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Figure 9.6e
Special Movements

Opposition – movement of the thumb to touch the
tips of other fingers
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Figure 9.6f
Hinge Joint – movement in one axis only like the elbow
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Figure 9.7b
Pivot Joint – proximal radio-ulnar
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Figure 9.7c
Ball and Socket

Ball-and-socket joints
 Spherical head of one bone fits into round socket of
another
 Classified as multiaxial – allow movement in all
axes
 Shoulder and hip joints
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Ball-and-Socket Joint
PLAY
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Movement of the
glenohumeral joint (a)
Figure 9.7f
Shoulder Joint
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Figure 9.8a
Selected Synovial Joints

Shoulder (Glenohumeral) joint
 The most freely movable joint lacks stability
 Articular capsule is thin and loose
 Muscle tendons contribute to joint stability
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Rotator Cuff

The rotator cuff is made up of four muscles and
their associated tendons
 Subscapularis
 Supraspinatus
 Infraspinatus
 Teres minor

Rotator cuff injuries are common shoulder injuries
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The shoulder joint
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Figure 9.8b, c
The Shoulder Joint
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Figure 9.8d, e
Selected Synovial Joints

Elbow joint
 Allows flexion and extension
 The humerus’ articulation with the trochlear notch
of the ulna forms the hinge
 Tendons of biceps and triceps brachii provide
stability
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Elbow Joint
Understand the features that are common to all joints
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Figure 9.9a, b
Selected Synovial Joints

Hip joint
 A ball-and-socket structure
 Movements occur in all axes
 Limited by ligaments and acetabulum
 Head of femur articulates with acetabulum
 Stability comes chiefly from acetabulum and
capsular ligaments
 Muscle tendons contribute somewhat to stability
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Frontal Section and Anterior View of the Hip Joint
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Figure 9.11a, b
Posterior View of the Hip Joint
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Figure 9.11c, d
Selected Synovial Joints

Knee joint
 The largest and most complex joint
 Primarily acts as a hinge joint
 Has some capacity for rotation when leg is flexed
 Structurally considered compound and bicondyloid
 Two fibrocartilage menisci occur within the joint
cavity
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Sagittal Section and Superior View of Knee Joint
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Figure 9.12a
Sagittal Section and Superior View of Knee Joint
Helps prevent ant/post
displacement
Helps prevent
lateral
displacement
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Figure 9.12b
Knee Joint

Capsule of knee joint
 Covers posterior and lateral aspects of the knee
 Covers tibial and femoral condyles
 Does not cover the anterior aspect of the knee
 Anteriorly covered by three ligaments
 Patellar, medial, and lateral retinacula
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Anterior View of Knee
AKA medial
collateral ligament
AKA
lateral
collateral
ligament
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Figure 9.12c
Posterior View of Knee Joint
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Figure 9.12d
Knee Joint

Intracapsular ligaments
 Cruciate ligaments
 Cross each other like an “X”
 Each cruciate ligament runs from the proximal tibia
to the distal femur
 Anterior cruciate ligament
 Posterior cruciate ligament
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Anterior View of Flexed Knee
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Figure 9.12e, f
Knee Joint

Cruciate ligaments
 Prevent
undesirable
movements at the
knee joint
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Figure 9.13a
Selected Synovial Joint

Ankle Joint
 A hinge joint between
 United inferior ends of tibia and fibula
 The talus of the foot
 Allows the movements
 Dorsiflexion and plantar flexion only
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Selected Synovial Joints

Temporomandibular joint (TMJ)



Lies anterior to the ear
Head of the mandible articulates with the mandibular fossa
Two surfaces of the articular disc allow two kinds of
movement
 Hinge-like movement
 Superior surface of disc glides anteriorly
 A condition that commonly leads to neck pain, ear problems
and pain when opening the mouth is called temporomandibular
disorder or “TMJ”
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The Temporomandibular Joint
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Figure 9.16a, b
Disorders of Joints
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

Structure of joints makes them prone to traumatic
stress
Function of joints makes them subject to friction
and wear
Affected by inflammatory and degenerative
processes
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Joint Injuries

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Sprains – ligaments of a reinforcing joint are
stretched or torn
Dislocation – occurs when the bones of a joint are
forced out of alignment
Torn cartilage – common injury to meniscus of
knee joint
Bursitis – inflammation of a bursa do to injury or
friction
Tendonitis – inflammation of a tendon sheath
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Inflammatory and Degenerative Conditions

Arthritis – describes over 100 kinds of jointdamaging diseases
 Osteoarthritis – most common type “wear and

tear” arthritis
 Rheumatoid arthritis – a chronic inflammatory
disorder
 Gouty arthritis (gout) – uric acid build-up causes
pain in joints
Lyme disease – inflammatory disease often
resulting in joint pain
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The Joints Throughout Life


Synovial joints develop from mesenchyme
By week 8 of fetal development, joints resemble
adult joints
 Outer region of mesenchyme becomes fibrous joint
capsule
 Inner region becomes the joint cavity
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The Joints Throughout Life



During youth – injury may tear an epiphysis off a
bone shaft
Advancing age – osteoarthritis becomes more
common
Exercise – helps maintain joint health
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