Download Joints

Joints
Joints (Articulations)
• Weakest parts of the skeleton
• Articulation – site where two or more
bones meet
• Functions of joints
– Give the skeleton mobility
– Hold the skeleton together
Classification of Joints
• Joints are classified based on:
– Structure
• Fibrous
• Cartilaginous
• Synovial
– Function
• Synarthroses – immovable
• Amphiarthroses – slightly movable
• Diarthroses – freely movable
Fibrous/Synarthroses
Classification of Joints:
Structural
• Structural classification focuses on the
material binding bones together and
whether or not a joint cavity is present
• The three structural classifications are:
– Fibrous
– Cartilaginous
– Synovial
Classification of Joints:
Functional
• Functional classification is based on the
amount of movement allowed by the joint
• The three functional classes of joints are:
– Synarthroses – immovable
– Amphiarthroses – slightly movable
– Diarthroses – freely movable
Classification of Joints: Structural
Fibrous Structural Joints
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The bones are joined by fibrous tissues
There is no joint cavity
Most are immovable
There are three types – sutures,
syndesmoses, and gomphoses
Fibrous Structural Joints:
Sutures
• Occur between the bones of the skull
• Comprised of interlocking junctions
completely filled with connective tissue
fibers
• Bind bones tightly together, but allow for
growth during youth
• In middle age, skull
bones fuse and are
called synostoses
Fibrous
Structural
Joints:
Syndesmoses
• Bones are connected by a fibrous tissue
ligament
• Movement varies from immovable to slightly
variable
• Examples include the connection between the
tibia and fibula, and the radius and ulna
Fibrous Structural Joints:
Gomphoses
• The peg-in-socket
fibrous joint between a
tooth and its alveolar
socket
• The fibrous connection
is the periodontal
ligament
Cartilaginous Joints
• Articulating bones are united by cartilage
• Lack a joint cavity
• Two types – synchondroses and
symphyses
Cartilaginous Joints:
Synchondroses
• A bar or plate of hyaline cartilage unites
the bones
• All synchondroses are synarthrotic
• Examples include:
– Epiphyseal plates
of children
– Joint between the
costal cartilage of
the first rib and the
sternum
Cartilaginous Joints:
Symphyses
• Hyaline cartilage covers the articulating surface
of the bone and is fused to an intervening pad of
fibrocartilage
• Amphiarthrotic joints designed for strength and
flexibility
• Examples include intervertebral joints and the
pubic symphysis of the pelvis
Synovial Joints
• Those joints in which the
articulating bones are
separated by a fluid-containing
joint cavity
• All are freely movable
diarthroses
• Examples – all limb joints,
and most joints of the body
Synovial Joints
Synovial Joints: General Structure
• Synovial joints all have the following
– Articular cartilage
– Joint (synovial) cavity
– Articular capsule
– Synovial fluid
– Reinforcing
ligaments
Synovial Joints: FrictionReducing Structures
• Bursae – flattened, fibrous sacs lined
with synovial membranes and containing
synovial fluid
• Common where ligaments, muscles,
skin, tendons, or bones rub together
• Tendon sheath – elongated bursa that
wraps completely around a tendon
Synovial Joints: Stability
• Stability is determined
by:
– Articular surfaces –
shape determines what
movements are possible
– Ligaments – unite bones
and prevent excessive or
undesirable motion
Synovial Joints: Range of
Motion
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Nonaxial – slipping movements only
Uniaxial – movement in one plane
Biaxial – movement in two planes
Multiaxial – movement in or around all
three planes
Gliding Movements
• One flat bone surface glides or slips over
another similar surface
• Examples – intercarpal and intertarsal
joints, and between the flat articular
processes of the vertebrae
Angular Movement
• Flexion — bending movement that
decreases the angle of the joint
• Extension — reverse of flexion; joint angle
is increased
• Dorsiflexion and plantar flexion — up and
down movement of the foot
• Abduction — movement away from the
midline
• Adduction — movement toward the
midline
• Circumduction — movement describes a
cone in space
Gliding Movement
Angular Movement
Angular Movement
Rotation
• The turning of a
bone around its
own long axis
• Examples
– Between first two
vertebrae
– Hip and shoulder
joints
Angular Movement
Special Movements
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Supination and pronation
Inversion and eversion
Protraction and retraction
Elevation and depression
Opposition
Special Movements
Special Movements
Special Movements
Special Movements
Special Movements
Synovial Joints: Knee
• Largest and most complex joint of the
body
• Allows flexion, extension, and some
rotation
• Three joints in one surrounded by a single
joint cavity
– Femoropatellar
– Lateral and medial tibiofemoral joints
Synovial Joints: Knee Ligaments
and Tendons – Anterior View
• Tendon of the
quadriceps
femoris muscle
• Lateral and
medial patellar
retinacula
• Fibular and tibial
collateral
ligaments
• Patellar ligament
Synovial Joints: Knee –
Other Supporting Structures
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Anterior cruciate ligament
Posterior cruciate ligament
Medial meniscus (semilunar cartilage)
Lateral meniscus
Synovial Joints: Knee –
Other Supporting Structures
Synovial Joints: Knee –
Posterior Superficial View
• Adductor magnus
tendon
• Articular capsule
• Oblique popliteal
ligament
• Arcuate popliteal
ligament
• Semimembranosus
tendon
Synovial Joints: Shoulder
(Glenohumeral)
• Ball-and-socket joint in which stability is
sacrificed to obtain greater freedom of
movement
• Head of humerus articulates with the
glenoid fossa of the scapula
Synovial Joints: Shoulder
Stability
• Weak stability is maintained by:
– Thin, loose joint capsule
– Four ligaments – coracohumeral, and three
glenohumeral
– Tendon of the long head of biceps, which
travels through the intertubercular groove and
secures the humerus to the glenoid cavity
– Rotator cuff (four tendons) that encircles the
shoulder joint and blends with the articular
capsule
Synovial Joints: Shoulder
Stability
Synovial Joints: Shoulder
Stability
Synovial Joints: Hip (Coxal)
Joint
• Ball-and-socket joint
• Head of the femur articulates with the
acetabulum
• Good range of motion, but limited by the
deep socket and strong ligaments
Synovial Joints: Hip Stability
• Acetabular
labrum
• Iliofemoral
ligament
• Pubofemoral
ligament
• Ischiofemoral
ligament
• Ligamentum
teres
Synovial Joints: Hip Stability
Synovial Joints: Elbow
• Hinge joint that allows flexion and
extension only
• Radius and ulna articulate with the
humerus
Synovial Joints: Elbow Stability
• Annular ligament
• Ulnar collateral ligament
• Radial collateral ligament
Synovial Joints: Elbow Stability
Injuries
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Sprains
Cartilage Injuries
Dislocations
Bursitis
Tendonitis
Arthritis
Osteoarthritis (OA)
Rheumatoid Arthritis (RA)
Gouty Arthritis
Sprains
• The ligaments reinforcing
a joint are stretched or
torn
• Partially torn ligaments
slowly repair themselves
• Completely torn
ligaments require prompt
surgical repair
Cartilage Injuries
• The snap and
pop of
overstressed
cartilage
• Common
aerobics injury
• Repaired with
arthroscopic
surgery
Dislocations
• Occur when bones are forced out of
alignment
• Usually accompanied by sprains,
inflammation, and joint immobilization
• Caused by serious falls and are common
sports injuries
• Subluxation – partial
dislocation of a joint
Inflammatory and Degenerative
Conditions
• Bursitis
– An inflammation of a bursa,
usually caused by a blow or
friction
– Symptoms are pain and swelling
– Treated with anti-inflammatory
drugs; excessive fluid may be
aspirated
• Tendonitis
– Inflammation of tendon sheaths
typically caused by overuse
– Symptoms and treatment are
similar to bursitis
Arthritis
• More than 100 different types of
inflammatory or degenerative
diseases that damage the joints
• Most widespread crippling disease
in the U.S.
• Symptoms – pain, stiffness, and
swelling of a joint
• Acute forms are caused by
bacteria and are treated with
antibiotics
• Chronic forms include osteoarthritis, rheumatoid
arthritis, and gouty arthritis
Osteoarthritis (OA)
• Most common chronic
arthritis; often called
“wear-and-tear” arthritis
• Affects women more than men
• 85% of all Americans develop OA
• More prevalent in the aged, and is probably
related to the normal aging process
Osteoarthritis: Course
• OA reflects the years of abrasion and
compression causing increased production of
metalloproteinase enzymes that break down
cartilage
• As one ages, cartilage is destroyed more quickly
than it is replaced
• The exposed bone ends thicken, enlarge, form
bone spurs, and restrict movement
• Joints most affected are the cervical and lumbar
spine, fingers, knuckles, knees, and hips
Osteoarthritis: Treatments
• OA is slow and irreversible
• Treatments include:
– Mild pain relievers, along with moderate
activity
– Magnetic therapy
– Glucosamine sulfate
decreases pain and
inflammation
Rheumatoid Arthritis
(RA)
• Chronic, inflammatory,
autoimmune disease of
unknown cause, with an
insidious onset
• Usually arises between the ages of 40 to
50, but may occur at any age
• Signs and symptoms include joint
tenderness, anemia, osteoporosis, muscle
atrophy, and cardiovascular problems
– The course of RA is marked with
exacerbations and remissions
Rheumatoid Arthritis: Course
• RA begins with synovitis of the affected joint
• Inflammatory chemicals are inappropriately
released
• Inflammatory blood cells migrate to the joint,
causing swelling
• Inflamed synovial membrane thickens into a
pannus
• Pannus erodes cartilage, scar tissue forms,
articulating bone ends connect
• The end result, ankylosis, produces bent,
deformed fingers
Rheumatoid Arthritis: Course
• RA begins with synovitis of the affected joint
• Inflammatory chemicals are inappropriately
released
• Inflammatory blood cells migrate to the joint,
causing swelling
• Inflamed synovial membrane thickens into a
pannus
• Pannus erodes cartilage, scar tissue forms,
articulating bone ends connect
• The end result, ankylosis, produces bent,
deformed fingers
Rheumatoid Arthritis: Treatment
• Conservative therapy – aspirin, long-term
use of antibiotics, and physical therapy
• Progressive treatment – anti-inflammatory
drugs or immunosuppressants
• The drug Enbrel, a biological response
modifier, neutralizes the harmful properties
of inflammatory chemicals
Gouty Arthritis
• Deposition of uric acid crystals in joints
and soft tissues, followed by an
inflammation response
• Typically, gouty arthritis affects the joint at
the base of the great toe
• In untreated gouty arthritis, the bone ends
fuse and immobilize the joint
• Treatment – colchicine, nonsteroidal antiinflammatory drugs, and glucocorticoids