Transcript Articulations (Joints) Chapter 8

Articulations (Joints)
Chapter 8
Weakest parts of the skeleton
Introduction to Joints
Articulation – site where two or more bones meet
Functions of joints
o Give the skeleton mobility
o Hold the skeleton together
Structural classification focuses on the material binding
bones together and whether or not a joint cavity is present
The three structural classifications are:
o Fibrous
o Cartilaginous
o Synovial
Functional classification is based on the
amount of movement allowed by the joint
The three functional classes of joints are:
o Synarthroses – immovable
o Amphiarthroses – slightly movable
o Diarthroses – freely movable
Fibrous Joints
Sutures occur between bones of skull
and use very short connective tissue
fibers to hold the bones together.
o Synostoses – fused in adult
In syndesmoses, the bones are
connected by a ligament, which is a
cord or band of fibrous tissue.
A gomphosis is a peg-in-socket
fibrous joint.
Cartilaginous Joints
Synchondroses involve a bar or plate of hyaline cartilage uniting the bones,
such as the epiphyseal plate.
In symphyses, such as the pubic symphysis, the articular surfaces are
covered with articular cartilage that is then fused to an intervening pad or
plate of fibrocartilage.
Synovial Joints
Those joints in which the articulating bones are separated by a fluidcontaining joint cavity
All are freely movable diarthroses
Examples – all limb joints, and most joints of the body
General Structure
Hyaline Cartilage
Synovial Joints: Friction-Reducing 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 Joint Stability
Stability is determined by:
o Articular surfaces – shape determines what movements are possible
o Ligaments – unite bones and prevent excessive or undesirable motion
o Labrums and menisci that deepen the articular
surface
o Muscle tone is accomplished by:
 Muscle tendons across joints
acting as stabilizing factors
 Tendons that are kept tight at
all times by muscle tone
o Fat pads – protect nerves and
blood vessels
Synovial Joints: Range of Motion
Nonaxial (translational) – slipping movements only
Uniaxial – movement in one plane
Biaxial – movement in two planes
Multiaxial – movement 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
Angular Movement
Angular Movement
Rotation
The turning of a bone around its
own long axis
Examples
o Between first two vertebrae
o Hip and shoulder joints
Special Movements
Special Movements
Special Movements
Special Movements
Synovial Joint: 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
o Femoropatellar
o Lateral and medial
tibiofemoral joints
Ligaments and tendons
o Quadriceps tendon
o Lateral and medial patellar
retinacula
o Fibular and tibial
collateral ligaments
o Patellar ligament
Synovial Joints: Knee –
Other Supporting Structures
Anterior cruciate ligament
Posterior cruciate ligament
Medial meniscus
Lateral meniscus
Shoulder (Glenohumeral)
Ball-and-socket joint - stability is sacrificed for greater freedom of movement
Head of humerus articulates with the glenoid fossa of the scapula
Weak stability is maintained by:
o Thin, loose joint capsule
o Four ligaments – coracohumeral, and three glenohumeral
o Tendon of the long head of biceps, which travels through the
intertubercular groove and secures the humerus to the glenoid cavity
o Rotator cuff that encircles shoulder joint and blends with articular capsule
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
o Acetabular labrum
o Iliofemoral ligament
o Pubofemoral ligament
o Ischiofemoral ligament
o Ligamentum teres
Injuries
Sprains
o The ligaments reinforcing a joint are stretched or torn
o Partially torn ligaments slowly repair themselves
o Completely torn ligaments require prompt surgical repair
Cartilage Injuries
o The snap and pop of overstressed cartilage
o Common aerobics injury
o Repaired with arthroscopic surgery
Dislocations
o Occur when bones are forced out of alignment
o Usually accompanied by sprains, inflammation, and joint immobilization
o Caused by serious falls and are common sports injuries
o Subluxation – partial dislocation of a joint
Inflammatory and Degenerative Conditions

Bursitis
o An inflammation of a bursa, usually
caused by a blow or friction
o Symptoms are pain and swelling
o Treated with anti-inflammatory drugs;
excessive fluid may be aspirated
Tendonitis
o Inflammation of tendon sheaths
typically caused by overuse
o 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 (OA)
Course of the Disease
o 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
Treatments
o OA is slow and irreversible
Treatments include:
o Mild pain relievers, along with moderate activity
o Magnetic therapy
o Glucosamine sulfate decreases pain and inflammation
Rheumatoid Arthritis (RA)
Chronic, inflammatory, autoimmune disease of unknown cause
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
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
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
More Information
Ganglion Cysts
Herniated Disc
Temporomandibular Joint Disorders
Tennis Elbow
Web Sites on Articulations.... Animations
Arthroscopic Surgery Arthritis.org
ACL Reconstruction