2. Articulations or Joints
8-2
• Ar ticulation or Joint
– Place where two bones (or bone and car tilage)
come together
• Ar thrology = study of the joints
• Kinesiology = study of musculoskeletal
• Functions of joints
– Give the skeleton mobility
– Hold the skeleton together
• Structure cor related with movement
3. Classification of Joints
• Structural classes: based on type of
connective tissue type that binds bones and
whether or not a joint cavity is present
8-3
– Fibrous
– Cartilaginous
– Synovial
• Functional classes: based on degree of motion
– Synarthrosis: non-movable
– Amphiarthrosis: slightly movable
– Diarthrosis: freely movable
4. 8-4
Fibrous Joints
• Characteristics
– United by fibrous connective tissue
– Have no joint cavity
– Move little or none
• Types:
– Sutures
– Syndesmoses
– Gomphoses
5. Fibrous Joints: Sutures
8-5
• Types of sutures
– Ser rated: Opposing bones interdigitate (Sagittal suture)
– Lap: Over lapping beveled edges (Squamosal suture)
– Plane: Straight, non-over lapping edges (Intermaxillary suture)
• Per iosteum of one bone is continuous with the
per iosteum of the other .
• In adults may ossify completely: synostosis.
• Fontanels: membranous areas in the suture between
bones. Allow change in shape of head dur ing bir th and
rapid growth of the brain after bir th.
7. Fibrous Joints: Syndesmoses
• Two bones joined by
ligament
– Interosseous membrane
• Most moveable of
fibrous joints
• Examples: radioulnar
joint and tibiofibular
joints
8-7
8. Fibrous Joints: Gomphoses
• Specialized joints
• Pegs that fit into sockets
• Periodontal
ligaments: hold teeth
in place
• Inflammations
– Gingivitis leads to…
– Periodontal disease
8-8
9. 8-9
Cartilaginous Joints
• Bones are joined by
car tilage
• Lack a joint cavity
• Types
– Synchondroses: bound
by hyaline car tilage
– Symphyses: bound by
fibrocar tilage
10. 8-10
Cartilaginous Joints:
Synchondroses
• Joined by hyaline
cartilage
• Little or no movement
• Some are temporary
and are replaced by
synostoses
• Some are permanent
• Some like
costochondral joints
develop into synovial
joints
• Examples: Epiphyseal
plates, 1st sternocostal
11. 8-11
Cartilaginous Joints:
Symphyses
• Fibrocartilage
uniting two bones
• Slightly movable
• Examples:
symphysis pubis,
between the
manubrium and the
body of the sternum,
intervertebral disks.
12. 8-12
Synovial Joints
• Contain synovial fluid in a joint cavity
called the synovial cavity
• Allow considerable movement
(diarthroses)
• Most joints that unite bones of
appendicular skeleton reflecting greater
mobility of appendicular skeleton
compared to axial
13. 8-13
Structure of
Synovial
Joints
• Articular cartilage: hyaline;
provides smooth surface on epiphysis
• Joint cavity: synovial; encloses
articular surfaces
• Articular Capsule encloses joint
cavity
– Fibrous capsule:
• dense irregular connective tissue
• continuous with periosteum.
• Portions may thicken to form ligaments.
– Synovial membrane and fluid:
• Thin, delicate membrane
• lines inside of joint capsule.
• Synovial fluid:
– complex mixture of polysaccharides,
proteins, fat and cells. Hyaluronic acid-slippery.
• No blood vessels or nerves in articular
cartilages; nutrients derived from
nearby blood vessels and synovial fluid
• Nerves in capsule help brain know
position of joints (proprioception)
14. 8-14
Accessory Structures
• Bursae
– Pockets of synovial membrane and fluid that extend from the
joint. Found in areas of friction
– Bursitis
• Ligaments and tendons: stabilization
• Articular discs: temperomandibular,
sternoclavicular, acromioclavicular
• Menisci: fibrocartilaginous pads in the knee.
• Tendon sheaths: synovial sacs that surround
tendons as they pass near or over bone
16. 8-16
Types of Movement
• Gliding: in plane joints; slight movement
• Angular
– Flexion and Extension
• Hyperextension
• Plantar and Dorsiflexion
– Abduction and Adduction
• Circular
– Rotation
– Pronation and Supination
– Circumduction
17. Flexion and Extension
• Flexion: movement of a body part anterior to
the coronal plane
• Extension: movement of a body part
posterior to the coronal plane
8-17
18. Dorsiflexion and Plantar
8-18
Flexion
• Exceptions to
definition
– Plantar flexion:
standing on the toes
– Dorsiflexion: foot
lifted toward the shin
19. Abduction and Adduction
• Abduction: movement
away from the midline
• Adduction: movement
toward the midline
8-19
20. Circular Movements: Rotation,
Pronation and Supination
• Rotation: turning of a
structure on its long axis
– Examples: rotation of the
head, humerus, entire body
– Medial and lateral rotation;
example, the rotation of the
arm
• Pronation/Supination:
refer to unique rotation of
the forearm
– Pronation: palm faces
posteriorly
– Supination: palm faces
anteriorly
8-20
21. 8-21
Circular Movement:
Circumduction
• Combination of
flexion, extension,
abduction,
adduction
• Appendage
describes a cone
22. 8-22
Special Movements
• Unique to only one or two joints
• Types
–Elevation and Depression
–Protraction and Retraction
–Excursion
–Opposition and Reposition
–Inversion and Eversion
23. Elevation and Depression
• Elevation: moves a
structure superior
• Depression: moves
a structure inferior
• Examples:
shrugging the
shoulders, opening
and closing the
mouth
8-23
24. Protraction and Retraction
8-24
• Protraction:
gliding motion
anteriorly
• Retraction: moves
structure back to
anatomic position or
even further
posteriorly
• Examples: scapulae
and mandibles
25. 8-25
Excursion
• Lateral: moving
mandible to the right or
left of midline
• Medial: return the
mandible to the midline
26. Opposition and Reposition
• Opposition:
movement of thumb
and little finger
toward each other
• Reposition: return
to anatomical
position
8-26
27. Inversion and Eversion
8-27
• Inversion: turning
the ankle so the
plantar surface of
foot faces medially
• Eversion: turning
the ankle so the
plantar surface of
foot faces laterally
28. Movements at Synovial joints
• Monoaxial: occurring around one axis
• Biaxial: occurring around two axes at
right angles to each other
• Multiaxial: occurring around several
axes
• See Table 8.2 in text
8-28
29. 8-29
Types of Synovial Joints:
Plane Joints
• Plane or gliding joints
– Monaxial. One flat bone
surface glides or slips over
another similar surface
– Sometimes considered an
amphiarthrosis
– Examples: intervertebral,
intercarpal, intertarsal
acromioclavicular,
carpometacarpal,
tarsometatarsal,
30. Hinge and Pivot Joints
• Hinge joints
– Monaxial
– Convex cylinder in one
bone; corresponding
concavity in the other
– Example: elbow, ankle,
interphalangeal
• Pivot joints
– Monaxial. Rotation around
a single axis.
– Cylindrical bony process
rotating within a circle of
bone and ligament
– Example: articulation
between dens of axis and
atlas (atlantoaxial),
proximal radioulnar
8-30
31. Saddle joints
• Each articular surface is
shaped like a saddle;
• Trapeziometacarpal joint
at base of the thumb
8-31
Types of Synovial Joints:
32. Ball-and-Socket and Ellipsoid
8-32
Joints
• Ball-and-socket
– Smooth heispherical head fits
within a cuplike depression
– Multiaxial
– Examples: shoulder and hip joints
• Condyloid (ellipsoid) joint
– Oval convex surface on one bone
fits into a similarly shaped
depression on the next
• Atlantooccipital joint (C1-C2)
• Metacarpophalangeal joints
33. 8-33
Shoulder
(Glenohumeral)
Joint
• Most freely moveable joint in body
– Shallowness and looseness
– Stability is reduced
– Deepened by glenoid labrum, a rim of
cartilage built up around glenoid cavity
• Supported by rotator cuff musculature
– tendons fuse to joint capsule
– Stabilize and strengthen it
– supraspinatus, infraspinatus, teres
minor and subscapularis,
• Bursae: subacromial and subscapular
• Tendon of biceps brachii passes
through the joint capsule
• Flexion/extension,
abduction/adduction, rotation,
circumduction
35. 8-35
The Knee Joint
• Most complex diarthrosis
– patellofemoral = gliding joint
– tibiofemoral = gliding with slight
rotation and gliding possible in
flexed position
• Joint capsule anteriorly consists
of patella and extensions of
quadriceps femoris tendon
• Capsule strengthened by
extracapsular and intracapsular
ligaments
36. 8-36
Knee, cont.
• Cruciate ligaments:
extend between
intercondylar eminence
of tibia and fossa of the
femur
– Anterior cruciate
ligament (ACL). Prevents
anterior displacement of
tibia
– Posterior cruciate
ligament (PCL). Prevents
posterior displacement of
tibia
• Collateral and
popliteal ligaments:
along with tendons of
thigh muscles strengthen
the joint
•
37. Knee Joint – Anterior and
8-37
Posterior Views
• Anterior and lateral cruciate ligaments limit anterior and
posterior sliding movements
• Medial and lateral collateral ligaments prevent rotation of
extended knee
38. Knee Joint – Superior View
• Medial and lateral meniscus absorb shock and shape
joint
8-38
39. Knee Injuries and Disorders
• Football injuries: often tear
the tibial collateral
ligament, the anterior
cruciate ligament, and
damage the medial
meniscus
• Bursitis
• Chondromalacia:
softening of cartilage due to
abnormal movement of the
patella or to accumulation
of fluid in fat pad posterior
to patella
• Hemarthrosis: acute
accumulation of blood in
joint
8-39
40. Effects of Aging on Joints
• Tissue repair slows; rate of new blood vessel
development decreases
• Articular cartilages wear down and matrix
becomes more rigid
• Production of synovial fluid declines
• Ligaments and tendons become shorter and
less flexible: decrease in range of motion
(ROM)
• Muscles around joints weaken
• A decrease in activity causes less flexibility
and decreased ROM
8-40
41. 8-41
Sprains
• The ligaments reinforcing a joint are
stretched or torn
• Partially torn ligaments slowly repair
themselves
• Completely torn ligaments require
prompt surgical repair
42. 8-42
Cartilage Injuries
• The snap and pop of overstressed
cartilage
• Common aerobics injury
• Repaired with arthroscopic surgery
43. 8-43
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
44. 8-44
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
45. 8-45
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
46. 8-46
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
47. 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
8-47
48. 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
8-48
49. 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
8-49
51. Rheumatoid Arthritis:
8-51
Treatment
• Conservative therapy – aspirin, long-term
use of antibiotics, and physical
therapy
• Progressive treatment – anti-inflammatory
drugs or
immunosuppressants
52. 8-52
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 anti-inflammatory
drugs, and glucocorticoids
