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Types of Synovial Joints
Six major categories:
Plane
Hinge
Pivot
Condyloid
Saddle
Ball & socket
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Plane Joint
Plane joints
Articular surfaces are essentially flat
Allow only slipping or gliding
movements
Only examples of nonaxial joints
E.g. intercarpal/intertarsal joints
E.g. vertebral articular processes
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 8.7a
Types of Synovial Joints
Hinge joints
Cylindrical projections of one bone fits into a trough-shaped surface on
another
Motion is along a single plane (like a mechanical hinge)
Uniaxial joints permit flexion and extension only
Examples: elbow and interphalangeal joints
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Pivot Joints
Rounded end of one bone protrudes into a “sleeve,” or ring, composed of
bone (and possibly ligaments) of another
uniaxial rotation of one bone around its own long axis
Examples: “No” motion of the head via joint between the axis and the dens,
and the proximal radioulnar joint (radius rotates within ring-like ligament
secured to the ulna
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Condyloid or Ellipsoidal Joints
Oval articular surface of one bone fits into a complementary depression in
another
Both articular surfaces are oval
Biaxial joints permit all angular motions
Examples: radiocarpal (wrist) joints, and metacarpophalangeal (knuckle)
joints
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Saddle Joints
Similar to condyloid joints but allow greater movement
Each articular surface has both a concave and a convex surface
Example: carpometacarpal joint of the thumb
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Ball-and-Socket Joints
A spherical or hemispherical head of one bone articulates with a cuplike
socket of another
Multiaxial joints permit the most freely moving synovial joints
Examples: shoulder and hip joints
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Selected Synovial Joints
We’ll look at five selected synovial joints:
Knee
Shoulder
Hip
Elbow
Temporomandibular (jaw)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
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
Intermediate: Femoropatellar joint. Between the patella and distal end
of the femur
Lateral and medial tibiofemoral joints: between the femoral condyles
above and c-shaped menisci (semilunar cartilage) of the tibia below
(lateral & medial joints)
Acts as a hinge. Permits flexing and extension
Bicondylar joint
Some rotation when the knee is flexed
The joint cavity is only partially enclosed by a capsule
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Synovial Joints: Knee Ligaments and
Tendons – Anterior View
Anteriorly, 3 ligaments run from the
patella to the tibia:
Patellar ligament
Medial patellar retinaculum
Lateral patellar retinaculum
All 3 are continuous with the
quadriceps muscle tendon
There are many bursae associated with the
knee
The ligaments of the knee:
Capsular & extracapsular
ligaments act to prevent
hyperextension of the knee and are
stretched tight when the knee is
extended
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 8.8c
Synovial Joints: Knee Ligaments and Tendons –
Anterior View
Tendon of the quadriceps femoris muscle
Fibular and tibial collateral ligaments
(extracapsular):
Run from the medail epicondyle of the
femur to the medial condyle of the tibia
and fuse to the medial meniscus
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Synovial Joints: Knee – Other Supporting
Structures
Intracapsular ligaments:
Prevent anterior/posterior displacement of the articular surfaces & secure
bones when standing
Anterior cruciate ligament:
Attaches to the anterior intercondylar area of the tibia, passes posteriorly,
laterally, and superiorly to attach to the femur on the medial side of its
lateral condyle
Prevents forward sliding of the tibia on the femur
Checks hyperextension of the knee
Is tight when the knee is extended
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Synovial Joints: Knee – Other Supporting Structures
Posterior cruciate ligament:
Attached to the posterior intercondylar area of the tibia and passes anteriorly,
,medially, and superiorly to attach to the lateral side of the medial femural
condyle
Functions in preventing backward displacement of the tibia or forward sliding
of the femur
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Synovial Joints: Knee – Other Supporting Structures
Medial meniscus & lateral meniscus (semilunar cartilage)
The menisci are two pads of cartilagenous tissue which serve to disperse friction in
the knee joint between the lower leg (tibia) and the thigh (femur).
They are shaped concave on the top and flat on the bottom, articulating the tibia.
They are attached to the fossae between the condyles of the tibia (intercondyloid
fossa), and towards the center they are unattached and their shape narrows to a thin
shelf
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Synovial Joints: Knee – Locking the knee
The lateral femural condyle stops rolling before the medial condyle causing
the femur to rotate medially on the tibia until all the major ligaments of the
knee are tight and the menisci are compressed
The popliteus muscle rotates the femur and “unlocks” the knee
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Synovial Joints: Elbow
Hinge joint that allows flexion and extension only
Hinge joint formed by the trochlea of the humerus being “gripped” by the ulna’s
trochlear notch
The articular capsule is thin and allows freedom to flex and extend
Side to side movements are restricted by:
Ulnar collateral ligament (medially)
Radial collateral ligament (laterally)
The biceps and triceps provide some stability
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Synovial Joints: Shoulder (Glenohumeral)
Ball-and-socket joint in which stability is sacrificed to obtain most freely moving
joint of the body
Head of humerus articulates with the glenoid cavity of the scapula
The glenoid cavity contributes little to joint stability
Glenoid labrum: the rim of fibrocartilage that helps support the joint
Ligaments are located on the anterior aspect
The coracohumeral ligament:
Superiorly located & provides only a strong thickening of the capsule
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Synovial Joints: Shoulder Stability
Weak stability is maintained by:
Thin, loose joint capsule
Muscle tendons that cross the shoulder joint contribute most to this
joint’s stability
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
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Rotator cuff (four tendons and associated muscles) that encircles the shoulder
joint and blends with the articular capsule
The muscles are:
Subscapularis
Supraspinatus
Infraspinatus
Teres minor
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Synovial Joints: Hip (Coxal) Joint
Ball-and-socket joint
Formed by the articulation of the spherical head of the femur with the acetabulum of the
coxal
Acetabulum labrum:
Fibrocartilage that enhances the depth of the acetabulum
Ligaments that reinforce the capsule of the hip joint:
Iliofemoral ligament (anteriorly)
Pubofemoral ligament (inferiorly)
Ischiofemural ligament (posteriorly)
Ligamentum teres:
the ligament of the head of the femur
Intracapsular
Contains artery to the head of the femur
Thus, the socket and ligaments contribute most to the stability of the hip joint but limited
range of motion
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Synovial Joints: Hip Stability
Acetabular labrum
Iliofemoral ligament
Pubofemoral ligament
Ischiofemoral ligament
Ligamentum teres
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Figure 8.12a
Synovial Joints: Hip Stability
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 8.12c, d
Temporomandibular Joint (TMJ)
Lies just anterior to the ear
Mandibular condyle articulate with the inferior surface of the temporal bone
Articular surface of the temporal bone:
Posteriorly: concave mandibular fossa
Anteriorly: convex articular tubercle
The lateral aspects of the joint are strengthened by a lateral ligament
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Temporomandibular Joint (TMJ)
Three types of movement
Hinge – depression and elevation of mandible
Side to side – (lateral excursion) grinding of teeth
Anterior movement of the superior disc and superior mandibular
condyle (when mouth is wide open…like during a yawn…but please
don’t yawn now…you did didn’t you)
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Sprains
The ligaments reinforcing a joint are stretched or
torn
These injuries are slow to heal due to poor
vascularization
Completely torn ligaments require prompt surgical
repair. Inflammation in the joint will break down
neighboring tissues
If damaged beyond repair, substitute or grafted
ligaments are used
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Cartilage Injuries
Mostly tearing of the knee’s menisci
Avascular: can not repair itself
Loose bodies (cartilage fragments) can interfere
with joint function by binding or locking the joint
Removal of part of the meniscus makes the joint
less stable…
BUT, prevents more tearing as I have drawn and
demonstrated on the board
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
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
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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
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Inflammatory and Degenerative Conditions
Tendonitis
Inflammation of tendon sheaths typically caused by
overuse
Symptoms and treatment are similar to bursitis
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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
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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
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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
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Osteoarthritis: Treatments
OA is slow and irreversible
Treatments include:
Mild pain relievers, along with moderate activity
Magnetic therapy
Glucosamine sulfate decreases pain and
inflammation
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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
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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
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Rheumatoid Arthritis: Course
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
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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
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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
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Developmental Aspects of Joints
By embryonic week 8, synovial joints resemble
adult joints
Few problems occur until late middle age
Advancing years take their toll on joints:
Ligaments and tendons shorten and weaken
Intervertebral discs become more likely to herniate
Most people in their 70s have some degree of OA
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Developmental Aspects of Joints
Prudent exercise (especially swimming) that
coaxes joints through their full range of motion is
key to postponing joint problems
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings