Transcript joints - Capital High School

Joints
Function: hold
bones together &
Increase mobility
Classification of Joints
Structural classification -binding material & presence or
absence of a joint cavity
 Fibrous
 Cartilagenous
 Synovial
Functional classification - amount of movement
 Synarthroses (immovable joints)
 Amphiarthroses (slightly movable joints)
 Diarthroses (freely movable joints)
Fibrous joints/Synarthroses
 Bones connected by
dense regular connective tissue
 No joint cavity
 Slightly immovable or
not at all
 Types
 Sutures
 Between tibia/fibula
Cartilagenous joints/
Amphiarthoroses


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
Articulating bones united by cartilage
Lack a joint cavity
Not highly movable
Ex
 Intervertebral discs
 Pubic symphysis of the pelvis
Amphiarthroses
Also pubic symphsis
Synovial joints/ Diarthroses
 Include most of the body’s joints
 freely movable
 All contain fluid-filled joint cavity
General Structure of Synovial Joints
1. Articular cartilage


Spongy cushions absorb
compression
Protects ends of bones
from being crushed
2. Synovial cavity


Potential space
Small amount of synovial
fluid
3. Articular capsule

layered covering of joint
General structure of synovial joints (cont.)
4. Synovial fluid
 Nourishes cartilage and
functions as slippery
lubricant
5. Reinforcing ligaments (some
joints) link bones
6. Nerves
 Detect pain
 Monitor stretch
7. Blood vessels
General structure of synovial joints
Joint stability
 Articular surfaces
 Shape usually plays only minor role
 Some deep sockets or grooves do provide stability
 Ligaments
 Usually the more, the stronger the joint
 Can stretch only 6% beyond normal length before
tear
 Once stretched, stay stretched
 Muscle tone
 Constant, low level of contractile force
 Keeps tension on the ligaments
 Especially important at shoulders, knees, arches of
foot
Movements allowed by synovial joints
 Gliding
 Angular movements: hor i the angle between
two bones
DO TOGETHER
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
Flexion
Extension
Abduction
Adduction
Circumduction
 Rotation
 Special movements
Special movements
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Pronation
Supination
Dorsiflexion
Plantar flexion
Inversion
Eversion

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Protraction
Retraction
Elevation
Depression
Opposition
Joint movements pics
(from Marieb, 4th ed.)
Synovial joints
classified by shape
(of their articular surfaces)


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Plane (see right)
Hinge (see right)
Pivot
Condyloid
Saddle
Ball-and-socket
Selected synovial joints
Shoulder
(glenohumeral) joint
 Stability sacrificed for
mobility
 Ball and socket: head of
humerus with glenoid
cavity of scapula
 Glenoid labrum: rim of
fibrocartilage
 Thin, loose capsule
 Strongest ligament:
coracohumeral
 Muscle tendons help
stability
 Disorders
Rotator cuff muscles add to stability
Biceps tendon is intra-articular
Elbow joint
 Hinge: allows only flexion
and extension
 Annular ligament of
radius attaches to
capsule
 Capsule thickens into:
 Radial collateral
ligament
 Ulnar collateral
ligament
 Muscles cross joint
 Trauma
Wrist joint
Two major joint surfaces
Several ligaments stabilize
1. Radiocarpal joint
 Between radius and
proximal carpals
(scaphoid and lunate)
 Condyloid joint
 Flexion extension
adduction, abduction,
circumduction
2. Intercarpal or
midcarpal joint
 Between the proximal
and distal rows of
carpals
Hip (coxal) joint
 Ball and socket
 Moves in all axes but
limited by ligaments
and deep socket
 Three ext. ligaments
“screw in” head of
femur when standing
 Iliofemoral
 Pubofemoral
 Ischiofemoral
 Acetabular labrum
diameter smaller than
head of femur
 Dislocations rare
 Ligament of head of
femur supplies artery
 Muscle tendons cross
joint
 Hip fractures common
in elderly because of
osteoporosis
Right hip, AP view
Knee joint
 Largest and most complex joint
 Primarily a hinge
 Compound and bicondyloid: femur and
tibia both have 2 condyles
 Femoropatellar joint shares joint cavity
 At least a dozen bursae
 Prepatellar
 Suprapatellar
 Lateral and medial
menisci
 “torn cartilage”
 Capsule absent
anteriorly
 Capsular and
extracapsular ligaments
 Taut when knee
extended to prevent
hyperextension
 Patellar ligament
 Continuation of
quad tendon
 Medial and lateral
retinacula
 Fibular and tibial
collateral ligaments
 Called medial and
lateral
 Extracapsular
 Oblique popliteal
 Arcuate popliteal
Cruciate ligaments
 Cross each other
(cruciate means cross)
 Anterior cruciate (ACL)
 Anterior intercondylar area
of tibia to medial side of
lateral condyl of femur
 Posterior cruciate
 Posterior intercondylar
area of tibia to lateral side
of medial condyl
 Restraining straps
 Lock the knee
Cruciate ligaments
Knee injuries
 Flat tibial surface
predisposes to
horizontal injuries
 Lateral blow: multiple
tears
 ACL injuries
 Stop and twist
 Commoner in women
athletes
 Heal poorly
 Require surgery
Ankle joint
 Hinge joint
 Distal tibia and fibula to talus
 Dorsiflexion and plantar
flexion only
 Medial deltoid ligament
 Lateral ligaments: 3 bands
 Anterior talofibular
 Posterior talofibular
 Calcaneofibular
 Anterior and posterior
tibiofibular (syndesmosis)
Right ankle, lateral view
Temporomandibular
joint (TMJ)
 Head of mandible
articulates with temporal
bone
 Disc protects thin
mandibular fossa of
temporal bone
 Many movements
Demonstrate movements together
 Disorders common
Table of Joint Types
Functional across
Synarthroses
(immovable joints)
Amphiarthroses
(some movement)
Diarthroses
(freely movable)
Syndesmoses
-ligaments only
between bones; here,
short so some but not
a lot of movement
(example: tib-fib
ligament)
Syndesmoses
-ligament longer
(example: radioulnar
interosseous
membrane)
Structural down
Bony Fusion
Synostosis
(frontal=metopic
suture; epiphyseal
lines)
Fibrous
Suture (skull only)
-fibrous tissue is
continuous with
periosteum
Gomphoses (teeth)
-ligament is
periodontal ligament
Cartilagenous
(bone united by
cartilage only)
Synovial
Synchondroses
-hyaline cartilage
(examples:
manubrium-C1,
epiphyseal plates)
Sympheses
-fibrocartilage
(examples: between
discs, pubic
symphesis
Are all diarthrotic
Sternoclavicular joint
 Saddle joint
 Only other example is trapezium
and metacarpal 1 (thumb),
allowing opposion
 Sternum and 1st costal (rib)
cartilage articulate with clavicle
 Very stable: clavicle usually
breaks before dislocation of joint
 Only bony attachment of axial
skeleton to pectoral girdle
Demonstrate movements together
Disorders of joints
 Injuries
 Sprains
 Dislocatios
 Torn cartilage
 Inflammatory and degenerative conditions
 Bursitis
 Tendinitis
 Arthritis
 Osteoarthritis (“DJD” – degenerative joint disease)
 Rheumatoid arthritis (one of many “autoimmune” arthritites)
 Gout (crystal arthropathy)