Joint Classification - The Anatomy Academy

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Chapter 9
Lecture Outline
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Joints
 Joints



and their classification
bony joints
fibrous joints
cartilaginous joints
 Synovial
joints
2
Joints and Their Classification
 Arthrology
= study of the joints
 Kinesiology = study of musculoskeletal
movement
 Classified by freedom of movement



diarthrosis (freely movable)
amphiarthrosis (slightly movable)
synarthrosis (little or no movement)
 Classified

how adjacent bones are joined
fibrous, cartilaginous, bony or synovial
3
Bony Joint (Synostosis)
 Gap



between two bones ossifies
frontal and mandibular bones in infants
cranial sutures in elderly
attachment of first rib and sternum
 Can
occur in either fibrous or cartilaginous
joint
4
Fibrous Joints (Synarthrosis)
 Collagen
fibers span the space
between bones

sutures, gomphoses and syndesmoses
5
Fibrous Joint -- Sutures

Immovable fibrous joints

bind skull bones together

Lap - overlapping beveled edges

Plane - straight, nonoverlapping
edges

palatine processes of the maxillae
6
Types of Sutures
7
Fibrous Joint -- Gomphoses
 Attachment
of a tooth to its
socket
 Held in place by fibrous
periodontal ligament

collagen fibers attach
tooth to jawbone
 Some
movement while
chewing
8
Fibrous Joint -- Syndesmosis
 Two
bones bound
by ligament only

interosseus
membrane
 Most
movable of fibrous joints
 Interosseus membranes unite radius to ulna
and tibia to fibula
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Cartilaginous Joint -- Synchondrosis
 Bones
are joined by
hyaline cartilage


rib attachment to
sternum
epiphyseal plate in
children binds
epiphysis and
diaphysis
10
Cartilaginous Joint -- Symphysis
2
bones joined by
fibrocartilage

pubic symphysis
and intervertebral
discs
 Only
slight amount
of movement is
possible
11
Synovial Joint

Joint in which two bones are separated by a
space called a joint cavity
 Most are freely movable
12
General Anatomy

Articular capsule encloses joint cavity


continuous with periosteum
lined by synovial membrane

Synovial fluid = slippery fluid; feeds cartilages
 Articular cartilage = hyaline cartilage covering the joint
surfaces
 Articular discs and menisci




jaw, wrist, sternoclavicular and knee joints
absorbs shock, guides bone movements and distributes forces
Tendon attaches muscle to bone
Ligament attaches bone to bone
13
Tendon Sheaths and Bursae

Bursa = saclike extension of joint capsule


between nearby structures so slide more easily past each other
Tendon sheaths = cylinders of connective tissue lined with
synovial membrane and wrapped around a tendon
14
Components of a Lever
 A lever
is a rigid object that rotates around a
fixed point called a fulcrum
 Rotation occurs when effort overcomes
resistance

resistance arm and effort arm are described
relative to fulcrum
15
Mechanical Advantage of a Lever
 Two

kinds of levers
lever that helps increase output of force
• human moving a heavy object with help of crowbar

lever move object further and faster
• movement of row boat with paddle
 Types
of levers produce either increase in
speed or force
16
First-Class Lever


Has fulcrum in the middle between effort and resistance
Atlantooccipital joint lies between the muscles on the back of
the neck and the weight of the face

loss of muscle tone occurs when you nod off in class
17
Second-Class Lever

Resistance between fulcrum and effort
 Resistance from the muscle tone of the temporalis
muscle lies between the jaw joint and the pull of the
diagastric muscle on the chin as it opens the mouth
quickly
18
Third-Class Lever

Effort between the resistance and the fulcrum


most joints of the body
The effort applied by the biceps muscle is applied to
the forearm between the elbow joint and the weight of
the hand and the forearm
19
Range of Motion
 Degrees
through which a joint can move
 Determined by


structure of the articular surfaces
strength and tautness of ligaments, tendons and
capsule
• stretching of ligaments increases range of motion
• double-jointed people have long or slack ligaments

action of the muscles and tendons
• nervous system monitors joint position and muscle
tone
20
Axes of Rotation

Shoulder joint has 3 degrees of freedom =
multiaxial joint
 Other joints – monoaxial or biaxial
21
Types of Synovial Joints
22
Ball-and-Socket Joints
 Smooth
hemispherical head fits within a
cuplike depression


head of humerus into glenoid cavity of
scapula
head of femur into acetabulum of hip bone
 Multiaxial
joint
23
Condyloid (ellipsoid) Joints
 Oval
convex surface on one bone fits into
a similarly shaped depression on the next


radiocarpal joint of the wrist
metacarpophalangeal joints at the bases of
the fingers
 Biaxial
joints
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Saddle Joints
 Each
articular surface is shaped like a
saddle, concave in one direction and convex
in the other

trapeziometacarpal joint at the base of the
thumb
 Biaxial

joint
more movable than a condyloid or hinge joint
forming the primate opposable thumb
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Gliding Joints
 Flat
articular surfaces in which bones slide
over each other
 Limited monoaxial joint
 Considered amphiarthroses
26
Hinge Joints
 One
bone with convex surface that fits into
a concave depression on other bone



ulna and humerus at elbow joint
femur and tibia at knee joint
finger and toe joints
 Monoaxial
joint
27
Pivot Joints
 One
bone has a projection that fits into a
ringlike ligament of another
 First bone rotates on its longitudinal axis
relative to the other


atlantoaxial joint (dens and atlas)
proximal radioulnar joint allows the radius during
pronation and supination
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Flexion, Extension and Hyperextension
 Flexion
decreases the
angle of a joint
 Extension straightens
and returns to the
anatomical position
 Hyperextension =
extension beyond 180
degrees
29
Flexion, Extension and Hyperextension
30
Abduction and Adduction

Abduction is movement of a part away from the
midline


hyperabduction – raise arm over back or front of head
Adduction is movement towards the midline

hyperadduction – crossing fingers
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Elevation and Depression

Elevation is a movement that raises a bone vertically


mandibles are elevated during biting and clavicles during
a shrug
Depression is lowering the mandible or the
shoulders
32
Protraction and Retraction
 Protraction
= movement
anteriorly on horizontal
plane

thrusting the jaw
forward, shoulders or
pelvis forward
 Retraction
is movement
posteriorly
33
Circumduction

Movement in which one end
of an appendage remains
stationary while the other end
makes a circular motion
 Sequence of flexion,
abduction, extension and
adduction movements

baseball player winding up for
a pitch
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Rotation
 Movement
on
longitudinal axis

rotation of trunk,
thigh, head or arm
 Medial
rotation
turns the bone
inwards
 Lateral rotation
turns the bone
outwards
35
Supination and Pronation

In the forearm and foot
 Supination



rotation of forearm so that the
palm faces forward
inversion and abduction of foot
(raising the medial edge of the
foot)
Pronation


rotation of forearm so the palm
faces to the rear
eversion and abduction of foot
(raising the lateral edge of the
36
foot)
Movements of Head and Trunk

Flexion, hyperextension and lateral flexion of
vertebral column
37
Rotation of Trunk and Head

Right rotation of trunk; rotation of head
38
Movements of Mandible

Lateral excursion = sideways movement
 Medial excursion = movement back to the
midline


side-to-side grinding during chewing
Protraction – retraction of mandible
39
Movement of Hand and Digits

Radial and ulnar
flexion
 Abduction of fingers
and thumb
 Opposition is
movement of the
thumb to approach
or touch the
fingertips
 Reposition is
movement back to
the anatomical
position
40
Movements of the Foot




Dorsiflexion is raising of the toes as when you swing the
foot forward to take a step (heel strike)
Plantarflexion is extension of the foot so that the toes point
downward as in standing on tiptoe
Inversion is a movement in which the soles are turned
medially
Eversion is a turning of the soles to face laterally
41
The Humeroscapular Joint




Most freely movable joint in the body
 shallowness and looseness
 deepened by glenoid labrum
Supported by ligaments and tendons
 3 glenohumeral, coracohumeral,
transverse humeral and biceps tendon
are
important joint stabilizer
Supported by rotator cuff musculature
 tendons fuse to joint capsule and
strengthens it
 supraspinatus, infraspinatus, teres
minor and subscapularis,
4 Bursae associated with shoulder joint
42
Stabilizers of the Shoulder Joint
43
Tendons of Rotator Cuff
Muscles
44
The Elbow Joint
 Single
joint capsule
enclosing the
humeroulnar and
humeroradial joints
 Humeroulnar joint is
supported by collateral
ligaments.
 Radioulnar joint is head
of radius held in place
by the anular ligament
encircling the head
45
Elbow Joint
46
The Coaxal (hip) Joint

Head of femur articulates with acetabulum
 Socket deepened by acetabular labrum
 Blood supply to head of femur found in ligament of
the head of the femur Joint capsule strengthened by
ligaments
47
Hip Joint

Joint capsule
strengthened by
ligaments



pubofemoral
ischiofemoral
iliofemoral
48
Dissection of Hip Joint
49
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
50
Knee Joint – Sagittal Section
51
Knee Joint – Anterior and Posterior
Views

Anterior and lateral cruciate ligaments limit
anterior and posterior sliding movements
 Medial and lateral collateral ligaments prevent
rotation of extended knee
52
Knee Joint – Superior View

Medial and lateral meniscus absorb shock and
shape joint
53
Dissection of Knee Joint
54
Arthritis
 Arthritis
is a broad term for pain and
inflammation
 Osteoarthritis results from years of joint wear



articular cartilage softens and degenerates
accompanied by crackling sounds called
crepitus
bone spurs develop on exposed bone tissue
causing pain
55
Arthritis and Artificial Joints
 Rheumatoid
arthritis is autoimmune attack
on joint


antibodies attack synovial membrane,
enzymes in synovial fluid degrade the
cartilage, bones ossify
remissions occur, steroids and aspirin control
inflammation
 Arthroplasty
is replacement of diseased
joint with artificial device called prosthesis
56
Rheumatoid Arthritis
57
Joint Prostheses
58
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