Articulations and Joints
Muse lecture #6
10/19/11
Joints
Chapter 9







Joint Classifications
Fibrous Joints
Cartilaginous Joints
Synovial Joints
Types of Movements at Synovial Joints
Types of Synovial Joints
Factors Affecting Contact and Range of Motion
at Synovial Joints
 Selected Joints of the Body
 Aging and Joints
 Arthroplasty
Muse Lecture #6
An Introduction to Articulations
 Articulations
 Body movement occurs at joints
(articulations) where two bones connect
 Joint Structure
 Determines direction and distance of
movement (range of motion)
 Joint strength decreases as mobility increases
Classification of Joints
 Two methods of classification
 Functional classification is based on range
of motion of the joint
 Structural classification relies on the
anatomical organization of the joint
Classification of Joints
 Functional Classifications
Party on Arth!
 Synarthrosis (immovable joint)
 No movement
 Fibrous or cartilaginous connections
 May fuse over time
 Amphiarthrosis (slightly movable joint)
 Little movement
 Fibrous or cartilaginous connections
 Diarthrosis (freely movable joint)
 More movement
 Also called synovial joints
 Subdivided by type of motion
Classification of Joints
Classification of Joints
Classification of Joints
 Structural Classifications
 Bony
 Fibrous
 Cartilaginous
 Synovial (capsulated)
Classification of Joints
Classification of Joints
 Functional Classifications
 Synarthroses (immovable joints)
 Are very strong
 Edges of bones may touch or interlock
 Four types of synarthrotic joints:
– suture
– gomphosis
– synchondrosis
– synostosis
Classification of Joints
 Synarthrotic Joints
 Suture
 Bones interlocked
 Are bound by dense fibrous connective tissue
 Are found only in skull
 Gomphosis
 Fibrous connection (periodontal ligament)
 Binds teeth to sockets
Yah can’t chomp without the gomph
Joints (Fibrous Joints)
 Sutures
 Occur only between bones of
the skull
 Syndesmoses
 Permits slight movement
 Interosseous membrane
 Between the tibia and fibula in
the leg
 Gomphoses
 Immovable joint
 Joint in which a cone-shaped
peg fits into a socket
 Articulations of the teeth with
the sockets of the maxillae
and mandible
(b) Syndesmosis
Joint held together by a ligament.
Fibrous tissue can vary in length, but
is longer than in sutures.
Fibula
Tibia
Ligament
Figure 8.1b
Joints (Fibrous Joints)
 Lack a synovial cavity
 The articulating bones are held very closely
together by dense irregular connective tissue
 Fibrous joints permit little or no movement
 Three types of fibrous joints
 Sutures
 Syndesmoses
 Gomphoses
Classification of Joints
 Synarthrotic Joints
 Synchondrosis
 Is a rigid cartilaginous bridge between two bones:
– epiphyseal cartilage of long bones
– between vertebrosternal ribs and sternum
 Synostosis
 Fused bones, immovable:
– metopic suture of skull
– epiphyseal lines of long bones
Classification of Joints
 Functional Classifications
 Amphiarthroses
 More movable than synarthrosis
 Stronger than freely movable joint
 Two types of amphiarthroses
– syndesmosis:
» bones connected by ligaments
– symphysis:
» bones separated by fibrous cartilage
Classification of Joints
 Functional Classifications
 Synovial joints (diarthroses)
 Also called movable joints
 At ends of long bones
 Within articular capsules
 Lined with synovial membrane
Synovial Joints
 Components of Synovial Joints
 Articular cartilages
 Pad articulating surfaces within articular
capsules:
– prevent bones from touching
 Smooth surfaces lubricated by synovial fluid:
– reduce friction
Ligament
Joint cavity
(contains
synovial fluid)
Articular (hyaline)
cartilage
Fibrous
capsule
Synovial
membrane
Articular
capsule
Periosteum
Figure 8.3
Synovial Joints
 Components of Synovial Joints
 Synovial fluid
 Contains slippery proteoglycans secreted by
fibroblasts
 Functions of synovial fluid:
– lubrication
– nutrient distribution
– shock absorption
Synovial Joints
 Components of Synovial Joints
 Accessory structures
 Cartilages:
– cushion the joint:
» Fibrous cartilage pad called a meniscus
(articular disc)
 Fat pads:
– superficial to the joint capsule
– protect articular cartilages
 Ligaments:
– support, strengthen joints
– sprain: ligaments with torn collagen fibers
Synovial Joints
 Components of Synovial Joints
 Accessory structures
 Tendons:
– attach to muscles around joint
– help support joint
 Bursae:
– pockets of synovial fluid
– cushion areas where tendons or ligaments rub
Coracoacromial
ligament
Subacromial
bursa
Cavity in
bursa containing
synovial fluid
Humerus
resting
Bursa rolls
and lessens
friction.
Humerus head
rolls medially as
arm abducts.
Humerus
moving
(b) Enlargement of (a), showing how a bursa
eliminates friction where a ligament (or other
structure) would rub against a bone
Figure 8.4b
Synovial Joints
 Factors That Stabilize Synovial Joints
 Prevent injury by limiting range of motion
 Collagen fibers (joint capsule, ligaments)
 Articulating surfaces and menisci
 Other bones, muscles, or fat pads
 Tendons of articulating bones
Synovial Joints
[INSERT FIG. 9.1a]
Figure 9–1a The Structure of a Synovial Joint.
Synovial Joints
Figure 9–1b The Structure of a Synovial Joint.
Synovial Joints
 Injuries
 Dislocation (luxation)
 Articulating surfaces forced out of position
 Damages articular cartilage, ligaments, joint capsule
 Subluxation
 A partial dislocation
Movements
 Types of Dynamic Motion
 Linear motion (gliding)
 Angular motion
 Rotation
 Planes (Axes) of Dynamic Motion
 Monaxial (1 axis)
 Biaxial (2 axes)
 Triaxial (3 axes)
Movements
Figure 9–2 A Simple Model of Articular Motion.
Movements
Figure 9–2 A Simple Model of Articular Motion.
Movements
 Types of Movements at Synovial Joints
 Terms describe
 Plane or direction of motion
 Relationship between structures
Movements
 Types of Movements at Synovial Joints
 Linear motion
 Also called gliding
 Two surfaces slide past each other:
– between carpal or tarsal bones
Movements
 Angular Motion
 Flexion
 Angular motion
 Anterior–posterior plane
 Reduces angle between elements
 Extension
 Angular motion
 Anterior–posterior plane
 Increases angle between elements
Movements
 Angular Motion
 Hyperextension
 Angular motion
 Extension past anatomical position
Angular Movements
Movements
Figure 9–3a Angular Movements.
Movements
 Angular Motion
 Abduction
Think kidnapping
 Angular motion
 Frontal plane
 Moves away from longitudinal axis
 Adduction
Think adding
 Angular motion
 Frontal plane
 Moves toward longitudinal axis
Movements
Figure 9–3 Angular Movements.
Movements
Figure 9–3 Angular Movements.
Movements
 Angular Motion
 Circumduction
 Circular motion without rotation
 Angular motion
Movements
Figure 9–3 Angular Movements.
Movements
 Types of Movement at Synovial Joints
 Rotation
 Direction of rotation from anatomical position
 Relative to longitudinal axis of body
 Left or right rotation
 Medial rotation (inward rotation):
– rotates toward axis
 Lateral rotation (outward rotation):
– rotates away from axis
Movements
Figure 9–4a Rotational Movements.
Movements
 Types of Movements at Synovial Joints
 Rotation
 Pronation:
– rotates forearm, radius over ulna
 Supination:
– forearm in anatomical position
Movements
Figure 9–4b Rotational Movements.
Movements
 Types of Movements at Synovial Joints
 Special movements
 Inversion:
– twists sole of foot medially
 Eversion:
– twists sole of foot laterally
 Dorsiflexion:
– flexion at ankle (lifting toes)
 Plantar flexion:
Plant your feet
– extension at ankle (pointing toes)
Movements
 Special Movements at Synovial Joints
 Opposition
 Thumb movement toward fingers or palm
(grasping)
 Protraction
 Moves anteriorly
 In the horizontal plane (pushing forward)
 Retraction
 Opposite of protraction
 Moving anteriorly (pulling back)
Movements
 Special Movements at Synovial Joints
 Elevation
 Moves in superior direction (up)
 Depression
 Moves in inferior direction (down)
 Lateral flexion
 Bends vertebral column from side to side
Movements
Figure 9–5 Special Movements.
Movements
Figure 9–5 Special Movements.
Movements
 Classification of Synovial Joints by Shape






Gliding
Hinge
Pivot
Ellipsoid
Saddle
Ball-and-socket
A Functional Classification of Synovial Joints
Movements
 Gliding Joints
 Flattened or slightly curved faces
 Limited motion (nonaxial)
 Hinge Joints
 Angular motion in a single plane (monaxial)
 Pivot Joints
 Rotation only (monaxial)
Movements
Figure 9–6 Movements at Synovial Joints.
Movements
 Ellipsoid Joints
 Oval articular face within a depression
 Motion in two planes (biaxial)
 Saddle Joints
 Two concave, straddled (biaxial)
 Ball-and-Socket Joints
 Round articular face in a depression (triaxial)
Movements
Figure 9–6 Movements at Synovial Joints.
Movements
 A joint cannot be both mobile and strong
 The greater the mobility, the weaker the
joint
 Mobile joints are supported by muscles
and ligaments, not bone-to-bone
connections
Intervertebral Articulations
 Intervertebral Articulations
 C2 to L5 spinal vertebrae articulate
 At inferior and superior articular processes (gliding
joints)
 Between adjacent vertebral bodies (symphyseal
joints)
Intervertebral Articulations
 Intervertebral Articulations
 C2 to L5 spinal vertebrae articulate
 Intervertebral discs:
– pads of fibrous cartilage
– separate vertebral bodies
– anulus fibrosus:
» tough outer layer
» attaches disc to vertebrae
– nucleus pulposus:
» elastic, gelatinous core
» absorbs shocks
Intervertebral Articulations
Figure 9–7 Intervertebral Articulations.
Intervertebral Articulations
 Vertebral Joints
 Also called symphyseal joints
 As vertebral column moves
 Nucleus pulposus shifts
 Disc shape conforms to motion
 Intervertebral Ligaments
 Bind vertebrae together
 Stabilize the vertebral column
Intervertebral Articulations
 Six Intervertebral Ligaments
 Anterior longitudinal ligament
 Connects anterior bodies
 Posterior longitudinal ligament
 Connects posterior bodies
 Ligamentum flavum
 Connects laminae
Intervertebral Articulations
 Six Intervertebral Ligaments
 Interspinous ligament
 Connects spinous processes
 Supraspinous ligament
 Connects tips of spinous processes (C7 to sacrum)
 Ligamentum nuchae
 Continues supraspinous ligament (C7 to skull)
Intervertebral Articulations
 Damage to Intervertebral Discs
 Slipped disc
 Bulge in anulus fibrosus
 Invades vertebral canal
 Herniated disc
 Nucleus pulposus breaks through anulus fibrosus
 Presses on spinal cord or nerves
Intervertebral Articulations
Figure 9–8a Damage to the Intervertebral Discs.
Intervertebral Articulations
Figure 9–8b Damage to the Intervertebral Discs.
Intervertebral Articulations
 Movements of the Vertebral Column
 Flexion
 Bends anteriorly
 Extension
 Bends posteriorly
 Lateral flexion
 Bends laterally
 Rotation
 Turning
Articulations of the Axial Skeleton
Articulations of the Axial Skeleton
Articulations of the Axial Skeleton
Joints (Selected Joints of the Body)
 Temporomandibular Joint
 Combined hinge and planar joint formed by the
mandible and the temporal bone
 Only movable joint between skull bones
 Only the mandible moves
Superior view
Outline of
the mandibular
fossa
Lateral excursion: lateral (side-to-side) movements of the
mandible
Figure 8.13c
Mandibular fossa
Articular tubercle
Zygomatic process
Infratemporal fossa
External
acoustic
meatus
Lateral
ligament
Articular
capsule
Ramus of
mandible
(a) Location of the joint in the skull
Figure 8.13a
Articular disc
Mandibular
fossa
Articular
tubercle
Superior
joint
cavity
Articular
capsule
Synovial
membranes
Mandibular
condyle
Ramus of
mandible
Inferior joint
cavity
(b) Enlargement of a sagittal section through the joint
Figure 8.13b
The Shoulder Joint
 Also called the glenohumeral joint
 Allows more motion than any other joint
 Is the least stable
 Supported by skeletal muscles, tendons, ligaments
 Ball-and-socket diarthrosis
 Between head of humerus and glenoid cavity of
scapula
The Shoulder Joint
 Socket of the Shoulder Joint
 Glenoid labrum
 Deepens socket of glenoid cavity
 Fibrous cartilage lining
 Extends past the bone
 Processes of the Shoulder Joint
 Acromion (clavicle) and coracoid process (scapula)
 Project laterally, superior to the humerus
 Help stabilize the joint
The Shoulder Joint
 Shoulder Ligaments
 Glenohumeral
 Coracohumeral
 Coraco-acromial
 Coracoclavicular
 Acromioclavicular
 Shoulder Separation
 Dislocation of the shoulder joint
The Shoulder Joint
 Shoulder Muscles (also called rotator cuff)




Supraspinatus
Infraspinatus
Subscapularis
Teres minor
 Shoulder Bursae
 Subacromial
 Subcoracoid
 Subdeltoid
 Subscapular
The Shoulder Joint
Figure 9–9a The Shoulder Joint.
The Shoulder Joint
Figure 9–9b The Shoulder Joint.
The Elbow Joint
 A stable hinge joint
 With articulations involving humerus,
radius, and ulna
The Elbow Joint
 Articulations of the Elbow
 Humero-ulnar joint
 Largest articulation
 Trochlea of humerus and trochlear notch of ulna
 Limited movement
 Humeroradial joint:
 Smaller articulation
 Capitulum of humerus and head of radius
The Elbow Joint
Figure 9–10a The Elbow Joint.
The Elbow Joint
 Supporting Structures of the Elbow
 Biceps brachii muscle
 Attached to radial tuberosity
 Controls elbow motion
 Elbow Ligaments
 Radial collateral
 Annular
 Ulnar collateral
The Elbow Joint
Figure 9–10b The Elbow Joint.
The Hip Joint
 Also called coxal joint
 Strong ball-and-socket diarthrosis
 Wide range of motion
The Hip Joint
 Structures of the Hip Joint
 Head of femur fits into it
 Socket of acetabulum
 Which is extended by fibrocartilaginous acetabular
labrum
 Ligaments of the Hip Joint
 Iliofemoral
 Pubofemoral
 Ischiofemoral
 Transverse acetabular
 Ligamentum teres
The Hip Joint
Figure 9–11a The Hip Joint.
The Hip Joint
Figure 9–11b The Hip Joint.
The Hip Joint
Figure 9–11c The Hip Joint.
The Knee Joint
 A complicated hinge joint
 Transfers weight from femur to tibia
 Articulations of the knee joint
 Two femur–tibia articulations
 At medial and lateral condyles
 One between patella and patellar surface of femur
The Knee Joint
 Menisci of the Knee
 Medial and lateral menisci
 Fibrous cartilage pads
 At femur–tibia articulations
 Cushion and stabilize joint
 Give lateral support
 Locking knees
 Standing with legs straight:
– “locks” knees by jamming lateral meniscus between tibia
and femur
The Knee Joint
 Seven Ligaments of the Knee Joint
 Patellar ligament (anterior)
 Two popliteal ligaments (posterior)
 Anterior and posterior cruciate ligaments (inside joint
capsule)
 Tibial collateral ligament (medial)
 Fibular collateral ligament (lateral)
The Knee Joint
Figure 9–12a The Knee Joint.
The Knee Joint
Figure 9–12b The Knee Joint.
The Knee Joint
Figure 9–12c The Knee Joint.
The Knee Joint
Figure 9–12d The Knee Joint.
Torn
meniscus
Figure 8.14
The Knee Joint
The Knee Joint
Aging
 Rheumatism
 A pain and stiffness of skeletal and muscular
systems
 Arthritis
 All forms of rheumatism that damage articular
cartilages of synovial joints
 Osteoarthritis
 Caused by wear and tear of joint surfaces, or
genetic factors affecting collagen formation
 Generally in people over age 60
Developmental Aspects of Joints
 By embryonic week 8, synovial joints resemble
adult joints
 A joint’s size, shape, and flexibility are modified
by use
 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
 Exercise that coaxes joints through their full
range of motion is key to postponing joint
problems
Aging
 Rheumatoid Arthritis
 An inflammatory condition
 Caused by infection, allergy, or autoimmune
disease
 Involves the immune system
 Gouty Arthritis
 Occurs when crystals (uric acid or calcium
salts)
 Form within synovial fluid
 Due to metabolic disorders
Rheumatoid Arthritis
 RA begins with synovitis of the affected
joint
 Inflammatory blood cells migrate to the
joint, release inflammatory chemicals
 Inflamed synovial membrane thickens into
a pannus
 Pannus erodes cartilage, scar tissue
forms, articulating bone ends connect
(ankylosis)
Figure 8.15
Gouty Arthritis
 Deposition of uric acid crystals in joints
and soft tissues, followed by inflammation
 More common in men
 Typically affects the joint at the base of the
great toe
 In untreated gouty arthritis, the bone ends
fuse and immobilize the joint
 Treatment: drugs, plenty of water,
avoidance of alcohol
Aging
 Joint Immobilization
 Reduces flow of synovial fluid
 Can cause arthritis symptoms
 Treated by continuous passive motion
(therapy)
 Bones and Aging
 Bone mass decreases
 Bones weaken
 Increases risk of hip fracture, hip dislocation,
or pelvic fracture
Joints (Arthroplasty)
 Arthroplasty
 Joints may be replaced surgically with artificial
joints
 Most commonly replaced are the hips, knees, and
shoulders
 Hip Replacements
 Partial hip replacements involve only the femur
 Total hip replacements involve both the
acetabulum and head of the femur
 Knee Replacements
 Actually a resurfacing of cartilage and may be
partial or total
 Potential complications of arthroplasty include
infection, blood clots, loosening or dislocation of
the replacement components, and nerve injury
Joints (Arthroplasty)
Joints (Arthroplasty)
Osteoarthritis (OA)
 Common, irreversible, degenerative
(“wear-and-tear”) arthritis
 85% of all Americans develop OA, more
women than men
 Probably related to the normal aging
process
Osteoarthritis (OA)
 More cartilage is destroyed than replaced
in badly aligned or overworked joints
 Exposed bone ends thicken, enlarge, form
bone spurs, and restrict movement
 Treatment: moderate activity, mild pain
relievers, capsaicin creams, glucosamine
and chondroitin sulfate
Lyme Disease
 Caused by bacteria transmitted by the
bites of ticks
 Symptoms: skin rash, flu-like symptoms,
and foggy thinking
 May lead to joint pain and arthritis
 Treatment: antibiotics
Integration with Other Systems
 Bone Recycling
 Living bones maintain equilibrium between
 Bone building (osteoblasts)
 And breakdown (osteoclasts)
 Factors Affecting Bone Strength
 Age
 Physical stress
 Hormone levels
 Calcium and phosphorus uptake and excretion
 Genetic and environmental factors
Integration with Other Systems
 Bones Support Body Systems
 The skeletal system
 Supports and protects other systems
 Stores fat, calcium, and phosphorus
 Manufactures cells for immune system
 Disorders in other body systems can cause
 Bone tumors
 Osteoporosis
 Arthritis
 Rickets (vitamin D deficiency)
Integration with Other Systems
Figure 9–13 Functional Relationships between the Skeletal System and
Other Systems.
Integration with Other Systems
Figure 9–13 Functional Relationships between the Skeletal System and
Other Systems.