Chapter 9: Articulations

1
Chapter 9Articulations
2
Articulations

• Body movement occurs at joints where 2 bones
  connect
• Articulation joints site where two or more
  bones meet

3
Joint Structure

• Determines direction and distance of movement
  (range of motion)
• Joint strength decreases as mobility increases

4
Anatomical/Structural Classification of Joints
(based on connecting material

• Fibrous bones joined by fibrous CT with no space
• Cartilaginous bones joined by pad or bridge of
  cartilage
• Synovial bones separated by fluid-filled cavity,
  surrounded by CT

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Structural Classification
Table 92
6
Physiological/Functional Classifications of
Joints(based on the amount of movement)

• Synarthrosis immovable joints
• - No movement
• - Fibrous or cartilaginous connections
• Amphiarthrosis slightly moveable joint
• - Little movement
• - Fibrous or cartilaginous connections
• Diarthrosis freely moveable joint
• - More movement
• - always synovial connections

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What common characteristics do typical
synarthrotic and amphiarthrotic joints share?

• joint capsules filled with fluids
• non-restricted movement of bony regions
• bony regions separated by fibrous connective
  tissue
• articular cartilages and bursae

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Synarthroses (Immovable Joints)

• Are very strong
• Edges of bones may touch or interlock
• 4 Types of Synarthrotic Joints
• Suture
• Gomphosis
• Synchondrosis
• Synostosis

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1. Synarthoroses

• Immoveable Strength
• Synotosis fused bones
• - Suture of skull and epiphyseal lines of long
  bones
• Suture interlocked bones, sealed with dense CT
• - Found only in the skull
• Gomphosis tooth in alveolar socket, held by
  peridontal ligament
• - Binds teeth to sockets
• Synchrondrosis hyaline cartilage bridge between
  bones
• - Epiphyseal cartilage of long bones and
  between
• vertebrosternal ribs and sternum

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2. Amphiarthroses

• Slightly Moveable, strength with some mobility
• Syndesmosis bones connected by ligament
• Symphasis bones separated by pad of
  fibrocartilage

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3. Diarthorses Synovial Joints

• Great mobility, less strength and stability
• At ends of long bones
• Within articular capsules
• Lined with synovial membrane

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Features of Synovial Joints

• Articular Cartilage
• Synovial Cavity
• Articular Capsule
• Synovial Fluid
• Accessory Structures
• - Meniscus, fat pad, accessory ligaments,
  tendons, bursa, synovial tendon sheath

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1. Articular Cartilages

• Hyaline cartilage
• No perichondrium or periosteum
• Pad articulating surfaces within articular
  capsules
• prevent bones from touching
• Smooth surfaces lubricated by synovial fluid
• reduce friction

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Features of Synovial Joints

• Synovial cavity
• Space between/around opposing bones
• Has synovial fluid
• Articular Capsule 2 layers
• Outer
• dense irregular connective tissue, continuous
  with periosteum
• Inner
• synovial membrane (areolar CT), covers inside
  surface of cavity except articular cartilage,
  secretes synovial fluid

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4. Synovial Fluid

• filtrate from blood plasma hyaluronic acid
  from fibroblasts
• Functions
• 1. Lubrication
• 2. Nutrient distribution diffusion
• medium
• 3. Shock absorption

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Synovial Joints Accessory Structures

• Cartilages (Meniscus)
• Fat pads
• Ligaments
• Tendons
• Bursae
• Synovial Tendon Sheath

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Synovial Joints Accessory Structures

• Meniscus
• fibrocartilage pad articular disc
• Subdivides cavity or changes shape of articular
  surface, limits range of motion
• Cushion the joint
• Fat Pad
• Adipose
• Superficial to joint capsule,
• Function protection and space filler

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Synovial Joints Accessory Structures

• Accessory Ligaments
• Dense regular connective tissue
• Either part of capsule, inside joint, or outside
  capsule
• Function support and strengthen joint
• Sprain Ligaments with torn collagen fibers
• Tendons
• Dense regular connective tissue
• Attach muscle to bone
• Function Add stability to the joint

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Synovial Joints Accessory Structures

• Bursa
• Synovial fluid filled pocket
• Function reduces friction
• Cushion areas where tendons or ligaments rub
• Synovial Tendon Sheath
• - Tubular bursa around a tendon

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Synovial Joints Stabilizing Factors

• 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

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Functional Classification
Table 91
23
In a newborn infant, the large bones of the skull
are joined by fibrous connective tissue. Which
type of joints are these? The bones later grow,
interlock, and form immovable joints. Which type
of joints are these?

• synarthrosis gomphosis
• symphysis sutural
• synchondrosis synostosis
• syndesmosis sutural

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Why would improper circulation of synovial fluid
lead to the degeneration of articular cartilages
in the affected joint?

• Synovial fluid nourishes articular cartilage.
• Blood flow follows synovial fluid circulation.
• Articular cartilage is composed of synovial
  fluid.
• Both A and B.

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Joint Injuries

• Sprain damage to ligament
• Some collagen torn, slow to heal
• Bursitis
• Inflammation of a bursa due to trauma, infection,
  or repetitive motion
• Synovial joints stabilized by articular
  capsule and accessory structures to restrict
  mobility
• Increase Mobility Decrease Stability Increase
  chance of
• dislocation

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Injuries

• Luxation
• Dislocation
• articulating surfaces forced out of position
• Joint Displacement
• Usually damages articular cartilage, ligaments,
  and joint capsule
• Pain receptors in all CT of the Joint, except
  articular cartilage, to prevent actions
• Subluxation
• Partial dislocation
• Displacement beyond usual anatomical limitation
• Double Jointed

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The dynamic movements of the skeleton.
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Movements at Synovial Joints

• Linear Movements
• Gliding slight movement in any direction
• Angular Movements one plane of motion
• Flexion reduce angle in frontal plane
• Extension increase angle in frontal place
• Hyperextension extension past anatomical
  position
• Abduction move away from longitudinal axis in
• sagittal plane
• Adduction move toward longitudinal axis in
• sagittal plane
• Circumduction move in loop without rotation
• Rotational Movements turn on axis
• Medial Rotation turn in toward body
• Lateral Rotation turn out away from body

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Linear Motion

• Pencil maintains vertical orientation, but
  changes position

Figure 92a, b
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Angular Motion

• Pencil maintains position, but changes orientation

Figure 92c
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Circumduction

• Circular angular motion

Figure 92d
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Rotation

• Pencil maintains position and orientation, but
  spins

Figure 92e
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Angular Motion Flexion
Figure 93a
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Angular Movement Flexion Vs. Extension

• Flexion
• Angular motion
• Anteriorposterior plane
• Reduces angle between elements
• Extension
• Angular motion
• Anteriorposterior plane
• Increases angle between elements

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Angular Motion Abduction Vs. Adduction
Figure 93b, c
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Abduction Vs. Adduction

• Abduction
• Angular motion
• Frontal plane
• Moves away from longitudinal axis
• Adduction
• Angular motion
• Frontal plane
• Moves toward longitudinal axis

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Circumduction

• Circular motion without rotation
• Angular motion

Figure 93d
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Special and Specific Motion

• Inversion turn sole inward
• Eversion turn sole outward
• Dorsiflexion lift toes
• Plantar flexion lift heal
• Opposition thumb across palm
• Pronation medial rotation of radius
• Superination lateral rotation of radius
• Protraction move anterior (toward front)
• Retraction move posterior (toward back)
• Elevation move superior (toward head)
• Depression move inferior (toward feet)

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Inversion and Eversion
Figure 95a
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Dorsiflexion and Plantar Flexion
Figure 95b
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Ranges of Motion

• Monaxial movement in 1 plane
• Biaxial movement in 2 planes
• Triaxial movement in 3 planes
• Multiaxial gliding joints, all directions

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When you do jumping jacks, which lower limb
movements are necessary?

• flexion and extension
• abduction and adduction
• flexion and abduction
• plantar flexion and eversion

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The types of synovial joints, and the
relationship of motion to structure.
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Classification of Synovial Joints by Shape

• Gliding
• Hinge
• Pivot
• Ellipsoidal
• Saddle
• Ball-and-socket

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Gliding/Plane Joints

• Flattened or slightly curved faces
• Slide in any direction

Figure 96 (1 of 6)
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Hinge Joints

• Cylindrical projections in trough-shaped surface
• Angular motion in a single plane (monaxial)

Figure 96 (2 of 6)
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Pivot Joints

• Round projection in ring shaped depression
• Rotation only (monaxial)

Figure 96 (3 of 6)
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Ellipsoidal Joints

• Oval articular facet within an oval depression
• Motion in 2 planes (biaxial)

Figure 96 (4 of 6)
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Saddle Joints

• 2 concave faces into convex
• Straddled (biaxial)

Figure 96 (5 of 6)
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Ball-and-Socket Joints

• Spherical head into cup-like socket
• Round articular face in a depression (triaxial)

Figure 96 (6 of 6)
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KEY CONCEPT

• A joint cant 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

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How the vertebrae in the vertebral column
articulate.
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Intervertebral Articulations
Figure 97
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Damage to Intervertebral Discs
Figure 98
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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

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Articulations and Movements of the Axial Skeleton
Table 93 (1 of 2)
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Articulations and Movements of the Axial Skeleton
Table 93 (2 of 2)
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The Elbow Joint
Figure 910
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The Hip Joint
Figure 911b, c
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The Knee Joint
Figure 912a, b
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Articulations of the Appendicular Skeleton
Table 94 (1 of 2)
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Articulations of the Appendicular Skeleton
Table 94 (2 of 2)
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The effects of aging on articulations, and the
most common clinical problems.
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Age Related Changes

• Rheumatism
• Pain and stiffness of skeletal system
• Arthritis
• Rheumatism of synovial joints, caused by damage
  to articular cartilage
• Osteoarthritis
• - Age 60, cumulative wear and tear erodes
  cartilage
• Rheumatoid Arthritis
• - Autoimmune attack, chronic inflammation and
  damage to joint
• - Ankylosis ossification of the joint due to
  untreated RA
• Gouty Arthritis
• Crystals of uric acid from nucleic acid
  metabolism form in synovial fluid, damage
  cartilage
• Due to metabolic disorders