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PART A
Joints
Joints (Articulations)
 Weakest parts of the skeleton
 Articulation – site where two or more bones meet
 Functions of joints
 Give the skeleton mobility
 Hold the skeleton together
Classification of Joints: Structural

Structural classification focuses on the material
binding bones together and whether or not a joint
cavity is present
The three structural classifications are:

1.
2.
3.
Fibrous
Cartilaginous
Synovial
Classification of Joints: Functional

Functional classification is based on the amount of
movement
The three functional classes of joints are:

1.
2.
3.
Synarthroses – immovable
Amphiarthroses – slightly movable
Diarthroses – freely movable
Fibrous Structural Joints
 The bones are joined by fibrous tissues
 No joint cavity
 Most are immovable
 There are three types – sutures, syndesmoses, and
gomphoses
Fibrous Structural Joints: Sutures
 Occur between the bones of the skull
 Comprised of interlocking junctions filled with
connective tissue fibers
 Bind bones tightly together, but allow for growth
during youth
 Fusion of bones = synostoses
Fibrous Structural Joints: Sutures
Figure 8.1a
Fibrous Structural Joints:
Syndesmoses
 Bones are connected by a fibrous ligament
 Either immovable or slightly moveable
 Examples include the connections between the tibia
and fibula, and the radius and ulna
Fibrous Structural Joints:
Syndesmoses
Figure 8.1b
Fibrous Structural Joints:
Gomphoses
 The peg-in-socket fibrous joint between a tooth and its
alveolar socket
 The fibrous connection is the periodontal ligament
Cartilaginous Joints
 Articulating bones are united by cartilage
 Lack a joint cavity
 Two types – synchondroses and symphyses
Cartilaginous Joints:
Synchondroses
 A plate of hyaline cartilage unites the bones
 All synchondroses are synarthrotic
 Examples include:
 Epiphyseal plates of children
 Joint between the first rib and the sternum
Cartilaginous Joints:
Synchondroses
Figure 8.2a, b
Cartilaginous Joints: Symphyses
 Hyaline cartilage covers bone and is fused to a pad of
fibrocartilage
 Amphiarthrotic joints designed for strength and
flexibility
 Examples include intervertebral joints and the pubic
symphysis of the pelvis
Cartilaginous Joints: Symphyses
Figure 8.2c
Synovial Joints
 Bones are separated by a fluid-containing joint cavity
 All are freely movable diarthroses
 Examples – all limb joints, and most joints of the body
Synovial Joints: General Structure
 Synovial joints all have the following
 Articular cartilage
 Joint (synovial) cavity
 Articular capsule
 Synovial fluid
 Reinforcing ligaments
Synovial Joints: General Structure
Figure 8.3a, b
Synovial Joints: Friction-Reducing
Structures
 Bursae – flattened, fibrous sacs containing synovial
fluid
 Common where ligaments, muscles, tendons, or bones
rub together
 Tendon sheath – elongated bursa that wraps
completely around a tendon
Synovial Joints: Friction-Reducing
Structures
Figure 8.4
Synovial Joints: Stability

Stability is determined by:
1.
2.
Articular surfaces – shape determines what
movements are possible
Ligaments – prevent excessive or undesirable motion
Synovial Joints: Movement

The two muscle attachments across a joint are:
1.
2.

Origin – attachment to the immovable bone
Insertion – attachment to the movable bone
Described as movement along transverse, frontal, or
sagittal planes
Synovial Joints: Range of Motion
 Nonaxial – slipping movements only
 Uniaxial – movement in one plane
 Biaxial – movement in two planes
 Multiaxial – movement in or around all three planes
Gliding Movements
 Nonaxial
 One flat bone surface glides or slips over another
 Examples – intercarpal and intertarsal joints, and
between the vertebrae
Angular Movement
 Flexion — decreases the angle of the joint
 Extension — reverse of flexion; joint angle is increased
 Dorsiflexion and plantar flexion — up and down
movement of the foot
Angular Movement
 Abduction — movement away from the midline
 Adduction — movement toward the midline
 Circumduction — movement describes a cone in space
Gliding Movement
Figure 8.5a
Angular Movement
Figure 8.5b
Angular Movement
Figure 8.5c, d
Angular Movement
Figure 8.5e, f
Rotation
 The turning of a bone
around its own long axis
 Uniaxial
 Examples
 Between first two
vertebrae
 Hip and shoulder joints
Figure 8.5g
Special Movements
 Supination and pronation
 Inversion and eversion
 Protraction and retraction
 Elevation and depression
 Opposition
Special Movements
Figure 8.6a
Special Movements
Figure 8.6b
Special Movements
Figure 8.6c
Special Movements
Figure 8.6d
Special Movements
Figure 8.6e