1. The Skeletal System: Articulations
Unit 02
The Skeletal System: Articulations
Frederic Martini
Michael Timmons
Robert Tallitsch

2. Introduction
Joints, or articulations, are connections between bones that may or may not permit movement.
Cartilage, fluid, or dense connective tissues is usually involved in holding joints together.
Joints are classified functionally by the amount of movement they allow.
Immoveable or slightly moveable joints tend to be in the axial skeleton.
Freely moveable joints are more common in the appendicular skeleton.

3. Synarthroses (Immovable Joints)
Sutures are joints found only in the skull.
Bony edges interlock and short dense connective tissue fiber hold the bones together.
A gomphosis is the joint between a tooth and the alveolar fossa of the maxillae or mandible.
Periodontal ligaments hold the tooth to the bone in the gomphosis.
A synchondrosis is a joint in which hyaline cartilage separates the ends of the bones involved in the joint.
A synostosis occurs if bones fuse together to form one bone.

4. Amphiarthroses (Slightly Movable Joints)
A syndesmosis occurs when to bones are connected by relatively long connective tissue ligaments.
Connecting bones using a fibrocartilage pad forms a symphysis. 

5. Diarthroses (Freely Movable Joints)
Synovial joints are typically found at the ends of long bones in the upper and lower limbs.
All synovial joints have six basic characteristics:
A joint capsule
Articular cartilages
A joint cavity filled with synovial fluid
A synovial membrane lining the joint capsule
Accessory structures
Sensory nerves and blood vessels

6. Synovial Joints
Structure of a Synovial Joint

7. Synovial fluid has three functions:
Lubricates the surfaces of the articular cartilages on the ends of the bones.
Nourishes the chondrocytes by entering and exiting the articular cartilages due to the forces acting on the joint.
Acts as a shock absorber.

8. Types of Movements
Angular movements
Rotation

9. Movements at the ankle include:
Special Movements
Movements at the ankle include:
Eversion/inversion
Dorsiflexion/plantar flexion
Movement of the vertebral column includes:
Lateral flexion
Movement of the pollex (thumb):
Opposition/reposition

10. Movements that occur at many joints include:
Special Movements
Movements that occur at many joints include:
Protraction: anterior movement in the horizontal plane
Retraction: posterior movement in the horizontal plane
Elevation: cranial movement in the vertical axis
Depression: caudal movement in the vertical axis

11. Structural Classification of Synovial Joints
Plane joints:  
Nonaxial or multiaxial
Hinge joints:
flexion and extension
Pivot joints:
rotational movements

12. Structural Classification of Synovial Joints
Condylar joints:
flexion/extension and abduction/adduction
Saddle joints:
biaxial joints that also allow circumduction
Ball and socket joints:
triaxial joints

13. The Temporomandibular Joint
The Temporomandibular Joint (TMJ)

14. Intervertebral Articulations
Anterior Vertebral Column
Lateral Vertebral Column

15. There are four possible movements of the vertebral column:
Vertebral Movements
There are four possible movements of the vertebral column:
Anterior flexion, or bending forward
Extension, or bending backward
Lateral flexion, or bending to the side
Rotation–twisting

16. The Sternoclavicular Joint

17. The Shoulder Joint
The Anterior Shoulder
The Lateral Shoulder

18. The Shoulder Joint
Sectional Shoulder
Superior Shoulder

19. The Elbow Joint
Medial Elbow
Longitudinal Elbow

20. The Wrist
Wrist Joints
Wrist Ligaments

21. The Joints of the Hand
Joints of the Hand

22. The Hip Joint
Lateral Hip
Posterior Hip

23. The Hip Joint
Anterior Hip
Sectional Hip

24. The Knee
Anterior Knee
Parasagittal Knee

25. The Knee
Posterior Superficial
Posterior Deep

26. The Knee
Anterior Knee

27. The Ankle and Foot
Ankle and Foot
Ankle and Foot MRI