Articulations are where bones meet, and are classified based on their structure and function. The three main types of joints are fibrous, cartilaginous, and synovial joints. Synovial joints are the most common and include ball-and-socket joints like the shoulder, hinge joints like the elbow, and gliding joints like those between vertebrae. Joints allow various movements like flexion, extension, and rotation through the interaction of bones, ligaments, muscles, and other tissues.

1. Unit 4: The Skeleton System
Section 5: Articulations & Movement
Anatomy & Physiology
Mrs. DeFord

2. • Articulations are areas of the body where two or more bones meet.
Cartilage covers ends of movable bones to reduce friction.
Articulations (Joints)
• General function of joints
are to:
– Hold the skeleton together
– Allow for increased mobility
and flexibility of the skeleton

3. • Joints can be classified based on:
– Structure (what material is found in the joint and if there is a joint
cavity present)
– Function (what kind of movement they allow)
Classification of Joints

4. • The structural classification of joints:
– Fibrous joints
• Bones held together by dense collagen fibers
• Ex: skull sutures
– Cartilaginous joints
• Bones held together by cartilage
• Ex: pelvic girdle, intervertebral discs
– Synovial joints
• Bones held together by ligaments to absorb shock and protect the
bone; bathed in synovial fluid
• Most common
Structural Classification of Joints

5. • The functional classification of joints:
– Synarthrodial joints
• Fibrous joints
• An immovable joint
• Ex: sutures such as skull sutures, teeth
– Amphiarthrodial joints
• Cartilaginous joints
• A slightly movable joint
• Ex: joints of the ribs with the sternum, pubic symphysis
– Diarthrodial joints
• Synovial joints
• A freely movable joint; most joints that unite bone of appendicular
skeleton
Functional Classification of Joints

6. Fibrous Joints (Synarthroses)

7. Cartilaginous Joints (Amphiarthroses)

8. Synovial Joints (Diarthroses)

9. – Diarthrodial joints (synovial joints; a freely movable joint)
• Hinge joint – allows motion in only one direction, up/down; EX:
elbow, knee
• Pivot joint – the rotation of one bone around another; EX: proximal
end of radius and ulna, neck
• Condyloid joint – allows for all movement except rotation; EX:
fingers and jaw
• Saddle joint – allows back and forth and side/side motion but little
rotation; EX: thumb
• Ball & Socket joint – joint with the widest range of motion; EX: hips
and shoulder
• Gliding (plane) joint – allows bones to glide past one another, or
twist; EX: vertebrae, ankle, wrist
Types of Synovial Joints (Diarthroses)

10. • Factors contribute to keeping the articular surfaces in contact and affect range of motion:
– Structure or shape of the articulating bones determines how closely they fit together
– Strength and tension of the joint ligaments
• Ligaments are tense when the joint is in certain positions
• Tense ligaments restrict the range of motion
– Arrangement and tension of the muscles; muscle tension reinforces the restraint
placed on a joint by its ligaments, and thus restricts movement
– Contact of soft parts: the point at which one body surface contacts another may limit
mobility; movement is restricted by the presence of adipose tissue
– Hormones
• Flexibility may also be affected by hormones: Relaxin increases the flexibility of the
pubic symphysis and loosens the ligaments between the sacrum and hip bone
toward the end of pregnancy
– Disuse: movement may be restricted if a joint has not been used for an extended
period
Joint Movements

11. • Gliding – bony surfaces of bones
slide or glide over each other
Synovial Joint Movements

12. Synovial Joint Movements
• Flexion – bending movement
that decreases the angle of a
joint
• Extension – movement that
increases the angle of a joint
• Hyperextension – extending
a joint beyond its normal
range of motion

13. Synovial Joint Movements
• Abduction – movement
away from the midline of
the body
• Adduction – movement
toward the midline of the
body

14. Synovial Joint Movements
• Pronation – rotating the
forearm medially such that
the palm faces inferiorly
• Supination – rotating the
forearm laterally such that
the palm faces superiorly

15. Synovial Joint Movements
• Protraction – moving a body
part forward
• Retraction – moving a body
part backward

16. • Depression – moving the
body part inferiorly
• Elevation – moving the
body part superiorly
Synovial Joint Movements

17. • Dorsiflexion – movement that
points the toes up toward the
shin
• Plantar Flexion – movement
that points the toes down
toward the sole
Synovial Joint Movements

18. • Inversion – moving the sole of
the foot to face medially
• Eversion – moving the sole of
the foot to face laterally
Synovial Joint Movements

19. • Rotation – turning the
bone or limb around its
long axis
• Lateral Rotation – rotation
away from the midline
• Medial Rotation – rotation
toward the midline
Synovial Joint Movements

20. Synovial Joint Movements
• Circumduction – circular
movement of a limb

21. Synovial Joint Movements
• Opposition – to bring the
thumb and index finger tips
together