1. Joints Also called articulations Functional junctions between bones
Functions:
Bind parts of the skeleton together
Make bone growth possible
Permit parts of the skeleton to change shape during childbirth
Enable the body to move in response to skeletal muscle contractions

2. Classification of Joints
If classified by function (the degree of movement they make possible):
Synarthrotic or immovable
Amphiarthrotic or slightly movable
Diarthrotic or freely movable
If classified by structure (the type of tissue that binds the bones together at each junction):
Fibrous
Cartilaginous
Synovial
Currently, the structural classification is more commonly used.

3. Fibrous Joints Lie between bones that closely contact each other
The type of tissue that joins the bones is a thin layer of dense connective tissue
Examples:
Sutures of the skull (synarthrotic)
Between the distal ends of the tibia and fibula (amphiarthrotic)

4. Cartilaginous Joints
Joined by either hyaline cartilage or fibrocartilage
Allow only limited movement (amphiarthrotic) as when the back is bent forward or to the side, or when twisted.
Examples:
Intervertebral discs separate vertebrae of the spinal column and function to absorb shocks and equalize pressure between adjacent vertebrae when the body moves.
Symphysis pubis functions to separate the pubis bones anteriorly.

5. Cartilaginous Joints

6. Synovial Joints Allow free movement (diarthrotic)
Most common type of joint in the body
More structurally complex than fibrous or cartilaginous joints
Contain a joint capsule made of dense connective tissue
Composed of an outer layer of ligaments to hold the joint in place
Inner lining called a synovial membrane secretes a thick jelly-like fluid called synovial fluid that lubricates the joints

7. Synovial Joints Some synovial joints contain special structures:
Menisci are flattened pads of fibrocartilage found between articulating surfaces of bones
Act as shock-absorbers
Bursae are fluid-filled sacs lined with synovial membrane
Commonly located between tendons and underlying bony prominences
Aid the movement of tendons that glide over these bony parts or other tendons.

8. Synovial Joints – Ball & Socket
Consists of a bone with a globular or slightly egg-shaped head that articulates with the cup-shaped cavity of another bone
Allows a wider range of motion than any other type of joint
Permits movements in all planes as well as rotational movement around a central axis
Examples:
Shoulder joint
Hip joint

9. Synovial Joints – Condyloid
Also called ellipsoidal joint
Oval-shaped condyle of one bone fits into an elliptical cavity of another bone
Permits a variety of movements in different planes
No rotational movement
Examples:
Joint between the metacarpals and the phalanges

10. Synovial Joints – Gliding
Also called plane joint
Nearly flat or slightly curved
Allow twisting or sliding movements
Examples:
Most of the joints of the ankle and wrist
Joints between the articular processes of adjacent vertebrae
Sacroiliac joint
Joints formed by ribs 2 through 7 connecting with the sternum

11. Synovial Joints – Hinge
Convex surface of one bone fits into the concave surface of another
Permits movement in one plane only
Resembles the hinge of a door
Examples:
Joints of the phalanges
Elbow
The knee is considered to be a modified hinge joint because it also allows some rotation in addition to extension and flexion

12. Synovial Joints – Pivot
Cylindrical surface of one bone rotates within a ring formed of bone and ligament
Movement is limited to rotation around a central axis
Examples:
Joint between the proximal ends of the radius and ulna
Joint between the first and second vertebrae (atlas and axis)

13. Synovial Joints – Saddle
Forms between bones whose articulating surfaces have both concave and convex regions
The surface of one bone fits the complementary surface of the other
Permits a variety of movements
Example:
Joint between the carpal (trapezium) and metacarpal bones of the thumb

14. Synovial Joints

15. Arthritis
Group of disorders that cause inflamed, swollen, and painful joints
More than a hundred different types world-wide
Most common types:
Rheumatoid arthritis – most painful and debilitating type
Synovial membrane becomes inflamed and thickened
Articular cartilage is damaged and fibrous tissue infiltrates, interfering with joint movement
Joints may ossify, fusing the articulating bones
Autoimmune disorder in which the immune system attacks the body’s healthy tissues

16. Arthritis Osteoarthritis
degenerative disorder that occurs as a result of aging.
An inherited form exists
Articular cartilage softens and disintegrates gradually
Joints become painful and restrict movement
Most often affects joint used the most such as the fingers, hips, knees, and lower vertebral column.

17. Types of Joint Movements
Skeletal muscle action produces movements at synovial joints.
One end of a muscle is attached to a relatively fixed part on one side of a joint, while the other end of the muscle is fastened to a movable part on the other side.
When the muscle contracts, its fibers pull its moveable end toward the fixed end and movement occurs at the joint.

18. Types of Joint Movements
Flexion
Bending parts at a joint so that the angle between them decreases and the parts come closer together
Example:
Bending the elbow
Extension
Straightening parts at a joint so that the angle between them increases and the parts move further apart
Straightening the elbow

19. Types of Joint Movements
Dorsiflexion
Movement at the ankle that brings the foot closer to the shin
Example:
Walking on the heels
Plantarflexion
Movement at the ankle that brings the foot further from the shin
Walking or standing on the toes

20. Types of Joint Movements
Hyperextension
Extension of the parts at a joint beyond the anatomical position
Often used to describe an abnormal extension beyond the normal range of motion, resulting in injury
Examples:
Bending the head back beyond the upright position
Bending the knee beyond vertical

21. Types of Joint Movements
Abduction
Moving a part away from the midline
Example:
Lifting the upper limb horizontally to form a right angle with the side of the body
Adduction
Moving a part toward the midline
Returning the upper limb from the horizontal position to the side of the body.

22. Types of Joint Movements
Rotation
Moving a part around an axis
Example: twisting the head from side to side
Circumduction
Moving a part so that its end follows a circular path
Example: moving the finger in a circular motion without moving the hand

23. Types of Joint Movements
Pronation
Turning the hand so that the palm is downward or facing posteriorly
Supination
Turning the hand so that the palm is upward or facing anteriorly

24. Types of Joint Movements
Eversion
Turning the foot so that the plantar surface faces laterally
Inversion
Turning the foot so that the plantar surface faces medially

25. Types of Joint Movements
Retraction
Moving a part backward
Example: Pulling the chin backward
Protraction
Moving a part forward
Example: Thrusting the chin forward

26. Types of Joint Movements
Elevation
Raising a part
Example: shrugging the shoulders
Depression
Lowering a part
Example: drooping the shoulders

27. Arthroscopy
Procedure used to diagnose and treat injuries to joints such as the elbow, shoulder, and knee
Enables a surgeon to visualize the interior of a joint and perform diagnostic or therapeutic procedures guided by the image on a video screen
The surgeon inserts the device through a small incision in the joint capsule
Less invasive than conventional surgery