Chapter 8 Joints

Question 1

What are the three functional classifications of joints?

Answer 1

1 - Synarthroses - immovable
2 - amphiarthroses - slightly movable
3 - diarthroses - freely moveable
(These are distinct from the structural classifications)

Question 2

What are Sutures?

Answer 2

Fibrous joint - ‘seam’ connected by fibrous tissues that are a continuation of periosteum. Wavy, interlocking, rigid splices. During middle age they ossify and skull bones become a single unit.

Question 3

What are Syndesmoses?

Answer 3

Fibrous joint - The bones will be connected exclusively by ligaments. Examples include between radius and ulna as well as tibia and fibula with more movement in the latter due to longer fibers.

Question 4

What are Gomphoses?

Answer 4

Fibrous joint - a peg in socket fibrous joint. Teeth embedded in sockets. Connected by periodontal ligament.

Question 5

What are the three types of fibrous joints?

Answer 5

1-Suture
2-Syndesmosis
3-Gomphosis

Question 6

What makes a cartilaginous joint? And name two types.

Answer 6

The articulating bones are joined by cartilage.
1- Synchondroses
2 - Symphyses

Question 7

What is a Synchondrosis?

Answer 7

A cartilaginous joint - where the articulating bones are joint by a bar or plate of hyaline cartilage. Virtually all are immovable. Such as epiphyseal plate and first rib with manubrium.

Question 8

What is a Symphyses?

Answer 8

A cartilaginous joint - where fibrocartilage unites the bone. Hyaline cartilage is also present on the articular surfaces of bones. Compressible and resilient. Such as intervertebral joints.

Question 9

What are Synovial Joints?

Answer 9

The articulating bones are separated by a fluid containing joint cavity. All synovial joints are freely movable diarthroses.

Question 10

What are the six distinguishing features of Synovial Joints?

Answer 10

1 - Articular cartilage
2 - Joint (articular) cavity
3 - Articular capsule
4 - Synovial fluid
5 - Reinforcing ligaments
6 - Nerves and Blood vessels

Question 11

What is Articular Cartilage?

Answer 11

Hyaline cartilage that covers opposing bone surfaces. It’s spongy and smooth.

Question 12

What is a Joint Cavity?

Answer 12

It is a potential space with a small amount of synovial fluid. It can expand with more fluid such as with inflammation.

Question 13

What is an Articular Capsule?

Answer 13

A two layered capsule with an external fibrous layer and an inner layer synovial membrane (covers all internal surfaces that are not hyaline cartilage. The membrane makes synovial fluid.

Question 14

What is Synovial Fluid?

Answer 14

It’s a lubricant that is found within articular cartilage as well as in all free spaces of joint capsule. Cartilage absorbs and releases synovial fluid like a sponge, known as weeping lubrication. The fluid also contains phagocytic cells that clean up the joint.

Question 15

What are the roles of Reinforcing Ligaments in a synovial joint?

Answer 15

They reinforce the joint. Mostly they are capsular ligaments - thickened parts of fibrous layer. In some cases they are found outside, as in extracapsular or intracapsular ligaments.

Question 16

What is the role of Nerves and Blood Vessels in synovial joints?

Answer 16

Joint capsules are innervated and will signal pain from damage. Most nerves monitor position and stretch. Extensive capillary networks provide blood filtrate - the basis for synovial fluid.

Question 17

What do fatty pads do in synovial joints?

Answer 17

Cushion between fibrous layer and synovial membrane or bone.

Question 18

What are articular discs, or menisci?

Answer 18

They are crescents that extend inward from the articular capsule and partially or fully divide the cavity in two (e.g. the knee)

Question 19

What are bursae?

Answer 19

They are “purses” of synovial membrane with a thin layer of synovial fluid found near many synovial joints and are positioned anywhere ligaments, muscles, skin, tendons, or bones rub together.

Question 20

What is a tendon sheath?

Answer 20

An elongated bursa.

Question 21

What factors determine the stability of a synovial joint?

Answer 21

Shape of articulating surfaces.
Muscle Tone. The low level ongoing activity of a muscle that keeps it ready to react to the environment is the most important feature of joint stability.
The number and position of ligaments. As a rule the more ligaments the stronger. Ligaments will not retract after being stretched.

Question 22

What are the Range of Motions allowed by synovial joints?

Answer 22

Types of motion possible are
Non-axial - gliding only
Uni-axial - one plane of movement
Bi-axial - two planes of movement
Multi-axial - movement in or around all three planes of space or axes

Question 23

What are the Movements allowed by Synovial Joints?

Answer 23

Gliding - gliding or slipping of one bone over another (intercarpal joints)
Angular movements - increase or decrease the angle between two bones.
Flexion - bending movement usually along sagittal plan and usually to decrease joint angle.
Extension - reverse of flexion, increases angle
Abduction - movement away from midline
Adduction - movement towards the midline
Circumduction - movement so the limb describes a cone. The distal end will move in a circle.
Rotation
Supination and pronation
Dorsiflexion and plantar flextion
Protraction and retraction
elevation and depression
opposition

Question 24

What are the six types of synovial joints?

Answer 24

1 Plane
2 Hinge
3 Pivot4 
4 Condylar
5 Saddle
6 Ball-and-socket

Question 25

What is Osteoarthritis?

Answer 25

Most common type.
Chronic degenerative condition. Prevalent in elderly and more common among females. An enzyme is released that breaks down cartilage surfaces. In young populations it is repaired however with aging, breakdown occurs faster than replacement/repair. Bony spurs appear where cartilage no long protects articulating surfaces.

Question 26

What is Rheumatoid Arthritis?

Answer 26

RA is an autoimmune disease. Inflammatory cells migrate to the joint cavity and inflammatory chemicals that destroy body tissues. Steroidal and non-steroidal anti-inflammatory drugs can be prescribed as can immune suppressants.