Joints

Question 1

What is a joint?

Answer 1

The ARTICULATION or union of two rigid structures (bone or cartilage).

Question 2

Why do we need articulating joints?

Answer 2

• Movement (not all)

- Growth

Question 3

Fibrous joints - Sutures

Answer 3

• Immovable joint
• Only found between the bones of the skull
• There is limited movement until about 20 yrs, after which they become fixed.

Question 4

Fibrous joints - Gomphoses

Answer 4

• Immovable joint

- Where the teeth articulate with their sockets

Question 5

Fibrous joints - Syndesmoses

Answer 5

-Slightly movable joints
-Bones held together by an interosseous membrane!!
E.g. Middle radio-ulnar and middle & inferior tibiofibular joint.

Question 6

Cartilaginous joints

Answer 6

In cartilaginous joints, the bones are attached by fibrocartilage or hyaline cartilage.
They be split into primary and secondary cartilaginous joints.

Question 7

Primary cartilaginous joints

Answer 7

• Primary cartilaginous joints only involve hyaline cartilage.
• The joints can be immovable or slightly movable.
• E.g. the joint between the diaphysis and epiphysis of a growing long bone (epiphyseal plate). This is a temporary joint with no movement.

Question 8

Secondary cartilaginous joints

Answer 8

• Secondary cartilaginous joints involve hyaline cartilage and fibrocartilage, e.g. symphysis.
• These occur in the midline of the body, e.g. pubic symphysis and intervertebral discs.

Question 9

What is a synovial joint?

Answer 9

A synovial joint is a joint filled with synovial fluid. These joints tend to be fully movable and are the main type of joint found around the body.

Question 10

Synovial joints - characteristics

Answer 10

1. Joint cavity - the space between articulating bones lined with synovial membrane.
2. Joint capsule - surrounding joint cavity
3. Synovial Membrane - secretes synovial fluid whih lubricates and nourishes the joint.
4. Articular (Hyaline) cartilage - covers the ends of bones that articulate with each other. Consists of hyaline cartilage lubricated with synovial fluid. Reduces friction in the joint.
5. Accessory Structures - Ligaments, Bursae, Fibrocartilaginous discs, Labra, Menisci , Muscles.

Question 11

How to study/describe a synovial joint

Answer 11

Start on the inside and proceed to the outside:

1. Bones & articulating surfaces (hyaline cartilage)
2. Synovial membrane
3. Intracapsular structures - discs, menisci, etc.
4. Capsule
5. Extracapsular structures - bursae
6. Stabilising ligaments
7. Nerve and arterial supply
8. Movements permitted & muscles