Joints

Question 1

What is considered when Joints are classified?

Answer 1

by structure and/or presence of a cavity between the two opposing bones involved in the joint

Question 2

What are the three MAIN categories of Joint?

Answer 2

1. Fibrous
2. Cartilaginous
3. Synovial

Question 3

What are three types of Fibrous joint?

Answer 3

• Sutures (the fibrous joint that joins the bones of the skull to each other, excl. mandible) NIL Mvmt
• Gomphosis (fibrous joint that anchors the teeth) SLIGHT Mvmt
• Syndesmosis (fibrous joint where two bones are linked by a strong membrane or ligaments) NIL Mvmt

Question 4

What are the two types of Cartilaginous joint?

Answer 4

• Symphysis (a fibrocartilaginous fusion between two bones)
• Intervertebral Disc (fused disk that provides limited motion)

Question 5

What are Synovial Joints characterised by?

Answer 5

The presence of a fluid filled cavity which is present between the ends of the opposing bones.

Question 6

There are many features of a Synovial joint - name all 5

Answer 6

1. Cartilage
   (thin layer that covers the articulating surface of the bone)
2. Joint capsule
   (enclosing both ends of the bones, forming a “sleeve”. outer fibrous layer and inner lining that comprises the synovial membrane. many nerves that can transmit signals to the brain about motion)
3. Synovial fluid
   (weight bearing element preventing the articulating bones from touching - provides nourishment to the cartilage)
4. Ligaments
   (strengthens the synovial joint on the external surface of the capsule or inside the joint capsule if the joint is complex or vulnerable (knee))
5. Bursae
   (small sac like structures with synovial fluid present to reduce friction. usually found between bone and muscle near joints)

Question 7

What are Bursae?

Answer 7

Feature of a Synovial Joint.

Bursae are small sac like structures with synovial fluid present to reduce friction. usually found between bone and muscle near joints

Question 8

What does the Joint capsule do?

Answer 8

Feature of a Synovial Joint.

The joint capsule encloses both ends of the opposing bones, forming a “sleeve”.
It has an outer fibrous layer and inner lining that comprises the synovial membrane.

This contains many nerves that can transmit signals to the brain about motion

Question 9

What does articular cartilage do in a Synovial Joint?

Answer 9

A thin layer of hyaline cartilage covers the articulating surface of the bone.

Reduces frictional forces between bones.

Question 10

What do Ligaments do for the synovial joint?

Answer 10

Because the presence of the joint capsule is insufficient on its own to prevent dislocation of the joint, the Ligament strengthens and stabilises the joint to prevent dislocation or subluxation (minor dislocation)

Question 11

What does Synovial fluid do?

Answer 11

Synovial fluid serves as the weight bearing element and prevents the bones articulating surfaces from touching one another.

also provides nourishment to the articular cartilage.

Question 12

what are the 6 types of Synovial joints?

Bonus: describe their movement pattern

Answer 12

1. Plane or Gliding Joint (limited movement allowed in various directions, e.g., carpals)
2. Hinge Joint
   (uniaxial)
3. Pivot Joint (uniaxial)
4. Condyloid Joint (movement at two planes at right angles to each other - biaxial)
5. Saddle Joint
   (thumb joint - biaxial)
6. Ball & Socket Joint
   (triaxial - large range of movement, shoulder & hip joint)

Question 13

What factors dictate the role of a joint?

Answer 13

• classification according to its structure
• amount of movement available (uniaxial, biaxial, triaxial)
• position of the joint in the body (upper or lower limb)
• presence of intra and extra capsular ligaments
• presence of muscles and tendons running over the joint confer more stability and protection