Joints

Question 1

Describe the principal features of fibrous joints.

Answer 1

In fibrous joints, articulating bones are joined by a dense fibrous connective tissue.
This has a high tensile strength and provides little movement in adults.

Question 2

Describe the principle features of cartilaginous joints.

Answer 2

Cartilaginous joints are formed by layers of cartilage, and there are two types;
- Primary (synchondrosis), these joints allow for bone growth (by endochondral ossification) and are found in long bones. These joints disappear in adults.
- Secondary (symphyses), this type of joint does not ossify with age, it is found in the midline of the body and provides little movement.
The binding tissue is a fibrocartilaginous disc.
E.g. in vertebrae, the intervertebral disc is composed of fibrocartilage sandwiched between hyaline cartilage on either side.

Question 3

Describe the principle features of synovial joints.

Answer 3

In a synovial joint the two bones are separated by the characteristic joint cavity (containing synovial fluid) but are joined by an articular capsule = a fibrous capsule lined with synovial membrane.
The bearing surfaces of the bones are covered with articular cartilage.
These joints provide free movement.

Question 4

List the different kinds of synovial joints;

Answer 4

Hinge
Pivot
Saddle
Ball and socket
Condylar
Plane

Question 5

Briefly explain the concept of joint stability.

Answer 5

• The fibrous capsule and ligaments reinforce the joints
• The shape of articular surfaces.
  -Muscles.

Question 6

Briefly describe the blood supply to joints.

Answer 6

Joints receive blood from articular arteries that arise from vessels around the joint.
The arteries often communicate to form networks which ensure a continuous blood supply to a joint throughout its range of movement.
Articular veins are communicating veins that accompany the arteries and, like the arteries, are located in the joint capsule, mostly in the synovial membrane.

Question 7

Briefly describe the nerve supply to joints.

Answer 7

Joints have a rich nerve supply; the nerve endings are numerous in the joint capsule. In the distal part of limbs, the articular nerves are branches of the nerves supplying the overlying skin.
Otherwise, most articular nerves are branches of nerves that supply the muscles that cross and therefore move the joint.

Question 8

State ‘Hiltons Law’

Answer 8

The Hiltons Law states that the nerves supplying a joint also supply the muscles moving the joint and the skin covering their attachments, i.e. innervates this joint.

Question 9

Describe the function of synovial fluid.

Answer 9

Synovial fluid is found in the articular cavity of synovial joints.
Synovial fluid serves the dual function of nourishing the articular cartilage and lubricating the joint surfaces.