08 (undone)Joints And Dislocations

Question 1

Describe fibrous joints and give an example of each.

Describe the roles of the fontanelles during descent of the fetus through the birth canal.

Answer 1

Fibrous joints have generally limited mobility and they are quite stable

1) syndesmoses which unite bones with a fibrous sheet/membrane
Eg. Interosseous membranes between the fibula and tibia which are partially movable

2) sutures between the bones of the skull
Eg. Coronal sutures which are highly stable
With advancing age, these sutures will fuse together

3) fontanelles which are Wide sutures in the neonatal skull
- anterior, posterior and lateral fontanelles

These allow the growing parietal, frontal, temporal and occipital bones to slide over each other

Thus making the baby’s head smaller for passage through the birth canal (moulding)

Question 2

Describe cartilaginous joints and give an example for each type

Answer 2

Cartilaginous joints have fairly limited mobility and are relatively stable

1) primary cartilaginous
- synchondroses
- bones are joined by hyaline cartilage
- eg epiphyseal growth plate in Long bones which allows for growth in length of bone
- ossification and fusion

2) secondary cartilaginous
- symphyses
- strong
- slightly movable
- fibrocartilage
- will never fuse
- eg intervertebral disc

Both types can slip
Primary- slipped femoral epiphysis
Secondary - slipped disc

Question 3

Summarise the basic anatomy of an intervertebral disc and describe what is meant by the term ‘disc herniation’(slipped disc)

Answer 3

An intervertebral disc has an outer fibrous annulus fibrosis which is a fibrous ring made of fibrocartilage. It has an inner soft nucleus pulposes. It produces small amounts of movements in all directions. Added together to produce considerable movement.

Disc herniation happens when some of the nucleus pulposes leaks out of the annulus fibrosis. A slipped disc can also compress the spinal cord.