Essay 6

Do not memorise these answers! These are guidelines. Be creative, devise your own expression and organisation! You can elaborate on the points in your own language.
Remember that there is no 'perfect' answer - a little shortfall in content is easily compensated by presentation.
You should aim at writing an essay in this examination in approximately 20 minutes.

Joints and ligaments of the vertebral column.

The vertebral column forms the central support of the body. In order to allow movements of the trunk the column needs a high degree of mobility. However, the fact that it contains the delicate spinal cord, excessive movement between vertebrae could be dangerous.

Nature has surmounted this by creating joints which give a small degree of movement between adjacent vertebrae, yet the column as a whole has a considerable range of movement. Anatomically this leads to the concept of a motion segment.

The largest joint between the vertebrae is between the bodies. It is a symphysis where a disc of white fibrocartilage is interposed between the bones. The deformability of this tissue allows a small degree of movement. Movements can be those of bending in any one of the directions and even in the form of twisting.

Besides this there are two small, plane synovial joints between the articular processes. These have a slight degree of sliding movements. These movements serve mainly to adjust the parts of vertebrae in their movements. While the thoracic vertebrae have facets which allow some rotation, this movement is largely restricted by the orientation of facets in other regions.

The bodies of vertebrae are also bound together by strong anterior and posterior longitudinal ligaments. interspinous (between adjacent spines) and supraspinous (spanning three or four spines) ligaments hold the spines together. The ligaments between the laminae of vertebrae (ligamenta flava) have a large proportion of elastic fibres.