Origin, Structure and Functions of the Cranial Nerves and All Parts of the Brain
Objectives:
By the end of this section, the student will be able to:
- Relate the different stages of development to the adult structures of the central nervous system
- Locate regions of the cerebral cortex by common anatomical landmarks
- Relate the structures of the CNS with their functions
- Describe the protective coverings of the CNS and how they protect the brain and spinal cord
- Explain the blood-brain barrier and how the blood and cerebrospinal fluid nourish and protect the brain
- Explain the expansion of the ventricular system of the adult brain from the central canal of the neural tube
- Describe the connections of the diencephalon and cerebellum on the basis of patterns of embryonic development
- Understand the blood circulation to the brain is provided by two pathways into a loop called the Circle of Willis
The brain is a complex organ composed of gray parts and white matter, which can be hard to distinguish. Starting from an embryologic perspective allows you to understand more easily how the parts relate to each other. The embryonic nervous system begins as a very simple structure—essentially just a straight line, which then gets increasingly complex. Looking at the development of the nervous system with a couple of early snapshots makes it easier to understand the whole complex system. By following the developmental pattern, it is possible to learn what the major regions of the nervous system are, their locations and functions. There is a physiological concept known as localization of function that states that certain structures are specifically responsible for prescribed functions. It is an underlying concept in all of anatomy and physiology, but the nervous system illustrates the concept very well.
Figure 1. Gray Matter and White Matter. A brain removed during an autopsy, with a partial section removed, shows white matter surrounded by gray matter on the surface. Gray matter makes up the outer layer or cortex of the brain.
(credit: modification of work by "Suseno"/Wikimedia Commons)
