The structures that are not part of the brain stem are:
- a) Cerebral Hemispheres
- d) Cerebellum
- f) Diencephalon
To elaborate, the brain stem is primarily composed of three structures: the midbrain, pons, and medulla oblongata. The cerebral hemispheres are the larger portions of the brain located above the brain stem and are responsible for higher brain functions such as thought and action. The cerebellum, located behind the brain stem, plays a crucial role in coordination and balance. The diencephalon, which includes the thalamus and hypothalamus, is situated above the brain stem but is not considered part of it. Therefore, options a, d, and f are indeed not part of the brain stem.