The brainstem is made up of all unpaired structures that connect the cerebrum with the spinal cord. Most rostral (forward) in the brainstem are structures often collectively referred to as the diencephalon.
The diencephalon is situated between the midbrain of the brainstem and the cerebrum. Sometimes, certain components of the diencephalon are grouped into the brainstem and are discussed as though they are the uppermost part of the brainstem. These structures are the epithalamus, the thalamus, the hypothalamus, and the subthalamus.
Directly beneath the diencephalon is the midbrain (mesencephalon), and beneath the midbrain is the hindbrain where the pons, the medulla oblongata, and the reticular formation can be found. For ease of understanding and clarity, the hindbrain will be discussed in its own module.
In this module, however, we will discuss the characteristics and function of structures within the diencephalon and how they relate to surrounding structures.