where is the bottom part organ that you just mentioned, located?
The brainstem is the posterior part of the brain, continuous with the spinal cord
Brainstem
The brainstem (or brain stem) is the posterior part of the brain, continuous with the spinal cord.
several cranial nerves innervate structures of the tongue Called the hypoglossal nerve what are its functions? It provides motor control of the extrinsic muscles of the tongue- genioglossus, hyoglossus, styloglossus, and the intrinsic muscles of the tongue. can you describe its structure? It  arises as a number of small rootlets from the front of the medulla, the bottom part of the brainstem, in the anterolateral sulcus which separates the olive and the pyramid
wiki:11725607
Brainstem [SEP] Introduction
The brainstem (or brain stem) is the posterior part of the brain, continuous with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is continuous with the thalamus of the diencephalon through the tentorial notch, and sometimes the diencephalon is included in the brainstem. The brainstem is a very small component of the brain, making up only around 2.6 percent of its total weight. It has the critical role of regulating cardiac and respiratory function, helping to control heart rate and breathing rate. It also provides the main motor and sensory nerve supply to the face and neck via the cranial nerves.