A cross section of the lower part of the pons showing the pontine<unk>  labeled as #9 The human<unk>  is composed of almost 100 brain nuclei and contains many projections into the forebrain, brainstem, and cerebellum, among other regions. It includes the<unk>  nuclei, reticulothalamic projection fibers, diffuse thalamocortical projections, ascending cholinergic projections, descending non-cholinergic projections, and descending reticulospinal projections. The<unk>  also contains two major neural subsystems, the ascending<unk>  activating system and descending reticulospinal tracts, which mediate distinct cognitive and physiological processes. It has been functionally cleaved both sagittally and coronally. Traditionally the<unk>  nuclei are divided into three columns: * In the median column – the raphe nuclei * In the medial column – gigantocellular nuclei (because of larger size of the cells) * In the lateral column – parvocellular nuclei (because of smaller size of the cells) The original functional differentiation was a division of caudal and rostral. This was based upon the observation that the lesioning of the rostral<unk>  induces a hypersomnia in the cat brain. In contrast, lesioning of the more caudal portion of the<unk>  produces insomnia in cats. This study has led to the idea that the caudal portion inhibits the rostral portion of the<unk> . Sagittal division reveals more morphological distinctions. The raphe nuclei form a ridge in the middle of the<unk> , and, directly to its periphery, there is a division called the medial<unk> . The medial<unk>  is large and has long ascending and descending fibers, and is surrounded by the lateral<unk> . The lateral<unk>  is close to the motor nuclei of the cranial nerves, and mostly mediates their function. Medial and lateral<unk>  The medial<unk>  and lateral<unk>  are two columns of nuclei with ill-defined boundaries that send projections through the medulla and into the midbrain. The nuclei can be differentiated by function, cell type, and projections of efferent or afferent nerves. Moving caudally from the rostral midbrain, at the site of the rostral pons and the midbrain, the medial<unk>  becomes less prominent, and the lateral<unk>  becomes more prominent. Existing on the sides of the medial<unk>  is its lateral cousin, which is particularly pronounced in the rostral medulla and caudal pons. Out from this area spring the cranial nerves, including the very important vagus nerve. The lateral<unk>  is known for its ganglions and areas of interneurons around the cranial nerves, which serve to mediate their characteristic reflexes and functions.
Reticular formation
Moist desquamation
Craterization
Hyperkeratinization
Organ gifting
Desquamation
Glomerulation
Tissue expansion