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The human brain contains 86 billion neurons, with 16 billion neurons in the cerebral cortex. [ 2 ] [ 1 ] Neuron counts constitute an important source of insight on the topic of neuroscience and intelligence : the question of how the evolution of a set of components and parameters (~10 11 neurons, ~10 14 synapses) of a complex system leads to ...
The brain can thus be described as being divided into left and right cerebral hemispheres. Each of these hemispheres has an outer layer of grey matter, the cerebral cortex, that is supported by an inner layer of white matter. In eutherian (placental) mammals, the hemispheres are linked by the corpus callosum, a very large bundle of nerve fibers.
Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), of which there are conventionally considered twelve pairs.Cranial nerves relay information between the brain and parts of the body, primarily to and from regions of the head and neck, including the special senses of vision, taste, smell, and hearing.
The cerebellum consists of three parts, a median and two lateral, which are continuous with each other, and are substantially the same in structure. The median portion is constricted, and is called the vermis, from its annulated appearance which it owes to the transverse ridges and furrows upon it; the lateral expanded portions are named the hemispheres.
The cerebral peduncles (In Latin, ped-means 'foot'.) are the two stalks that attach the cerebrum to the brainstem. [1] They are structures at the front of the midbrain which arise from the ventral pons and contain the large ascending (sensory) and descending (motor) tracts that run to and from the cerebrum from the pons.
The falx cerebelli is a small sickle-shaped fold of dura mater projecting forwards into the posterior cerebellar notch as well as projecting into the vallecula of the cerebellum between the two cerebellar hemispheres.
The falx cerebri is a strong, crescent-shaped sheet of dura mater lying in the sagittal plane between the two cerebral hemispheres. [3] It is one of four dural partitions of the brain along with the falx cerebelli, tentorium cerebelli, and diaphragma sellae; it is formed through invagination of the dura mater into the longitudinal fissure between the cerebral hemispheres.
The corpus callosum has four main parts – individual nerve tracts that connect different parts of the hemispheres. These are the rostrum, the genu, the trunk or body, and the splenium. [4] Fibres from the trunk and the splenium, known together as the tapetum ("carpet"), form the roof of each lateral ventricle. [6]