The midbrain (mesencephalon) is one of the structures of the brain stem. It distinguish the roof at the back, or dorsal pover x NOSTA, and brain stem, lying at the front, or ventral, n of surface. The roof of the midbrain (tectum) is a plate on which there are four hillocks (quadrochromium) – two upper, or front, and two lower, or rear. They contain the kernel of gray vesch e -OPERATION through which visual and auditory pathways Port and nyayutsya with extrapyramidal system. The legs of the brain consist of the base of the legs of the brain and the tire, or tegmentum, of the midbrain. On the border , I wait for them to lie black substance Or the substantia nigra (front or ventral part of it – is reticular or mesh, the part consisting of the pigment-containing fibers and clusters not diffusely located minutes tron and dorsal – compact part, consisting of neurons, containing a boiling pigment). The neurons of the substantia nigra are dopaminergic and their axons reach the basal ganglia and the cerebral cortex. As a part of the midbrain are conductive (upward and downward I boiling) way, as well as the number of nuclear structures, ie. e. clusters of neurons that enforce conduction, sensory, vegetati in hydrochloric and motor functions of the midbrain. They also provide for the realization of important biological reactions – an orientation and a stop on the chewing reflex . In particular, superior colliculus organize orientation reflexes to visual stimuli, including zra h kovy reflex and eye and rotation of the trunk to the light source. Neither w of bumps carried indicative reflexes auditory irritation and life – turning the head and body to the source of sound, the alarm of the ears. The watchdog reflex manifests itself in an increase in the tone of the flexor muscles and a decrease in the tone of the extensor muscles with a sudden impact on the organization of a sound or light stimulus. This prepares org and nism to implement escape from the stimulus (passive oboronitel s ny reflex) or acts counter irritant (active defenses and Tel’nykh reflex). When people abuse watchdog reflex m not about Jette quickly switch from one movement to another.
Through the midbrain are rising all the way to the overlying of t the brain works: the thalamus, a large brain and cerebellum, as well as the downstream path (pyramidal pathway) providing introducer function Wed forth his brain. The sensory functions of the midbrain are associated with the activity of the nuclei of the quadrilateral. Superior colliculus is a primary subcortical about vym center of the visual analyzer (together with the lateral geniculate s E diencephalon bodies), lower – auditory (together with media s GOVERNMENTAL geniculate bodies diencephalon). The upper hillocks Th t veroholmiya processing occurs sensory information received th conductive fibers of the optic nerve from the retina, which then Lane e is given to the lateral geniculate body, and from it – in the visual cortex. In the lower colliculus information is processed by fonoretse n tori. Motor functions are realized by the neurons of oculomotor nerve motor nuclei, neurons quadrigemina, red nucleus and Th p hydrochloric substance.
As noted above, in the medulla oblongata, in the bridge and in the midbrain, neurons of the reticular formation are contained . Some of these cores pre d assigned to the regulation of motor activity, and some – for the regulation of autonomic functions, including those of the respiratory, cardiovascular, digestive and other systems). Certain structures of the brainstem reticular formation are components of sensory systems that provide a non-specific sensory flow, through which the activation of the cerebral cortex occurs. In this regard, it is customary to talk about the downward and upward influence of the ret and kulyarnoy formation. The downward impact of the reticular formation proya in It is involved in the regulation of the activity of spinal cord and brainstem motoneurons, and thus in the control of movement. Pedigree influence – it is part of the reticular formation in the processing of sensory information r mation and in the activities of activating brain systems.
Under the reticular formation is generally understood L cell mass e zhaschuyu in brainstem thicker lower sections of the elongated until the diencephalon. This cell mass is poorly structured, has no clear boundaries, inside the reticular formation there are interspersed feelings and body and motor nuclei of the medulla oblongus, median and diencephalon. The neurons of the reticular formation are characterized by few long, straight and little – branching dendrites, the spines of which are poorly differentiated, without thickening at the ends. In the medial part of the reticular formation are the so-called large and giant cells. In the medulla, they are concentrated in giga n tokeletal nucleus. It is from these cells and extend axons to form efferent pathways, in particular, reticulospinal path towards Tal and Musa, cerebellum, basal ganglia, cerebral cortex. Susches t exist two kinds of influences the ascending reticular formation – the asset and ruyuschee (forebrain to maintain the active state) and then p bremsstrahlung. Ascending reticular effects on the cortex are tonic and cancer, increasing the level of excitability of cortical neurons, without fundamentally changing the nature of their responses to specific signals. Since the asset and the reticular formation tion available from a variety of news sources and the Cove and its rising influence spread to vast areas to of ry, the obvious role of this structure in the orientation reaction and IU Well touch interaction. According to modern concepts, the reticulo p naya formation of the brain stem is part of the so-called ascending nonspecific system, which includes and nespets and features e skie nucleus of the thalamus, the front frontal lobe and caudate nucleus.