The brain is the main regulator of all functions of the body, provides the higher nervous activity of a person.
The brain is located in the cerebral part of the skull. The mass of the brain of an adult is about 1400-1500 g.
The brain consists of five divisions:
- midbrain (sometimes another section is distinguished in the midbrain – the bridge, or the pons varoli),
- large hemispheres of the brain.
The most ancient part of the brain is the brain stem, which consists of: the medulla oblongata, pons, midbrain and diencephalon. From here come 12 pairs of cranial nerves, which connect the human brain to the sense organs, muscles and glands, located mainly in the head region.
The medulla oblongata is an extension of the spinal cord. It performs reflex and conductive functions.
The following centers are located in the medulla oblongata:
- cardiac activity;
- unconditioned food reflexes;
- protective reflexes (coughing, sneezing, blinking, tearing);
- centers of changes in the tone of some muscle groups and body position.
The hindbrain consists of the pons varoli and the cerebellum.
The cerebellum plays a major role in the coordination of movements.
The cerebellum receives information from muscles, tendons and motor centers of the cerebral cortex. This allows the cerebellum to control balance, muscle tone and posture.
If the cerebellum is damaged, coordination of movements is impaired, the gait becomes staggering, and the movements of the arms and legs become abrupt.
The midbrain contains nuclei that regulate muscle tension, or muscle tone. Impulses emanating from the nuclei provide the ratio of the tone of the flexor and extensor muscles. Reflex arcs of orienting reflexes to visual and sound stimuli pass through the midbrain. They manifest themselves in turning the head and body towards light or sound stimuli.
The diencephalon includes: the visual hillocks (thalamus), the supra-hillock region (epithalamus), the hypothalamus region (hypothalamus), and the geniculate bodies.
The thalamus is responsible for all types of sensitivity (except olfactory) and coordinates facial expressions, gestures, and other manifestations of emotions. Nerve impulses from all senses (sight, hearing, taste, etc.) pass through the thalamus to the cerebral cortex. Most of the complex movements, such as walking, running, swimming, are associated with the diencephalon. On top of the thalamus is the epiphysis – the endocrine gland. The pineal gland nuclei are involved in the work of the olfactory analyzer. Below is another endocrine gland – the pituitary gland.
The hypothalamus controls the activity of the autonomic nervous system, participates in maintaining an optimal level of metabolism and energy, in thermoregulation, in the regulation of the activity of the digestive, cardiovascular, respiratory and endocrine systems. Under his control are such endocrine glands as the pituitary gland, thyroid gland, sex glands, pancreas, adrenal glands.
The diencephalon contains the subcortical centers of vision and hearing.
The forebrain consists of the right and left hemispheres, connected by the corpus callosum. The gray matter forms the cerebral cortex. The cerebral cortex is formed by gray matter, consisting of the bodies of neurons. The cortex covers the entire forebrain in a thin layer several millimeters thick. White matter forms the pathways of the hemispheres. The nuclei of the gray matter (subcortical structures) are scattered in the white matter.