Nociceptive sensation. Somatic sensory analyzer
Also different changes in human organism followed by pain are observed: increase of muscle tone, accelerated heartbeat, increase of blood pressure, intensification of sweating, dilatation of pupils and elevation of glucose and cuprum level in plasma, activation of hemostasis. It considered to cause the majority of both visceral and biochemical reactions by excitation of sympathetic nervous system, which is presented by neurons of hypothalamus, hypophisis and cells in medullar substance of adrenal glands.
Afferent nociceptive impulses are collected into central nervous system by two kinds of nervous fibers: quick a-delta myelinated nerve fibers and C-fibers without myelin. The ascending fibers are included in spinothalamic tract, which passes through the spinal cord and reach medulla oblongata. Here there are second order sensory neurons of spinomesencephalic tract. Fibers of spinothalamic tract synapse with third-order neurons in the thalamus, which in turn project to the postcentral gyrus of the contralateral cerebral hemisphere.
Location of pathway terminations video