Almost all sensory info from the physical segments of the body enters the medulla spinalis through the dorsal roots of the spinal nerves. However, from the entry purpose into the twine and so to the brain, the sensory signals ar carried through one amongst 2 different sensory pathways: (1) the dorsal column–medial lemniscal system or (2) the anterolateral system. These two systems return along partly at the extent of the neural structure. The dorsal column–medial lemniscal system, as its name implies, carries signals upward to the medulla of the brain chiefly within the dorsal columns of the twine.
Then, when the signals colligation and cross to the other facet within the medulla, they continue upward through the brain stem to the neural structure by manner of the medial lemniscus. Conversely, signals within the anterolateral system, immediately when getting into the medulla spinalis from the dorsal nervus roots, colligation within the dorsal horns of the spinal nerve tissue, then cross to the other facet of the twine and ascend through the anterior and lateral white columns of the twine. They terminate at all levels of the lower brain stem and within the thalamus. The dorsal column–medial lemniscal system consists of huge, fat nerve fibers that transmit signals to the brain at velocities of thirty to one hundred ten m/sec, whereas the anterolateral system consists of smaller fat fibers that transmit signals at velocities starting from some meters per second up to 40 m/sec. Another distinction between the 2 systems is that the dorsal column–medial lemniscal system contains a high degree of spatial orientation of the nerve fibers with relevancy their origin, whereas the anterolateral system has a lot of less spatial orientation.
These differences right away characterize the kinds of sensory info which will be transmitted by the two systems. That is, sensory info that has to be transmitted apace and with temporal and spatial fidelity is transmitted chiefly within the dorsal column–medial lemniscal system; that that doesn’t need to be transmitted apace or with nice spatial fidelity is transmitted chiefly within the anterolateral system. The anterolateral system contains a special capability that the dorsal system doesn’t have: the power to transmit a broad spectrum of sensory modalities— pain, warmth, cold, and crude tactile sensations; The dorsal system is proscribed to distinct styles of mechanoreceptive sensations. With this differentiation in mind, we can now list the kinds of sensations transmitted within the 2 systems.