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Date: 28. November 2017
Introduction of the Ascending Tracts
In this lecture the educator explains about the Ascending Tracts. The educator has divided the lecture in 5 sections. In first section she explains about the introduction of the Ascending Tracts, Anatomic Organization and Functions of Ascending Tract. The ascending tracts refers to the neural pathways by which sensory information from the peripheral nerves is transmitted to the cerebral cortex.
The Ascending tracts are also known as Somatosensory Pathways or systems.
The General information from peripheral sensory endings is conducted through series of neurons. In the First Order Neuron, its cell bodies lie in posterior root ganglion of spinal nerve. Central process enters the spinal cord in the posterior root to synapse with second order neuron. The Second Order Neuron give rise to an axon that decussate ascend to higher level of CNS where it synapses with Third Order Neuron. In Third Order Neuron thalamus is present that give rise to projection fibres that passes to sensory region of the Cerebral Cortex.Then the functions of Ascending tracts were discussed.
In section two the educator explains about the Spinothalamic Tracts. That involves Lateral Spinothalamic Tract, Spinal Lemniscus and Anterior Lemniscus Tract. Lateral Spinothalamic Tract consists of Receptors, First Order Neuron, Second Order Neurons Spinal Lemniscus and Third Order Neurons.
Where Anterior Spinothalamic Tract consists of Light Crude Touch and Pressure Pathway that has First Order Neuron, Second Order Neurons, Spinal Lemniscus and Third Order Neurons.
Fasciculi Gracilise and Cuneatus
In section three the educator briefs about Fasciculi Gracilise and Cuneatus, and Medial Lemniscus. In First Order Neuron the Fibers enter in posterior Root Ganglion, the posterior white column of spinal cord divides into Long Ascending and Short Descending branches.
In Second Order Neuron the Axons which are called Internal Arcuate Fibers, sweep anteromedially around central gray matter. Third Order Neurons have Synapse, VPN of thalamus and Axons.
The section four includes Spinocerebellar Tract. There are two types of tracts i.e. Anterior Spinocerebellar Tract and Posterior Spinocerebellar Tract. In Anterior Spinocerebellar Tract the Muscle Joint Sense Pathway has First Order Neuron, Posterior root ganglion, posterior Gray column, Synapse on second order neuron. Second Order Neuron that is also called Nucleus Dorsalis or Clarks Column.
Other Ascending Pathways
Spinotectal Tract, Spinoreticular Tract and Spino-olivary Tract are included in section five. Spinotectal Tract has got two order neurons. First order Neuron has the axons that enter posterior root ganglion. In Second Order Neuron the axons cross median plane.
Spinoreticular Tract has got two order neurons. First order Neuron has the axons that enter posterior root ganglion. In Second Order Neuron the axons ascend in lateral white column with Lateral Spinothalamic tract and in Spino-olivary Tract there are three order neurons. In First Order Neuron the axons enter posterior root ganglion. In Second Order Neuron the axons are cross the mid line and in Third Order Neuron the axons end by synapsing with the neurons in Inferior olivary nucleus in Medulla Oblongata.