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The first-order neuron is a pseudounipolar neuron (shown left), with a single axon originating from the cell body then splitting into two branches. The body is situated in the dorsal root ganglion, with one axon traveling peripherally to tissue, and one traveling into the dorsal column.
The dorsal column nuclei each have an associated nerve tract in the spinal cord, the gracile fasciculus and the cuneate fasciculus, together forming the dorsal columns. Both dorsal column nuclei contain synapses from afferent nerve fibers that have travelled in the spinal cord. [2] They then send on second-order neurons of the dorsal column ...
The dorsal column nuclei are responsible for fine touch, vibration, proprioception and two-point discrimination. The fibers of this decussation are called the internal arcuate fibers and are found at the superior aspect of the closed medulla oblongata, superior to the motor decussation. Neurons of these nuclei are second-order neurons in the ...
The ventral trigeminal tract - consists of second-order axons from the spinal trigeminal nucleus. These fibers cross the midline and ascend to the contralateral thalamus. The dorsal trigeminal tract - consists of second-order axons from the principal sensory nucleus of trigeminal nerve. These fibers do not cross the midline, and ascend to the ...
Glutamate and acetylcholine pathways from mesopontine ... Dorsal column–medial lemniscus pathway. Gracile fasciculus; ... Central gray and dorsal and ventral nuclei ...
All of these neurons are sensory (first order, or primary) and have their cell bodies in the dorsal root ganglia. They pass through Rexed laminae layers I-VI of the posterior grey column (dorsal horn) to form synapses with second order or secondary neurons in layer VII just beneath the dorsal horn.
The cutaneous receptors of the skin project in an orderly fashion to the spinal cord, and from there, via different afferent pathways (dorsal column-medial lemniscus tract and spinothalamic tract), to the ventral posterior nucleus of the thalamus and the primary somatosensory cortex. Again, adjacent areas on the skin are represented by adjacent ...
The first-order neuron is a type of pseudounipolar neuron and always has its cell body in the dorsal root ganglion of the spinal nerve with a peripheral axon innervating touch mechanoreceptors and a central axon synapsing on the second-order neuron. If the somatosensory pathway is in parts of the head or neck not covered by the cervical nerves ...