WEEK 2: SPINAL CORD, SPINAL NERVES, SENSORY PATHWAY Flashcards
State the 2 main spinal tracts.
1.Ascending and descending tracts
(Sensory or motor tracts)
State the functions of 1st, 2nd and 3rd order neurons in the ascending pathway.
1.They deliver the sensations to the CNS, their cell body is in the dorsal or cranial root ganglion.
2.They are interneurons with the cell body in the spinal cord.
3.Transmit information to the cerebral cortex.
State the 3 major sensory tracts.
*Posterior column
2.Spinothalamic pathway
3.Spinocerebellar pathway.
What is the other name for the posterior column?
Describe the 2 types of the posterior column.
Dorsal column or the medial lemniscus pathway
1.Fasciculus Gracilis: Carry sensations for touch, pressure and vibration below T6. (Medially)
2.Fasciculus cuneatus: Carry sensations for touch, pressure and vibrations from above T6. (Laterally)
3.Nucleus Gracilis and cuneatus on the medulla, decussation happens here, the second order neuron joins the medial lemniscus pathway.
4.Ventral Posteriorolateral nucleus of the thalamus
5.Third order neuron takes impulse to the cerebral cortex.
Describe the 2 types of spinothalamic pathway.
1.Lateral spinothalamic pathway: Temperature and pain
2.Anterior spinothalamic pathway: crude touch and pressure
3.There is synapse of the first and second order at the dorsal gray horn.
4.The lateral decussates to the lateral funiculus after synapse while the anterior decussates to the anterior funiculus after decussates.
5.The two ascends to the ventral posterior lateral nucleus of the thalamus where the third order synapses and proceeds to the cerebral cortex.
Describe the 2 types of spinocerebellar tract.
1.Anterior and posterior spinocerebellar tracts.
2.They are both carry sensory information from the lower limbs.
3
*The posterior spinocerebellar tract conveys sensory information from the muscle spindles, Golgi tendon organs, about the muscle tone of synergistic muscles, strength and speed of movement from the lower extremities.
*The anterior spinocerebellar tract appears to relay information regarding their status (posture) during their movement.
POSTERIOR SPINOCEREBELLAR TRACT.
*The fibers originate from the posterior grey horn, travel posterolaterally through the white matter without decussating and project onto the cerebellar cortex by passing through the inferior cerebellar peduncle.
ANTERIOR SPINOCEREBELLAR TRACT
*The first order neuron is localized in the spinal ganglion. Its axon reaches the posterior horn through the posterior root and synapses with the second-order neurons.
*Their fibers immediately cross at the same level of the spinal cord through anterior commissural fibers and ascend contralaterally along the anterolateral funiculus.
*The majority of fibers from the second-order neurons reach the contralateral cerebellum by passing through the superior cerebellar peduncle and medullary velum.
*The fibers then cross over again, ending up in the ipsilateral cerebellar cortex.
State the 2 spinocerebellar tracts that carry proprioceptive information from the upper limbs and neck.
They are the upper extremity homologs of the posterior/dorsal and the anterior/ventral spinocerebellar tracts, respectively.
The Cuneocerebellar and Rostral spinocerebellar tracts
