Across 2. This is the most caudal region of the spinal cord (do not use spaces) 7. Indentation of the spinal cord located in the front at the midline (do not use spaces) 9. Fibers which cross from one side of the brain or spinal cord to the opposite side are ______ fibers. 11. The dorsal root contains this type of nerve fibers 12. Motor neurons leave the spinal cord through this structure (do not use spaces) 13. This important nerve of the cervical plexus supplies the diaphragm 14. This structure contains dorsal and ventral rootlets and roots of the spinal cord exiting the vertebral column between L2 and S1 (do not use spaces) 15. This is a hole in the center of the spinal cord, lined with ependymal cells and contains CSF (do not use spaces) Down 1. The third cranial nerve is 3. This structure is distal to the spinal nerve and contains both motor and sensory nerve fibers 4. The sciatic nerve comes from this nerve plexus 5. The anterior portion of the grey matter of the spinal cord (do not use spaces) 6. Group of spinal nerve rami which come together to form the nerves which go down the upper extremity. Nerves include the ulnar nerve (do not use spaces) 8. This type of tract carries efferent information from the brain, down the cord, to terminate on a lower motor neuron 10. Three columns of white matter run up and down the spinal cord. Each column is called a
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1. List the 3 spinal meninges and three associated spaces. Next to each, describe its structure. 2. For each of the following structures, indicate which part of which type of neuron is found in the structure. As an example, I have provided an example for the anterior root: - posterior horn - lateral horn - anterior horn - posterior column - lateral column - anterior column - posterior root - anterior root - axons of motor neurons - posterior root ganglion 3. List the 3 types of connective tissues found in nerves and indicate which structure it surrounds. 4. Give a description of each of the following external structures of the spinal cord: - cervical enlargement - lumbar enlargement - cauda equina - conus medullaris - filum terminale 5. List the 4 major plexuses. For each plexus, list the spinal nerves that contribute nerve fibers to the plexus and the major nerves that emerge from the plexus.
Supreeta N.
CNS - Spinal Cord LAB ACTIVITY 9: Neuronal Pathways. Provide the word that best fits each blank. (Word Bank: Contralateral, Corticospinal, Indirect, Medulla oblongata, Primary Motor, Pyramidal, Receptor, Somatosensory, Thalamus, Ventral) Ascending neuronal pathways transmit input from receptors to higher brain centers. These pathways usually consist of three neurons. The first order neuron conducts impulses from the 1) to the central nervous system, where it synapses with the second order neuron. The second order neuron ascends to the 2) , where it synapses with the third order neuron. Third order neuron route impulses to the appropriate area of the 3) cortex. Depending on the pathway, sensory tracts ascend to the cerebral cortex can decussate in the spinal cord or at the level of the medulla oblongata. Tracts that deliver input to the cerebellum lack third order neurons and do not decussate. Descending neuronal pathways transmit motor output from the brain toward peripheral effectors. There are two different types of voluntary descending pathways. The direct pathway, also called the corticospinal pathway, involves only two neurons. The cell body of the upper motor neuron, also called a 4) cell, is located in the 5) cortex. The axon descends within the 6) white matter tract, and synapses with lower motor neuron in the 7) horn of the gray matter. The lower motor neuron extends to peripheral effectors that are under voluntary control, such as skeletal muscles. Axons in the direct motor pathway decussate at the level of the 8) , so the primary motor cortex of each cerebral hemisphere is responsible for fine motor control of the opposite, or 9) side of the body. All other motor pathways, called 10) pathways, consist of more than two neurons and involve input from motor nuclei within the brain. These pathways are responsible for control of posture and coarse movements of the limbs.
Sri K.
CNS – Spinal Cord LAB ACTIVITY 9: Neuronal Pathways. Provide the word that best fits each blank. (Word Bank: Contralateral, Corticospinal, Indirect, Medulla oblongata, Primary Motor, Pyramidal, Receptor, Somatosensory, Thalamus, Ventral) Ascending neuronal pathways transmit input from receptors to higher brain centers. These pathways usually consist of three neurons. The first order neuron conducts impulses from the 1) ———————— to the central nervous system, where it synapses with the second order neuron. The second order neuron ascends to the 2) ————————, where it synapses with the third order neuron. Third order neuron route impulses to the appropriate area of the 3) ———————— cortex. Depending on the pathway, sensory tracts ascend to the cerebral cortex can decussate in the spinal cord or at the level of the medulla oblongata. Tracts that deliver input to the cerebellum lack third order neurons and do not decussate. Descending neuronal pathways transmit motor output from the brain toward peripheral effectors. There are two different types of voluntary descending pathways. The direct pathway, also called the corticospinal pathway, involves only two neurons. The cell body of the upper motor neuron, also called a 4) ———————— cell, is located in the 5) ———————— cortex. The axon descends within the 6) ———————— white matter tract, and synapses with lower motor neuron in the 7) ———————— horn of the gray matter. The lower motor neuron extends to peripheral effectors that are under voluntary control, such as skeletal muscles. Axons in the direct motor pathway decussate at the level of the 8) ————————, so the primary motor cortex of each cerebral hemisphere is responsible for fine motor control of the opposite, or 9) ———————— side of the body. All other motor pathways, called 10) ———————— pathways, consist of more than two neurons and involve input from motor nuclei within the brain. These pathways are responsible for control of posture and coarse movements of the limbs.
Madhur L.
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