1. Label and discuss the motor pathway from the cortex to the muscles. Define and distinguish upper motor neurons from lower motor neurons. 2. Illustrate the divisions of the Autonomic Nervous System; include the general visceral afferents and general visceral efferent.
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I will address each question separately. **Question 1: Label and discuss the motor pathway from the cortex to the muscles. Define and distinguish upper motor neurons from lower motor neurons.** **Motor Pathway from Cortex to Muscles:** The primary motor pathway Show more…
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NERVOUS SYSTEM HOMEWORK SPINAL NERVE TRACTS: Neurons carry impulses from the brain to the appropriate spinal nerve, then to the effector by way of motor tracts. There are a number of motor tracts, both voluntary and involuntary. The voluntary motor path to skeletal muscles is called the pyramidal system (named for the pyramidal cells of the motor cortex). One of the most common pyramidal system tracts, and the one you are responsible for knowing, is the corticospinal tract. The name describes the path from the motor cortex to the spinal cord and nerves. Neurons that carry impulses from receptors within the body, up the spinal cord, to the brain do so by means of sensory pathways. There are several sensory pathways depending on the type of stimulus involved, region of the spinal cord that the neurons travel, or the ultimate destination of the path. You will be learning a general sensory pathway that incorporates a couple of these specific tracts. 1. General Motor Tract: Review the corticospinal tract presented in the text. Study the basic format and the example provided below. This tract is the same for all of the motor tracings you are responsible for. Variations only occur at the appropriate ramus, appropriate plexus, appropriate spinal nerve, and appropriate skeletal muscle. FORMAT: Motor Cortex of cerebrum -> Internal Capsule -> Mesencephalon -> Pons -> Medulla -> Anterior Horn (synapse) -> Anterior Root -> Exit appropriate ramus -> Appropriate plexus -> Appropriate Spinal Nerve(s) -> Muscle(synapse) 2. General Sensation Tracts: Review the general sensory tract presented in the text. Study the basic format and the example provided below. This tract is the same for all of the sensory tracings you are responsible for. Variations only occur at the appropriate receptor, appropriate spinal nerve, appropriate plexus, and appropriate ramus. FORMAT: Specific receptor -> Appropriate spinal nerve(s) -> Appropriate plexus (if needed) -> Enters appropriate ramus -> Dorsal Root Ganglion -> Dorsal Root -> Dorsal Horn (Synapse) -> Thalamus (Synapse) -> Internal Capsule -> Appropriate Sensory Cortex (Cerebrum) 3. Sensory and Motor Tracings: Review the sensory and motor tracings presented and complete the following tracings. Remember that specific receptors (chemoreceptors, proprioceptors, nociceptors, thermoreceptors, photoreceptors, mechanoreceptors), effectors, nerves, plexuses, or rami will vary depending on the specific example studied. a) You step barefoot on hot sand. Trace the sensory message of pain from the receptor on the bottom of your foot to the appropriate sensory cortex. Include the specific nerves. b) Your friend is massaging your back with deep pressure. Trace the sensory message of pressure from the receptor on your back to the appropriate sensory cortex. c) While hanging a picture on the wall, the hammer slips and you hit your thumb. You experience a great deal of pain. 1) Using the general sensation tract, trace the sensory pathway from the appropriate receptor to the brain. Include the specific nerves. 2) Now trace the motor pathway from the brain to the wrist extensors to move your thumb away from the hammer. d) In order to perform bicep curls, you must flex the anterior flexor muscles of your arm. Trace the motor pathway from the brain to the appropriate muscles.
Adi S.
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.
Spinal Nerve Tracts: Neurons carry impulses from the brain to the appropriate spinal nerve, then to the effector by way of motor tracts. There are a number of motor tracts, both voluntary and involuntary. The voluntary motor path to skeletal muscles is called the pyramidal system (named for the pyramidal cells of the motor cortex). One of the most common pyramidal system tracts, and the one you are responsible for knowing, is the corticospinal tract. The name describes the path from the motor cortex to the spinal cord and nerves. Neurons that carry impulses from receptors within the body, up the spinal cord, to the brain do so by means of sensory pathways. There are several sensory pathways depending on the type of stimulus involved, region of the spinal cord that the neurons travel, or the ultimate destination of the path. You will be learning a general sensory pathway that incorporates a couple of these specific tracts.
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