Term
What is another name for motor fibers and sensory fibers? |
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Definition
Afferent and Efferent Afferent (sensory) General somatic afferent General visceral afferent efferent (motor) General Somatic Efferent Genreal visceral efferent |
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Term
| Where do somatic fibers travel to? |
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Definition
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Term
What do you call a nerve fiber that is: 1. sensory and travels to the body wall 2. Sensory and travels to the viscera 3. Motor and travels to the body wall 4. Motor and travels to the viscera |
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Definition
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Term
| With respect to somatotropic organization, explain how the motor cell bodies are organized in the ventral horns the spinal cord gray matter. |
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Definition
The flexors are more dorsal, the extensors are more vental. The trunk and shoulder are more medial while the hands and fingers are more lateral. |
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Term
What horns of the spinal cord do the sensory fibers enter? Where do the motor fibers exit? The autonomic fibers? |
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Definition
Sensory fibers- dorsal horn Motor fibers- ventral horn Autonomic- originate in the intermediolateral and excit via the ventral horn. |
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Term
| Compare and contrast gray matter of the spinal cord with white matter. |
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Definition
The gray matter has cell bodies for GSA, GVA, GSE, and GVE. It contains somatotropic organization. The white matter has both sensory and motor fibers traveling between the brain and peripheral nervous system (spinothalamic, dorsal column, and corticospinal). |
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Term
| Name the three basic tracts of spinal cord white matter. |
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Definition
1. Spinothalamic (ascending-sensory) 2. Dorsal Column (ascending-sensory) 3. Corticospinal (descending-motor) |
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Term
| Sensory input to the cerebral cortex involves how many neurons? |
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Definition
The spinal cord ascending tracts involve three neurons |
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Term
| In the cases of pain and temperature sensation, where are the primary neurons located? What is their origin? |
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Definition
The primary neurons for pain and temperature are located outside of the spinal cord in the dorsal root ganglion. These cells originate from neural crest cells. FYI: The impulse then synapses with secondary neurons in the dorsal horn on the ipsilateral side of the pain sensation. The nerve impulse then crosses over to the contralateral side and ascends the spinal cord via the spinothalamic tract. It then synapses with the tertiary neurons in the thalamus before traveling to the contralateral side of the cerebral cortex. |
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Term
| In the cases of pain and temperature sensation, where are the secondary neurons located? |
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Definition
They are located in the dorsal horn on the ipsilateral side of the pain sensation. The nerve impulse then crosses over to the contralateral side and ascends the spinal cord via the spinothalamic tract. |
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Term
| If you burn your left hand on the stove, what side of the cerebral cortex recieves that information. Trace the pathway. |
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Definition
1. The GSA fibers sense the pain and send a signal towards the spinal cord. 2. Signal synapses in the primary neurons in the dorsal root ganglion. 3. The signal enters the dorsal horn of the spinal cord and immediately synapses with the secondary neurons on the left side (ipsilateral) of the spinal cord. 4. The signal then crosses over to the contralateral side of the spine where it travels up the spinothalamic tract. 5. The signal then travels up to the thalamus where it synapses with tertiary neurons and is routed to the right (contralateral) side of the cerebral cortex! |
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Term
| In the case of proprioception, where are the three neurons located? |
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Definition
1. primary- dorsal root ganglia 2. Secondary- medulla 3. tertiary- thalamus |
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Term
Without looking, you know your holding up two fingers on your right hand. What sense is this and trace its path up to the cerebral cortex. |
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Definition
PROPRIOCEPTION 1. GSA fibers sense the position of the two fingers on your right hand and send a signal towards the spinal cord. 2. The signal synapses first in the dorsal root ganglia (as always and remember neural crest cells!) 3. The signal enters the dorsal root of the spinal cord and immediately ascends to the medulla via the ipsilateral dorsal column. 4. In the medulla, it synapses with its secondary neurons and crosses over to the contralateral side before traveling up to the thalamus via the medial lemniscus! 5. The signal finally synapses with its tertiary neurons in the thalamus before entering the cerebral cortex on the left (contralateral) side. (remember signal originated in you right hand) |
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Term
| How many neurons are in the motor pathway? How about the sensory pathway? |
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Definition
The motor pathway has Two (2) neurons The sensory has three! |
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Term
| Where are upper motor neurons (UMNs) located? |
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Definition
UMNs are located in the cerebral cortex, cerebellum, or basal ganglia. |
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Term
| Where is the primary motor area located? |
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Definition
| In the precentral gyrus (Brodmann's area) of the cerebral cortex. |
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Term
| You want to move you right hand, discuss the pathway of that signal starting in the cerebral cortex. |
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Definition
1. Start in the left primary motor area, known as the precentral gyrus (Brodmann's Area) 2. The fibers cross over to the contralateral side at the junction of the brainstem and spinal cord (The Medulla Oblongata), in an area known as the pyramidal decussation. 3. It then travels down the contralateral side of the spinal cord via the corticospinal tract. 4. The signal synapses in the lower motor neuron. |
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Term
| Why is the central sulcus such an important landmark on the brain? |
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Definition
| It separates the precentral gyrus (MOTOR) from the postcentral gyrus (SENSORY) |
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Term
| In the postcentral gyrus, what is the somatotopic organization? (humunculus) |
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Definition
From the top, midline of the brain to the bottom it goes: Toes-->knee-->hip-->trunk ----------------------------------------------------- Shoulder->arm->elbow->wrist->hand->fingers ----------------------------------------------------- Neck->brow->eye->face->LIPS->jaw->TONGUE |
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Term
| If there was a lesion in the anterior white comissure at one vertebral level, what would be affected? |
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Definition
| According to Babler, not much would be affected because more than one peripheral nerve makes up a spinal nerve. If you cut at only one level then other peripheral nerves will make up for it. |
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Term
| Where is pain first perceived? |
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Definition
The thalamus is the first area to perceive pain. The cerebral cortex is usually the place where senses are perceived, it involved with pain localization. |
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Term
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Definition
| It is the precentral gyrus (motor) area of the brain |
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