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Neuro-Sens. Pathways
Somatosensory Pathways
| Question | Answer |
|---|---|
| Modalities | Touch, propioception, pain, temperature and vibration |
| 5 purposes of Somatosensory System | 1. Recognize objects by touch 2. Manipulate objects with accuracy 3. Monitor and control movement 4. Sense and prevent damage 5. Provide efficiency and flexibility in movement |
| 3 Components of Skilled Movement | 1. Efficiency 2. Flexibility 3. Accuracy |
| Efficiency | Being able to accomplish a task without focusing all attention on that task |
| Flexibility | Being able to sense differences and changes in the environment |
| Accuracy | Completing the task correctly |
| The AP generated by mechanosensory stimuli are transmitted to teh spinal cord by afferent sensory neurons that travel in ____________ | peripheral nerves |
| All modalities are carried by the ___________ peripheral nerve | same |
| Large myelinated axons innervate | low-threshold mechanoreceptors from large ganglion cells |
| Small axons innervate | high-threshold receptors (pain/temp) from smaller ganglion cells |
| DC-ML 1st Order Neurons | Large and myelinated |
| Anterolateral (spinothalamic) 1st Order Neurons | small, unmyelinated or thinly myelinated or myelinated |
| Spinocerebellar 1st Order Neurons | Large and myelinated |
| DC-ML Carries | fine touch discrimination, active touch, joint position (propioception) and vibration |
| DC-ML ascends | ipsilaterally in teh dorsal columns |
| Gracile tract | more medial, represents lower extremity touch, propioception and vibration |
| Cunate tract | more lateral, represents trunk, UE and neck touch, propioception and vibration |
| DC-ML 1st Order Neurons project to | Medulla |
| DC-ML first order neurons synapse with the 2nd Order Neurons in the | Gracile and cuneate nuclei |
| DC-ML 2nd Order Neurons | Form internal arcuate tract |
| Internal arcuate axons (DC-ML 2nd order) decussate in the ___________ | caudal medulla |
| DC-ML 2nd order neurons synapse with 3rd order in _________ | VPL |
| DC-ML axons from VPL project to ______ | somatosensory cortex (layer IV) |
| Location of primary somatosensory cortex (SI) | postcentral gyrus of parietal lob |
| Brodmann's areas included in SI | 3a, 3b, 1 and 2 |
| 3a | propioception |
| 3b and 1 | cutaneous stimuli |
| 2 | propioception and cutaneous stimuli |
| Somatosensory information projects from S1 to ______________ and ____________ | higher-order cortical fields, subcortical structures |
| Higher order cortical regions that S1 projects to | S2, amygdala, hippocampus, and motor control areas |
| S1 descending pathways may | modulate ascending sensory information |
| Spinothalamic tract carries: | Pain, temperature and crude touch |
| Spinothalamic tract 1st order neurons synapse with 2nd order in the _________ | ipsilateral dorsal hord of the spinal cord |
| Spinothalamic 2nd order neurons decussate _____ | at the level of entry into the spinal cord |
| The spinothalmic tract 2nd order neurons ascend | in the anterolateral quadrant of the contralateral spinal cord |
| Spinothalmic tract 2nd order neuron synapses on the | VPL through both direct and indirect paths |
| Spinothalamic 3rd order nerves terminate in | S1 |
| Brown-Sequard Syndrome | A hemisection of the spinal cord that resutls in loss of pain, temperature and crude touch on the contralateral side and loss of fine descrimination, active touch, propioception and vibration on the ipsilateral side |
| Dermatomes | area of skin innervated b the nerve fibers comprising a dorsal root |
| Trigeminal Somatic Sensory System | conveys somatosensory information from the face |
| 1st order neurons for Trigeminal somatic sensory system | Trigeminal nerver (cranial nerve V) |
| Trigeminal nerve enters brain at _________-- | the level of the pons |
| Trigeminal nerve synapses on the | trigeminal brainstem complex |
| Two major components of the trigeminal brainstem complex | Principal nucleus and Spinal nucleus |
| Analogous to DCML for face (carries tactile and propioceptive stimuli) | principal nucleus of trigeminal system |
| Analogous to Spinothalamic for face (painful and thermal stimuli) | Spinal nucleus of trigeminal system |
| Trigeminal 2nd order neurons deccussate in the ___- | pons |
| Trigeminal 2nd order neurons terminate on | VML |
| Trigeminal 3rd order neurons project to ) | S1 (layer IV |
| Spinocerebellar pathways | carry somatosensory information from the spinal cord to the cerebellum via direct and indirect pathways |
| Spinocerebellar pathways provide | joint and muscle propioception from the body (especially the legs) and different versions of the changing state of the body and its environment for comparison |
| Spinocerebellar pathway orginates | from internneurons in te spinal grey matter |
| Spinocerebellar pathway nerves terminate as __________- | mossy fibers in teh vermis or intermediate cortex of the cerebellum |
| Ventral spinocerebellar pathway | carries internally generated information about the central locomotor rhythm |
| Dorsal spinocerebellar pathway | provides the cerebellar with sensory beedback during evolving movements (propioception) |
| Dysmetria | impaired ability to judge distance or range of movement |
| Ataxia | uncoordinated movement, loss of order of joint motions |
Created by:
aglade
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