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Med Neuro2 Lect1
Med Neuro2 Lect1 Central Somato Sensory
| Question | Answer |
|---|---|
| Review: What all is contained within the Dorsal Spinal tract? fiber types? where to they synapse in the brainstem? decussation point? target in the thalamus? | 1.large, encapuslated cutaneous neurons ascend in the fasciculus gracilis (< T6) & the fasciculus cuneatus (> T5). 2.Synapse their respective nuclei in dorsal medulla, 3.Decussate in internal arcuate fibers. 4.Ascend to VPL thalamus via medial lamnisc |
| What is carried on the Dorsal Spinocerebellar Tract? | Type I fibers carrying info from muscle spindles and GTOs ONLY from lower extremities T6 and below |
| Somatotopy of Dorsal spinal tract? of Anterolateral system? | DORSAL: 1.Medial: Feet/sacral. 2.Lateral: Arms/cervical. ALS: 1.Medial: Arms/cervical. 2.Laterla: Feet/sacral. |
| Within the Ventroposterior Lateral (VPL) Thalamus, which dorsal column nucleus tract will sysnapse more medial? more lateral? | MEDIALLY: Cuneatus. LATERALLY: Gracilis. |
| Since the VPL represents the body from the neck down, what is responsible for the sensory info from the head? | VPM via the trigeminal system. |
| Where do group I sensory neurons from the lower extremity synpase after the DRG to reach the Dorsal Spinocerebellar system? What levels do these nuclei run? | DORSAL NUCLEI OF CLARKE. **extends from L3 to C8 levels in the spinal cord, receiving large group I fibers. |
| What if a Group I fiber is located below the level of L3? | That neuron would have to ascend on the gracilis fasciculas tract until it reached L3, then leave and terminate on Clarks nucleus which would allow it to move laterally to the Dorsal Spinocerebellar tract to ascend upwards. |
| What do the fibers in the Dorsal Spinocerebellar (DSC) tract form as they approach the dorsal medulla? Where do they eventually terminate? | The DSC tract fibers form the inferior cerebellar peduncle (ICP) and will terminate in the ANTERIOR lobe of the cerebellum (controls lower extremitY). |
| Since the upper extremity does use the DSC tract to reach the cerebellum b/c the nuclei of Clarke end at C8, how does it get there? Where do they terminate? | Those Group I fibers ascend on the fasciculus cuneatus. Once at the nucleus cuneatus, Group I fibers will synapse onto accessory nucleus cuneatus which project up into the ICP. They terminate in the Posterior cerebellum. |
| What is the main function of the cerebellum? | It allows us to make coordinated movements oreinted with space and time. |
| What are 2 different ways you test the cerebellum? | Rhombergs Test: stand with feet close together with eye closed and see if they maintain balance. **Also Tandom walking can be used (heel to toe: this is impeeded by alcohol) |
| How do we get "concious" and "unconcious" proprioception? | As info ascends up towards the ICP via nucleus of Clarke or accessory cuneate nucleus, it splits, going to both the cerebellum (unconcious) and up the medial lamniscus to the thalamus & opposite cerebral postcentral gyrus (concious). |
| If a patient had an ICP or cerebellar lesion, would they be aware of their limbs in space? would they have coordinated movement? | Yes, b/c of the duplicated info from group I neurons travelling up medial lamniscus. NO, b/c lost the cerebellum causing ataxia |
| If a patient had a medical lamniscus lesion, would they be aware of their limbs in space? would they have coordinated movement? | NO, duplicate info would NOT reach cerebrum. YES they would still move fine. **could result from stroke, no awareness of limbs with eyes closed. |
| How is the Postcentral gyrus really divided up? | By somites, with a coronally dividing line separating each somite into a Rapidly & a Slowly adapting receptor section. |
| Primary Somatic Sensory Cortex regions in the Postcentral gyrus? provide examples of each area type | 1.Area 1: rapidly adapting cutaneous receptors (pacinian & meisner’s corpuscles). 2.Area 2: Joint receptors. 3.Area 3a: Muscle stretch receptors (spindles & GTOs). 4.Area 3b: slowly adapting cutaneous receptors (merkel's discs). |
| Is the Non-isomorphic representation of the Primary Somatic Sensory Cortex stable? (meaning it doesn't change) | NO. Practicing something enough will cause the postcentral gyrus to start to over sensitize & over represent those areas of sense. *conversely, repetitive stress can cause dec sense & under representation, running a jack hammer all day. |
| In terms of breaking the Primary Somatic Sensory Cortex into lines, what would the horizontal lines represent? Longitudinal lines? | HORIZ: Somite body map. LONG: representation of modalities. |
| Where is the info from the Postcentral gyrus (somatic sensory cortex) projected to? | Posterior Parietal Cortex (association cortex). **contains a representation of the world with our senses, visual, hearing, and vestibular systems mapped into it. |
| Phantom Limb Syndrome | 1.Intact Posterior Parietal Cortex. 2.Devoid of specific sensory input. **Lost the limb but still recieves spontaneous stimulation of Post Parietal cortex from spinal cord due to prolonged/intense pain at time of injury sensitizing these cell bodies. |
| Neglect Syndrome | 1.Intact Posterior Parietal Cortex. 2.Devoid of specific sensory input. **Infarct to the cerebrum can cause the pt to not recognize their own limb even though they can still move it. |
| Where does information from the Posterior Parietal Cortex travel to in order to associate senses with emotion? | Medially and Frontal crotex. |
Created by:
WeeG
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