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227 Cards in this Set
- Front
- Back
A-α Fibers |
Diameter: 13-20 Myelinated: Yes Receptors: Muscle Spindle & Golgi Tendon Organ Sensory: Proprioception
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A-β Fibers
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Diameter: 6-12 Myelinated: Yes Receptors: Muscle Spindle = Proprioception, Meissner's Corcpuscle = Superficial touch, Merkel's Receptor = Superficial touch, Pacinian Corpuscle = Deep touch & Vibration, Ruffini Ending = Deep Touch & Vibration, Hair Receptor = Touch & Vibration
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A-δ Fibers
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Diameter: 1-5 Myelinated: Yes Receptors: Bare Nerve Ending Sensory: Pain, Temperature (Cool), Itch
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C Fibers Fibers
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Diameter: 0.2-1.5 Myelinated: Yes Receptors: Bare Nerve Ending Sensory: Temperature (Warm), Itch
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Ventral Posterior Lateral Nucleus (VPL)
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Inputs: Medial Lemniscus & Spinothalamic Outputs: Somatosensory Cortex Function: Relays Somatosensory sinput to cortex
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Ventral Posteromedial Nucleus (VPM)
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Inputs: Trigeminal Lemniscus, Trigeminothalamic tract, Taste inputs Outputs: Somatosensory and Taste Cortex Function: Relays somatosensory cranial nerve inputs and taste to cortex
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Lateral Geniculate Nucleus (LGN)
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Inputs: Retina Outputs: Primary Visual Cortex Function: Relays visual inputs to cortex
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Medial Geniculate Nucleus (MGN)
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Inputs: Inferior Colliculus Outputs: Primary Auditory Cortex Function: Relays auditory inputs to cortex
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Ventral Lateral Nucleus (VL)
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Inputs: 1 Internal Globus Pallidus, deep cerebellar nuclei, substantia nigra, pars reticulata Outputs: Motor, Premotor, Supplementary Cortex Function: Relays basal ganglia and cerebellar inputs to cortex
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Ventral Anterior Nucleus (VA)
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Inputs: 1 Outputs: 2 Function: 8
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Pulvinar
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Inputs: 1 Outputs: 2 Function: 9
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VPL (ventral posterior lateral nucleus)
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Major thalamic nuclei: Relays somatosensory spinal inputs to cortex
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VPM (ventral posteromedial nucleus)
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Major thalamic nuclei: Relays somatosensory cranial nerve inputs and taste to cortex
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Lateral geniculate nucleus (LGN)
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Major thalamic nuclei: Relays visual inputs to cortex
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Mediate geniculate nucleus (MGN)
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Major thalamic nuclei: Relays auditory inputs to cortex
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ventral lateral nucleus (VL)
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Major thalamic nuclei: Relays basal ganglia and cerebllar inputs to cortex
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Pulvinar
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Major thalamic nuclei: Behavioral orientation toward relevant visual and other stimuli
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Mediodorsal nucleus (MD)
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Major thalamic nuclei: limbic pathways, major relay to frontal cortex
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Anterior Nucleus
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Major thalamic nuclei: gets input from mammillary body-->cingulate gyrus... relays limbic pathways
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Intralaminar Nuclei
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Major thalamic nuclei: maintains alert consciousness; motor relay for basal ganglia and cerebellum
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Reticular Nucleus
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Major thalamic nuclei: regulates state of other thalamic nuclei |
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Lesions of the posterior column-medial lemniscal pathways often produce these effects in patients:
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tingling, numb sensation; feeling of a tight, bandlike sensation around the trunk or limbs; or a sensation similar to gauze on the fingers when trying to palpate objects |
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Lesions of the anterolateral pathways often produce these effects in patients:
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sharp, burning, or searing pain
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Lesions of the parietal lobe or primary sensory cortex may cause these effects
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contralateral numb tingling,
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lesions of the thalamus that cause severe contralateral pain
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Dejerine-Roussy syndrome
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Lhermitte's sign
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Lesions of the cervical spine: an electricity like sensation running down the back and into the extremities upon neck flexion
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lesions of the nerve roots often produce ___ pain
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radicular pain (it radiates down the limb in a dermatomal distribution and is accompanied by numbness and tingling, and is provoked by movements that stretch the nerve root)
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Dysesthesia
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unpleasant, abnormal sensation
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Allodynia
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painful sensations provoked by normally nonpainful stimuli such as light touch
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hyperpathia or hyperalgesia
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enhanced pain to normally painful stimuli
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spinal shock
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flaccid paralysis below a lesion in the spinal cord... results in loss of tendon reflexes, decreased sympathetic outflow to vascular smooth muscle causing moderately decreased BP, absent sphincteric reflexes and tone.. Over weeks-months spasticity and upper motor neuron signs develop... can be improved if treated within first 8 hours of lesion with high doses of steroids
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myelopathy
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spinal cord dysfunction
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infarction of the spinal cord is usually caused by
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an anterior spinal artery occlusion-->this leads to anterior cord syndrome
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infectious or inflammatory in etiology. Pts present with spinal cord dysfunction that develops quickly (hours)
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myelitis -CSF will have increased WBC count (lymphocytic) and an MRI will reveal T2 bright areas
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Stereognosis
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the ability to perceive and recognize the form of an object using cues from texture, size, spatial properties, and temperature
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stereognosis is mediated by the ____ pathway of the CNS
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posterior column/medial lemniscal pathway
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Graphesthesia
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ability to recognize writing on the skin purely by the sensation of touch
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What does loss of graphesthesia indicate
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Loss of graphesthesia indicates either parietal lobe damage on the side opposite the hand tested or damage to the dorsal columns pathway at any point between the tested point and the contralateral parietal lobe.
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Hemianopia
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decreased vision or blindness which takes place in half the visual field of one or both eyes
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involving the internal capsule, lateral geniculate, or optic radiations
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hemianopia can be caused by lesions.. (where)
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sensory level
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diminished sensation in all dermatomes below the level of the lesion
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transverse cord lesions
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sensory level is often found in _____ lesions
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Hemicord Lesions: Brown Sequard Syndrome-- Damage to the lateral corticospinal tract causes _____ upper motor neuron type weakness
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Damage to the lateral corticospinal tract causes *ipsilateral* upper motor neuron type weakness
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Hemicord Lesions: Brown Sequard Syndrome-- damage to the posterior columns causes ______ loss of vibration and joint position sense
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damage to the posterior columns causes *ipsilateral* loss of vibration and joint position sense
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Hemicord Lesions: Brown Sequard Syndrome-- interruption of the anterolateral system will cause _____ loss of pain and temperature sensation
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interruption of the anterolateral system will cause *contralateral* loss of pain and temperature sensation
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common causes of Brown-Sequard syndrome
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penetrating injuries, multiple sclerosis, lateral compression from tumors
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_____ lesions in the _____ cord produces a cape distribution
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*Central cord* lesions in the *cervical* cord produce a cape distribution
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common causes of central cord syndrome
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spinal cord contusion, nontraumatic or posttraumatic syringomelia, intrinsic spinal cord tumors (hemangioblastoma, ependymoma, astrocytoma)
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small lesion: damage to the spinothalamic fibers crossing the ventral comissure cause bilateral regions of suspended sensory loss to pain and temp ->what syndrome?
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central cord syndrome
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larger lesions of central cord syndrome also affect...
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the anterior horn cells.. therefore it will produce lower motor neuron deficits at the level of the lesions... may also have sacral sparing
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Lesions of the posterior columns cause loss of vibratin and position sense below the level of the lesion
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posterior cord syndrome
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what two diseases preferentially affect the posterior cord
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Vitamin B12 deficiency and tabes dorsalis (tertiary syphillis)
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damage to the anterolateral pathways causes loss of pain and temperature sensation below the level of the lesions, and damage to the anterior horn cells produoces lower motor neuron weakness a the level of the lesion
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anterior cord syndrome***incontinence is common because the descending pathways controlling sphincter function tend to be more ventrally located
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causes of anterior cord syndrome
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trauma, MS, anterior spinal artery infarct
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What nerves are sensory information from the rectum, bladder, urethra, and genitalia conveyed to the spinal cord by
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S2-4
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somatic innervation of urethra sphincter: what nerve roots and what nuclei for motor pathway
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S3*, S4; onuf's nucleus
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somatic innervation of external anal sphincter: what nerve roots and what nuclei for motor pathway
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S3, S4*; onuf's nucleus
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Where do pelvic parasympathetics arise from
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sacral parasympathetic nuclei at S2-S4
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Where do pelvic sympathetics arise from
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intermediolateral cell column at T11-L1
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An infarct of the left postcentral gyrus arm area and adjacent parietal cortex would be caused by occlusion of *a cortical branch of the left middle cerebral artery
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An infarct of the left postcentral gyrus arm area and adjacent parietal cortex would be caused by occlusion of ___
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dysmetria
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refers to a lack of coordination of movement typified by the undershoot or overshoot of intended position with the hand, arm, leg, or eye
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with clinical localization of a lesion, what level are arms involved
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C5
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innervation of finger extensors and muscles for grip
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C8-T1
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triceps innervation
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C7
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urinary retnetion caused by flaccid bladder with preserved hyperactive urinary sphincter reflexes can be caused by...
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lesions below the pontine micturition center and above the conus medullaris
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fecal incontinence with absent rectal tone can be seen in _____ lesions
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cauda equina or acute spinal cord lesions
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Hypesthesia
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diminished sensitivity
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when tactile stimulie appear to be grossly exaggerated
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hyperesthesia
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What mechanoreceptor detects vibration
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pacinian corpuscles
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What mechanoreceptor mediates superficial phasic touch sensation
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Meissner's corpuscles
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What mechanoreceptor relays information about static limb position
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muscle spindle afferents
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A lesion of the dorsal column usually abolishes ____ tactile discrimination
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ipsilateral
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A lesion of the spinothalamic tract, pain perception is lost on the ____ side of the body
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contralateral
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complete loss of proprioceptive sensation from a spinal lesions requires..
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bilateral interruption of the dorolateral pathway (both dorsal columns and the lateral cervical system in the dorsal part of the lateral columns)
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the loss of ability to recognize common objects such as keys, coins, by touching and handling them with the eyes closed
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astereognosis (could be a sign of injury to the lemniscal pathway)
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Romberg sign
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patient stands with feet closed together. Sway is observed. Patient then closes eyes and sway is observed. If there is an increase in sway with the eyes closed, the sign is +. (can be a sign of a dorsolateral lesion)
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Lesions of the thalamus can cause severe contralateral pain called what?
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Dejerine-Roussy syndrome
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What sign often accompanies lesions of the cervical spine?
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Lhermitte's sign --an electric like sensation running down the back and into the extremities upon neck flexion
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hyperalgesia or hyperpathia
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enhanced pain to normally painful stimuli
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What are 3 of the most common causes of spinal cord dysfunction?
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Extrinsic compression due to: 1.) degenerative disease of the spine 2.) trauma 3.) metastatic cancer
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What phase characterizes acute severe lesions of the spinal cord?
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spinal shock --characterized by flaccid paralysis below the lesion, loss of tendon reflexes, decreased sympathetic outflow to vascular smooth muscle causing moderately decreased BP and absent sphinteric reflexes and tone
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Spread of a metastasis to the _______ is by far the most common cause of neoplastic spinal cord compression.
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epidural space
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What vessel usually occluded in spinal cord infarction?
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anterior spinal artery occlusion
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Neurons in the posterior column/medial lemniscal system carry what type of sensation?
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vibration and position sense
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The anterolateral or trigeminothalamic systems carry what sensation in the spinal cord?
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pain and temperature sensation
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Deficit is contralateral to the lesion. Discriminative touch and joint position sense are often most severely affected. What is the lesion?
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primary somatosensorycortex
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Deficit is contralateral to the lesion. Deficit may be more noticeable in the face, hand (particularly in the lips and fingertips), and foot. All sensory modalities may be involved, sometimes w/ no motor deficit. What type of lesion?
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Lesion to thalamic ventral posterior lateral (VPL) and ventral posterior medial (VMP) nuclei or thalamic somatosensory radiations.
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What type of lesion causes loss of pain and temp sensation in the body opposite the lesion, and loss of pain and temp sensation in the face on the same side as the lesion? The lesion involves anterolateral pathways and the spinal trigeminal nucleus on the same side
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Lateral pons or lateral medulla
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Lesion involves the medial lemniscus, causing contralateral loss of vibration and joint position sense. What lesion?
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medial medulla
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All sensory and motor pathways are either partially or completely interrupted. Diminished sensation present in all dermatomes below the level of the lesion. What lesion?
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transverse cord lesion
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Lesion of the posterior columns causes loss of vibration and position sense below the level of the lesion. What type of lesion?
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posterior cord syndrome
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Damage to the anterolateral pathways causes loss of pain and temp sensation below the level of the lesion, and damage to the anterior horn cells produces lower motor neuron weakness at the level of the lesion. What type of lesion?
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Anterior cord syndrome
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What nucleus controls the urethral and anal sphincters?
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sphincteromotor nucleus of Onuf or just Onuf's nucleus
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Sympathetics for bladder function, erection and ejaculatory function come from what vertebral level?
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T11, T12, L1 from the intermediolateral column
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Sacral parasympathetic nuclei arise from what vertebral level?
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S2-S4
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What brain center activates the detrusor (voiding) reflex?
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pontine micturition center
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Micturition is initiated by what brain center?
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medial frontal micturition center that activates the voiding, or detrusor, reflex
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How does the detrusor reflex work?
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1.) Have voluntary relaxation of the external urethral sphincter 2.) Get inhibition of sympathetics to the bladder neck causing it to relax 3.) Activation of PNS, causing the detrusor muscle to contract
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What are Sx of a lesion affecting bilateral medial frontal micturition centers (activate voiding)?
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Have reflex activation of pontine and spinal micturition when the bladder is full --Urine flow and bladder emptying is normal --Loss of voluntary control --Individual may or may not be aware of incontinence
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What are Sx of a lesion below the pontine micturition center and above the conus medullaris levels S2-S4?
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Initially have a flaccid, acontractile (atonic) bladder --Then get hyperreflexic (spastic) bladder --Results in urinary retention and bladder distention --Catheter required
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What condition often occurs in a hyperreflexic bladder?
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detrusor-sphincter dyssynergia --in which both detrusor and urethral sphincter tone are increased in an uncoordinated/antagonistic fashion --Have urinary frequency and incontinence
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What deficit caused by lesions of the peripheral nerves or of the spinal cord at S2-S4?
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flaccid areflexic bladder, --causes overflow incontinence
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How would an acute spinal cord lesion affect bowel function?
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anal sphincter is completely flaccid, --loss of sacral parasympathetic outflow, causes severe constipation
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Sensation from the genitalia is conveyed by what nerve?
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pudendal nerve (S2-S4)
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What part of the ANS causes ejaculation?
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sympathetic mediated contraction of smooth muscle (seminal vesicles, vas deferens, prostate, bladder neck) --causes emission of semen into the urethra
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what does somatosensory refer to
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sensations of touch, pain, temperature, vibration, and proprioception
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What does the posterior column-medial lemniscal pathway convey
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proprioception, vibration sense, and fine discriminative touch
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What does the anterolateral pathway convey
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pain, tmperature sense, and crude touch
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conduction velocity of small vs large and mylinated vs unmylinated
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large faster-diameter mylinated axons conduct faster than smaller diameter unmyelinated axons
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where are sensory neuron cell bodies
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dorsal root ganglia
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type of axons of neurons in dorsal root ganglia
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stem axon that bifurcates resulting in one long process that conveys sensory information from the periphery and a second that carries info into spinal cord
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peripheral region innervated by sensory fibers from a single nerve root level
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dermatome
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somatotopic organization of posterior column
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as fibers asend, supior structures add on making lower sensory fibers more medial
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where do many of the posterior column axons ascend to
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ipsilateral to posterior column nuclei in medulla; axon collaterals also enter spinal cord gray matter and synapse onto interneurons and motor neurons
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gracile fasciculus
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medial portion that carries info from legs and lower trunk
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cuneate fasciculus
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lateral that carries info from upper trunk above ~T6 and from arms and neck
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where do first order neurons in gracile and cuneate fasciculi synapse
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2nd order neurons in nucleus gracilis and nucleus cuneatus in lower medulla
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where do axons of second order neurons decussate (cross)
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as internal arcuate fibers and then form medial lemniscus on the other side of the medulla
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orientation of medial lemniscus
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initially vertical, then progressively more lateral and inclined as it ascends in the brainstem
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where do secondary neurons of posterior column synapse
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ventral posterior lateral nucleus (VPL) of the thalamus
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Where do axons from VPL go
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project through the posterior limb of the internal capule in the thalamic somatosensory radiations to reach the primary somatosensory cortex
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What pathway conveys touch sensation for the face
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trigeminal lemniscus
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pathway of trigeminal lemniscus
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ventral posterior medial nucleus (VPM) to somatosensory cortex
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What cortical layer do synaptic inputs to the primary somatosensory cortex from both the face and body occur
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cortical layer IV mostly and deeper portions of layer III
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smaller diameter unmylinated axons carring pain and temp info enter spinal cord via dorsal root ganglia and go where
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synapse immediately in gray matter of spinal cord
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where in the spinal cord do these axons synapse
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mainly dorsal horn marginal zone (lamina I), and deeper in dorsal horn (lamina V)
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Lissauer's tract
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tract where fibers ascend or descend before entering gray matter
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Where do axons from 2nd order sensory neurons in the central gray cross over
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spinal cord anterior (ventral) commissure)
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where do the 2nd order axons ascend once crossing over in the spinal cord
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anterolateral white matter; takes 2 or 3 segments for decussating fibers to reach opposite side
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lateral cord lesion will affect contralateral pain and temperature beginning where
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a few segments below the level of lesion
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somatotopic organization of anterolateral pathways
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feet most laterally represented; fibers added on medially as they ascend
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where are anterolateral pathways located when they reach the medulla
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laterally, running in the groove btwn the olives and the inferior cerebral peuncles
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where do axons of anterolateral pathways go after medulla
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enter pontine tegmentum to lie just lateral to the medial lemniscus in the pons and midbrain
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where do the 2nd order axons of the anterolateral pathways synapse
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thalamus, which project via thalamic somatosensory radiations to primary somatosensory cortex
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whar carries pain and temp sensation for the face
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trigeminothalamic tract; similar to anterolateral pathway
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three tracts in the anterolateral pathway
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spinothalamic, spinoreticular, and spinomesencephalic tracts
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which tract mediates discriminative aspects of pain and temperature sensation such as location and intensity of stimulus
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spinothalamic tract
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main relay for the spinothalamic tract
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VPL of the thalamus is main relay; also intralaminar thalamic nuclei (central lateral nucleus) and medial thalamic nuclei (mediodorsal nuclei)
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where does the spinoreticular tract terminate
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on medullary-pontine reticular formation-projects to the intralaminar thalamic nuclei
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where do the intralaminar thalamic nuclei project
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diffusely to the entire cerebral cortex (thought to be involved in behavioral arousal)
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where does the spinomesencephalic tract project
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to midbrain periaqueductal gray matter and the superior colliculi
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periaqueductal gray matter participates in
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central modulation of pain
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What spinal cord laminae do the spinothalamic and spinomesencephalic tracts mainly arise from
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cord laminae I and V
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What spinal cord laminae does the spinoreticular tract mainly arise from
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diffusely from intermediate zone and ventral horn laminae 6-8
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Brodmann areas of primary somatosensory cortex
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3/1/2002
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somatotopic organization of primary sensory cortex
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face lateral and leg medial
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where is info from the primary somatosensory cortex conveyed
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secondary somatosensroy association cortex within the sylvian fissure (parietal operculum)
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where does further processing of somatosensory info occur
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association cortex of posterior parietal lobe (brodman's areas 5 and 7)
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when does cortical sensory loss occur
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lesions of somatosensory cortex and adjacent regions
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what does pain modulation involve
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interactions btwn local circuits at level of spinal cord dorsal horn and long-range modulatory inputs
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gate control theory
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sensory inputs from large diameter non-pain A-Beta fibers reduce pain transmission through the dorsal horn
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what does the periqueductal gray receive inputs from
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hypothalamus, amygdala, and cortex
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what does periaqueductal gray do
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inhibits pain transmission in the dorsal horn via the rostral ventral medulla (RVM)
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where is the RVM
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pontomedullary jxn
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what neurons does the RVM have
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serotoneurgic (5-HT) neurons of the raphe nuclei
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what do the serotoneurgic nerons do
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project to the spinal cord and modulate pain in the dorsal horn
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what does substance P do to the RVM
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causes it to send inputs to the locus ceruleus-which sends noradrenergic projections to modulate pain in the spinal cord dorsal horn
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divisions of the thalamus
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medial nuclear group, lateral nuclear group, and anterior nuclear group
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what divided the thalamus into these regions
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Y-shaped white matter structure called internal medullary lamina
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intralaminar nuclei
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nuclei within the internal medullary lamina
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midline thalamic cuclei
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additional collection of nuclei adjacent to the third ventricle; several continuous with and similar to the intralaminar nuclei
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thalamic reticular nucleus
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extensive, but thin sheet enveloping the lateral aspect of the thalamus
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Three main categories of thalamic nuclei
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1) relay 2) intralaminar 3) reticular
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relay nuclei
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most of thalamus; receive inputs and project to cortex - localized and diffuse distributions
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what information is relayed in the lateral geniculate nucleus (LGN)
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visual
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what information is relayed in the medial geniculate nucleus (MGN)
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auditory
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mnemonic for LGN and MGN
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lateral light and medial music
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anterior nuclear group projects to
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limbic pathways in cortex (anterior cingulate cortex)
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pulvinar
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large, pillow-shaped nucleus that occupies most of the posterior thalamus
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mediodorsal nucleus (MD)
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major thalamic relay for frontal association cortec
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intralaminar nuclei receive main inputs and outputs from
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basal ganglia
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two functional regions of intralaminar nuclei
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caudal intralaminar nuclei and rostral intralaminar nuclei
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what are caudal intralaminar nuclei involved in
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basal ganglia circuitry
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rostal intralaminar nuclei are involved in
|
basal ganglia input/output; also ascending reticular activating systems (ARAS) to the cortex
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reticular nucleus location
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thin sheet just lateral ro the rest of thalamus and just medial to internal capsule; doesn't project to cortex
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what inputs does the reticular nucleus receive
|
from other thalamic nuclei and cortex and projects back to thalamus
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what neurons make up most of the reticular nucleus
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inhibitory GABAergic neurons
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paresthesias
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abnormal positive sensory phenomenon
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presentation of posterior column-medial lemniscal pathways lesions
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tingling, numb sensation, feeling of a tight band around trunk or limbs, sensation of gauze on fingers when touching objects
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presentation of anterolateral pathways lesions
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sharp, burning, or searing pain
|
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lesions of parietal lobe
|
contralateral numb tingling, pain can be prominent
|
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lesions of thalamus
|
severe contralateral pain (Dejerine-Roussy syndrome)
|
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lesions of c-spine
|
Lhermitte's sign-electricity like sensation running down back into extremities upon neck flexion
|
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lesions of nerve roots often produces
|
radicular pain that radiates down limb in a dermatomal distribution; numbness and tingling
|
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hyperpathia or allodynia
|
painful sensations provoked by minor stimuli such as light touch
|
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lateral pons or lateral medulla lesion
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involves anterolateral pathways and spinal trigeminal nucleus on same side; loss pain/temp contralateral body; pain/temp ipsilateral face
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midial medulla lesion
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involves medial lemniscus causing contralateral loss vibration/joint position sense
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common causes of transverse spinal cord lesion
|
trauma, tumors, multiple sclerosis, transverse myelitis
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hemicord lesions (Brown-Sequard syndrome)
|
ipsilateral UMN-type weakness (corticospinal), ipsilateral loss vibration and joint position sense (posterior columns), contralateral loss pain and temp (anterolateral systems)
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common causes of hemicord lesions (Brown-Sequard syndrome)
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penetrating injuries, MS, lateral compression from tumors
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central cord syndrome in small lesions
|
bilateral regions of suspended sensory loss to pain and temp (spinothalmic fibers)
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central cord lesion distribution in c-spine lesions
|
cape distribution
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central cord syndrome in larger lesions
|
anterior horn cells damaged producing LMN deficits, UMN deficits (corticospinal), posterior columns may be involved; sacral sparing
|
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common causes of central cord syndrome
|
spinal cord contusion, posttraumatic syringomyelia, intrinsic spinal cord tumors (hemangioblastoma), ependymoma, astrocytoma
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posterior cord syndrome
|
loss of vibration and position sense below lesion
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what can occur with large posterior cord syndrome lesions
|
encroachment on lateral corticospinal tracts
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common causes of posterior cord syndrome
|
trauma, extrinsic compression from posteriorly located tumors, MS; vit B12 deficiency and tabes dorsalis affect posterior cord
|
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anterior cord syndrome
|
loss of pain and temp sense (anterolateral pathways), LMN weakness (anterior horn cell damage)
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what is involved with larger anterior cord syndrome lesions
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corticospinal tracts causeing UMN signs
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what symptom is common in anterior cord syndrome
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incontinence-descending pathways controlling sphincter fxn tend to be more ventrally located
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common causes of anterior cord syndrome
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trauma, MS, anterior spinal artery infarct
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sensory info from rectum, bladder, urethra, and genitalia is via sacral nerve roots
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S2-4
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where do voluntary somatic motor fibers arise that control pelvic floor muscles
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anterior horn cells of S2-4
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where do sympathetics arise for bladder intervation
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intermediolateral cell column at T11 to L1
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bilateral pathways are involved in
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lesions that affect bowel, bladder, or sexual fxn
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detrusor reflex is mediated by
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intrinsic spinal cord circuits regulated by pontine micturition center and possibly cerebellar and basal ganglia pathways
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micturition
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initialed by voluntary relaxation of external sphincter, triggers inhibition of sympathetics to bladder neck causing relaxation, acitvation of parasympathetics causing detrusor contraction
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urethral reflex
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urethral sphincter contration triggers detrusor relaxation
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lesions affecting bilateral medial frontal micturation centers result in
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reflex activation of pontine and spinal micturition centers when bladder is full
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common causes of frontal-type incontinence
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hydrocephalus, parasagittal meningioma, bifrontal glioblastoma, traumatic brain injury, neurodegenerative disorders
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lesions below pontine micturation center and above conus medullaris levels S2-4
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initially cause flaccid, acontractile bladder--then over weeks/months into hyperreflexive bladder
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common spinal cord lesions causing acontractile or hyperreflexic bladder
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trauma, tumors, transverse myelitis, MS
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Lesion of the peripheral nerves or spinal cord at S2-4
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flaccid areflexic bladder; due to loss of parasympathetic outflow to detrusor and/or loss afferent sensory info from bladder and urethra
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common causes of Lesion of the peripheral nerves or spinal cord at S2-4
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diabetic neuropathy and compression of conus medullaris or cauda equina by trauma, tumor, disc herniation
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What else can cause urinary incontinence and retention
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prostatic hypertrophy, urethral strictures, intrinsic sphincter deficiency
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what origin do desending pathways controlling fecal continence have
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medial frontal lobes
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internal smooth muscle sphincter innervation
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sacral parasympathetics
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external striated muscle sphincter innervation
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pelvic nerves arising from Onuf's nucleus
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pelvic floor muscle innervation
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sacral anterior horn cells
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what does GI motility depend on
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parasympathetics from S2-4 for colorectal smooth muscle beyond splenic flexture; above flexture parasympathetic from vagus
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what can fecal incontinence be caused by
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diffuse cerebral or midial frontal lesions, spinal cord lesions, lesions of sacral nerve roots or pelvic or pudendal nerves
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what occurs in acute spinal cord lesions
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anal sphincter is completely flaccid; loss of parasympathetic outflow causing severe constipation
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sensation from genetalia is via
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pudendal nerve reaching to S2-4
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what mediates female secretion of lubricating mucus by Bartholin's glands
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parasympathetics
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what mediates female increases in vaginal blood flow and secretions
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sympathetics
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ejaculation is mediated via
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sympathetics - contraction of smooth muscle
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what can cause sexual dysfunction
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peripheral nerve lesions, higher-order cortical lesions, and psychological factors
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