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The dorsal root of the spinal nerves has what divisions
- Medial (large diameter)
- Lateral (small diameter)
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What does the medial division of the dorsal root carry
Touch, 2 point discrimination, proprioception, vibration, sharp pain, temperature sensations
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What does the lateral division of the dorsal root carry
Chronic, aching pain, and itching sensations
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The receptive fields of all dorsal root ganglion make up a single
Dermatome
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Conus medullaris ends where in adults and newborns
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Where are the cervical and lumbar enlargements located in the spinal cord and why are they there
- C5-T1
- L1-S3
- This is to accommodate the extremities that arise from these levels
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What is one way of immediately identifying a cross section of a thoracic spinal cord section
The grey matter is thinner, and a intermedial cell column is present as a sharp protrusion from between the dorsal and ventral horns
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How are the faciculus cuneatus and gracilis seperated
The two gracilis are separated by the posterior median sulcus, and the posterior intermediate sulcus seperates cuneatus and gracilis
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Intermediate grey matter and the lateral horns are found only where
C8-L2
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What type of neuron cell bodies are found in the lateral horn
Preganglionic sympathetic
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Sacral autonomic nuclei are found where in the spinal cord
Intermediate zone S2-S4
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Clarks column (Nucleus dorsalis) sends what information where
Unconcious proprioception to cerebellum
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What are the main neuron types found in the ventral horn
Motor neurons Alpha and Gamma
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Alpha motor neurons supply what
Skeletal muscles with extrafusal fibers
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Gamma motor neurons supply
Muscle spindles
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Limb innervation is organized how in the ventral horn of the spinal cord
- In the ventral horn, proximal muscles to distal are organized medially to lateral
- Flexor to extensors are organized dorsal to ventral
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Most Upper motor neurons reach the spinal cord through what tract
Corticospinal
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What are the two Corticospinal Nuclear groups in the ventral horn
- Medial motor cell column (all levels)
- Lateral motor cell column (C3-T2 and L1-S3 where the limbs are)
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Lower motor neurons are located where
Ventral horn of the spinal cord, and the cranial nerve nuclei of the brain stem
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What is present in a lesion of Upper Motor Neurons (UMN)
- Spastic paralysis
- Muscle weakness
- Hyper-reflexia
- Hypertonia
- Babinski (+)
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A lesion of Lower Motor Neurons (LMN) presents how
- Flaccid paralysis
- Hypotonicity
- Hypotonic reflexes
- Twitching (fasciculations)
- Muscle atrophy
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What is a positive Babinski sign
When a blunt prob is stroked on the plantar side of the patients foot (heel to toe), the toes fan out instead of flexing in to "protect".
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Anterograde vs Retrograde degeneration
- Ant. degeneration distal to the injury
- Retro. degeneration proximal to injury
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Why are the CNS neurons less apt to regenerate
Inhibitory proteins that are expressed by oligodendrocytes
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Dorsal columns (posterior) communicate what sensations
- Vibration
- Proprioception
- Light touch
- "Vib pro light"
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The anterior side of the spinal cord communicates what sensations
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Brown-Sequard syndrome
- Compression of half of the spinal cord resulting in ipsilateral motor and proprioception and descriminative touch
- Contralateral loss of pain and temperature
- SEQual half the story "continues" to other side
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Syringomyelia
- A cyst in the center of the spinal cord resulting in a loss of pain/temp at or below the cyst
- This is due to the compression of the white commisure where the nerves cross
syRINGomyelia "making the cross section of the cord look like a ring"
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Friedrichs Ataxia
- Hereditary disease with degeneration spinal cord white matter
- Spinocerebellar tracts
- Dorsal columns
- Corticospinal tracts
Fried chicken "white meat"
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Subacute combined degeneration
- Commonly seen in vit B12 deficiency
- Bilateral spastic paralysis
- Bilateral loss of proprioception, and discriminative touch
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Amyotrophic Lateral Sclerosis
- Lou Gehrigs Disease
- Motor system disease that affects both UMN and LMN
- Flaccid paralysis at the levels of the lesion, spastic levels below
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Tabes dorsalis
- One manifestation of neurosyphilis
- Destroys dorsal root fibers and cell bodies usually in the lumbar sacral regions
- Sensory loss
- Tabetic gate
- Incontinece
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