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What type of pain is characterized by having an identifiable external cause?
Which type of nerve fibers are primarily involved in transmitting somatic pain?
What is a common characteristic of visceral pain as mentioned in the content?
Which statement about C fibers in the context of nociceptive pain is correct?
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What type of pain is typically described as sharp and localized?
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When should one expect nociceptive pain to be reproduced by touch or movement?
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Which of the following fibers facilitate the transmission of touch sensation?
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What type of pain usually lacks a clear and localized location for the patient?
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What primarily characterizes the modality of touch/pressure in terms of localization?
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Which neuron synapses in the thalamus when transmitting pain signals?
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What is the role of the periaqueductal grey matter (PAG) in pain signaling?
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What do enkephalin-releasing neurons primarily bind to for pain modulation?
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What is the primary function of upper motor neurons (UMN)?
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Which condition is described as a breakdown in upper motor neuron function?
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What role do serotonergic (5-HT) and noradrenergic (NA) neurons play in pain modulation?
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Which descending motor pathway is considered particularly important for voluntary muscle movement?
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What structure does the spinal cord continue from?
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Which term refers to the collection of lumbar and sacral nerves at the end of the spinal cord?
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What type of information does the spinothalamic tract convey?
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At what spinal level do the spinal nerves typically end?
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Which of the following neurotransmitters is released from nociceptors in response to injury?
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Which tract is primarily responsible for carrying sensory information from muscle and joint receptors?
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What is the primary purpose of the intervertebral foramina?
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What process activates nociceptors during inflammation?
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What is the role of lower motor neurons in skeletal muscle contraction?
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What happens to lower motor neurons (LMN) after a lesion occurs?
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Which of the following symptoms indicates an upper motor neuron lesion?
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Where do upper motor neurons (UMN) typically synapse with lower motor neurons (LMN)?
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What is a common effect of upper motor neuron syndrome?
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What is the main function of ganglions in the nervous system?
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What is the consequence of occlusion in the anterior spinal artery?
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Which structure is primarily affected in lower motor neuron syndrome?
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The Babinski reflex is typically associated with which type of neuron lesion?
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Study Notes
Spinal Cord Anatomy
- Continues from the brainstem
- Located within the vertebral canal
- Receives information from and controls trunk and limbs
- 31 pairs of spinal nerves exit the spinal cord
- Intervertebral foramina (openings between vertebral bones) allow spinal nerves to pass through
- Cauda equina (collection of nerve roots) extends from the end of the spinal cord at L1/L2, resembling a horse’s tail
- Cauda equina syndrome (compression of the nerve roots) can cause pain, numbness, and weakness in the legs and bladder
- Some neurological systems (e.g. olfactory, visual, auditory) are partially or fully reversed in the brain.
Spinal Cord Tracts
- Ascending tracts transmit sensory information from the body up to the brain.
- Descending tracts transmit motor commands from the brain down to the body.
- Spinothalamic tract - transmits pain, temperature, crude touch, and pressure sensations to the thalamus.
Pain Pathway
- Nociceptors (pain receptors) in the skin are activated by chemical signals released from tissue injury.
- Substance P and glutamate (neurotransmitters) are released by nociceptors, causing the feeling of pain.
- Prostaglandins (chemicals released during inflammation) further activate nociceptors.
- There are two types of nociceptive pain: Somatic pain (from skin and muscle) and visceral pain (from internal organs).
Pain Transmission
- First order neuron: located in the dorsal root ganglion, carries signals from the periphery to the spinal cord.
- Second order neuron: travels up the spinothalamic tract to the thalamus.
- Third order neuron: carries signals from the thalamus to the somatosensory cortex in the brain.
Pain Inhibition
- Descending pathway modulates pain sensation.
- Periaqueductal gray matter (PAG) is a brain region involved in descending pathway and pain modulation.
- Serotonin descends to the dorsal horn of the spinal cord and excites interneurons.
- Activated interneurons release enkephalins or dynorphin, which bind to opioid receptors and inhibit pain signals.
Upper and Lower Motor Neurons
- Upper motor neurons (UMN): located in the cerebral cortex, transmit signals from the brain to the spinal cord.
- Lower motor neurons (LMN): located in the spinal cord and brainstem, send signals directly to muscles.
Upper Motor Neuron Syndrome
- Weakness or paralysis of specific movements
- Muscles not wasted.
- Increased resistance to passive stretching (spasticity).
- Hyperactive deep tendon reflexes (hyperreflexia).
- Extensor plantar response (Babinski reflex).
- Loss of abdominal reflexes.
Lower Motor Neuron Syndrome
- Weakness (paresis) or paralysis (plegia) of individual muscles
- Muscle wasting
- Fasciculations (muscle twitches).
- Decreased resistance to passive stretching (hypotonia).
- Reduced or absent deep tendon reflexes (hyporeflexia or areflexia).
Blood Supply of the Spinal Cord
- Anterior and posterior spinal arteries supply the spinal cord.
- Radicular arteries provide additional blood flow.
- Blood supply is vulnerable in the thoracic region and anterior portion of the cord.
- Occlusion of the anterior spinal artery can lead to paraplegia (paralysis of the lower limbs) and incontinence.
Venous Drainage of the Spinal Cord
- Anterior and posterior spinal veins drain the spinal cord.
- These veins connect to anterior and posterior radicular veins, which lead to internal vertebral venous plexus.
- Venous drainage ascends to lumbar veins, azygos vein, and hemiazygos veins.
Ganglia
- Ganglia are clusters of nerve cell bodies.
- House the cell bodies of afferent (sensory) and efferent (motor) nerve fibers.
- Function as relay points between neurological structures.
- Types include dorsal root ganglia (spinal ganglia) for sensory neurons, cranial nerve ganglia for cranial nerves, and autonomic ganglia for autonomic nerves.
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Description
This quiz covers the anatomy and functions of the spinal cord, including its structure, spinal tracts, and pain pathways. You'll explore important concepts such as ascending and descending tracts, spinal nerves, and conditions like cauda equina syndrome. Test your understanding of how the spinal cord interacts with the brain and body.
