Spinal Cord Anatomy and Physiology
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Questions and Answers

What type of pain is characterized by having an identifiable external cause?

  • Psychogenic pain
  • Visceral pain
  • Neuropathic pain
  • Somatic pain (correct)
  • Which type of nerve fibers are primarily involved in transmitting somatic pain?

  • C fibers
  • Aδ fibers (correct)
  • Alpha beta fibers
  • Aα fibers
  • What is a common characteristic of visceral pain as mentioned in the content?

  • It can be identified precisely by the patient.
  • It arises from internal organs. (correct)
  • It has a localized and sharp quality.
  • It is transmitted via Aδ fibers.
  • Which statement about C fibers in the context of nociceptive pain is correct?

    <p>C fibers have a small diameter and low conduction velocity.</p> Signup and view all the answers

    What type of pain is typically described as sharp and localized?

    <p>Somatic pain</p> Signup and view all the answers

    When should one expect nociceptive pain to be reproduced by touch or movement?

    <p>In cases of somatic pain</p> Signup and view all the answers

    Which of the following fibers facilitate the transmission of touch sensation?

    <p>Alpha beta fibers</p> Signup and view all the answers

    What type of pain usually lacks a clear and localized location for the patient?

    <p>Visceral pain</p> Signup and view all the answers

    What primarily characterizes the modality of touch/pressure in terms of localization?

    <p>Often poorly localized</p> Signup and view all the answers

    Which neuron synapses in the thalamus when transmitting pain signals?

    <p>2nd order neuron</p> Signup and view all the answers

    What is the role of the periaqueductal grey matter (PAG) in pain signaling?

    <p>It facilitates pain inhibition.</p> Signup and view all the answers

    What do enkephalin-releasing neurons primarily bind to for pain modulation?

    <p>Mu opioid receptors</p> Signup and view all the answers

    What is the primary function of upper motor neurons (UMN)?

    <p>Facilitate transmission of signals from the brain to spinal cord nerves.</p> Signup and view all the answers

    Which condition is described as a breakdown in upper motor neuron function?

    <p>Pyramidal weakness</p> Signup and view all the answers

    What role do serotonergic (5-HT) and noradrenergic (NA) neurons play in pain modulation?

    <p>They prevent nociceptive neurotransmitters' effects.</p> Signup and view all the answers

    Which descending motor pathway is considered particularly important for voluntary muscle movement?

    <p>Corticospinal (pyramidal) pathway</p> Signup and view all the answers

    What structure does the spinal cord continue from?

    <p>Brain stem</p> Signup and view all the answers

    Which term refers to the collection of lumbar and sacral nerves at the end of the spinal cord?

    <p>Cauda equina</p> Signup and view all the answers

    What type of information does the spinothalamic tract convey?

    <p>Nociceptive and temperature sensations</p> Signup and view all the answers

    At what spinal level do the spinal nerves typically end?

    <p>L1/L2</p> Signup and view all the answers

    Which of the following neurotransmitters is released from nociceptors in response to injury?

    <p>Substance P</p> Signup and view all the answers

    Which tract is primarily responsible for carrying sensory information from muscle and joint receptors?

    <p>Spinocerebellar tract</p> Signup and view all the answers

    What is the primary purpose of the intervertebral foramina?

    <p>Exit points for spinal nerves</p> Signup and view all the answers

    What process activates nociceptors during inflammation?

    <p>Prostaglandin release</p> Signup and view all the answers

    What is the role of lower motor neurons in skeletal muscle contraction?

    <p>They initiate contraction by transmitting signals from the spinal cord directly to the muscles.</p> Signup and view all the answers

    What happens to lower motor neurons (LMN) after a lesion occurs?

    <p>They cause paralysis or paresis of the affected muscles.</p> Signup and view all the answers

    Which of the following symptoms indicates an upper motor neuron lesion?

    <p>Weakness or paralysis without muscle wasting.</p> Signup and view all the answers

    Where do upper motor neurons (UMN) typically synapse with lower motor neurons (LMN)?

    <p>At the anterior horn of the spinal cord.</p> Signup and view all the answers

    What is a common effect of upper motor neuron syndrome?

    <p>Spasticity and hyperreflexia.</p> Signup and view all the answers

    What is the main function of ganglions in the nervous system?

    <p>To serve as relay points and intermediary connections between different neurological structures.</p> Signup and view all the answers

    What is the consequence of occlusion in the anterior spinal artery?

    <p>Paraplegia and potential incontinence.</p> Signup and view all the answers

    Which structure is primarily affected in lower motor neuron syndrome?

    <p>Anterior horn of the spinal cord.</p> Signup and view all the answers

    The Babinski reflex is typically associated with which type of neuron lesion?

    <p>Upper motor neuron lesions.</p> Signup and view all the answers

    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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    Neuroanatomy Spinal Cord PDF

    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.

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