Peripheral Nervous System Quiz
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Questions and Answers

What is the primary function of the peripheral nervous system?

  • To process information within the central nervous system
  • To coordinate physical responses to stimuli independently
  • To protect the central nervous system from external damage
  • To establish communication between the internal and external media and the central nervous system (correct)

Which layer of connective tissue surrounds each individual nerve fiber in a peripheral nerve?

  • Perineurium
  • Epineurium
  • Endoneurium (correct)
  • Fascia

What type of neuron is primarily responsible for transmitting information from the CNS to skeletal muscles?

  • Autonomous motor neuron
  • Sensitive neuron
  • Afferent neuron
  • Somatic motor neuron (correct)

Which type of neuron is found in afferent nerves and is responsible for sending information from receptors to the CNS?

<p>Sensitive neuron (D)</p> Signup and view all the answers

What is the main role of ganglia in the peripheral nervous system?

<p>To serve as relay points for nerve impulses (D)</p> Signup and view all the answers

What is the primary function of spinal nerve roots?

<p>To provide neural continuity between peripheral nerves and spinal cord (A)</p> Signup and view all the answers

Which of the following characteristics is specific to spinal nerve roots?

<p>Smaller in cross-sectional area compared to peripheral nerves (A)</p> Signup and view all the answers

What are the two types of spinal nerve roots and their functions?

<p>Anterior root: motor and Posterior root: sensory (D)</p> Signup and view all the answers

Which plexus corresponds to roots L1-L4?

<p>Lumbar plexus (C)</p> Signup and view all the answers

In what order does sensory information travel through the spinal reflex arc?

<p>From posterior root to spinal ganglia to posterior horn (B)</p> Signup and view all the answers

What happens if an afferent signal is more complex than a simple reflex?

<p>It is transmitted to the brain for processing (D)</p> Signup and view all the answers

Which nerve plexus is responsible for innervation of the upper limb?

<p>Brachial plexus (A)</p> Signup and view all the answers

Which statement is true regarding the histological characteristics of spinal nerve roots?

<p>They lack protective connective sheaths (A)</p> Signup and view all the answers

What role does the elasticity of connective layers play in peripheral nerves?

<p>It enables nerves to adapt to limb position changes. (A)</p> Signup and view all the answers

What occurs during progressive stretch of peripheral nerves?

<p>The more fragile fascicles rupture before the trunk. (B)</p> Signup and view all the answers

In terms of tensile stress, what is meant by 'toe region'?

<p>Nerve is markedly elongated relative to the applied load. (D)</p> Signup and view all the answers

How does compressive stress affect the internal contents of a nerve?

<p>It causes displacement in both transverse and longitudinal directions. (D)</p> Signup and view all the answers

What happens to myelin at the edges of a compression zone?

<p>It retracts and can become demyelinated. (A)</p> Signup and view all the answers

What is the impact of nerve compression on epineurium thickness?

<p>Nerves with thick epineurium tolerate compression better. (C)</p> Signup and view all the answers

What occurs during the ultimate load phase of nerve tensile stress?

<p>There is a clear transition between recoverable and permanent strain. (B)</p> Signup and view all the answers

How does endoneurial fluid respond to external compression of a nerve?

<p>It escapes to the outer surface of the nerve immediately. (A)</p> Signup and view all the answers

What is the proportional limit force related to spinal nerve roots?

<p>The maximum force tolerated before failure (D)</p> Signup and view all the answers

Which grade of nerve injury does not involve loss of nerve continuity?

<p>Neuropraxia (Grade 1) (A)</p> Signup and view all the answers

What does axonotmesis grade 3 specifically lead to?

<p>Retractation of the ends of the nerve fibers (A)</p> Signup and view all the answers

What characterizes the pathological changes in neuropraxia grade 1?

<p>Mild or absent pathological changes (A)</p> Signup and view all the answers

Which term describes the physical fragmentations seen in axonotmesis grade 2?

<p>Wallerian degeneration (A)</p> Signup and view all the answers

What is the first step in the sequence of neural regeneration?

<p>Neuronal cell body (B)</p> Signup and view all the answers

What happens to the endoneurial tubes in axonotmesis grade 4 and neurotmesis grade 5?

<p>They are disrupted, leading to confinement loss of axons and Schwann cells (B)</p> Signup and view all the answers

What is the main difference in mechanical properties between spinal nerve roots and peripheral nerves?

<p>Spinal nerve roots exhibit lower strength and stiffness (A)</p> Signup and view all the answers

What is the primary function of the sympathetic autonomous nervous system (SNS)?

<p>To prepare the body for stressful situations (C)</p> Signup and view all the answers

Where is the parasympathetic autonomous nervous system (PNS) primarily located?

<p>Craniosacral (B)</p> Signup and view all the answers

What describes the all-or-none principle in action potentials?

<p>Once the threshold is reached, the action potential remains constant regardless of stimulus intensity (B)</p> Signup and view all the answers

During which stage of action potentials does the membrane potential become more positive?

<p>Rapid depolarization (C)</p> Signup and view all the answers

Which statement correctly describes the sodium channel during the activated state?

<p>The M gate opens and sodium ions enter the cell (A)</p> Signup and view all the answers

What occurs during hyperpolarization of a neuron?

<p>The membrane potential becomes more negative than the resting value (B)</p> Signup and view all the answers

What is the role of the N gate in the potassium channel during depolarization?

<p>It opens slowly to allow potassium to leave the cell (B)</p> Signup and view all the answers

What distinguishes voluntary motor responses from involuntary motor responses?

<p>Involuntary responses operate without conscious control (C)</p> Signup and view all the answers

What is a possible sequel of regeneration related to sensory recovery?

<p>Increase in pain sensitivity (C)</p> Signup and view all the answers

Which condition is primarily a metabolic abnormality that can lead to neuropathy?

<p>Diabetes (D)</p> Signup and view all the answers

What distinguishes polyneuropathies from other forms of neuropathies?

<p>Affect multiple nerves symmetrically distally (C)</p> Signup and view all the answers

In the training for nerve injury, which aspect should be prioritized when dealing with proprioception?

<p>Work a lot on proprioception (D)</p> Signup and view all the answers

Which of the following is NOT a classification of neuropathies?

<p>Psychological neuropathies (A)</p> Signup and view all the answers

What type of neuropathy involves the degeneration of nerve roots?

<p>Radiculopathy (B)</p> Signup and view all the answers

Which symptom is associated with neuropathies affecting the peripheral nervous system?

<p>Abnormalities in the electromyogram (D)</p> Signup and view all the answers

What should be included in training for patients with neuropathies experiencing significant pain?

<p>Neuropedagogy of pain (C)</p> Signup and view all the answers

Flashcards

Peripheral Nervous System (PNS)

The network of nerves that connects the central nervous system (brain and spinal cord) to the rest of the body.

Peripheral Nerves

Bundles of nerve fibers that transmit signals between the CNS and the body.

Endoneurium

Thin layer of connective tissue surrounding each individual nerve fiber.

Perineurium

Connective tissue layer that surrounds each nerve fascicle (a bundle of nerve fibers).

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Epineurium

Dense connective tissue that encases the entire peripheral nerve.

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Autonomic Nervous System

The part of the nervous system that controls involuntary actions like breathing, heart rate, and digestion. It consists of two branches: the sympathetic and parasympathetic nervous systems.

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Sympathetic Nervous System (SNS)

The branch of the autonomic nervous system responsible for the "fight or flight" response, preparing the body for stressful situations.

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Parasympathetic Nervous System (PNS)

The branch of the autonomic nervous system responsible for "rest and digest" functions, calming the body and promoting relaxation.

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Neural Drive

The process by which a nerve cell transmits an electrical signal.

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Action Potential

A rapid change in the electrical potential across the membrane of a nerve cell, which propagates along the axon.

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All-or-None Principle

The principle that an action potential always occurs with the same strength, regardless of the intensity of the stimulus.

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Latency Period

The initial stage of an action potential where the membrane potential remains stable.

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Depolarization

A change in the membrane potential that makes it less negative, moving it closer to zero.

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Spinal Nerve Roots

The junction between the spinal cord and peripheral nerves, providing neural pathways for communication.

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Posterior vs. Anterior Roots

Sensory information enters the spinal cord through the posterior root, while motor commands exit through the anterior root.

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Spinal Nerve Trunk

The point where the posterior and anterior roots unite to form a single spinal nerve.

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Nerve Plexuses

The anterior ramus of a spinal nerve branches out to form nerve plexuses, which innervate specific parts of the body.

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Cervical Plexus

A network of nerves in the neck that innervates the neck, shoulder, and head.

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Brachial Plexus

A network of nerves in the upper arm that innervates the upper limb.

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Lumbar Plexus

A network of nerves in the lower back that innervates the abdomen, genitals, and lower limb.

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Sacral Plexus

A network of nerves in the pelvis that innervates the perineum, gluteal region, and lower limb.

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Nerve Flexibility

The ability of nerves to adjust their length by stretching or shortening, which allows them to adapt to changes in limb positions.

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Nerve Architecture

The arrangement of connective tissues within nerves that allows them to stretch and become longer.

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Nerve Stretch Damage

Stretching a nerve beyond its elastic limit can damage individual nerve fibers and impair circulation within the nerve.

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Nerve Compression Vulnerability

Nerves with a high number of nerve fibers and thin outer covering are more susceptible to damage from compression.

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Nerve Excursion

The displacement of a nerve relative to its surrounding tissue, caused by tensile forces.

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Toe Region

The curve in the stress-strain relationship of a nerve, showing its initial flexibility before resisting further stretch.

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Linear Region

The linear portion of the stress-strain curve, where the nerve stretches uniformly with applied load.

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Ultimate Load

The point on the stress-strain curve where the nerve transitions from recoverable to permanent deformation.

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Neuropathy

A group of disorders affecting the peripheral nervous system, impacting the second neurons of the pyramidal pathway.

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Polyneuropathy

A condition where the nerves in the body are damaged, resulting in weakness, numbness, and pain. It affects many nerves symmetrically and distally.

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Mononeuropathy

A condition where a single nerve is damaged, causing weakness, numbness, or pain in a specific area.

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Multiple mononeuropathies

A condition where several individual nerves are damaged, affecting different parts of the body asymmetrically.

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Radiculopathy

A condition where the nerve roots, which connect the spinal cord to nerves, are affected.

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Acute Neuropathy

Neuropathy that develops quickly, within a week.

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Subacute Neuropathy

Neuropathy that develops over a period of weeks or months.

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Chronic Neuropathy

Neuropathy that develops over a period of months or years.

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Proportional limit force of spinal nerve roots

The force at which a spinal nerve root will start to break, often representing the maximum force it can tolerate.

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Strength of Spinal Nerve Roots

It is the maximum amount of force that a nerve root can withstand before it begins to deform permanently. This force is directly related to the cross-sectional area of the nerve root—larger roots can withstand greater forces.

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Stiffness of Spinal Nerve Roots

The amount of force required to stretch a nerve root to a given amount. Nerve roots are less stiff than peripheral nerves, meaning they stretch more easily under the same force.

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Density of Spinal Nerve Roots

The density of nerve roots is lower than that of peripheral nerves. This means that they contain less tissue per unit volume.

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Seddon & Sunderland Nerve Injury Classification

A classification system for nerve injuries based on the severity and the potential for repair.

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Axonotmesis (Grade 2, 3, 4)

A type of nerve injury where the nerve fibers are interrupted and the myelin sheath is damaged, but the connective tissue structures remain intact.

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Neurotmesis (Grade 5)

A type of nerve injury where the nerve is completely severed, causing a complete loss of function.

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Neural Regeneration

The process by which nerve fibers regenerate after injury. It starts at the cell body of the neuron and progresses towards the end organ.

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Study Notes

Peripheral Nervous System

  • Composed of nerves that carry signals between internal and external environments and the central nervous system
  • Includes afferent (sensory) and efferent (motor) nerves
  • Ganglia are collections of nerve cell bodies, including craniospinal (sensory) and autonomic (motor) ganglia
  • Nerve endings act as receptors or effectors

Peripheral Nerve Structure

  • Bundles of nerve fascicles held together by vascular connective tissue (epineurium)
  • Each fascicle is surrounded by perineurium
  • Individual nerve fibers are surrounded by endoneurium

Types of Neurons

  • Sensory neurons: located in afferent nerves, carrying information from receptors to the central nervous system
  • Somatic motor neurons: located in efferent nerves, carrying signals from the central nervous system to skeletal muscles
  • Autonomic motor neurons: located in efferent nerves, carrying signals from the central nervous system to smooth muscle, cardiac muscle, and glands

Autonomic Nervous System

  • Sympathetic nervous system (thoracolumbar): prepares the body for stressful situations or physical activity ("fight or flight")
  • Parasympathetic nervous system (craniosacral): controls bodily functions during rest ("rest and digest")

Neural Drive (Action Potential)

  • Rapid change in membrane potential that propagates along a nerve
  • All-or-none principle: action potential is always the same size, regardless of stimulus intensity
  • 5 stages: latency, slow depolarization, rapid depolarization, rapid repolarization, and hyperpolarization
  • Ions (sodium and potassium) flow across the nerve membrane during these stages

Ionic Changes in Action Potential

  • Sodium channels: open during depolarization, allowing sodium ions to enter
  • Potassium channels: open during repolarization, allowing potassium ions to exit
  • These ion movements restore the membrane potential to its resting value

Spinal Nerve Roots

  • Provide neural continuity between peripheral nerves and the spinal cord
  • Roots are less complex than peripheral nerves, lacking some of the protective sheaths
  • More sensitive to damage than peripheral nerves due to lack of sheaths, making them more susceptible to compression and irritation
  • Posterior roots are sensory (afferent)
  • Anterior roots are motor (efferent)
  • Trunk of spinal nerve is formed by the union of the posterior and anterior roots
  • Trunk is divided into Anterior/Ventral ramus and Posterior/Dorsal ramus

Nerve Plexuses

  • Networks formed by the axons of anterior rami
  • Cervical Plexus: neck, thorax, and head
  • Brachial Plexus: upper limb
  • Lumbar Plexus: abdomen, genitals, and lower limb
  • Sacral Plexus: perineal and gluteal region, and lower limb
  • Coccygeal Plexus: coccygeus region

Spinal Nerve Root Physiology

  • Sensory information travels through the posterior root to the posterior horn of the spinal cord
  • It synapses with an alpha motor neuron
  • Afferent fibers exit through the anterior horn of the spinal cord to the anterior root
  • The impulse travels through the anterior root to the muscle

Mechanical Properties of Peripheral Nerves

  • Sliding properties allow nerve trunks to adapt to positions
  • Wavy architecture helps nerves adapt to stretching forces
  • Progressive stretch can cause rupture of fascicles

Tensile Stress

  • Displacement of the nerve relative to surrounding tissue (excursion)
  • Convergence or divergence based on elongation or tension release
  • Nerve response relative to applied load

Compressive Stress

  • Displacement of intracellular contents of the nerve in transverse and longitudinal directions
  • Damage to axons and myelin is greatest at the edges of the compression zone

Mechanical Properties of Spinal Nerve Roots

  • Proportional limit force is frequently the maximum force roots tolerate
  • Force sustained at the proportional limit is correlated with the cross-sectional area
  • Roots have smaller values of strength, stiffness, density, and proportional limit force than peripheral nerves

Nerve Injury and Pain

  • Neuropraxia: does not involve loss of nerve continuity
  • Axonotmesis: complete interruption of nerve axon and myelin, but mesenchymal structures are preserved
  • Neurotmesis: disconnection of the nerve, with functional and structural loss

Neural Regeneration

  • Sequence of regeneration: neural body, segment between cell and injury, injury site, segment between injury and end organ, and end organ
  • Possible sequels after regeneration could involve impairment in functional motor recovery, failures in sensory recovery, or decrease/increase of sensitivity and pain

Neuropathies

  • Injury to peripheral nervous system, potentially affecting the second neurons of the pyramidal pathway
  • Symptoms may include hypotonia, abnormalities in electromyography, hypoactive or absent tendon reflexes, and loss of strength in small muscle groups
  • Etiology can include metabolic abnormalities, infections, autoimmune diseases, toxic exposures, hereditary conditions, or drug interactions

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Biomechanics of Peripheral Nerves and Spinal Nerve Roots PDF

Description

Test your knowledge on the Peripheral Nervous System, including its structure, types of neurons, and functions. This quiz covers essential aspects such as afferent and efferent nerves, ganglia, and nerve fascicles. Challenge yourself and enhance your understanding of how signals are transmitted throughout the body.

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