Spinal Cord Anatomy Quiz
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Questions and Answers

What primarily composes gray matter in the spinal cord?

  • Myelinated nerve fibers
  • Nerve cell bodies, dendrites, and unmyelinated axon terminals (correct)
  • Commissure fibers and connective tissue
  • Muscle fibers and epithelial cells

    • What is the primary function of the posterior horns of gray matter?

  • Coordination of reflex actions
  • Integration of motor commands
  • Afferent sensory input (correct)
  • Efferent somatic output

    • Which part of the spinal cord is responsible for motor signals transmitted from the brain?

  • Lateral horns
  • Descending tracts (correct)
  • Ascending tracts
  • Anterior commissure

    • What are the three columns of neurons in the gray matter of the spinal cord known as?

    <p>Horns</p> Signup and view all the answers

    The white matter of the spinal cord is characterized by what?

    <p>Myelinated nerve fibers</p> Signup and view all the answers

    What is the function of the gray commissure in the spinal cord?

    <p>Cross reflexes</p> Signup and view all the answers

    What is a spinal nerve classified as?

    <p>Mixed spinal nerve</p> Signup and view all the answers

    What is the significance of the myelin in white matter?

    <p>It insulates nerve fibers and increases conduction speed</p> Signup and view all the answers

    What is the primary function of the fibers in the dorsal nerve root?

    <p>Carrying sensory information into the spinal canal</p> Signup and view all the answers

    What type of neurons are found in the cell bodies of the dorsal root ganglion?

    <p>Unipolar sensory neurons</p> Signup and view all the answers

    Which structure is formed by the joining of dorsal and ventral nerve roots?

    <p>Spinal nerve</p> Signup and view all the answers

    What is the location of intercerebral interneurons within the spinal cord?

    <p>In the gray matter core</p> Signup and view all the answers

    What anatomical feature divides the spinal cord into right and left halves?

    <p>Anterior median fissure</p> Signup and view all the answers

    How many pairs of spinal nerves are associated with the spinal cord?

    <p>31 pairs</p> Signup and view all the answers

    What is the shape of the spinal cord as it extends from the brainstem?

    <p>Oval-shaped and tapering</p> Signup and view all the answers

    What is the function of the cauda equina in the spinal column?

    <p>A bundle of nerve roots extending from the conus medullaris</p> Signup and view all the answers

    What happens when the voltage reaches the threshold (TH)?

    <p>Na+ floods into the axon, establishing a new action potential.</p> Signup and view all the answers

    What is the significance of the refractory period (ReP)?

    <p>It prevents Na+ from diffusing into the previous action potential site.</p> Signup and view all the answers

    How does the action potential travel along an axon?

    <p>As a result of the action potential being all-or-nothing.</p> Signup and view all the answers

    What role do voltage-gated ion channels play in the formation of an action potential?

    <p>They open in response to changes in membrane potential.</p> Signup and view all the answers

    Why is the action potential described as never being attenuated?

    <p>The all-or-nothing principle ensures consistent amplitude.</p> Signup and view all the answers

    How many pairs of cervical spinal nerves are present in humans?

    <p>8 pairs</p> Signup and view all the answers

    What is a myotome?

    <p>Skeletal muscle supplied by motor fibers</p> Signup and view all the answers

    Which area does the autonomic nervous system primarily regulate?

    <p>Routine involuntary functions</p> Signup and view all the answers

    What is the total number of cranial nerves in humans?

    <p>12 pairs</p> Signup and view all the answers

    Which cranial nerve is responsible for vision?

    <p>Optic nerve</p> Signup and view all the answers

    The sympathetic and parasympathetic systems are components of which nervous system?

    <p>Autonomic nervous system</p> Signup and view all the answers

    How many thoracic spinal nerve pairs are there in humans?

    <p>12 pairs</p> Signup and view all the answers

    Which of the following is NOT a function of the cranial nerves?

    <p>Performing voluntary muscle contractions</p> Signup and view all the answers

    What occurs during depolarization of a neuron?

    <p>The membrane potential switches from negative to positive.</p> Signup and view all the answers

    What happens during the repolarization phase of an action potential?

    <p>The membrane potential returns to its negative resting state.</p> Signup and view all the answers

    Which statement accurately describes the propagation of a nerve impulse along an axon?

    <p>The propagation of the nerve impulse is influenced by the presence of myelin sheaths.</p> Signup and view all the answers

    What will happen if the threshold is not reached during depolarization?

    <p>The membrane potential will stabilize at resting levels.</p> Signup and view all the answers

    How does Na+ concentration affect the opening of voltage-gated channels during an action potential?

    <p>High Na+ concentration causes the channels to open, initiating depolarization.</p> Signup and view all the answers

    What is the refractory period in the context of action potentials?

    <p>The period after depolarization where another action potential cannot be generated.</p> Signup and view all the answers

    What role do voltage-gated Na+ channels play during the action potential?

    <p>They open to allow Na+ to flow into the neuron and cause depolarization.</p> Signup and view all the answers

    What is the directional nature of nerve impulse propagation in an axon?

    <p>It moves in one direction from the cell body to the axon terminal.</p> Signup and view all the answers

    Which system is dominant during dangerous and stressful activities?

    <p>Sympathetic nervous system</p> Signup and view all the answers

    What type of neurotransmitter is primarily released at the effector site by the parasympathetic system?

    <p>Acetylcholine</p> Signup and view all the answers

    How does the length of preganglionic fibers compare between the sympathetic and parasympathetic systems?

    <p>Parasympathetic has long preganglionic fibers; sympathetic has short.</p> Signup and view all the answers

    What is primarily responsible for the body's routine activities during rest?

    <p>Parasympathetic nervous system</p> Signup and view all the answers

    Which receptors are associated with the postganglionic fibers of the sympathetic nervous system?

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

    What is the resting potential of a nerve?

    <p>Negative charge when at rest</p> Signup and view all the answers

    From which areas do sympathetic preganglionic fibers emerge?

    <p>Thoracic and lumbar regions</p> Signup and view all the answers

    Which statement accurately describes neurotransmitter release at effector sites?

    <p>Parasympathetic releases acetylcholine, sympathetic releases noradrenaline/epinephrine.</p> Signup and view all the answers

    Study Notes

    Organization of the Nervous System (Part 3)

    • The nervous system is divided into the central nervous system (CNS) and peripheral nervous system (PNS)
    • The CNS consists of the brain and spinal cord
    • The PNS includes nerves that connect the CNS to the rest of the body
    • The brain has protective coverings: cerebrum, cerebellum, brainstem, and diencephalon.

    Structural Classification of Neurons

    • Neuroglia are supportive cells in the nervous system
    • Astrocytes are star-shaped glial cells
    • Ependymal cells line cavities of the CNS
    • Microglial cells are phagocytic cells
    • Oligodendrocytes produce myelin sheath in the CNS
    • Schwann cells produce myelin sheath in the PNS

    Spinal Cord

    • Elongated cylinder extending from the brainstem through the foramen magnum of the skull
    • Contains grey matter (interior) and white matter (surrounding)
    • Has 31 pairs of spinal nerves attached by dorsal and ventral nerve roots
    • Lies within the spinal canal, extends to the first lumbar vertebra, and tapers from above downward
    • Bulges in cervical and lumbar regions
    • Two deep grooves: anterior median fissure & posterior median sulcus; anterior fissure is deeper

    Spinal Cord Nerve Roots

    • Dorsal nerve root fibers carry sensory information into the spinal canal
    • Dorsal root ganglion houses cell bodies of unipolar sensory neurons forming a gray matter region in the dorsal nerve root
    • Ventral nerve root fibers carry motor information out of the spinal cord
    • Ventral nerve root houses cell bodies of multipolar motor neurons in the gray matter of the spinal cord

    Spinal Cord

    • Interneurons are located in the spinal cord's gray matter core
    • Spinal nerve is a single mixed nerve on each side of the spinal cord, merging dorsal and ventral nerve roots
    • Cauda equina is a bundle of nerve roots extending from the conus medullaris (inferior end of the spinal cord)

    Cauda Equina

    • Collection of spinal nerves descending from the spinal column's lower part (distal end)
    • Extends to the lower third of the spinal canal
    • Resembles a horse's tail, hence the name (Latin)

    Grey Matter

    • Composed of nerve cell bodies, dendrites, axon terminals (unmyelinated), and neuroglia
    • Pinkish-gray color due to a rich network of blood vessels
    • Forms an H shape, consisting of posterior, anterior, and lateral horns
    • Projections of gray matter toward the outer surface of the spinal cord are called horns

    Grey Matter

    • Dorsally-running posterior horns handle afferent input
    • Ventrally-running anterior horns oversee efferent somatic output
    • Laterally-running lateral horns are involved in autonomic function
    • Function: integration of spinal reflexes & filtering of info to higher centers
    • Cross reflexes function within the gray commissure

    White Matter

    • Composed primarily of myelinated nerve fibers, appearing whitish
    • Divided into three pairs of columns (funiculi): anterior, posterior, and lateral
    • Within each funiculus, bundles of fibers are called fasciculi
    • Ascending tracts carry sensory impulses to the brain
    • Descending tracts transmit motor impulses from the brain

    Learning Outcome 4

    • Describe the structure and function of spinal nerves
    • Define dermatome and myotome (skin & muscle areas supplied)
    • Compare somatic (voluntary) & autonomic (involuntary) structure & function
    • Compare sympathetic & parasympathetic structure & function
    • Differentiate the effects of the autonomic nervous system
    • Describe membrane potentials and impulse transmission processes

    Spinal Nerve

    • Mixed nerve carrying motor, sensory, & autonomic signals between spinal cord & body
    • 31 pairs roughly corresponding to vertebral column segments (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal)

    Types of Spinal Nerves

    • Cervical nerves supply movement & feeling to arms, neck, & upper trunk; control breathing
    • Thoracic nerves supply the upper back & trunk
    • Lumbar nerves supply the lower back, abdomen, thighs, knees, and calves
    • Sacral nerves supply lower back, legs, bladder, bowel, sexual organs
    • Coccygeal nerves innervate the coccygeal region

    Dermatomes

    • Regions of skin surface supplied by sensory fibers of a specific spinal nerve

    Myotomes

    • Skeletal muscle or muscle groups supplied by motor fibers of a given spinal nerve

    Cranial Nerves

    • 12 pairs of cranial nerves arising from the brain and controlling functions like sight, smell, taste, facial expressions, etc.
    • Identified by Roman numerals and names
    • Afferent & efferent nerve fibers run in pairs within them
    • Cranial nerve nuclei: cell groupings within the brain stem housing termination of sensory fibers & origin of motor fibers in cranial nerves.

    Somatic vs. Autonomic

    • Somatic controls voluntary body functions (skeletal muscles) with input from sense organs
    • Autonomic controls involuntary body functions (smooth muscles, glands) with input from internal receptors

    Comparison of Somatic & Autonomic Nervous Systems

    • Autonomic has two neurons, somatic one
    • Autonomic innervates smooth, cardiac muscle, glands; somatic, skeletal muscles
    • Autonomic often has dual antagonistic innervation; somatic does not

    Autonomic Nervous System (Sympathetic vs. Parasympathetic)

    • Sympathetic and parasympathetic systems work antagonistically on many organs
    • The sympathetic nervous system is dominant during danger and stressful events and promotes fight or flight response while parasympathetic is dominant during rest and control routine body activities

    Comparison of Sympathetic & Parasympathetic Systems

    • Structure: Origin, length of fibers, position of ganglia, transmitters
    • Function: Types of responses (increase vs. decrease), general effects (increase vs. decrease in metabolic levels, rhythmic activities)

    Difference in Effect of Autonomic Nervous System

    • Specific responses of various organs to sympathetic and parasympathetic stimulations. (e.g., pupil dilation/constriction, heart rate increase/decrease).

    Learning Outcome 5

    • Describes the concept of membrane potentials
    • Explains the formation of resting and action potentials
    • Describes the mechanism of impulse transmission & spreading along the axon
    • Explains the propagation of action potential along axon

    Action Potential

    • Resting Potential: Nerve at rest, holding a negative charge
    • Depolarization: A shift from negative to positive charge
    • Repolarization: A return to the negative resting potential
    • Refractory period: Period to recover from the action
    • Threshold: Level of stimulation required to produce an action potential

    Transmission of Impulse Along Axon

    • Action potential moves along axon automatically (without external stimulation)
    • Voltage-gated channels detect the reversal of membrane potential and respond
    • Refractory period prevents propagation backwards, ensuring unidirectional movement
    • Threshold triggers the opening of voltage-gated channels, leading to action potential propagation

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    Nervous System Part 3 PDF

    Description

    Test your knowledge on the anatomy and functions of the spinal cord. This quiz covers the composition of gray matter, the functions of spinal structures, and the classifications of spinal nerves. Perfect for students studying anatomy or neuroscience!

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