Spinal Cord Anatomy and Meninges Review
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Questions and Answers

What does the central canal of the spinal cord contain?

  • Epineurium
  • Nerve fibers
  • Blood vessels
  • Cerebrospinal fluid (CSF) (correct)

    • White matter consists of cell bodies surrounding the central canal.

    False

    List the two main types of matter found in the spinal cord.

    Gray matter and white matter

    The _____ root contains sensory neurons that transmit signals to the spinal cord.

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

    What is the primary function of the spinal meninges?

    <p>To provide protection and stability</p> Signup and view all the answers

    Match the components of the spinal cord with their functions:

    <p>Dorsal root = Carries sensory information Ventral root = Carries motor information Gray matter = Contains cell bodies White matter = Contains axons</p> Signup and view all the answers

    The dura mater is the innermost layer of the meninges.

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

    Which of the following structures is located outside the gray matter area?

    <p>White matter</p> Signup and view all the answers

    At what vertebral level does the spinal cord typically end?

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

    The ________ layer of the meninges is separated from the pia mater by the subarachnoid space.

    <p>arachnoid mater</p> Signup and view all the answers

    The pia mater is the outermost layer of the spinal cord membranes.

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

    Match the following layers of the meninges with their descriptions:

    <p>Dura Mater = Tough fibrous outermost layer that stabilizes the spinal cord Arachnoid Mater = Middle layer with cerebrospinal fluid in the subarachnoid space Pia Mater = Deepest layer that is bound to spinal cord tissue Subarachnoid Space = Region where cerebrospinal fluid flows</p> Signup and view all the answers

    What structure is indicated by the posterior median sulcus in the spinal cord?

    <p>A groove located on the posterior side of the spinal cord</p> Signup and view all the answers

    Which layer of the meninges contains blood vessels?

    <p>Pia mater</p> Signup and view all the answers

    The ventral root and dorsal root come together to form the spinal nerve.

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

    What fluid flows within the subarachnoid space?

    <p>Cerebrospinal fluid</p> Signup and view all the answers

    What are the main components of a neuron?

    <p>Dendrites, soma, axon</p> Signup and view all the answers

    Neuroglia are responsible for processing information in the nervous system.

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

    What is the function of the axon in a neuron?

    <p>To conduct nerve impulses (action potentials) toward the synaptic terminals.</p> Signup and view all the answers

    The __________ are clusters of rough endoplasmic reticulum and free ribosomes found in neurons.

    <p>Nissl bodies</p> Signup and view all the answers

    Match the neuron types with their characteristics:

    <p>Anaxonic = Have more than two processes, but no true axon Bipolar = Have two processes separated by the soma Pseudounipolar = Have a single elongate process with a branching axon Multipolar = Have a single axon and multiple dendrites</p> Signup and view all the answers

    Which of the following neuronal structures contains the nucleus?

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

    Dendritic spines are responsible for conducting nerve impulses away from the cell body.

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

    What is the role of terminal boutons in a neuron?

    <p>To affect another neuron or effector organ (muscle or gland).</p> Signup and view all the answers

    A __________ neuron has a single axon and multiple dendrites.

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

    Match the neuron types with their respective characteristics:

    <p>Anaxonic = Often found in the brain and retina Bipolar = Common in sensory organs Pseudounipolar = Typical for sensory neurons Multipolar = Most common type in the human body</p> Signup and view all the answers

    What initiates the reflex arc associated with muscle contraction?

    <p>Stretching of muscle</p> Signup and view all the answers

    The sensory neuron is activated only after the motor neuron has been stimulated.

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

    What is the role of the spinal cord in the reflex arc?

    <p>It processes information received from sensory neurons.</p> Signup and view all the answers

    The __________ reflex is controlled by muscle spindles in the quadriceps muscle group.

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

    Match the following steps to their correct sequence in the reflex arc:

    <p>Stimulus (stretching of muscle) = 1 Activation of sensory neuron = 2 Information processing = 3 Activation of motor neuron = 4 Muscle contraction = 5</p> Signup and view all the answers

    Which of the following best describes an effector in the context of reflex actions?

    <p>Muscle that contracts in response to motor neuron activation</p> Signup and view all the answers

    The activation of motor neurons results in muscle contraction.

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

    What is the function of muscle spindles in the stretch reflex?

    <p>They detect the stretch of the muscle and activate sensory neurons.</p> Signup and view all the answers

    What is the first step in the pathway of a reflex arc?

    <p>Arrival of stimulus and activation of a receptor</p> Signup and view all the answers

    A reflex arc starts at a peripheral receptor and ends at a sensory receptor.

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

    What is the term for the neural wiring of a single reflex?

    <p>Reflex Arc</p> Signup and view all the answers

    The __________ is responsible for processing information in the reflex arc.

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

    Match the component of reflexes with its function:

    <p>Sensory receptor = Detects stimulus Motor neuron = Delivers response command CNS = Processes information Effector = Carries out the response</p> Signup and view all the answers

    Which of the following is NOT a step in the reflex arc mechanism?

    <p>Conscious decision making</p> Signup and view all the answers

    All reflex responses are voluntary.

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

    Describe the role of the dorsal root in a reflex arc.

    <p>The dorsal root carries sensory information to the CNS.</p> Signup and view all the answers

    Which column of the spinal cord contains sensory tracts?

    <p>Posterior white column</p> Signup and view all the answers

    The anterior white column contains descending motor tracts.

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

    Name one type of information conveyed by the lateral white column.

    <p>Motor tracts or sensory tracts</p> Signup and view all the answers

    The _____ ramus connects to smooth muscles, glands, and visceral organs.

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

    Match the following spinal plexuses with their corresponding spinal nerves:

    <p>Cervical plexus = C1–C5 Brachial plexus = C5–T1 Lumbar plexus = T12–L4 Sacral plexus = L4–S4</p> Signup and view all the answers

    What type of fibers do the dorsal roots contain?

    <p>Sensory fibers</p> Signup and view all the answers

    All spinal nerves are strictly motor in function.

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

    How many pairs of spinal nerves are there in total?

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

    The ____ white column is primarily responsible for conveying motor commands to skeletal muscles.

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

    Match the tracts with their functions:

    <p>Ascending tracts = Carry sensory information to the brain Descending tracts = Carry motor commands from the brain Visceral motor commands = Innervate internal organs Somatic motor commands = Innervate skeletal muscles</p> Signup and view all the answers

    Which of the following structures does NOT belong to the peripheral distribution of spinal nerves?

    <p>Lateral white column</p> Signup and view all the answers

    The visceral motor commands are mainly associated with skeletal muscle function.

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

    What type of sensory receptors do the dorsal roots receive information from?

    <p>Interoceptors, exteroceptors, and proprioceptors</p> Signup and view all the answers

    Study Notes

    Nervous System Overview

    • The nervous system controls and adjusts bodily activities, producing rapid but short-lived responses.
    • The system includes the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).

    Central Nervous System (CNS)

    • The CNS (brain and spinal cord) integrates, processes, and coordinates sensory input with motor output.
    • It's the center for intelligence, memory, learning, and emotions.
    • The CNS processes and coordinates sensory input and motor output.

    Peripheral Nervous System (PNS)

    • The PNS consists of all peripheral nerves and nervous tissue outside the CNS.
    • It delivers sensory information to and carries motor commands from the CNS.
    • The afferent division brings sensory information to the CNS.
    • The efferent division carries motor commands to muscles and glands.

    Overview

    • Information processing within the CNS leads to motor commands passing through the efferent division of PNS.
    • The Somatic and Autonomic Systems are components of the nervous system.
    • The autonomic system (efferent) is further subdivided, into voluntary and involuntary functions.
    • Sensory receptors receive information relayed to the CNS.

    Cellular Organization in Neural Tissue

    • Neurons transmit electrical signals throughout the body.
    • Neurons consist of a soma, axon, and dendrites.
    • Neuroglia support and protect the neurons.

    Neuron Structure

    • Dendrites receive stimuli from other cells or environmental changes.
    • The cell body contains the nucleus, ribosomes, mitochondria, etc.
    • The axon transmits electrical signals.
    • The axon terminal transmits signals.
    • An action potential travels down the axon.

    Nissl Bodies & Chromatophilic Substance

    • Nissl bodies and Chromatophilic substance are clusters of RER and free ribosomes.

    Structural Classification of Neurons

    • Anaxonic neurons have multiple processes, but axons are indistinguishable.
    • Bipolar neurons have two processes separated by the cell body.
    • Pseudounipolar neurons have a single process that elongates.
    • Multipolar neurons have one axon and multiple dendrites.

    Synapses

    • Synapses are intercellular communication sites.
    • There are synapses between neurons, between neurons and muscles (neuromuscular), and between neurons and glands (neuroglandular)
    • Synapses typically, involve a presynaptic cell, neurotransmitters, and a postsynaptic cell.

    Structure of a Synapse

    • Terminal arborization and terminal boutons are part of an axon's structure.
    • Neurotransmitters are released from the axon terminal boutons to affect postsynaptic neurons.
    • The synapse is an important structural feature that affects postsynaptic neurons.
    • A synapse’s structure dictates its functionality.
    • Vesicular Synapse is one type of synapse

    Multiple Synapses

    • Neurons can form multiple synapses.

    Neuronal Circuits

    • Divergence spreads signal to multiple neurons/pools in the CNS.
    • Convergence brings input to a single neuron/pool from multiple sources.
    • Serial processing works in a sequential manner.
    • Parallel processing works in a simultaneous manner.
    • Reverberation enables feedback mechanisms that can be either excitatory or inhibitory.

    Neuroglia Functions

    • They form the framework for neural tissue in the CNS.
    • They support the cellular environment.
    • They perform phagocytosis (immune cells).
    • They can reproduce (mitosis division).

    Neuroglia Cell Types in the CNS

    • Astrocytes
    • Oligodendrocytes
    • Microglia
    • Ependymal cells

    Neuroglia Cell Types in the PNS

    • Satellite cells
    • Schwann cells (neurolemmocytes)

    Classification of Neuroglia

    • Satellite cells and Schwann cells are PNS support glial cells.
    • Oligodendrocytes and Astrocytes are CNS support glial cells.
    • Different kinds of glial cells support neurons in different roles.

    Astrocytes

    • They have many cytoplasmic processes.
    • They control the chemical content of the interstitial environment.
    • They help maintain the blood-brain barrier.
    • They isolate neurons from general circulation.
    • They provide structural framework.
    • They help repair damaged neurons.
    • They guide neurogenesis.

    Blood-Brain Barrier

    • Tight junctions and astrocytes facilitate the blood-brain barrier function.
    • Tight junctions prevent the movement of solutes between endothelial cells.
    • Astrocyte feet secrete paracrines promoting tight junctions.

    Oligodendrocytes

    • Similar to astrocytes in function.
    • They have smaller cell bodies and fewer cytoplasmic processes.
    • They produce Myelin to wrap axons effectively.

    White Matter and Grey Matter

    • White matter contains myelinated axons; grey matter contains neuron bodies, dendrites, and unmyelinated axons.

    Myelination of the CNS (White matter)

    • Myelinated axons are in white matter, unmyelinated are in grey matter
    • Oligodendrocytes myelinate the axons of CNS (brain and spinal cord)
    • White matter and grey matter each have distinct neuron compositions.

    Neuroglia of the PNS

    • Satellite cells regulate matter exchange, while Schwann cells form myelin sheaths.
    • Schwann cells, also called neurolemmocytes, form the myelin sheath surrounding peripheral axons.

    Peripheral Axons & Schwann Cells

    • Every peripheral axon, myelinated or unmyelinated, is covered by Schwann cells (neurolemmocytes).

    Anatomy of a Peripheral Nerve

    • Epineurium surrounds the entire nerve.
    • Perineurium surrounds each fascicle (bundle of axons).
    • Endoneurium surrounds individual axons.

    Spinal Cord

    • The spinal cord conducts nerve impulses to and from the brain.
    • The spinal cord processes sensory information for reflex/motor actions.
    • It's about 45 cm long, passing from the brain to vertebra L1-L2.
    • It has cervical, thoracic, lumbar, sacral, and coccygeal regions.

    Gross Anatomy of the Spinal Cord

    • 31 spinal segments. Each segment has: dorsal root, dorsal root ganglia, ventral root, and spinal nerves.
    • The conus medullaris is the inferior tip of the spinal cord.
    • The cauda equina resembles a horse's tail.

    Spinal Meninges

    • These specialized membranes protect, stabilize, and absorb shock.
    • Continuous with cranial meninges.
    • Denticulate ligaments anchor the spinal cord.
    • Dura mater is the outermost, tough layer.
    • Arachnoid mater lies between dura and pia mater; cerebrospinal fluid flows in the subarachnoid space.
    • Pia mater is the deepest layer, tightly bound to the spinal cord.

    Sectional Anatomy of the Spinal Cord

    • Gray matter consists of the central canal (CSF filled), with neuron cell bodies and glial cells.
    • White matter contains axons organized into tracts (columns) located outside the gray matter.
    • Gray matter is organized into posterior, lateral, and anterior horns, and a gray commissure.
    • White matter contains posterior, lateral, and anterior columns, conveying sensory and motor tracts.

    Features of the Spinal Cord

    • Structures observed in a transverse (cross-section) view of the spinal cord include white matter, gray matter, central canal, anterior median fissure, and posterior median sulcus

    Organization of the Spinal Cord's Gray Matter

    • Neuronal cell bodies are organized into groups (nuclei) within the spinal cord's gray matter; sensory and motor nuclei are important distinctions—sensory nuclei receive information, motor nuclei send information.
    • Gray matter is organized into posterior, lateral, and anterior horns, in a transverse sectional view.
    • A gray commissure connects the anterior horns.

    Organization of the Spinal Cord's White Matter

    • Columns of nerves (funiculi) form the white matter.
    • Posterior, lateral, and anterior white columns exist.
    • Columns contain sensory and motor tracts (ascending and descending, respectively).

    Spinal Cord Sensory Information

    • Sensory information from the back, body wall, and limbs enters through the dorsal root.
    • Information enters sensory receptors and travels through the spinal cord.
    • Interoceptors for visceral organs and exteroceptors for body wall and limbs relay sensory input.
    • Rami communicantes are structures associated with sensory and visceral pathways

    Spinal Nerves

    • 31 pairs of nerves arise from the spinal cord. There are 8 cervical, 12 thoracic, 5 lumbar, and 5 sacral, and 1 coccygeal nerves.

    Reflexes

    • A reflex is an involuntary motor response.
    • The reflex arc is the neural pathway involved in a reflex.
    • A reflex arc starts at a sensory receptor and concludes at a peripheral receptor.
    • Reflex arcs include receptor, sensory neuron, interneuron, motor neuron, and effector regions.

    Pathway of a Reflex Arc

    • The sequence of events begins with sensory receptor activation, followed by sensory information relay to the CNS.
    • The CNS processes this information, triggering motor neuron response.
    • The response is then signaled to effectors.

    Spinal Reflexes (Stretch reflex)

    • A reflex action initiated when a muscle is stretched.
    • The stretch reflex is used for physical adjustments to maintain posture or balance.
    • Sensory neurons, spinal cord processing, and motor neuron activation cause the muscle to contract to return to its original length.

    Steps of a Stretch Reflex

    • Stimulus stretches the muscle.
    • Muscle spindle activation of sensory neurons
    • Sensory neuron information processing in CNS
    • Motor neuron activation occurs
    • Muscle contraction occurs as a response.

    Patellar Reflex

    • The patellar reflex is a stretch reflex involving quadriceps muscle spindles.
    • Striking the patellar tendon stretches the quadriceps muscle spindles, activating sensory neurons.
    • Spinal cord processing activates motor neurons in the quadriceps.
    • Resulting quadriceps contraction produces a reflexive kick.

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    Description

    Test your knowledge on the anatomy of the spinal cord and the layers of the meninges with this quiz. From the functions of different types of matter to the structure of the meninges, this quiz covers essential concepts. Perfect for students in anatomy or neuroscience classes.

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