Chapter 13: Spinal Nerves and Reflexes Flashcards
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Questions and Answers

Which is the name of a plexus?

  • Brachial (correct)
  • Cervical (correct)
  • Sacral (correct)
  • Lumbar (correct)

    • The anterior rami of spinal nerves form which nerve plexuses?

  • Lumbar (correct)
  • Brachial
  • Sacral (correct)
  • Cervical (correct)

    • The posterior root of spinal nerve carries______nerve fibers.

    sensory

    Moving peripherally from the spinal cord, which anterior and posterior structures form the spinal nerve?

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

    The somas of which neurons are found within the posterior root ganglion?

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

    An anterior root of a spinal nerve contains axons of somatic_____neurons.

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

    Spinal nerves are described as______nerves because they carry both afferent and efferent signals.

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

    Which ramus of a spinal nerve innervates the local muscles, joints, and skin on the back?

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

    The larger____ramus of a spinal nerve innervates the anterior and lateral skin and muscles of the trunk and gives rise to the nerves of the limbs.

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

    The anterior root of a spinal nerve contains axons of which neurons?

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

    How many spinal nerves are there in order from superior to inferior?

    <p>8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal</p> Signup and view all the answers

    What are the four components of a monosynaptic somatic reflex arc?

    <p>Skeletal muscle, afferent nerve fiber, receptor in skin muscle or tendon, efferent nerve fiber</p> Signup and view all the answers

    Which type of reflex arc consists of only an afferent neuron and an efferent neuron?

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

    A reflex involving one or more interneurons is a monosynaptic reflex.

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

    Which branch of the spinal nerve is indicated by the arrow?

    <p>anterior ramus</p> Signup and view all the answers

    Within a nerve, nerve fibers are gathered into bundles called____.

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

    What is a quick, involuntary, stereotyped response to a stimulus called?

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

    What is an efferent fiber?

    <p>motor nerve fiber</p> Signup and view all the answers

    Within a nerve, each fascicle is wrapped in a layer called a______.

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

    What is the loose connective tissue surrounding an individual nerve fiber called?

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

    Which is composed of dense irregular connective tissue?

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

    A_____nerve is a peripheral nerve carrying nerve signals to the CNS.

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

    A____nerve is a nerve containing only fibers outgoing nerve signals from the CNS.

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

    The first cervical spinal nerve emerges above vertebrae____.

    <p>C1</p> Signup and view all the answers

    All spinal nerves except C1 pass through a____foramen to emerge from the vertebral column.

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

    Which rami connect the anterior rami to the sympathetic chain?

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

    Which rami of spinal nerves T1-L2 connect to the sympathetic chain ganglia?

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

    What are the properties of a reflex?

    <p>require stimulation, quick, involuntary, stereotyped</p> Signup and view all the answers

    The bundle indicated by the blue arrow is a____and contains several nerve fibers.

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

    Which structure is indicated by the arrow?

    <p>posterior root</p> Signup and view all the answers

    The connective tissue layer indicated by the arrow is the____.

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

    In the PNS, the____cells form a neurilemma and the myelin sheath around an axon.

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

    A nerve fiber refers to which part of the neuron?

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

    A____is a cordlike organ composed of numerous nerve fibers (fascicles) bound together by connective tissue.

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

    Which branch of the spinal nerve is indicated by the arrow?

    <p>posterior ramus</p> Signup and view all the answers

    ____fibers are nerve fibers that innervate blood vessels, glands, and internal organs.

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

    What structure is indicated by the arrow?

    <p>anterior root</p> Signup and view all the answers

    The structure indicated by the arrow is called the____root ganglion.

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

    Which are considered a distal branch of a spinal nerve?

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

    A somatic fiber innervates which of the following?

    <p>skin, skeletal muscles, bones, and joints</p> Signup and view all the answers

    A___nerve fiber innervates widespread organs such as muscles, skin, glands, viscera, and blood vessels.

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

    A special fiber innervates which of the following?

    <p>localized organs in the head (eyes, ears, olfactory and taste receptors, etc.)</p> Signup and view all the answers

    A___is a rapid, involuntary response to a stimulus.

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

    What is an afferent fiber?

    <p>sensory nerve fiber</p> Signup and view all the answers

    The connective tissue layer indicated by the arrow is the____.

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

    Which describes a mixed nerve?

    <p>a nerve containing both sensory and motor nerve fibers</p> Signup and view all the answers

    A___is an area of skin innervated by a spinal nerve.

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

    What is the relationship between efferent neurons and the CNS?

    <p>Efferent neurons carry impulses away from the CNS</p> Signup and view all the answers

    A quick contraction of flexor muscles in response to a painful stimulus is called a___reflex.

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

    Where are the receptors for somatic reflexes found?

    <p>skin, muscle, and tendons</p> Signup and view all the answers

    What are four possible effectors of a reflex?

    <p>cardiac muscles, smooth muscle, skeletal muscles, gland</p> Signup and view all the answers

    The cluster of nerves circled on the figure is the____plexus.

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

    What is the circled structure?

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

    What are two examples of nerves that carry only sensory information?

    <p>optic and olfactory nerve</p> Signup and view all the answers

    A___is a cluster of neuron cell bodies found outside of the CNS.

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

    Which type of stretch receptor is embedded in skeletal muscle?

    <p>muscle spindle</p> Signup and view all the answers

    The cluster of nerves indicated on the figure is the___plexus.

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

    What is the neural pathway that mediates a reflex called?

    <p>reflex arc</p> Signup and view all the answers

    The crossed___reflex is contralateral.

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

    Which carries the sensory nerve to the effector in the reflex arc?

    <p>afferent nerve fiber</p> Signup and view all the answers

    Nerve fibers of peripheral nerves are encased in which cells?

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

    Paralysis of all four limbs is called___

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

    What is the cluster of nerves indicated on the figure called?

    <p>sacral plexus</p> Signup and view all the answers

    What is the paralysis of both lower limbs called?

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

    The structures indicated by the circle are called____.

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

    The flexor reflex uses an ipsilateral reflex arc.

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

    The cluster of nerves indicated on the figure is the____plexus.

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

    Which is a somatosensory stimulus?

    <p>pressure, temperature, pain, touch, stretch</p> Signup and view all the answers

    Which stimulus causes a muscle to reflexively contract?

    <p>increased stretch</p> Signup and view all the answers

    Which spinal nerves carry sensory nerve signals?

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

    The dense irregular connective tissue layer enclosing an entire nerve is called the____.

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

    Which are the closest to the spinal cord?

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

    ____muscle fibers are modified muscle fibers within a muscle spindle.

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

    What structure is indicated by the arrow?

    <p>anterior root</p> Signup and view all the answers

    A____nerve fiber innervates widespread organs such as muscles, skin, glands, viscera, and blood vessels.

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

    Which branches of the spinal nerve are indicated by the arrow?

    <p>communicating rami</p> Signup and view all the answers

    The bundle indicated by the blue arrow is a____and contains several nerve fibers.

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

    In which reflex does a contralateral extensor muscle contract?

    <p>crossed extension</p> Signup and view all the answers

    The typical location for muscle____is at the ends of a muscle, near the tendons.

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

    What is hemiplegia?

    <p>paralysis of one side of the body</p> Signup and view all the answers

    A____reflex occurs in response to excessive tension on a tendon.

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

    ____fibers are working muscle fibers outside a muscle spindle.

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

    What branch of a spinal nerve innervates the meninges?

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

    The intercostal nerves arise from the anterior rami of the___spinal nerves.

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

    Which reflex is ipsilateral?

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

    A spinal cord injury above segment____will lead to respiratory failure.

    <p>C4</p> Signup and view all the answers

    What is a tendon organ?

    <p>proprioceptors located in a tendon near its junction with a muscle</p> Signup and view all the answers

    What is a drop in blood pressure due to loss of sympathetic stimulation to the blood vessels called?

    <p>neurogenic shock</p> Signup and view all the answers

    The____center of a reflex arc is located within the gray matter of the spinal cord or brain stem.

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

    Study Notes

    Spinal Nerves and Plexuses

    • Plexuses include Brachial, Cervical, Lumbar, and Sacral regions.
    • Anterior rami of spinal nerves form Cervical, Lumbar, and Sacral plexuses.
    • Spinal nerves carry both sensory (afferent) and motor (efferent) signals; thus, they are classified as mixed nerves.

    Structure and Function of Spinal Nerves

    • Anterior roots contain axons of motor neurons, while posterior roots carry sensory nerve fibers.
    • The posterior root ganglion houses the somas of sensory neurons.
    • Each spinal nerve has a posterior ramus that innervates local back muscles, joints, and skin, and a larger anterior ramus for anterior and lateral trunk innervation and limb nerves.

    Reflex Arcs

    • A monosynaptic reflex arc includes receptor in skin/muscle/tendon, afferent nerve fiber, efferent nerve fiber, and skeletal muscle as the effector.
    • Monosynaptic reflex arcs have only one afferent and one efferent neuron; those involving interneurons are classified as polysynaptic.
    • Reflexes require stimulation, are quick, involuntary, and stereotyped responses to stimuli.

    Nerve Fiber Types

    • Efferent fibers are motor fibers carrying signals from the CNS; afferent fibers are sensory fibers sending signals to the CNS.
    • General nerve fibers innervate widespread organs, while special fibers target localized organs, specifically in the head.

    Connective Tissue Layers

    • Nerve fibers are organized into bundles called fascicles, surrounded by connective tissue layers: endoneurium (individual fibers), perineurium (fascicles), and epineurium (entire nerve).

    Neuroanatomy and Injury

    • The first cervical spinal nerve emerges above the C1 vertebra; all spinal nerves except C1 exit through intervertebral foramina.
    • Spinal nerves from T1-L2 connect to the sympathetic chain through communicating rami.
    • Damage to spinal cord segments above C4 may lead to respiratory failure.

    Reflex Responses

    • A flexor reflex contracts flexor muscles in response to pain.
    • Tenon reflexes respond to excessive tension in tendons, while crossed extension reflexes involve contralateral extensor muscle contraction.
    • Specific regions of skin innervated by spinal nerves are called dermatomes.

    Pathway and Physiological Functions

    • A reflex arc includes an integrating center located in the spinal cord or brain stem which processes input and generates an output response.
    • Neurogenic shock results from loss of sympathetic stimulation to blood vessels, leading to blood pressure drops.

    Types of Paralysis

    • Quadriplegia refers to paralysis of all four limbs, while paraplegia describes paralysis of the lower limbs only. Hemiplegia results in paralysis on one side of the body.

    Sensory Perception and Reflex Conditions

    • Somatosensory stimuli include pressure, temperature, pain, touch, and stretch, which can trigger reflex actions.
    • Muscle spindles are sensory receptors located within muscles that respond to stretch.

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    Test your knowledge of spinal nerves and somatic reflexes with these informative flashcards. Covering key concepts such as plexuses and nerve fiber functions, this quiz is perfect for students studying human anatomy. Ideal for review or quick studying before exams.

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