Peripheral Nervous System Overview
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Questions and Answers

What is the primary function of myotomes in the nervous system?

  • To connect cranial nerves to the brain
  • To provide sensory input from the skin
  • To innervate muscles or muscle groups (correct)
  • To transmit signals between spinal nerves

    • Which of the following statements about cranial nerves is FALSE?

  • Cranial nerves are only motor in function (correct)
  • They arise from the undersurface of the brain and brainstem
  • They can be sensory, motor, or mixed
  • There are 12 pairs of cranial nerves

    • Which cranial nerve is primarily associated with the ophthalmic division of the trigeminal nerve?

  • Facial Nerve
  • Trigeminal Nerve (correct)
  • Hypoglossal Nerve
  • Optic Nerve

    • What method is used to identify cranial nerves?

    <p>By both numbers and names according to their order and function</p> Signup and view all the answers

    Shingles, also known as Herpes Zoster, affects which part of the nervous system?

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

    How many pairs of cranial nerves emerge from the brain?

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

    Which part of the spinal nerve is responsible for sensory input?

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

    What is the primary function of the ventral ramus?

    <p>To innervate muscles and glands in extremities and lateral portions of the body</p> Signup and view all the answers

    What is the main characteristic of mixed nerves?

    <p>They contain both sensory and motor fibers</p> Signup and view all the answers

    How many cervical nerve pairs are there?

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

    What do nerve plexuses primarily allow for?

    <p>Simplification of neural pathways by reducing the number of nerves</p> Signup and view all the answers

    Where do the lumbar, sacral, and coccygeal nerve pairs descend from?

    <p>Termination of the spinal cord at approximately L1</p> Signup and view all the answers

    Which spinal nerves are described as having no plexuses and run in segments directly to their body regions?

    <p>Thoracic nerves</p> Signup and view all the answers

    What is the primary function of the Cervical Plexus?

    <p>Innervates the diaphragm and parts of the neck and shoulders</p> Signup and view all the answers

    Which plexus is primarily responsible for innervating the thigh and leg?

    <p>Lumbar Plexus</p> Signup and view all the answers

    What nerves are included in the Brachial Plexus?

    <p>Radial, Ulnar, Median</p> Signup and view all the answers

    Which statement about the Sacral Plexus is correct?

    <p>It innervates the pelvic cavity and posterior thigh muscles.</p> Signup and view all the answers

    What is the role of the phrenic nerve?

    <p>To innervate the diaphragm</p> Signup and view all the answers

    What region does the Lumbar Plexus primarily innervate?

    <p>Thigh and leg</p> Signup and view all the answers

    What can dermatomes illustrate?

    <p>Sensory regions associated with spinal nerves</p> Signup and view all the answers

    Where is the Brachial Plexus located?

    <p>Deep in the shoulders</p> Signup and view all the answers

    Which of the following structures is part of the Sacral Plexus?

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

    What vertebral levels correspond to the Cervical Plexus?

    <p>C1-C4 and part of C5</p> Signup and view all the answers

    What is the primary function of the Olfactory Nerve (CN I)?

    <p>Sensory input for smell</p> Signup and view all the answers

    Which muscles are innervated by the Oculomotor Nerve (CN III)?

    <p>Medial rectus, superior rectus, inferior oblique, inferior rectus</p> Signup and view all the answers

    Which function is associated with the Vestibulocochlear Nerve (CN VIII)?

    <p>Hearing and balance</p> Signup and view all the answers

    What condition is typically caused by injury to CN VII (Facial Nerve)?

    <p>Bell's Palsy</p> Signup and view all the answers

    What does the Glossopharyngeal Nerve (CN IX) primarily innervate?

    <p>Tongue and pharynx</p> Signup and view all the answers

    How does the Vagus Nerve (CN X) affect the body's organs?

    <p>It innervates various visceral organs, influencing heart rate and digestion.</p> Signup and view all the answers

    What type of nerve is the Trigeminal Nerve (CN V)?

    <p>Mixed nerve with both sensory and motor components</p> Signup and view all the answers

    Which cranial nerve primarily helps in the swallowing process?

    <p>Glossopharyngeal Nerve (CN IX)</p> Signup and view all the answers

    Which cranial nerve is uniquely formed by a union of cranial and spinal roots?

    <p>Accessory Nerve (CN XI)</p> Signup and view all the answers

    What is the main function of the Hypoglossal Nerve (CN XII)?

    <p>Movement of the tongue muscles</p> Signup and view all the answers

    Which cranial nerve is responsible for detecting facial sensations?

    <p>Trigeminal Nerve (CN V)</p> Signup and view all the answers

    What is a common result of injury to the Abducens Nerve (CN VI)?

    <p>Double vision and inability to turn eye down and out</p> Signup and view all the answers

    Which cranial nerve is directly involved in facial expression?

    <p>Facial Nerve (CN VII)</p> Signup and view all the answers

    Study Notes

    Peripheral Nervous System (PNS)

    • The PNS comprises pathways to and from the CNS
    • It has 31 pairs of spinal nerves originating from the spinal cord
    • It also has 12 pairs of cranial nerves emerging from the brain
    • Spinal and cranial nerves branch to form the nerves in the body

    Spinal Nerves

    • Spinal nerves are not named descriptively, but are named according to their location on the vertebral column.
    • There are 8 cervical nerve pairs (C1-C8)
    • 12 thoracic nerve pairs (T1-T12)
    • 5 lumbar nerve pairs (L1-L5)
    • 5 sacral nerve pairs (S1-S5)
    • 1 coccygeal nerve pair
    • Spinal cord ends at approximately L1, and nerves from L1 and below descend to their exit point.
    • All spinal nerves are mixed nerves, formed of a dorsal root (sensory) and a ventral root (motor).

    Nerve Plexuses

    • Complex networks of nerves formed from ventral rami of spinal nerves (except T2-T12)
    • Fibers from several rami create "braids" that supply particular body regions.
    • Plexuses combine adjacent spinal nerve branches to reduce the number of nerves needed for particular areas
    • Examples: Cervical, Brachial, Lumbar, Sacral, Coccygeal

    Cervical Plexus

    • Located deep in the neck
    • Innervates muscles and skin in the neck, upper shoulders, part of the head

    Brachial Plexus

    • Located deep within the shoulders
    • Innervates lower parts of the shoulders, and entire arms

    Lumbar Plexus

    • Located in the lumbar region of the back
    • Innervates the thigh and leg

    Sacral and Coccygeal Plexus

    • Located in the pelvic cavity
    • Innervate parts of the leg, posterior thigh muscles, and leg/foot muscles
    • The coccygeal plexus innervates the floor of the pelvic cavity

    Dermatomes

    • Dermatomes define the sensory region of the body innervated by a particular spinal nerve.
    • The overlapping nature of dermatomes makes them less useful for precise diagnosis.

    Shingles

    • Shingles involves Herpes Zoster, affecting sensory nerve distribution.

    Myotomes

    • Myotomes refer to a muscle or muscle group supplied by a particular spinal nerve.
    • Their mapping is more challenging than dermatome mapping.

    Cranial Nerves

    • 12 pairs arising from brain's undersurface
    • Identified by numbers and names relating to their specific function and/or distribution
    • Some can be sensory only, motor only, or a combination of both
    • Detailed information on function can be found in specific texts or resources.

    Cranial Nerve Examples

    • Olfactory (I) -Sensory
    • Optic (II) - Sensory
    • Oculomotor (III) - Motor
    • Trochlear (IV) - Motor
    • Trigeminal (V) - Mixed (sensory and motor)
    • Abducens (VI) - Motor
    • Facial (VII) - Mixed
    • Vestibulocochlear (VIII) - Sensory
    • Glossopharyngeal (IX) - Mixed
    • Vagus (X) - Mixed
    • Accessory (XI) - Motor
    • Hypoglossal (XII) - Motor

    Common Cranial Nerve Injuries

    • Abducens (VI) - paralysis of the eye muscle causing the eye to turn in
    • Vestibulocochlear (VIII) - deafness
    • Facial (VII): loss of facial expression, drooping of the mouth corner (Bell's Palsy)

    Somatic Motor Nervous System

    • "Voluntary" motor pathways innervating skeletal muscles.
    • They use acetylcholine at the neuromuscular junction.
    • The function of peripheral motor pathways involves reflex arcs.

    Somatic Reflexes

    • Predictable responses to stimuli (conscious or unconscious).
    • The reflex arc pathway involves signal conduction between the CNS and peripheral effectors, often with interneurons.
    • Types include cranial reflexes (originating in the brain) and spinal reflexes (originating in the spinal cord).

    Clinically Important Somatic Reflexes

    • Knee-jerk (patellar) reflex
    • Ankle jerk reflex
    • Babinski sign
    • Corneal reflex
    • Abdominal reflex

    Withdrawal reflex (pain)

    • A reflex arc responding to pain by withdrawing a body part

    Autonomic Reflex Arc

    • Involves involuntary responses to stimuli.
    • Typically involves a sensory receptor, an afferent pathway, an integration center, an efferent pathway, and an effector.
    • Often involves more than one neuron in either the afferent or efferent pathway.

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    Related Documents

    Peripheral Nervous System - PARA 1002 PDF

    Description

    This quiz covers the structure and function of the Peripheral Nervous System (PNS), including spinal and cranial nerves. It explores the organization of spinal nerves and their roles in nerve plexuses, providing a comprehensive understanding of the pathways that connect the body to the central nervous system.

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