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

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

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

How many pairs of cranial nerves emerge from the brain?

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

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

<p>Dorsal root (B)</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 (C)</p> Signup and view all the answers

What is the main characteristic of mixed nerves?

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

How many cervical nerve pairs are there?

<p>8 pairs (B)</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 (B)</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 (A)</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 (D)</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 (A)</p> Signup and view all the answers

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

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

What nerves are included in the Brachial Plexus?

<p>Radial, Ulnar, Median (D)</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. (B)</p> Signup and view all the answers

What is the role of the phrenic nerve?

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

What region does the Lumbar Plexus primarily innervate?

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

What can dermatomes illustrate?

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

Where is the Brachial Plexus located?

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

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

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

What vertebral levels correspond to the Cervical Plexus?

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

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

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

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

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

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

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

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

<p>Tongue and pharynx (C)</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. (A)</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 (D)</p> Signup and view all the answers

Which cranial nerve primarily helps in the swallowing process?

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

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

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

Which cranial nerve is responsible for detecting facial sensations?

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

Which cranial nerve is directly involved in facial expression?

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

Flashcards

Cervical Plexus

A network of nerves located in the neck that innervates the skin and muscles of the neck, upper shoulders, and parts of the head.

Brachial Plexus

A network of nerves located in the shoulder region that innervates the lower part of the shoulder and the entire arm.

Lumbar Plexus

A network of nerves located in the lumbar region (lower back) of the spine that innervates the thigh and leg.

Sacral Plexus

A network of nerves located in the pelvic cavity that innervates the skin of the leg, posterior thigh muscles, and leg/foot muscles. This includes the sciatic nerve.

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Phrenic Nerve

This nerve originates from the cervical plexus (C3, C4, C5) and innervates the diaphragm, a vital muscle for breathing.

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Referred Pain

When pain is perceived in a different location than the source of the pain.

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Dermatomes

Specific areas of skin innervated by a single spinal nerve root. The spinal nerve root's origin can be determined based on the associated area of the skin.

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Radial Nerve

A nerve of the brachial plexus that innervates the back of the arm and hand.

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Musculocutaneous Nerve

A nerve of the brachial plexus that innervates the front of the arm.

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Ulnar Nerve

A nerve of the brachial plexus that innervates the little finger and part of the ring finger.

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What are Spinal Nerves?

Spinal nerves are bundles of nerve fibers that emerge from the spinal cord and carry signals to and from the body.

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How are Spinal Nerves Named?

Spinal nerves are named based on the region of the spinal cord they emerge from, with numbers corresponding to the vertebral level.

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How many Spinal Nerve Pairs are there?

There are a total of 31 pairs of spinal nerves, emerging from the vertebral column.

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What are Rami?

Rami are branches or divisions of spinal nerves that carry signals to specific regions of the body.

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What is the Dorsal Ramus?

The dorsal ramus is a branch of a spinal nerve that carries sensory and motor signals to the back of the head, neck, and trunk.

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What is the Ventral Ramus?

The ventral ramus is a branch of a spinal nerve that carries signals to the limbs, front of the neck, and trunk.

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What are Nerve Plexuses?

Nerve plexuses are complex networks of nerves formed by the ventral rami of spinal nerves, responsible for supplying specific regions of the body.

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What is the Advantage of Nerve Plexuses?

Nerve plexuses provide flexibility and redundancy in nerve pathways, allowing for efficient innervation of specific body regions.

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Shingles (Herpes Zoster)

A viral infection affecting sensory nerve distribution, causing painful rash and blisters.

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L1 of Lumbar plexus

The first spinal nerve of the lumbar plexus, which contributes to the innervation of the lower back, hips, and legs.

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Ophthalmic Division of Trigeminal Nerve

One of the three branches of the trigeminal nerve, supplying sensory innervation to the forehead, eyelids, and upper face.

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Myotome

A muscle or group of muscles innervated by a specific spinal nerve. Some muscles have multiple nerve supplies.

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Olfactory Nerve (CN I)

The sensory nerve responsible for carrying olfactory information from the nasal cavity to the brain.

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Optic Nerve (CN II)

The sensory nerve that transmits visual information from the retina to the brain.

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Oculomotor Nerve (CN III)

A motor nerve that controls four of the six extrinsic eye muscles, allowing for eye movement and pupil constriction.

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Trochlear Nerve (CN IV)

Primarily a motor nerve responsible for innervating the superior oblique muscle, which rotates the eye downwards and outwards.

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Trigeminal Nerve (CN V)

A mixed nerve with both sensory and motor functions. It controls facial sensations and mastication.

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Abducens Nerve (CN VI)

Mainly a motor nerve that innervates the lateral rectus muscle, which rotates the eye laterally.

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Facial Nerve (CN VII)

A mixed nerve that controls facial expressions, taste sensation from the anterior two-thirds of the tongue, and innervates some glands.

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Vestibulocochlear Nerve (CN VIII)

A sensory nerve responsible for hearing and balance.

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Glossopharyngeal Nerve (CN IX)

A mixed nerve that controls swallowing, taste from the posterior third of the tongue, and innervates glands.

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Vagus Nerve (CN X)

A mixed nerve that controls various internal organs, regulates breathing and heart rate, and provides sensory feedback.

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Accessory Nerve (CN XI)

A motor nerve formed from both cranial and spinal roots, that helps with swallowing and neck/shoulder movement.

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Hypoglossal Nerve (CN XII)

A motor nerve that controls tongue movement, important for speech, chewing, and swallowing.

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Somatic Motor Nervous System

The voluntary system of motor neurons that innervates skeletal muscles, controlled by acetylcholine at the neuromuscular junction.

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Somatic Reflexes

Predictable, automatic responses to stimuli involving skeletal muscles, often occurring unconsciously via reflex arcs.

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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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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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