Chapter 13: Spinal Nerves and Reflexes Flashcards

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?

roots Signup and view all the answers

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

sensory Signup and view all the answers

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

motor Signup and view all the answers

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

mixed Signup and view all the answers

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

posterior 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.

anterior Signup and view all the answers

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

motor Signup and view all the answers

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

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

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

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

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

monosynaptic Signup and view all the answers

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

False Signup and view all the answers

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

anterior ramus Signup and view all the answers

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

fascicles Signup and view all the answers

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

reflex Signup and view all the answers

What is an efferent fiber?

motor nerve fiber Signup and view all the answers

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

perineurium Signup and view all the answers

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

endoneurium Signup and view all the answers

Which is composed of dense irregular connective tissue?

epineurium Signup and view all the answers

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

sensory Signup and view all the answers

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

motor Signup and view all the answers

The first cervical spinal nerve emerges above vertebrae____.

C1 Signup and view all the answers

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

intervertebral Signup and view all the answers

Which rami connect the anterior rami to the sympathetic chain?

communicating Signup and view all the answers

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

communicating Signup and view all the answers

What are the properties of a reflex?

require stimulation, quick, involuntary, stereotyped Signup and view all the answers

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

fascicle Signup and view all the answers

Which structure is indicated by the arrow?

posterior root Signup and view all the answers

The connective tissue layer indicated by the arrow is the____.

epineurium Signup and view all the answers

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

Schwann Signup and view all the answers

A nerve fiber refers to which part of the neuron?

axon Signup and view all the answers

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

nerve Signup and view all the answers

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

posterior ramus Signup and view all the answers

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

visceral Signup and view all the answers

What structure is indicated by the arrow?

anterior root Signup and view all the answers

The structure indicated by the arrow is called the____root ganglion.

posterior Signup and view all the answers

Which are considered a distal branch of a spinal nerve?

Anterior ramus Signup and view all the answers

A somatic fiber innervates which of the following?

skin, skeletal muscles, bones, and joints Signup and view all the answers

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

general Signup and view all the answers

A special fiber innervates which of the following?

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

A___is a rapid, involuntary response to a stimulus.

reflex Signup and view all the answers

What is an afferent fiber?

sensory nerve fiber Signup and view all the answers

The connective tissue layer indicated by the arrow is the____.

perineurium Signup and view all the answers

Which describes a mixed nerve?

a nerve containing both sensory and motor nerve fibers Signup and view all the answers

A___is an area of skin innervated by a spinal nerve.

dermatome Signup and view all the answers

What is the relationship between efferent neurons and the CNS?

Efferent neurons carry impulses away from the CNS Signup and view all the answers

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

flexor Signup and view all the answers

Where are the receptors for somatic reflexes found?

skin, muscle, and tendons Signup and view all the answers

What are four possible effectors of a reflex?

cardiac muscles, smooth muscle, skeletal muscles, gland Signup and view all the answers

The cluster of nerves circled on the figure is the____plexus.

brachial Signup and view all the answers

What is the circled structure?

fascicle Signup and view all the answers

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

optic and olfactory nerve Signup and view all the answers

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

ganglion Signup and view all the answers

Which type of stretch receptor is embedded in skeletal muscle?

muscle spindle Signup and view all the answers

The cluster of nerves indicated on the figure is the___plexus.

cervical Signup and view all the answers

What is the neural pathway that mediates a reflex called?

reflex arc Signup and view all the answers

The crossed___reflex is contralateral.

extension Signup and view all the answers

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

afferent nerve fiber Signup and view all the answers

Nerve fibers of peripheral nerves are encased in which cells?

Schwann Signup and view all the answers

Paralysis of all four limbs is called___

quadriplegia Signup and view all the answers

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

sacral plexus Signup and view all the answers

What is the paralysis of both lower limbs called?

paraplegia Signup and view all the answers

The structures indicated by the circle are called____.

rootlets Signup and view all the answers

The flexor reflex uses an ipsilateral reflex arc.

True Signup and view all the answers

The cluster of nerves indicated on the figure is the____plexus.

lumbar Signup and view all the answers

Which is a somatosensory stimulus?

pressure, temperature, pain, touch, stretch Signup and view all the answers

Which stimulus causes a muscle to reflexively contract?

increased stretch Signup and view all the answers

Which spinal nerves carry sensory nerve signals?

posterior Signup and view all the answers

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

epineurium Signup and view all the answers

Which are the closest to the spinal cord?

rootlets Signup and view all the answers

____muscle fibers are modified muscle fibers within a muscle spindle.

intrafusal Signup and view all the answers

What structure is indicated by the arrow?

anterior root Signup and view all the answers

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

general Signup and view all the answers

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

communicating rami Signup and view all the answers

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

fascicle Signup and view all the answers

In which reflex does a contralateral extensor muscle contract?

crossed extension Signup and view all the answers

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

spindles Signup and view all the answers

What is hemiplegia?

paralysis of one side of the body Signup and view all the answers

A____reflex occurs in response to excessive tension on a tendon.

tendon Signup and view all the answers

____fibers are working muscle fibers outside a muscle spindle.

extrafusal Signup and view all the answers

What branch of a spinal nerve innervates the meninges?

meningeal Signup and view all the answers

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

thoracic Signup and view all the answers

Which reflex is ipsilateral?

False Signup and view all the answers

A spinal cord injury above segment____will lead to respiratory failure.

C4 Signup and view all the answers

What is a tendon organ?

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

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

neurogenic shock 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.

integrating 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.