A&PII Chapter 13

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What is the source of the sensory signals carried by the cuneate fasiculus?

Upper limbs & chest

____ fibers are nerve fibers that innervate blood vessels, glands & internal organs

Visceral

The nerve signals of the medial vestibulospinal tract help in controlling position of the ____

head

Define Spinal Meningitis

inflammation of spinal meniges

Spinal meningitis

inflammation of spinal meninges

The ___ center of a reflex arc is located within the gray matter of the spinal cord or brainstem

integrating

An ____ reflex arc is a reflex arc in which the input & output occur at different levels of the spinal cord

intersegmental

Fibers from the cuneate fasciculus end on the ___ side of the medulla oblongata

ipsilateral

Define cauda equina

is a bundle of spinal nerves and spinal nerve roots, consisting of the second through fifth lumbar nerve pairs, the first through fifth sacral nerve pairs, and the coccygeal nerve, all of which arise from the lumbar enlargement and the conus medullaris of the spinal cord.

3 functions of the spinal cord

reflexes, conduction, locomotion

The second-order neurons of the spinoreticular tract terminate in the ___ formation of the brainstem

reticular

The ___ tract originates in the reticular formation

reticulospinal

The ___ tracts carry signals that control muscles of the upper & lower limbs, especially for posture & balance

reticulospinal

Moving peripherally from the spinal cord, the anterior & posterior ___ form the spinal nerve

roots

In a sensory pathway, the ___ order neuron runs from the spinal cord or brainstem to the thalamus

second

A syndrome called spinal ____ occurs early after spinal injury. It involves absence of reflexes & flaccid paralysis of muscles below the injury

shock

In a sensory pathway, the ___ order neuron runs from the thalamus to the sensory cerebral cortex

third

4 regions of the spinal cord

thoracic, lumbar, sacral, cervical

Examples of a somatosensory stimulus

touch, pressure, stretch, temperature, pain

Define Gamma Motor Neuron

type of lower motor neuron that takes part in the process of muscle contraction, and represents about 30% of fibers going to the muscle

The vestibular nuclei of the brainstem receives input from the ___ of the inner ear

vestibule

Define Rabies

viral disease that spreads via somatic motor nerve fibers to the CNS & then to ANS fibers

Define Lumbar Plexus

web of nerves (a nervous plexus) in the lumbar region of the body which forms part of the larger lumbosacral plexus. It is formed by the divisions of the first four lumbar nerves (L1-L4) and from contributions of the subcostal nerve (T12), which is the last thoracic nerve.

All spinal nerves except C1 pass through which structure to emerge from the vertebral column?

Intervertebral foramen

Within a muscle, how are intrafusal fibers structurally different from extrafusal fibers?

Intrafusal fibers have sarcomeres at their ends; the middle lacks sacromeres

What ramus of a spinal nerve innervates the local muscles, joints, & skin of the back?

Posterior

What type of signal does the spinocerebellar tract carry?

Proprioception

Muscle spindles are classified as what type of receptor?

Proprioceptor

___ is a viral infection that spreads via somatic nerve fibers to the CNS

Rabies

What is a tangle of nerve endings entwined in collagen fibers?

Tendon organ

What does contralateral mean?

That 2 points are on opposite sides of the body

What does ipsilateral mean?

That 2 points are on the same side of the body

True of False: The neural pathway of a flexor reflex is more complex than that for the tendon reflex

True

True or False: The flexor reflex uses an ipsilateral reflex arc

True

In descending pathways, the which motor neurons have their somas in the cerebral cortex or brainstem?

Upper

Define paraplegia

paralysis of both lower limbs

Define Intercostal Nerve

part of the somatic nervous system, and arise from the anterior rami of the thoracic spinal nerves from T1 to T11

Inferior to the medullary cone, the ___ mater forms the terminal filum

pia

The third-order neurons of the spinoreticular tract runs from the ____ to the thalamus

pons

The ___ median sulcus is a longitudinal groove on the dorsal surface of the spinal cord

posterior

The ____ roots are the spinal nerve roots that carry sensory nerve signals

posterior

The cuneate fasiculus is located in the ___ column of the spinal cord

posterior

In a patellar reflex, the effector is the ___ ____ muscle group of the thigh

quadriceps femoris

4 properties of a reflex

quick, stereotyped, requires stimulation, involuntary

In some reflexes, ____ inhibition is used to inhibit the action of antagonists so they don't oppose the reflex response

reciprocal

Within a nerve, each fascicle is wrapped in which layer?

Perineurium

Which meninx is closely associated with the contours of the spinal cord?

Pia mater

What is a reflex involving one or more interneurons called?

Polysynaptic

Place the spinal cord regions in order from superior to inferior.

1. Cervical 2. Thoracic 3. Lumbar 4. Sacral

Place the meninges in order from superficial to deep.

1. Dura mater 2. Arachnoid mater 3. Pia mater

Place the components of a reflex arc in order.

1. Receptor 2. Afferent nerve fiber 3. Integration center 4. Efferent nerve fiber 5. Effector

Within the spinal cord, which tracts carry motor signals down from the brain?

Descending

The number of neurons in a descending pathway is ____

2

Sensory pathways consist of a particular number of neurons. Sensory pathways consist of a chain of ___ (what number?) neurons in sequence.

3

There are ___ pairs of spinal nerves.

31

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

8 Cervical, 12 Thoracic, 5 Lumbar, 5 Sacral, 1 Coccygeal

What is the caudal equine?

A bundle of nerve roots occupying the vertebral canal from L2 to S5

What is a nerve?

A cord of nerve fiber bundles bound together by connective tissue

What is a region of the spinal cord supplied by a pair of spinal nerves called?

A segment

What is a reflex?

A stereotyped, involuntary response to a stimulus

During a crossed extension reflex, which nerve fibers cross to the contralateral side?

Afferent

Fact about tendon reflex

Alpha motor neurons are inhibited & the muscle does not contract as strongly

In which disease are motor neurons destroyed & sclerosis of the lateral spinal cord occurs?

Amyotropic lateral sclerosis

What is parathesia?

An abnormal sensation

The spinoreticular tract is found in which columns of the spinal cord?

Anterior & Lateral

The spinothalamic tract is found in which columns of the spinal cord?

Anterior & Lateral

Which spinal cord areas are composed of gray matter?

Anterior horn, Lateral horn, Posterior horn

What 2 things are considered a distal branch of a spinal nerve?

Anterior ramus & Posterior ramus

What are the 3 columns of white matter found in the spinal cord?

Anterior, Posterior, Lateral

Which meninx consists of simple squamous epithelium with a mesh of fibers in the adjoining space?

Arachnoid mater

Where do gamma motor neurons innervate a muscle spindle?

At the contractile end of each infrafusal fiber

Where are muscle spindles typically located?

At the ends of a muscle, near the tendons

Where does the spinal cord arise from the medulla oblongata?

At the foramen magnum

What are 4 names of a plexus?

Brachial, Cervical, Sacral, Lumbar

The first cervical spinal nerve emerges above vertebrae ____

C1

A spinal cord injury above which segment will lead to respiratory failure?

C4

Where do signals ascending through the spinocerebellar tract terminate?

Cerebellum

Which structure is formed from nerves C1-C5?

Cervical plexus

What ligament is formed by the fusion of the lumbar cistern & dura mater?

Coccygeal

Which rami connect the anterior rami to the sympathetic chain?

Communicating

Which rami of spinal nerves T1-T2 connect to the sympathetic chain ganglia?

Communicating

The spinal cord contains ascending & descending nerve fibers that send information between the CNS & the periphery. This illustrates which function of the spinal cord?

Conduction

In response to stretching, a muscle reflexively does what?

Contracts

____ is a term meaning "on the opposite side of the body"

Contralateral

In the spinoreticular tract, the second order neurons decussate to where?

Contralateral anterolateral system

In which reflex does a contralateral extensor muscle contract?

Crossed extension

What factor accounts for the fact that the right side of the brain communicates with the left side of the body, & vice versa?

Decussation

What is an area of skin innervated by a spinal nerve called?

Dermatome

What is the dural sheath around the spinal cord made of?

Dura mater

____ neurons carry information away from the CNS to an effector

Efferent

What carries the nerve signal to the effector in a reflex arc?

Efferent nerve fiber

True of False: Severing a sensory nerve root will completely deaden sensation from a dermatome

False

True or False: Reflex pathways always involve the cerebral cortex

False

What are meninges?

Fibrous connective tissue membranes covering the central nervous system

Which order neuron of the spinothalamic tract ends in the posterior horn at the point of entry to the spinal cord?

First

Define Posterior Spinocerebellar Tract

Flechsig's fasciculus, Flechsig's tract) conveys proprioceptive information from proprioceptors in the skeletal muscles and joints to the cerebellum.

What are the 4 possible effectors of a reflex?

Gland, Skeletal Muscle, Cardiac Muscle, Smooth Muscle

Where do the nerve fibers of the gracile fasciculus terminate in the medulla oblongata?

Gracile nucleus

Both somatic & autonomic reflexes are exaggerated in what?

Hyperreflexia

Which nerve tracts do not decussate & have their origin & destination on the same side of the body?

Ipsilateral

In the spinothalamic tract, where do the second order neurons decussate?

Just after the synapse between the first-order & second-order neuron

In an adult, the spinal cord ends at vertebrae ____

L1

In descending tracts, which motor neuron innervates the target organ?

Lower

The second-order neurons from the gracile & cuneate nuclei from what?

Medial Lemniscus

Which branch of a spinal nerve innervates the meninges?

Meningeal

Where are nerve signals carried by the gracile fasciculus from?

Midthroacic & lower parts of the body

What are intrafusal fibers?

Modified muscle fibers within a muscle spindle

The pollovirus destroys which neurons in the brainstem & anterior horn of the spinal cord?

Motor

What do muscle spindles monitor?

Muscle length & body movements

What is a type of stretch receptor embedded in skeletal muscle?

Muscle spindle

Where do the first-order neurons of the spinocerebellar tract originate?

Muscles & Tendons

Muscle spindles would be more abundant in what?

Muscles that require fine control

What is the term used to describe nerve pain?

Neuralgia

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

Neurogenic shock

What are 2 examples of nerves that carry only sensory information?

Optic nerve & Olfactory nerve

What is quadriplegia?

Paralysis of all 4 limbs

What is hemiplegia?

Paralysis on one side of the body

Which of these structures is closest to the spinal cord?

Rootlet

Nerve fibers of peripheral nerves are encased in ___ cells

Schwann

____ cells form a neurilemma & the myelin sheath around axons in the PNS

Schwann

Within the sensory pathway that ascends via the cuneate fasiculus, which order neuron is the one that decussates?

Second

The posterior root of a spinal nerve carries what type of nerve fibers?

Sensory

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

Sensory

Within the spinal cord, which tracts carry information up to the brain?

Sensory

Which disease results from herpes virus residing in a posterior root ganglion?

Shingles

A somatic fiber innervates which of the following?

Skin, skeletal muscles, bones & joints

_____ reflexes use receptors located in the skin, muscle, & tendons

Somatic

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

Somatic motor

___ fibers are nerve fibers that innervate more localized organs in the head (eyes, ears, olfactory & taste receptors, etc.)

Special

What is responsible for the inhibition of antagonistic contraction during a reflex response?

Spinal cord interneurons inhibit alpha neurons to the antagonists

What is an inflammation of the spinal meninges due to infection called

Spinal meningitis

The patellar reflex is an example of which type of reflex?

Stretch

____ reflexes are important in stabilizing joints because they balance the tension between extensors & flexors

Stretch

Where does the cerebrospinal fluid circulate?

Subarachnoid space

In the spinal cord, where is the white matter in relation to the gray matter?

Superficial

The lateral gray horns of the spinal cord are found in which segments of the spinal cord?

T2 to L1

What is the cervical enlargement of the spinal cord?

The area of the spinal cord that gives ride to the nerves of the upper limbs

Stretch reflexes are mediated primarily by what?

The brain

What is peripheral neuropathy?

The loss of sensory or motor function due to nerve injury

Into what cavity is an epidural anesthetic delivered?

The space between the vertebral bones & dural sheath

Define Lateral Reticulospinal Tract

This tract is divided into two parts, the medial (or pontine) and lateral (or medullary) reticulospinal tracts (MRST and LRST). The MRST is responsible for exciting anti-gravity, extensor muscles

What is a bundle of nerve fibers within the white matter of the spinal cord called?

Tract

What is severance of the spinal cord called?

Transection

When are tendon organs stimulated?

When a muscle contracts

____ matter is composed of myelinated & unmyelinated axons & is superficial to the gray matter of the spinal cord

White

Define Anterior Spinocerebellar Tract

a bundle of fibers originating in the base of the posterior horn and zona intermedia throughout lumbosacral segments of the spinal cord, crossing to the opposite side and ascending in a peripheral position in the ventral half of the lateral funiculus.

Define Posterior Ganglion

a cluster of nerve cell bodies (a ganglion) in a posterior root of a spinal nerve. The dorsal root ganglia contain the cell bodies of sensory neurons (afferent).

Define Terminal Filum

a delicate strand of fibrous tissue, about 20 cm in length, proceeding downward from the apex of the conus medullaris. It is one of the modifications of pia mater.

Define Lateral Corticospinal Tract

a descending motor pathway that begins in the cerebral cortex, decussates in the pyramids of the lower medulla

Define sensory nerve

a nerve containing only fibers carrying incoming nerve signals to the CNS

Define Tectospinal Tract

a nerve pathway that coordinates head and eye movements

Define sacral plexus

a nerve plexus which provides motor and sensory nerves for the posterior thigh, most of the lower leg and foot, and part of the pelvis

Define Fascicle

a small bundle of nerve fibers, enclosed by the perineurium

Define Rootlets

a small root 1 of the ultimate divisions of a nerve root.

Define Guilliain-Barre syndrome

actue demyelinating nerve disorder

A ____ nerve is a peripheral nerve carrying nerve signals to the CNS

afferent

An ____ peripheral fiber is a nerve fiber carrying nerve signals toward the central nervous system

afferent

Define Spinoreticular tract

an ascending pathway in the white matter of the spinal cord, positioned closely to the lateral spinothalamic tract. The tract is from spinal cord—to reticular formation— to thalamus. It is responsible for automatic responses to pain, such as in the case of injury.

The ___ ramus of a spinal nerve innervates the anterior end & lateral skin & muscles of the trunk & gives rise to the nerves of the limbs

anterior

The ____ horns of the spinal cord contain the cell bodies of outgoing somatic motor neurons

anterior

The ____ median fissure is a longitudinal groove on the ventral surface of the spinal cord

anterior

The intercostal nerves arise from the ___ rami of the ____ spinal nerves

anterior; thoracic

The _____ mater is just below (deep to) the dura mater.

arachnoid

The middle layer of the meninges is the ___ mater

arachnoid

The neural pathway that mediates a reflex is called a reflex ____, consisting of a receptor, afferent nerve fiber, interneurons, efferent nerve fiber, & effector

arc

The term "nerve fiber" refers to the ____ of a neuron

axon

Define Posterior Ramus

refers to the posterior division of a spinal nerve

A quick, involuntary, stereotyped response to a stimulus is called a _______

reflex

Define Cuneate Fasciculus

bundle of axon fibers in the posterior column-medial lemniscus pathway of the spinal cord and carries information from the middle thoracic and lower limbs of the body

Define Gracile Fasciculus

bundle of axon fibers in the posterior column-medial lemniscus pathway of the spinal cord and carries information from the middle thoracic and lower limbs of the body

The lumbar cistern is the name of the hollow space that contains the ____ _____ & cerebrospinal fluid

cauda equina

In the spinal cord, the ____ canal is lined with ependymal cells & contains cerebrospinal fluid

central

The central canal of the spinal cord contains _____ fluid

cerebrospinal

The left & right sides of the gray matter in the spinal cord are connected by the gray ____

commissure

Define Communicating Rami

communicating branch between a spinal nerve and the sympathetic trunk

Since the corticospinal tracts decussate, innervation to the muscles will be across the body or _____

contralateral

The ___ tract carries signals for precise, finely coordinated limb movements

corticospinal

The ____ tract is also called the pyramidal tract

corticospinal

The nerve fibers of the ______ tract from ridges called pyramids on the anterior surface of the medulla

corticospinal

What are extensions of the pia mater that anchor the spinal cord?

denticulate ligaments

Also known as a motor nerve fiber, a _____ fiber is a nerve fiber carrying nerve signals away from the central nervous system

efferent

External to the neurilemma of a nerve fiber is the layer of loose connective tissue that surrounds a nerve fiber called an _______

endoneurium

The ___ space is located between the vertebrae & the dural sheath around the spinal cord

epidural

The dense irregular connective tissue layer enclosing an entire nerve is called the ______

epineurium

The crossed ___ reflex is contralateral

extensor

Within a nerve, nerve fibers are gathered into bundles called ______

fascicles

A _____ is a tract of nerve fibers within column of the spinal cord

fasciculus

In a sensory pathway, the ___ order neuron detects the stimulus & transmits the signal to the spinal cord or brainstem

first

A quick contraction of flexor muscle in response to a painful stimulus is called a ___ reflex

flexor

A flexor reflex involves contraction of ____ muscles & reciprocal inhibition of ____ muscles

flexor; extensor

Within a muscle spindle, ___ motor fibers contract the ends of the intrafusal fibers

gamma

A ____ is a cluster of neuron cell bodies found outside of the CNS

ganglion

A ___ fiber innervates widespread organs such as muscles, skin, glands, viscera & blood vessels

general

The ___ matter of the spinal cord contains the synapse & therefore is the site of synaptic integration

gray

Where are the neuron cell bodies, dendrites, & synapses found in the CNS?

gray matter

A flexor reflex uses a ____ after-discharge neural circuit

parallel

Define Spinothalamic tract

is a sensory pathway from the skin to the thalamus. From the ventral posterolateral nucleus in the thalamus, sensory information is relayed upward to the somatosensory cortex of the postcentral gyrus.

Define Corticospinal Tract

is a small bundle of descending fibers that connect the cerebral cortex to the spinal cord

Conscious awareness of the stimulus ____ required for a reflex response to occur

is not

Define Brachial Plexus

is the network of nerves that sends signals from your spine to your shoulder, arm and hand. A brachial plexus injury occurs when these nerves are stretched, compressed, or in the most serious cases, ripped apart or torn away from the spinal cord.

Describe a muscle spindle

it contains 7 or 8 modified muscle fibers & a few nerve fibers enclosed in a fibrous capsule

Define Alpha Motor Neuron

large, multipolar lower motor neurons of the brainstem and spinal cord. They innervate extrafusal muscle fibers of skeletal muscle and are directly responsible for initiating their contraction

The anterior spinocerebellar tract is found in the ___ column of the spinal cord

lateral

In descending pathways, the upper motor neurons synapse with ___ motor neurons in the brainstem or spinal cord

lower

The ___ enlargement is the area of spinal cord that gives rise to the nerves of the lower limbs & pelvis

lumbar

The subarachnoid space inferior to the medullary cone is called the ____ ______

lumbar cistern

The _____ ______ is the tapered end of the spinal cord

medullary cone

A nerve containing both sensory & motor nerve fibers is called a ___ nerve

mixed

Spinal nerves are described as ___ nerves because they carry both afferent & efferent signals

mixed

Reflex pathways are more likely to be ____ than _____.

monosynaptic; polysynaptic

A _____ reflex arc consists of only one synapse between 2 neurons

monosynpatic

The anterior horns of the spinal cord contain somas of somatic ____ neurons

motor

Define extrafusal fibers

muscle fibers outside of a muscle spindle

The ____ tract carries signals for the sensation of pain resulting from tissue injury

spinoreticular

The space between the arachnoid mater & pia mater is called the ____ space

subarachnoid

The lateral horns of the spinal cord contain somas of ____ motor neurons

sympathetic

Define Medullary Cone

tapered, lower end of the spinal cord

A ____ reflex occurs in response to excessive tension on a tendon

tendon

Define Posterior Root

the 1 of the 2 roots of a spinal nerve that passes posteriorly to the spinal cord separating the posterior and lateral funiculi and that consists of sensory fibers

Define Anterior Ramus

the anterior division of a spinal nerve. The anterior rami supply the antero-lateral parts of the trunk and the limbs. They are mainly larger than the posterior rami.

Define Anterior Root

the efferent motor root of a spinal nerve. At its distal end, the ventral root joins with the dorsal root to form a mixed spinal nerve.

Define Perineurium

the sheath of connective tissue surrounding a bundle (fascicle) of nerve fibers within a nerve.


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