Learn Smart 13

How many neurons are typically found in an ascending pathway between the receptor and the brain?

3

How many spinal nerves are in each region of the spinal cord in order from superior to inferior?

8,12,5,5,1

What is a reflex?

A stereotyped, involuntary response to a stimulus

What is a muscle spindle?

A type of stretch receptor embedded in skeletal muscle

In which disease does sclerosis of the lateral spinal cord occur, with destruction of motor neurons?

Amyotrophic lateral sclerosis

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

Anterior and lateral

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

Anterior and lateral

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

Ascending

Where does the spinal cord arise from the medulla oblongata?

At the foramen magnum

What is the white matter of the spinal cord?

Bundles of myelinated and unmyelinated axons found superficial to the gray matter

Where do signals ascending through the spinocerebellar tract terminate?

Cerebellum

The anterior rami of spinal nerves form which nerve plexuses?

Cervical, lumbar, sacral

Which tract will have its origin and destination of opposite sides of the body?

Contralateral

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

Contralateral anterolateral system

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

Decussation

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

Dermatome

What is the order of the meninges from superficial to deep?

Dura mater, arachnoid mater, pia mater

In a sensory pathway, which neuron detects the stimulus and transmits the signal to the spinal cord or brainstem?

First order

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

Gracile nucleus

Where does the first-order neuron of the spinothalamic tracts end?

In the posterior horn at the point of entry

All spinal nerves except C1 pass through a(n) foramen to emerge from the vertebral column.

Intervertebral

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

Intervertebral foramen

Which tract will have its origin and destination on the same side of the body?

Ipsilateral

In an adult, the spinal cord ends at which vertebra?

L1

A reflex arc consists of only one synapse between two neurons.

Monosynaptic

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

Monosynaptic

The poliovirus destroys which neurons in the brainstem and anterior horn of the spinal cord?

Motor

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

Muscle spindle

Which viral disease results in the destruction of motor neurons?

Poliomyelitis

Which are functions of the spinal cord?

Reflexes Conduction Locomotion

Moving peripherally from the spinal cord, the anterior and posterior form the spinal nerve.

Roots

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

Roots

In a sensory pathway, which neurons run from the spinal cord or brainstem to the thalamus?

Second-order

What effect does severing a sensory root that innervates a dermatome have?

Some sensation may remain.

Signals for proprioception are carried by the anterior and posterior tract.

Spinocerebellar

Where do the third-order neurons of the spinoreticular tract run from the pons to?

Thalamus

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

Upper

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

Upper limbs and chest

The spinothalamic tract is part of the ______ system in the anterior and lateral columns.

anterolateral

Which are nerve plexuses of the body?

brachial, lumbar, cervical, sacral

What is a nerve?

bundle of neurons

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

conduction

Because the nerve tracts of the spinal cord undergo , the right side of the brain communicates with the left side of the body, and vice versa.

decussation

The nerve fibers of the gracile fasciculus terminate at the nucleus of the medulla oblongata.

gracile

Fibers from the cuneate fasciculus end on the ______ side of the medulla oblongata.

ipsilateral

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

lower

The ______ motor neurons (which are the motor neurons connecting the brainstem and spinal cord to muscle fibers) of the descending pathway innervate skeletal muscle.

lower

Within the spinal cord, what type of information do the descending tracts carry?

motor

A is a cordlike organ composed of numerous nerve fibers (fascicles) bound together by connective ti

nerve

What does contralateral mean?

on the opposite side of the body

What does ipsilateral mean?

on the same side of the body

The spinoreticular tract carries what type of signals?

pain

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

pons

A is a rapid, involuntary response to a stimulus.

reflex

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

reticular

In the spinothalamic tract, the ______ -order neurons decussate from the posterior horn of the spinal cord.

second

Which pathways are made up of three neurons?

sensory

How many neurons are found in a descending tract?

two

The number of neurons in a descending pathway is

two

Consider the two motor neurons that form descending pathways. The neurons called the motor neurons have their somas in the cerebral cortex or brainstem.

upper

matter is composed of myelinated and unmyelinated axons and is superficial to the gray matter of the spinal cord.

white