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Spinal cord conducts signals up and down the body passing through gray and white matter, respectively.


Cervical and lumbar enlargements are wide points in the cord marking the emergence of motor nerves.


Each portion of the spinal cord served by a spinal nerve is called a segment of the cord.


Nerve fibers in a given tract in the white matter are similar in origin, destination, and function.


Motor signals typically begin in an upper motor neuron in the thalamus.


Most nerves are motor nerves.


A nerve fiber is enclosed in its own fibrous sleeve called perineurium


A ganglion is a swelling along a nerve containing cell bodies of peripheral neurons.


A dermatome is a nerve innervating a specific region in the skin.


Posterior root ganglia contain somas of unipolar neurons


Somatic reflexes are responses of skeletal, smooth and cardiac muscles.


The stretch reflex is a tendency of a muscle to stretch when it is overcontracted.


A stretch reflex is often accompanied by reciprocal inhibition.


The tendon reflex is the inhibition of a muscle contraction that occurs when its tendon is excessively stretched.


The cross extension reflex is the contraction of the extensors on one side of the body when the flexors are contracted on the other side

the precentral gyrus of the cerebrum.

The upper motor neurons that control skeletal muscles begin with a soma in

the corticospinal tract.

The signals that control your handwriting travel down the spinal cord in

the anterior horns.

Many upper motor neurons synapse with lower motor neurons in


Which of the following sensory functions involves neurons in the posterior root ganglia?


The spinal cord is divided into all of the following regions except

to protect neurons in both the ascending and descending tract.

The following are all functions associated with the spinal cord except

a fracture of vertebra L4

Which of the following fractures would be the least likely to cause a spinal cord injury

posterior root of a spinal nerve

This figure shows a detail of the spinal cord, meninges and spinal nerves. What does "1" represent?

arachnoid mater

This figure shows a detail of the spinal cord, meninges and spinal nerves. What does "4" represent?

dural sheath and vertebral bones

Epidural anesthesia is introduced in the epidural space between ___ to block pain signals during pregnancy.

anterior horn

This figure shows a cross section of the spinal cord. What does "3" represent?

arachnoid mater and pia mater.

Cerebrospinal fluid fills in the space between

white matter

Which of the following structures is the richest in lipid content?

neurosomas, dendrites, and proximal parts of axons of neurons.

Gray matter contains

Descending tracts

___ carry motor commands from the brain along the spinal cord


Second-order neurons synapse with third-order neurons in the


___ keep(s) nerve fibers insulated from one another.


___ fibers innervate eyes and ears.

cluster of neurosomas in the PNS.

A ganglion is a


There are __ pairs of spinal nerves.


This figure shows the anatomy of a nerve. What does "3" represent?

brachial plexus

This figure shows the posterior aspect of spinal nerve roots and plexuses. What does "3" represent?

the cervical enlargement

This figure shows the posterior aspect of spinal nerve roots and plexuses. What does "2" represent?

the thoracic region

The ventral rami of the spinal nerves form nerve plexuses in all regions except


The cervical plexus gives origin to the ___ nerve(s


Which of the following nerves originates in the coccygeal plexus?


This figure shows a dermatome map. A patient with no sensation in the left thumb would probably have a nerve damaged in

the gracile fasciculus

Which of these is an ascending tract of the spinal cord?

afferent and efferent fibers

A mixed nerve consists of both

posterior (dorsal) root

Which of the following branches of a spinal nerve have somas of solely sensory neurons?

cauda equina.

The bundle of nerve roots that occupy the vertebral canal from L2 to S5 is called the

the viscera.

Somatosensory refers to these sensory signals except the sensory signals from

posterior root ganglion; gray matter

Neurosomas of the posterior root are located in the ___, whereas neurosomas of the anterior root are located in the ___.

nerve; axons

A ___ is a cordlike organ composed of numerous ___.

somatic receptor afferent nerve fiber interneuron efferent nerve fiber skeletal muscle

Which one of the following best describes the order of a somatic reflex?

muscles of the hand

Which of the following groups of muscles have the most muscle spindles?

reflexes are spontaneous actions of the nervous system.

These are all properties of reflexes except

muscle fibers.

A muscle spindle contains mostly

flexor (withdrawal) reflex.

A nurse pricks your finger to type your blood. You flinch at the pain, pulling your hand back. This is called the


The quickest reflex arcs involve only two neurons, thus forming __ reflex arcs.

parallel after-discharge circuit

The flexor (withdrawal) reflex employs a ____, which maintains a sustained contraction.

an intersegmental reflex.

If a bee sting on the right thigh causes a quick involuntary reaction of the right arm, this would be an example of

gamma motor neurons.

The sensitivity of the muscle spindle is maintained by

alpha motor neurons.

The fibers that carry action potentials to cause skeletal muscle to contract are

stretch (myotatic) reflex.

You go to the movies after a long day and you begin to nod off as soon as the movie starts. Your head starts to lower a little but this reflex causes your head to rise. This is called the

contract and the antagonist muscles, the hamstrings, to relax.

In the patellar tendon reflex arc, the patellar ligament is stretched, which stretches the quadriceps femoris muscle of the thigh. This reflex will cause the quadriceps femoris to


A reflex where the sensory input and motor output are on opposite sides of the spinal cord is called a(n) _____ reflex arc.

prevents overcontraction of a muscle.

The tendon reflex

tendon reflex

This reflex shows the least synaptic delay.


Tendon organs are

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