chapter 13

The outward projections from the central gray matter of the spinal cord, seen easily in microscopic spinal cord cross sections, are called

horns

In which plexus does the ulnar nerve arise?

brachial

The ventral rami of spinal nerves C5 to T1 contribute fibers to the ________ plexus.

brachial

The white matter of the spinal cord contains

bundles of axons with common origins, destinations, and functions

The specific strip of skin that is innervated by a specific spinal nerve is called a

dermatome

In ________, one neuron synapses on several postsynaptic neurons.

divergence

The ________ of each spinal nerve innervates the skin and muscles of the back.

dorsal ramus

Blood vessels traveling within the ________ space deliver oxygen and nutrients to the spinal cord.

dura mater

The subdural space lies between

dura mater and arachnoid mater

The tough, fibrous, outermost covering of the spinal cord is the

dura mater.

The layer of connective tissue that surrounds individual axons within a peripheral nerve is termed the

endoneurium

The ________ separates the dura mater from the walls of the vertebral canal

epidural space

The outermost connective-tissue covering of nerves is the

epineurium

The dura mater tapers inferiorly to form the

coccygeal ligament

In the spinal cord, white matter is separated into ascending and descending tracts organized as

columns

A complex, interwoven network of nerves is called a

plexus

The complex, interwoven network formed by contributions from the ventral rami of neighboring spinal nerves is termed a(n)

plexus

A(n) ________ reflex has at least one interneuron placed between the sensory and motor neurons

polysynaptic

The condition in which a person loses all feeling and movement of the arms and legs due to spinal cord injury is termed

quadriplegia

The white ramus and the gray ramus collectively are called the

rami communicantes.

Spinal interneurons inhibit antagonist motor neurons in a process called

reciprocal inhibition

The neural "wiring" of a single reflex is called a(n)

reflex arc

As the ________ nerve approaches the knee, it divides into two branches, the fibular nerve and the tibial nerve

sciatic

Each of the following nerves originates in the lumbar plexus except the ________ nerve

sciatic

The dorsal root contains ________ neurons

sensory

If the dorsal root of a spinal nerve is severed,

sensory input would be blocked

The posterior horns of the spinal cord contain mainly

sensory nuclei.

In the condition ________, a virus infects dorsal root ganglia, causing a painful rash whose distribution corresponds to that of the affected sensory nerves as seen in their dermatomes

shingles

________ reflexes activate skeletal muscles

somatic

The anterior horns of the spinal cord contain mainly

somatic motor nuclei

Nerve tracts or fasciculi make up the

white columns

The preganglionic fibers that connect a spinal nerve with an autonomic ganglion in the thoracic and lumbar region of the spinal cord and carries visceral motor fibers that are myelinated form the

white rami communicantes

Which of the following is not true about a positive Babinski reflex?

why you close your eyes when you sneeze

The layer of the meninges in direct contact with the spinal cord is the

pia mater

the spinal cord consists of four regions and ________ segments

31

Which of the following associations is incorrect?

11 thoracic spinal nerves

After age ________, the vertebral column continues to elongate, but the spinal cord itself does not.

4

The spinal cord continues to elongate until about age

4

Which of the following is true regarding an epidural block?

It is commonly used as a method of pain control during labor and delivery, it affects only the spinal nerves in the immediate area of the injection, it can provide sensory and motor anesthesia, depending on the anesthetic selected, and it can provide mainly sensory anesthesia, depending on the anesthetic selected.

In an adult, the conus medullaris is found at about

L1.

Which statement is false regarding reflexes?

You have no conscious control or modification ability over reflex action.

In which of the following would the delay between stimulus and response be greater?

a polysynaptic reflex

The obturator nerve is distributed to the

adductors of the hip

All of the following are true of muscle spindles except that they

are found in tendons

Mary is in an automobile accident and suffers a spinal cord injury. She has lost feeling in her lower body. Her doctor tells her that swelling is compressing a portion of her spinal cord. Which part of her cord is likely to be compressed?

ascending tracts

The ventral root of a spinal nerve contains

axons of motor neurons

The dorsal root of a spinal nerve contains

axons of sensory neurons

Spinal nerves are

both sensory and motor

All of the following are true of neural reflexes except that they

cannot be modified by the brain

The dorsal root ganglia mainly contain

cell bodies of sensory neurons

The spinal cord is part of the ________ nervous system

central

Muscles of the neck and shoulder are innervated by spinal nerves from the ________ region

cervical

Reflexes that activate muscles on the opposite side of the body as the stimulus are called

contralateral

The ________ reflex complements the flexor reflex by activating contralateral muscles

crossed extensor

The ________ is a strand of fibrous tissue that provides longitudinal support to the spinal cord as a component of the coccygeal ligament

filum terminale

Axons crossing from one side of the spinal cord to the other within the gray matter are found in the

gray commissures

The postganglionic fibers that connect an autonomic ganglion in the thoracic or lumbar region with the spinal nerve and contain postganglionic fibers that innervate glands in the body wall or smooth muscles in limbs are

gray rami communicantes

In meningitis,

inflammation of the meninges occurs, bacteria can be the cause, viruses can be the cause, and CSF flow can be disrupted

Reflexes based on synapses formed during development are ________ reflexes

innate

The most complicated spinal reflexes are called

intersegmental reflex arcs

Reflexes that activate muscles on the same side of the body as the stimulus are called

ipsilateral

A viral disease that destroys the cells of the anterior gray horn will

lead to skeletal muscle weakness or paralysis

Spinal nerves from the sacral region of the cord innervate the ________ muscles

leg

Bill contracts a viral disease that destroys cells in the posterior gray horns in his spinal cord. As a result, which of the following would you expect?

loss of sensation in his torso

The ventral rami form four major plexuses, including all of the following except the ________ plexus.

nuchal

During the procedure known as a(n) ________, a needle is inserted into the subarachnoid space in the inferior lumbar region

lumbar puncture

If a person has a crush injury to the C3-C5 spinal segments, you would expect that he

might be unable to breathe on his own.

In a(n) ________ reflex, a sensory neuron synapses directly on a motor neuron

monosynaptic

The flexor reflex

moves a limb away from a painful stimulus

Recognized neuronal circuit patterns include all of the following except

multipolar.

The white matter of the spinal cord is mainly

myelinated axons

The gray horns of the spinal cord contain mainly

neuron cell bodies

Interneurons are organized into functional groups called

neuronal pools

You are sitting at a Mexican restaurant waiting for your food. The waiter brings a very hot plate, telling you to be careful about touching it. You touch it anyway, producing a pain sensation in your fingers, a withdrawal of your hand, and an auditory comment of what you are thinking. This scenario represents a ________ neuronal circuit.

parallel

The loss of feeling and movement of the legs is termed

paraplegia

The layer of connective tissue that surrounds a fascicle within a peripheral nerve is the

perineurium

The ________ nerve, which arises in the cervical plexus, innervates the diaphragm.

phrenic

The brachial plexus gives rise to all of the following nerves except the

phrenic

The nerve crucial for breathing that originates within the cervical plexus is called the ________ nerve.

phrenic

Blood vessels that supply the spinal cord run along the surface of the

pia mater

The specialized membranes that surround the spinal cord are termed the

spinal meninges

A dorsal and ventral root of each spinal segment unite to form a

spinal nerve

Cerebrospinal fluid flows within the

subarachnoid space

Samples of CSF for diagnostic purposes are normally obtained by placing the tip of a needle in the

subarachnoid space

Tina falls while climbing a tree and lands on her back. Her frightened parents take her to the emergency room, where she is examined. Her knee-jerk reflex is normal and she exhibits a plantar reflex (negative Babinski reflex). These results suggest that Tina has

suffered no damage to her spinal cord.

Postganglionic fibers of the autonomic nervous system that innervate internal organs are

sympathetic nerves

The reflex that prevents a muscle from exerting too much tension is the ________ reflex.

tendon

Into what spinal area would one inject a chemical whose purpose is to anesthetize the patient?

the epidural space

Suppose that you feel something brushing against your abdomen. The sensory information would be carried to the spinal cord over a(n) ________ ramus.

ventral

The ________ innervates the ventrolateral body surface, structures in the body wall, and the limbs

ventral ramus

Reflexes can be classified according to all of the following except

whether they are sensory or motor