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