Ch. 13 Spinal Cord, Spinal Nerves, and Spinal Reflexes

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

a polysynaptic reflex (GREATER) a monosynaptic reflex

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

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

pia mater.

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

spinal tap

Which of the following associations is incorrect?

11 thoracic spinal nerves (INCORRECT) 8 cervical spinal nerves 5 lumbar spinal nerves 5 sacral spinal nerves 1 coccygeal spinal nerve

The spinal cord consists of five regions and ________ segments.

31

The spinal cord continues to elongate until about age

4 years old

In meningitis,

CSF flow can be disrupted. viruses can be the cause. bacteria can be the cause. inflammation of the meninges occurs. all of the above

Visceral reflexes provide a mechanism for control of the abdominal muscles.

False

Which of the following is true regarding an epidural block?

It affects only the spinal nerves in the immediate area of the injection. It provides mainly sensory anesthesia. It can be difficult to achieve in the upper cervical and midthoracic region. It is commonly used as a method of pain control during labor and delivery. all of the above

In an adult, the conus medullaris is found at about

L1

________ reflexes activate skeletal muscles.

Somatic

The dorsal root of a spinal nerve contains

axons of sensory neurons.

The obturator nerve is distributed to the

adductors of the hip.

Axons cross from one side of the spinal cord to the other through the

anterior white commissure

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

Postganglionic fibers of the autonomic nervous system that innervate internal organs do not rejoin the spinal nerve but form

autonomic nerves.

The ventral root of a spinal nerve contains

axons of motor neurons.

Spinal nerves are

both sensory and motor.

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

brachial sacral cervical lumbar nuchal (NOT)

The white matter of the spinal cord contains

bundles of axons with common origins, destinations, and functions.

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.

The dorsal root ganglia mainly contain

cell bodies of sensory neurons.

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

cervical

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

The epidural space contains

connective tissue and blood vessels.

The region of the body surface monitored by a pair of spinal nerves is known as a(n) __________.

dermatome

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

dorsal ramus

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

dura mater.

A reflex arc always includes a(n) __________.

efferent axon, afferent axon, sensory receptor

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 ________ is a strand of fibrous tissue that provides longitudinal support 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 are

gray rami communicantes.

Enlargements of the spinal cord occur

in those spinal segments that control the limbs.

Reflexes based on synapses formed during development are ________ reflexes.

innate

The most complicated spinal reflexes are called ________.

intersegmental reflex arcs

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

involve at least two neurons. cannot be modified by the brain. (NOT) are automatic motor responses. are the simplest form of behavior. help preserve homeostasis.

The stretch reflex

is important in regulating muscle length and activated when a skeletal muscle lengthens.

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

lead to 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

Somatic motor neurons in the spinal cord control all of the following muscles, except those that

move the neck.(NOT) move the hand and fingers. position the pectoral girdle. move the forearm and hand. move the arm.

The white matter of the spinal cord is mainly

myelinated axons.

The gray horns of the spinal cord contain mainly

nerve cell bodies

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

normal in newborns why you close your eyes when you sneeze (NOT) abnormal in adults flaring of the toes when the sole is stroked a sign of injury to descending spinal tracts

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

perineurium

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

quadriplegia

Loss of feeling in the thumb and first two fingers is most likely due to a damaged ________ nerve.

radial

Spinal interneurons inhibit antagonist motor neurons in a process called

reciprocal inhibition.

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

sciatic

The largest peripheral nerve is the ________ nerve.

sciatic

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

sciatic(NOT) obturator genitofemoral femoral saphenous

If the dorsal root of a spinal nerve is severed,

sensory input would be blocked.

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

spinal nerve.

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

Compared to the vertebral column, the spinal cord is

shorter

The large anterior gray horns of the spinal cord contain mainly

somatic motor nuclei

The anterior horns of the spinal cord contain mainly

somatic motor nuclei.

The specialized membranes that surround the spinal cord are termed the

spinal meninges.

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.

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

tendon

The subdural space lies between

the dura mater and the arachnoid mater.

Bundles of axons in the central nervous system are known as

tracts

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

ulnar. radial. median. phrenic.(NOT) musculocutaneous.

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

where information processing occurs. whether they are sensory or motor. (NOT) their development. the complexity of the neural circuit. the motor response.

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 form the

white rami communicantes.