Ch. 12

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

Contralateral

Spinal nerves from the sacral region of the cord innervate the ____ muscles.

Leg

In the patellar reflex, identify the response observed and the effectors involved.

Leg extension and the effectors are the quadriceps femoris

Billy 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

In a ___ reflex, a sensory neuron synapses directly on a motor neuron.

Monosynaptic

Stretch reflex

Monosynaptic reflex that provides regulation of skeletal muscle length

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

Pia mater

A ___ reflex has at least one interneuron placed between the sensory and motor neurons

Polysynaptic

A ____ reflex has at least one interneuron placed between the sensory and motor neurons.

Polysynaptic

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

Posterior ramus

What is a reflex?

Rapid, automatic response triggered by a specific stimuli

A typical spinal cord has how many pairs of spinal nerves, and where does the spinal cord end?

31 pairs; lumbar vertebra 1 or 2

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

4

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

Columns

Define nerve plexus, and list the major nerve plexuses.

Complex, interwoven network of nerves; cervical, brachial, lumbar, and sacral

The epidural space contains

Connective tissue and blood vessels

Spinal nerves

Contain both sensory and motor

Which of the following describes the posterior root ganglion?

Contains cell bodies of sensory neurons

The ____ reflex complements the flexor reflex by activating contralateral muscles.

Crossed extensor

Reflexes, controlled by the spinal cord, act by

Motor output over spinal nerves to effectors

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

Move the face

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

A complex, interwoven network of nerves

Nerve plexus

The gray horns of the spinal cord contain mainly

Neuron cell bodies

The anterior rami form four major plexuses, including all of the following except the ____ plexus.

Nuchal

Identify the three layers of connective tissue of a spinal nerve and identify the major peripheral branches of a spinal nerve.

Outer epineurium, middle perineurium, & inner endoneurium; posterior ramus, anterior ramus, and rami communicantes

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

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

Damage to which nerve of the cervical plexus would interfere with the ability to breathe?

Phrenic nerve

Through which root of a spinal nerve does visceral sensory information arrive?

Posterior root

List the components of a reflex arc.

Receptor, sensory neuron, motor neuron, effector, and sometimes interneurons may be involved

Spinal interneurons inhibit antagonist motor neurons in a process

Reciprocal inhibition

What purpose does reflex testing serve?

Reflex testing provides information about the nervous system's functional status

Describe the lumbar plexus and sacral plexus.

The lumbar plexus is a nerve network formed by axons from the anterior rami of spinal nerve segments T12-L4; the sacral plexus is a nerve of spinal nerve segments L4-S4

A disease that damages myelin sheaths would affect which portion of the spinal cord?

White matter columns

The preganglionic fibers that carry visceral motor fibers and connect a spinal nerve with a sympathetic ganglion form the

White rami communicans

The posterior horns of the spinal cord contain mainly

Sensory nuclei

Which of the following associations is incorrect?

11 thoracic spinal nerves

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

A polysynaptic contralateral reflex

Describe the flexor reflex.

A stretch reflex is an example of a withdrawal reflex that contracts the flexor muscles of a limb in response to a painful stimulus.

The obturator nerve is distributed to the

Adductors of the hip

Identify the basic characteristics of polysynaptic reflexes.

All polysynaptic reflexes use interneurons, involve more than one spinal segment, involve reciprocal inhibition, and have reverberating circuits.

What are common characteristics of reflexes?

All reflexes are rapid, unconscious patterned responses to stimuli that restore and maintain homeostasis.

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

All three spinal meninges

Spinal reflex

An automatic response to a stimulus that is controlled in the spinal cord and can function without input from the brain

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

Anterior

A person with polio has lost the use of his leg muscles. In which area of the spinal cord would you expect the virus-infected motor neurons to be?

Anterior gray horns

Sensory input from interoceptors of the body walls and limbs is carried to the spinal nerve via the

Anterior rami

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

Anterior ramus

Which ramus carries sensory information from the limbs?

Anterior ramus

Nerve tracts or fasciculi make up the

Anterior white columns

Of the spinal meninges, the middle one is the ____ mater.

Arachnoid

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

Are arranged according to dermatomes

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 in the lumbar region of her spinal cord

The anterior root of a spinal nerve contains

Axons of motor neurons

Each peripheral nerve provides ____ innervation to peripheral structures.

Both sensory and motor

In which plexus does the ulnar nerve arise?

Brachial

The ventral rami of spinal nerves C4 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

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

Causes you to close your eyes when you sneeze

Describe the composition of the gray matter of the spinal cord.

Cell bodies of neurons, neuroglia, and unmyleniated axons

The posterior root ganglia mainly contain

Cell bodies of sensory neurons

The ___ plexus supplies innervation to the diaphragm.

Cervical

In a ____ neuronal pool, one neuron synapses on several postsynaptic neurons.

Diverging

Which ramus provides sensory and motor innervation to the skin and skeletal muscles of the back?

Dorsal/posterior ramus

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

Dura mater

The subdural space lies between the

Dura mater and arachnoid mater

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

Endoneurium

Define reinforcement as it pertains to spinal reflexes.

Enhancement of a spinal reflex through the facilitation of motor neurons involved in reflexes.

Name the structures and spinal coverings that are penetrated during a lumbar puncture procedure.

Epidermis, dermis, skeletal muscle, dura mater, arachnoid mater, subarachnoid space

The ____ space separates the dura mater from the walls of the vertebral canal.

Epidural

The outermost connective-tissue covering of nerves is the

Epineurium

The ____ is a strand of fibrous tissue that provides a 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

Gray commissures

The postganglionic fibers that connect a sympathetic ganglion and carry fibers that innervate glands and smooth muscle of the body wall or limbs are the

Gray rami communicans

The outward projections from the central gray matter of the spinal cord

Horns

Differentiate between divergent and convergent neural circuits.

In divergent circuits, information spreads from one neuron to several neurons. In convergent circuits, several neurons synapse with one postsynaptic neuron.

Enlargements of the spinal cord occur

In those spinal segments that control the limbs

Reflexes based on synapses formed during development are ____ reflexes.

Innate

All of the following are a part of a monosynaptic reflex except

Interneuron

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

Ipsilateral

The stretch reflex

Is important in regulating muscle length

Which of the following is not true of the spinal cord?

It interacts with the muscular system by initiating voluntary movement of skeletal muscles

What is the significance of the cauda equina?

It is made up of extensions of the posterior and anterior roots of spinal segments L2 to S5. It forms as the vertebral column continues to elongate after growth of the spinal cord ceases at about age 4.

Define a nerve plexus trunk and cord.

Large bundle of axons from several spinal nerves; a nerve plexus cord is a smaller branch of nerves that originates at a trunk

A viral disease that destroys the neuronal cell bodies of the anterior gray horn will

Lead to muscle weakness or paralysis

In ___, axon collaterals extend back toward the source of the impulse and further stimulate the earlier neurons.

Reverberation

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

Sciatic

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

Sciatic

Which nerve divides into the tibial nerve and common fibular nerve?

Sciatic

Describe the direction of sensory input and motor commands relative to the spinal cord.

Sensory input travels toward the spinal cord and motor commands travel away from the spinal cord

If the posterior root of a spinal nerve is severed,

Sensory input would be blocked

Differentiate between sensory nuclei and motor nuclei.

Sensory nuclei receive & relay sensory information from peripheral receptors; motor nuclei issue motor commands to peripheral receptors

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

Shingles

When an anesthetic blocks the function of the anterior rami of the cervical spinal nerves, which areas of the body will be affected?

Skin and muscles of the back of the neck and of the shoulders

The anterior horns of the spinal cord contain mainly

Somatic motor nuclei

A posterior and anterior root of each spinal segment unite to form a

Spinal nerve

The myotatic reflex is also known as the ___ reflex.

Stretch

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

Subarachnoid space

During the procedure known as a spinal tap, a needle is inserted into the ____ in the inferior ____ region.

Subarachnoid space; lumbar

List the major nerves of the sacral plexus.

Superior and inferior gluteal, posterior femoral cutaneous, sciatic, and pudendal nerves

Describe the brachial plexus.

The brachial plexus is a network of nerves formed by branches of spinal nerve segments C5-T1.

In the patellar reflex, how does stimulation of the muscle spindle by gamma motor neurons affect sensitivity and reaction time?

The muscle spindles become more sensitive and the reflex response occurs more quickly.

During a withdrawal reflex of the foot, what happens to the limb on the side opposite the stimulus? What is this response called?

The opposite is extended. This is called the crossed extensor reflex.

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

Usually cannot be suppressed by the brain

All of the following terms refer to ways that reflexes can be classified except

Voluntary

Reflexes can be classified according to all of the following except

Whether they are sensory or motor