chapter 14

What is the correct order for the parts of the spinal cord, from superior to inferior?

Cervical – thoracic – lumbar – sacral – coccygeal

A typical spinal cord in an adult is

16-18 inches long

In adults, the spinal cord is a different length than the vertebral canal, and most of the lumbar part of the spinal cord is within:

the thoracic vertebrae.

The inferior tip of the spinal cord is the ___________ part.

coccygeal

What is the thin strand of pia mater that helps to anchor the spinal cord to the coccyx?

Filum terminale

The spinal cord part with the largest diameter is the ___________ part.

cervical

The tapered, conical inferior end of the spinal cord is called the conus ___________.

medullaris

Each side of the spinal cord gives rise to _____ cervical nerves.

eight

The most inferior spinal nerve is:

Co1

Which statement accurately describes spinal nerves?

Each spinal nerve is mixed in that it contains some sensory axons and some motor axons.

Which space associated with the spinal cord meninges contains areolar connective tissue, blood vessels, and adipose connective tissue?

Epidural space

The subdural space is the region between the arachnoid mater and the dura mater.

TRUE

The spinal dura mater contains an outer periosteal layer and an inner meningeal layer.

FALSE

Which space associated with the spinal cord meninges contains cerebrospinal fluid?

Subarachnoid space

In a lumbar puncture (spinal tap), fluid is extracted from the:

subarachnoid space.

The most delicate of the meninges consists of elastic and collagen fibers and is known as the:

pia mater.

The innermost of the meninges is the pia mater.

TRUE

The posterior horns of the spinal cord contain:

axons of sensory neurons and cell bodies of interneurons.

The lateral horns of the spinal cord contain:

cell bodies of autonomic motor neurons.

This structure contains unmyelinated axons and serves as a communication route between the right and left sides of the gray matter in the spinal cord.

Gray commissure

Nuclei within the gray matter of the spinal cord that receive information from sensory receptors such as pain or pressure receptors in the skin are _____ nuclei.

somatic sensory

The _______ nuclei within the gray matter of the spinal cord send nerve impulses to skeletal muscles.

somatic motor

These nuclei are located in the lateral horns and innervate smooth muscle, cardiac muscle, and glands.

Autonomic motor nuclei

In sum, there are ____ pairs of spinal nerves.

31

The white matter of the spinal cord is surrounded by its grey matter.

FALSE

The lateral funiculus contains both ascending and descending tracts.

TRUE

The large section of spinal white matter that is found between the posterior gray horns is known as the posterior:

funiculus.

Which of the following accurately compares sections of spinal white matter?

A fasciculus is smaller than a funiculus.

An individual tract within the spinal cord contains either sensory nerve signals or motor nerve signals only.

TRUE

A conduction pathway consists of a:

tract and a nucleus.

A pathway has two parts: a bundle of CNS axons and a collection of neuron cell bodies in the CNS.

TRUE

Motor pathways are also called ascending pathways.

FALSE

Which accurately describes sensory and motor pathways?

Sensory pathways terminate in the brain, and motor pathways terminate at effectors.

Since most pathways decussate, each side of the brain processes information from the _________ side of the body.

contralateral

________ pathways have peripheral primary neurons and central secondary and tertiary neurons.

Sensory

Neurons of the thalamus that are part of sensory conduction pathways are considered:

tertiary neurons.

Information about temperature, proprioception, and pressure from skin, joints, and muscles is conveyed by:

somatosensory pathways.

Abdominal pain from digestive organs (e.g., from a stomach ulcer) would be conveyed to the brain by way of somatosensory pathways.

FALSE

The axons of primary sensory neurons make synaptic connections with:

secondary neurons in the CNS.

Neurons in the primary somatosensory cortex receive input from tertiary neurons that have their cell bodies residing in the thalamus.

TRUE

The fasciculus cuneatus is part of the:

posterior funiculus–medial lemniscal pathway.

The medial lemniscus is:

white matter in the brainstem that conducts information about proprioception and touch.

In both the anterolateral pathway and the posterior funiculus-medial lemniscal pathway, the axons of the ________ neurons decussate in the CNS.

secondary

Information about pain and temperature is conveyed to the brain by way of the:

anterolateral pathway.

The anterior spinocerebellar tract conducts signals about:

proprioception from the lower limbs.

The spinocerebellar pathway is an ascending somatosensory pathway.

TRUE

Some motor pathways originate in the cerebellum.

TRUE

The cell bodies of lower motor neurons are housed in the posterior horns of the spinal cord.

FALSE

The neurons that directly innervate skeletal muscles are called:

lower motor neurons.

The function of upper motor neurons is to:

excite or inhibit lower motor neurons.

Motor neurons that innervate the head and neck are located in the motor nuclei of cranial nerves and in the reticular formation.

TRUE

Lower motor neurons are always excitatory.

TRUE

The direct motor pathway originates in the:

motor cortex of the cerebral cortex.

The lateral corticospinal tracts include a ________ of the upper motor neuron axons that pass through the medulla, and they govern control of ___________.

majority, muscles used for finely controlled movements

The tectospinal tract is part of the medial pathway, which is an indirect motor pathway.

TRUE

Axons of the corticobulbar tracts:

do not pass through the spinal cord, as they synapse with lower motor neurons in brainstem cranial nuclei.

Axons of the anterior corticospinal tracts decussate in the medulla.

FALSE

Motor pathways are _________ tracts that control _________.

descending, effectors

Which of the rami is much smaller?

The posterior ramus

Which are not spinal nerve branches?

Lateral rami

A posterior root contains:

sensory axons only.

Which of the following structures is closest to the spinal cord?

Posterior rootlets

The third cervical spinal nerve exits the vertebral column through the:

intervertebral foramen between C2 and C3 vertebrae.

The second thoracic spinal nerve exits the spinal column through the:

intervertebral foramen between vertebrae T2 and T3.

If a patient experiences numbness in the boundaries of a dermatome, it is suggestive of damage to:

a spinal nerve.

The posterior ramus of a typical spinal nerve innervates the:

deep muscles of the back and the skin of the back.

The anterior ramus of a typical spinal nerve innervates the:

anterior and lateral trunk and the limbs.

A network of interwoven anterior rami of spinal nerves is a:

plexus.

The anterior rami of T1-T11 are called:

intercostal nerves.

The plexuses that lie on either side of the neck are the _____ plexuses.

cervical

If a person suffers a thorax-crushing injury and is unable to breathe properly, you would suspect that this nerve was damaged.

Phrenic nerve

The cervical plexus is formed by the:

anterior rami of spinal nerves C1-C4.

The plexus that supplies the upper limbs is the _________ plexus.

brachial

Which spinal nerves contribute to the brachial plexus?

C5-T1

Which of the following lists the components of the brachial plexus in correct order starting with the most medial?

Rami, trunks, divisions, cords

Within the axilla, axons of neurons are organized within:

three cords–the posterior, medial, and lateral cords.

The nerve that innervates the deltoid muscle and receives sensory input from the superolateral lateral arm is the:

axillary nerve.

Following an injury to his arm, a patient complains that he has no sensations from the thumb, index finger, middle finger, and part of the ring finger. What nerve do you suspect to be damaged?

Median nerve

Following an injury to his arm, a patient complains that he has lost the ability to flex his elbow and supinate his forearm. Which nerve do you suspect he has damaged?

Musculocutaneous nerve

Following an injury to his arm, a patient complains that he cannot extend the forearm, wrist, and digits. You suspect that he has damaged the:

radial nerve.

Following an injury to his arm, a patient complains that he has no sensations from his "pinky". You suspect that he has damaged the:

ulnar nerve.

A person suffering from carpal tunnel syndrome has lost function of the:

median nerve.

Two of the nerves of the lumbar plexus are the:

femoral and obturator nerves.

The nerve responsible for innervation (movement) of the quadriceps femoris muscle is the _____ nerve.

femoral

The obturator nerve innervates muscles of the lateral thigh.

FALSE

The largest and longest nerve in the body is the _________ nerve.

sciatic

This nerve helps to plant the foot and receives sensory signals from the skin of the sole.

Tibial nerve

The spinal nerves that give rise to the sacral plexus are:

L4-S4

Where the sciatic nerve splits, it branches directly to the:

tibial and common fibular nerves.

Reflexes are described as:

rapid and involuntary.

Usually, awareness of the stimulus occurs before a reflex action has been initiated.

FALSE

What is the correct order for the events that occur during a reflex? a: Impulse travels through sensory neuron to the CNS b: A stimulus activates a receptor c: Information is processed by interneurons d: Motor neuron transmits impulse to effector e: Effector responds

b, a, c, d, e

A reflex arc in which both the receptor and effector organs of the reflex are on the same side of the spinal cord is:

ipsilateral.

Late one night you are leaving the science building during a snowstorm. As you approach your car your right foot suddenly slips on a patch of ice. Your left leg immediately stiffens as you try to regain your balance. The reflex action you relied upon is a(n):

contralateral reflex.

Which type of reflex occurs with the smallest delay?

Monosynaptic

The simple knee-jerk reflex is an example of a(n) _____ reflex.

monosynaptic

Stepping on a piece of glass would most likely invoke a _____ reflex.

withdrawal

If someone steps on a sharp object with their right foot it will lead to:

polysynaptic reflexes involving contraction of the right hamstring and left quadriceps.

For many reflexes, including the stretch reflex, the excitation of a muscle leads to:

inhibition of motor neurons of its antagonist.

The Golgi tendon reflex:

prevents skeletal muscles from tensing excessively.

A monosynaptic reflex that monitors and regulates skeletal muscle length is a _____ reflex.

stretch

A diminished reflex response that may indicate damage to a segment of the spinal cord is a(n) _____ reflex.

hypoactive

Clonus often accompanies a ______ reflex after damage has occurred to the brain.

hyperactive

When the Achilles tendon is tapped or the bottom of the foot is stroked, the reflexive response is that the foot:

plantar flexes.

The embryonic feature that gives rise to the anterior and lateral horns of gray matter is the _____ plate.

basal

The alar plate of the embryo develops into the gray commissure of the spinal cord.

FALSE

The adult spinal cord extends inferiorly from the brain through the vertebral canal and ends at the level of the _____ vertebra.

L1

The nerves projecting inferiorly from the spinal cord are collectively called the:

cauda equina.

The cell bodies of sensory neurons are located in the:

posterior root ganglion.

Which of these spinal nerve counts is incorrect?

Thoracic nerves = 8 pairs

In the brain, the outer cerebral cortex consists of gray matter, but in the spinal cord, gray matter is confined to the innermost regions.

TRUE

In general, nerves from the posterior division of the brachial plexus tend to innervate muscles that extend the parts of the upper limb.

TRUE

A monosynaptic response is one that does not involve an interneuron.

TRUE