Rotation: Spinal Cord

Question 1

The axons now forming the lateral corticospinal tract will continue their caudal descent in the spinal cord until they reach their synaptic targets- a second neuron in the ______ of the spinal cord, called an alpha motorneuron.

Answer 1

ventral grey matter

Question 2

In the caudal medulla, approximately ___% of the fibers decussate.

Answer 2

80

Question 3

The nucleus gracilis’ axon immediately crosses the midline to ascend within the brainstem as part of a bundle called the _______.

Answer 3

medial lemniscus

Question 4

What happens when the anterior/ventral corticospinal tract reach their intended segment of the spinal cord?

Answer 4

they innervate not only the ipsilateral alpha motor neuron, but they also send a branch of their axon across the midline in a white matter band called the ventral white commisure to innervate some contralateral alpha motor neurons

Question 5

What is the corona radiata?

Answer 5

a bundle of white matter fibers extending from the cortex to the spinal cord

Question 6

This is a small band of white matter near the dorsal rootlet where pain and temperature afferents travel the spinal cord.

Answer 6

Lissauer’s fasciculus

Question 7

Alpha motor neurons located medially in the grey matter innervate _____ important for _____ and are innervated by the anterior corticiospinal pathways.

Answer 7

core muscles; posture

Question 8

What is the connection btw the caudate and the putamen called?

Answer 8

the ventral striatum

Question 9

The _____ splits into a medial caudate and a lateral putamen and globus pallidus- here they are part of white matter called the internal capsule.

Answer 9

corona radiata

Question 10

How does a dissociated sensory loss, in which one side of the body below the injury lacks pain and temperature sensation, and the other lacks dorsal column sensation, occur?

Answer 10

a hemisection injury of the spinal cord (Brown-Sequard syndrome)

Question 11

On the lateral surface of the brain, the primary motor cortex is found along the pre-central gyrus, just anterior to ______.

Answer 11

the central sulcus

Question 12

Alpha motor neurons located laterally in the ventral grey matter innervate muscles important for _____, like the ________. These neurons are innervated by the lateral corticospinal tract.

Answer 12

dexterity; fingers or thumb musculature

Question 13

What is upper motor neuron (UMN) syndrome?

Answer 13

1. muscles innervated by these lower motor neurons are weak.
2. There is an initial loss of reflex activity and muscle tone for a period between a few days and weeks.
3. After this time, the muscle tone and reflex activity returns in an exaggerated fashion (spasticity and hyperreflexia)

Question 14

On the lateral surface of the brain, the primary motor cortex is found along the ______, just anterior to the central sulcus.

Answer 14

pre-central gyrus

Question 15

The white matter fibers traverse the diencephalon laterally and then enter the midbrain, where they form a stalk-like white matter bundle called the ______- a part of the midbrain referred to as the cerebral peduncle.

Answer 15

crus cerebri

Question 16

The medial lemniscus will terminate on a third neuron in the pathway, located in a nucleus of the _____, called the ventral posteriolateral nucleus, or VPL.

Answer 16

thalamus

Question 17

What is the nucleus cuneatus?

Answer 17

a second order neuron in a nucleus lateral to the nucleus gracilis where axons about T6 synapse

Question 18

This is a second order neuron in a nucleus lateral to the nucleus gracilis where axons about T6 synapse.

Answer 18

the nucleus cuneatus

Question 19

The white matter fibers traverse the ______ laterally and then enter the ______, where they form a stalk-like white matter bundle called the crus cerebri- referred to as the cerebral peduncle.

Answer 19

diencephalon; midbrain

Question 20

The axons continue through the ____ then reemerge as part of a structure visible on the ventral surface of the medulla known as the pyramid.

Answer 20

pons

Question 21

What happens to the pt with a hemisection injury of the spinal cord (Brown-Sequard syndrome)?

Answer 21

a dissociated sensory loss, in which one side of the body below the injury lacks pain and temperature sensation, and the other lacks dorsal column sensation

Question 22

The axons now forming the lateral corticospinal tract will continue their caudal descent in the spinal cord until they reach their synaptic targets- a ______ in the ventral grey matter of the spinal cord, called ______.

Answer 22

second neuron; an alpha motorneuron

Question 23

What does the corticospinal tract divide into?

Answer 23

1. the anterior/ventral corticospinal tract
2. the lateral corticospinal tract

Question 24

Above ______, axons still enter the spinal cord at their respective segments, but then ascend in a white matter column that is just lateral to the fasciculus gracilis called the fasciculus cuneatus.

Answer 24

the T6 dermatome

Question 25

Dx?: * muscles innervated by these alpha motor neurons would fail to respond to commands from the UMNs, producing weakness * in those muscles, reflexes mediated by those segments would be attenuated * muscle tone would be decreased, producing hypotonia or flaccidity

Answer 25

lower motor neuron (LMN) syndrome

Question 26

The principal efferent pathway from the brain to the spinal cord is the \_\_\_\_\_\_\_.

Answer 26

corticospinal tract

Question 27

What is the column of white matter in the spinal cord called?

Answer 27

the lateral corticospinal tract

Question 28

\_\_\_\_\_\_\_ located medially in the grey matter innervate core muscles important for posture and are innervated by the anterior corticiospinal pathways.

Answer 28

Alpha motor neurons

Question 29

Alpha motor neurons located laterally in the ______ innervate muscles important for dexterity, like the fingers or thumb musculature. These neurons are innervated by the lateral corticospinal tract.

Answer 29

ventral grey matter

Question 30

The Babinski reflex is a hallmark of ____ syndrome.

Answer 30

UMN

Question 31

The axons continue through the pons then reemerge as part of a structure visible on the ventral surface of the medulla known as the \_\_\_\_\_\_.

Answer 31

pyramid

Question 32

The cells in layer 5 of the primary motor cortex are especially large- because of their shape they are known as “\_\_\_\_\_”, and these particular cells are called “\_\_\_\_\_."

Answer 32

pyramidal cells; Betz cells

Question 33

What does the anteriorlateral system (ALS) do?

Answer 33

transmits pain and temperature info

Question 34

These are the remaining 20% of white matter fibers that did not cross to the contralateral side.

Answer 34

the anterior/ventral corticospinal tract

Question 35

\_\_\_\_\_\_ located laterally in the ventral grey matter innervate muscles important for dexterity, like the fingers or thumb musculature. These neurons are innervated by the lateral corticospinal tract.

Answer 35

Alpha motor neurons

Question 36

The axons now forming the _______ will continue their caudal descent in the spinal cord until they reach their synaptic targets- a second neuron in the ventral grey matter of the spinal cord, called an alpha motorneuron.

Answer 36

lateral corticospinal tract

Question 37

What is Lissauer’s fasciculus?

Answer 37

a small band of white matter near the dorsal rootlet where pain and temperature afferents travel the spinal cord

Question 38

What is the ventral white commissure?

Answer 38

a white matter band arising from the anterior/ventral corticospinal tract that crosses the midline to innervate some contralateral alpha motor neurons

Question 39

The medial lemniscus will terminate on a third neuron in the pathway, located in a nucleus of the thalamus, called the \_\_\_\_\_\_.

Answer 39

ventral posteriolateral nucleus, or VPL

Question 40

The white matter fibers traverse the diencephalon laterally and then enter the midbrain, where they form a stalk-like white matter bundle called the crus cerebri- a part of the midbrain referred to as the \_\_\_\_\_\_.

Answer 40

cerebral peduncle

Question 41

This third order neuron in the thalamus will then innervate the \_\_\_\_\_\_.

Answer 41

primary somatosensory cortex

Question 42

This somatosensory pathway discriminative touch, vibration sense, and joint position sense or proprioception.

Answer 42

the Dorsal (or Posterior) Column/Medial Lemniscal (DC/ML) System

Question 43

What does the anterior/ventral corticospinal tract consist of?

Answer 43

the remaining 20% of white matter fibers that did not cross to the contralateral side

Question 44

Dx?: 1. muscles innervated by these lower motor neurons are weak. 2. There is an initial loss of reflex activity and muscle tone for a period between a few days and weeks. 3. After this time, the muscle tone and reflex activity returns in an exaggerated fashion (spasticity and hyperreflexia)

Answer 44

upper motor neuron (UMN) syndrome

Question 45

The corona radiata splits into a medial _____ and a lateral _____ and \_\_\_\_\_\_- here they are part of white matter called the internal capsule.

Answer 45

caudate; putamen and globus pallidus

Question 46

Alpha motor neurons located medially in the grey matter innervate core muscles important for posture and are innervated by \_\_\_\_\_.

Answer 46

the anterior corticiospinal pathways

Question 47

The principal _____ pathway from the brain to the spinal cord is the corticospinal tract.

Answer 47

efferent

Question 48

Fasciculations are a hallmark of _____ syndrome.

Answer 48

LMN

Question 49

This is a white matter band arising from the anterior/ventral corticospinal tract that crosses the midline to innervate some contralateral alpha motor neurons.

Answer 49

the ventral white commissure

Question 50

The nucleus gracilis' axon immediately ______ to ascend within the brainstem as part of a bundle called the medial lemniscus.

Answer 50

crosses the midline

Question 51

What is the internal capsule?

Answer 51

a bundle of white matter fibers w/I the basal ganglia that gives rise to the caudate, putamen, and globus pallidus

Question 52

What would happen to the muscle and reflex if the lower motor neuron was damaged or dysfunctional?

Answer 52

* muscles innervated by these alpha motor neurons would fail to respond to commands from the UMNs, producing weakness * in those muscles reflexes mediated by those segments would be attenuated * muscle tone would be decreased, producing hypotonia or flaccidity

Question 53

In the caudal medulla, approximately 80% of the fibers \_\_\_\_\_\_.

Answer 53

decussate

Question 54

The axon continues to ascend all the way to the bottom of the brainstem before it forms a synapse with a second neuron in the pathway, called the \_\_\_\_\_.

Answer 54

the nucleus gracilis

Question 55

This is dorsal gray matter in the spinal cord containing second order neurons in the pain/temperature afferent pathway.

Answer 55

the substantia gelatinosa

Question 56

Alpha motor neurons located laterally in the ventral grey matter innervate muscles important for dexterity, like the fingers or thumb musculature. These neurons are innervated by the \_\_\_\_\_\_\_.

Answer 56

lateral corticospinal tract

Question 57

What does the Dorsal (or Posterior) Column/Medial Lemniscal (DC/ML) System do?

Answer 57

transmits info about discriminative touch, vibration sense, and joint position sense or proprioception.

Question 58

The ______ will terminate on a third neuron in the pathway, located in a nucleus of the thalamus, called the ventral posteriolateral nucleus, or VPL.

Answer 58

medial lemniscus

Question 59

The cells in layer ___ of the primary motor cortex are especially large- because of their shape they are known as “pyramidal cells”, and these particular pyramidal cells are called “Betz cells."

Answer 59

5

Question 60

What is the 2 neuron pathway from brain to muscle?

Answer 60

* the Upper Motor Neuron (UMN) from brain to spinal cord * the Lower Motor Neuron (the alpha motor neuron) from spinal cord to neuromuscular junction

Question 61

Above the T6 dermatome, axons still enter the spinal cord at their respective segments, but then ascend in a white matter column that is just lateral to the fasciculus gracilis called \_\_\_\_\_\_.

Answer 61

the fasciculus cuneatus

Question 62

There are two principal pathways for transmission of somatosensory information to the central nervous system: the _____ and the \_\_\_\_\_.

Answer 62

1. the anteriorlateral system (ALS) 2. the Dorsal (or Posterior) Column/Medial Lemniscal (DC/ML) System

Question 63

On the lateral surface of the brain, the _____ is found along the pre-central gyrus, just anterior to the central sulcus.

Answer 63

primary motor cortex

Question 64

This is a bundle of white matter fibers extending from the cortex to the spinal cord.

Answer 64

corona radiata

Question 65

Name the 2 afferent/sensory pathways from the spinal cord to the brain.

Answer 65

1. the dorsal column/medial lemniscal system (aka the posterior column/medial lemniscal system- DCML) 2. the anterolateral system (aka the spinothalamic tract)

Question 66

The corona radiata splits into a medial caudate and a lateral putamen and globus pallidus- here they are part of white matter called the \_\_\_\_\_\_.

Answer 66

internal capsule

Question 67

The axons continue through the pons then reemerge as part of a structure visible on the ventral surface of the ______ known as the pyramid.

Answer 67

medulla

Question 68

Why does the pyramid taper caudally?

Answer 68

the majority of the fibers it contains are decussating- sharply crossing over to the other side of the neural tube, and turning dorsally as they do

Question 69

What is the subcentral gyrus?

Answer 69

connects the pre- and postcentral gyri

Question 70

The alpha motorneurons send their axons out the ______ of the spinal cord where they will ultimately innervate muscle tissue.

Answer 70

ventral rootlets

Question 71

This connects the pre- and postcentral gyri.

Answer 71

the subcentral gyrus

Question 72

What is the major role of the corticospinal tract?

Answer 72

voluntary control of skeletal muscle

Question 73

Once the axon enters the spinal cord via the dorsal rootlets, it will continue to ascend in a bundle of white matter called the \_\_\_\_\_\_.

Answer 73

fasciculus gracilis

Question 74

This somatosensory pathway transmits pain and temperature info.

Answer 74

the anteriorlateral system (ALS)

Question 75

What is the substantia gelatinosa?

Answer 75

dorsal gray matter in the spinal cord containing second order neurons in the pain/temperature afferent pathway

Question 76

What is the ventral striatum?

Answer 76

the connection btw the caudate and the putamen