N4N The Motor System

Front 1

Which areas participate in important feedback loops in which they project back to the cerebral cortex via the thalamus and do not themselves project to lower motor neurons?

Back 1

Basal ganglia and the cerebellum

Front 2

__________ carry motor system outputs to __________.

Back 2

Upper motor neurons
Lower motor neurons

Front 3

Descending upper motor neurons arise from the ____ and ____. And can be divided into ______ and _______

Back 3

cerebral cortex
brainstem
lateral motor systems
medial motor systems

Front 4

__________ carry motor system outputs to __________.

Back 4

Upper motor neurons
Lower motor neurons

Front 5

Descending upper motor neurons arise from the ____ and ____. And can be divided into ______ and _______

Back 5

cerebral cortex
brainstem
lateral motor systems
medial motor systems

Front 6

The lateral corticospinal tracts are essential for ______.

Back 6

Rapid, dextrous movements at individual digits or joints.

Front 7

How does the lateral corticospinal tract travel down?

Back 7

They cross over from their point of origin and descend to the contralateral lateral spinal cord to control the contralateral extremities.

Front 8

Over half of the corticospinal tracts originate from the ___. The remainder arise from the ____,_____ or ______.

Back 8

Primary motor cortex.
Premotor
supplementary motor
parietal lobe areas

Front 9

The two lateral motor systems are:

Back 9

The lateral corticospinal tract and the rubrospinal tract

Front 10

List the site of origin of the lateral spinocortical tract.

Back 10

Primary motor cortex and other frontal and parietal areas

Front 11

Where is the site of decussation for the lateral spinocortical tract?

Back 11

Pyramidal decussation at the cervicomedullary junction

Front 12

Where are the levels of termination in the lateral corticospinal tract?

Back 12

The entire cord (predominantly at the cervical and lumbosacral enlargements)

Front 13

What is the function of the lateral corticospinal tract?

Back 13

Movements of contralateral limbs.

Front 14

What are the four medial motor systems?

Back 14

Anterior corticospinal tract, the vestibulospinal tracts, the reticulospinal tracts and the tectospinal tract.

Front 15

Medial motor systems tend to terminate on ________ that project to _________, controlling movements that involve ________. Thus, unilateral lesions of these systems produce ________.

Back 15

Interneurons
both sides of the spinal cord
Multiple bilateral spinal segments
No obvious deficits.

Front 16

Lesions of the lateral corticospinal tract produce ______.

Back 16

dramatic deficits

Front 17

The lateral corticospinal tract is the most clinical important descending motor pathway in the nervous system. Lesions in this pathway _____.

Back 17

Can be precisely localised because they produce characteristic deficits.

Front 18

The primary motor cortex neurons contributing to the corticospinal tract are located mostly in ____.

Back 18

cortical layer 5

Front 19

Layer 5 pyramidal cell projections synapse directly onto _______ in the _______ of the _______, as well as onto _______.

Back 19

motor neurons
ventral horn
spinal cord
spinal interneurons

Front 20

Axons (of the LCT) from the cerebral cortex enter the ______ and descend toward the ______.

Back 20

upper portions of the cerebral white matter (or corona radiata)
internal capsule.

Front 21

In addition to the corticospinal tract, the cerebral white matter conveys __________ between cortex and ________ such as the _______________.

Back 21

bidirectional information
different cortical areas
deep structures
BG, thalamus and brainstem

Front 22

The ______ and ______ are always medial to the internal capsule.

Back 22

thalamus
caudate nucleus

Front 23

The ___ and __ are always lateral to the internal capsule.

Back 23

globus pallidus
putamen

Front 24

There are three parts to the internal capsule:

Back 24

a) anterior limb
b) posterior limb
c) genu

Front 25

The anterior limb of the interior capsule:

Back 25

separates the head of the caudate from the GP and putamen

Front 26

The posterior limb of the interior capsule:

Back 26

separates the thalamus from the GP and putamen

Front 27

The genu of the int. capsule

Back 27

The transition between the anterior and posterior limbs at the level of the foramen of monroe.

Front 28

The corticospinal tract lies in the ______ of the int capsule.

Back 28

posterior limb

Front 29

What is preserved in the internal capsule?

Back 29

the somatotopic map so motor fibers for the face are most anterior and those for the arm and leg are progressively more posterior.

Front 30

Fibres projecting from the cortex to the brainstem (including ______) are called ______ because they project from the cortex to the "____" (brainstem).

Back 30

motor fibers for the face
corticobulbar
bulb

Front 31

Lesions at the internal capsule cause:

Back 31

weakness of the entire contralateral side because the fibers are compact enough.They occasionally produce more selective motor deficits.

Front 32

What are all these places?

Back 32

Front 33

The internal capsules continues into the _____ _____ (Meaning literally the feet of the brain). The corticospinal tract fibers next descend through the ___ ____ where they form somewhat scattered fascicles. These collect on the ventral surface of the _____ to form the ____ _____. For this reason, the corticospinal tract is sometimes known as the ___ ____

Back 33

cerebral peduncles
ventral pons
medulla
medullary pyramids
pyramidal tract

Front 34

The pyramids not only hold fibers of the corticospinal tract but also include:

Back 34

reticulospinal and other brainstem pathways.

Front 35

The transition from the medulla to spinal cord is called the ____ and occurs at the level of the _____.

Back 35

cervicomedullary junction
foramen magnum

Front 36

At the cervicomedullary junction, what happens?

Back 36

About 85% of the pyramidal tract fibers decussate (i.e. the pyramidal decussation) to enter the lateral white matter columns of the spinal cord.

Front 37

Axons of the lateral corticospinal tract enter the spinal cord central grey matter to synapse onto the _____.

Back 37

anterior horn cells.

Front 38

15% of corticospinal tract fibers do what in the spinal cord?

Back 38

Enter the anterior white matter columns to form the anterior corticospinal tract.

Front 39

Label these areas

Back 39

Front 40

The spinal cord contains a butterfly-shaped _____ surrounded by ascending and descending _____ of ____.

Back 40

central gray matter
white matter columns (funiculi)

Front 41

Back 41

Front 42

Motor neurons exit the ____ ___ to form ____ nerves or from segments of the ___ ___ to form ___ nerves.

Back 42

Brain stem
cranial
Spinal cord
spinal

Front 43

Cranial and spinal segments are called

Back 43

dermatomes (areas on the skin supplied by sensory fibers of the spinal nerves).

Front 44

Label these

Back 44

Front 45

The ___ ___ and the ___ are histologically and embryologically closely related and can be thought of as a single large nucleus called the ___ (or the ___)

Back 45

Caudate nucleus
putamen
neostriatum
striatum

Front 46

The caudate nucleus is a what shaped structure?

Back 46

C shaped

Front 47

The CN is divided into three parts:

Back 47

head, body and tail - which do not have a distinct boundary from each other.

Front 48

The amygdala lies just anterior to the tip of the _____ ____ in the ___ lobe.

Back 48

caudate tail
temporal lobe

Front 49

The putamen is a large nucleus forming the ____ portion of the ___ ____.

Back 49

lateral
basal ganglia

Front 50

The putamen fuses with the ___ of the caudate. This region is called ___.

Back 50

anterior and ventral portion of the head
the ventral striatum

Front 51

Most of the ventral striatum consists of the ___ ___.

Back 51

nucleus accumbens

Front 52

Just medial to the putamen lies the ____ ____.

Back 52

Globus pallidus

Front 53

What does the globus pallidus stand for?

Back 53

"pale globe" because many myelinated fibers traverse this section.

Front 54

What is the lentiform nucleus?

Back 54

The putamen and globus pallidus together.

Front 55

Label these

Back 55

Front 57

Back 57

Front 58

Back 58

Front 59

Back 59

Front 60

Back 60

Front 61

Back 61

Front 62

Back 62

Front 63

Virtually all inputs to the BG arrive via the ____. Outputs leave the BG via the _____ and the closely related ____.

Back 63

striatum
internal segment of the globus pallidus
substantia nigra pars reticula.

Front 64

What are the parallel BG pathways for movement, eye movement, cognition and emotion? (or the extrapyramidal motor system-cortical channels). What are the cortical targets of output?

Back 64

Motor channel = supplementary motor area (BA 5), premotor cortex (BA 4), primary motor cortex (BA 6)

Oculomotor channel: Frontal eye fields (BA8) (not primary motor eye movements but it related to cognition)

Prefrontal Channel: DLPFC (BA 9/46)

Limbic Channel: Anterior cingulate gyrus (BA 24), subcallosal cortex (septal area) (BA 25, 32)

Front 65

Back 65

Front 66

The extrapyramidal motor system comprises a system of fibers originating from a variety of cortical regions which then pass through a number integrated ____ to reach the __ and ultimately ____ __ __.

Back 66

Subcortical and brain stem relay centres (basal ganglia, subthalamus, intralaminar thalamic nuclei, midbrain nuclei, reticular formation)

spinal cord

lower motor neurons

Front 67

Back 67

Front 68

Back 68

Front 69

Back 69

Front 70

Describe the pathway of the motor channel.

Back 70

Cortical inputs travel mainly to the putamen and outputs arise from the internal segment of the globus pallidus and the substantia nigra pars reticulata to reach the VA and VL of the thalamus. From the thalamus, the motor channel continues to the supplementary motor area, premotor cortex and the primary motor cortex.

Front 71

Describe the pathway of the oculomotor channel.

Back 71

input is mainly from the body of the caudate nucleus. Output is to the frontal eye fields and supplementary eye fields of the frontal lobes.

Front 72

Describe the pathway of the prefrontal channel.

Back 72

Input is primarily from the head of the caudate and output reaches the prefrontal cortex.

Front 73

Describe the pathway of the limbic channel.

Back 73

It is an important ventral pathway through the BG that is involved in limbic regulation of emotions and motivational drives. Inputs come from major areas for the limbic system and project to the nucleus accumbens and other regions of the ventral stream. Outputs arise from the ventral pallidum and go to the thalamus. They then reach the limbic cortex of the anterior cingulate gyrus and subcallosal cortex (septal area).