CNS Ex2 All

Which RL forms a thin cap over the dorsal horn?

I

Which RL is an important pain reception area?

II

Which RL is also known as the substantia gelatinosa?

II

Which RLs are also known as nucleus proprius?

III and IV

Which modalities are RLs III and IV concerned with?

Touch and pressure

Which RL sends axons to the spinothalamic tracts on the opposite side?

V

Is RL V present at all cord levels?

Yes

What is the lateral fringed area on RL V called?

Formatio reticularis

Where is the formatio reticularis present?

Only in cervical area

Where do cells bodies in RL V carry axons and in what way?

Spine to thalamus, contralateral

Does RL VI have any known function? Is it present at every cord level?

No and no

Where would you find RL VII?

Intermediate gray matter

In which RL do many descending tract fibers synapse?

VII

In which RL would you find nucleus dorsalis (Clarke's)? Which cord levels is this nucleus present at?

VII, C8-L3

In which RL would you find the intermediolateral (sacral parasympathetic) nucleus? Which cord levels is this nucleus present at?

VII, T1-T12

What do we know about RL VIII?

Location and some motor neurons are here

Which RL has class A (alpha) motor neurons?

IX

Which RL has the largest and fastest conducting motor neurons?

IX

Where does RL IX exit?

Anterior rootlets

What does RL IX innervated?

Voluntary movement of skeletal muscle

Which RL is more like a series of disconnected islands?

IX

Which RL is responsible for the ventral horn being called the somatic motor horn?

IX

Which RL surrounds the central canal at every cord level?

X

Which RL contains the anterior and posterior "gray commisures"?

X

In what funiciulus does the Anterior corticospinal tract run?

anterior funiculus

What type of motor neurons are present in the anterior and lateral corticospinal tracts?

pyramidal upper motor neurons

What type of motor neurons are present in the tectospinal, rubrospinal, reticulospinal, and vestibulospinal tracts?

Extrapyramidal upper motor neurons

What is the function of the anterior corticospinal tract?

INFLUENCES axial musculature of neck and shoulders

Where do the fibers of the anterior corticospinal tract cross over?

Just prior to termination in RL 7

Where do the fibers of the anterior corticospinal tract terminate?

T6

What is the origin of the anterior and lateral corticospinal tract?

motor cortex precentral gyrus

What is special about the axons in the anterior and lateral corticospinal tract?

only axons with cerebral cortex origin that run uninterrupted to spinal cord

In what funiciulus does the lateral corticospinal tract run?

lateral funiculus

What is the function of the lateral corticospinal tracts?

INITIATE precise, skilled, voluntary movement of distal extremities

Where do the fibers of the lateral corticospinal cross?

pyramids of MO

What is the main source of influence for both the anterior and lateral corticospinal tracts?

cerebrum

Does the lateral corticospinal tract terminate somewhere specifically or run the entire length of the spinal cord?

entire length of spinal cord

Which tract, anterior or lateral corticospinal, carries a majority of the corticospinal fibers? What percentage?

lateral corticospinal, 85-95%

In which Rexed Laminae does a majority of the lateral corticospinal tract synapse? Where do the rest synapse?

7; 9

Which special cells of the lateral corticospinal tract synapse directly in RL 9?

Giant Pyramidal Cells (Betz)

Which of the descending tracts is the shortest?

tectospinal

What is the function of the tectospinal tract?

postural reflex in neck, reflex enhancement via sight and hearing

Which two muscles are influenced by the tectospinal tract?

trapezius and SCM

How do the fibers of the tectospinal tract cross?

as they descend

Where does the tectospinal tract mostly terminate?

four upper cervical levels in CN XI

What is the main source of influence for the tectospinal tract?

cerebellum

Where does the tectospinal tract originate?

superior colliculus (tectum of midbrain)

Via what cranial nerve does the tectospinal tract influence the trapezius and SCM?

spinal accessory, XI

What is the function of the rubrospinal tract?

Influence hand and foot flexors

If there is a lesion above the cord impacting the rubrospinal tract, where will symptoms present?

contralateral

If there is a lesion on the spinal cord impacting the rubrospinal tract, where will symptoms present?

ipsilateral

How do the fibers of the rubrospinal tract cross?

as they descend

At what cord levels can you find the rubrospinal tract?

All cord levels

What is the main source of influence for the rubrospinal tract?

cerebellum and cortex

Where does the rubrospinal tract originate?

magnocellular region of red nucleus (tegmentum of midbrain)

Which tracts can take over if the corticospinal tracts are compromised?

rubrospinal and reticulospinal

What is the function of the vestibulospinal tract?

muscle tone and postural adjustment in ipsilateral extensors, proper orientation while falling, enhances spinal reflexes

What musculature does the vestibulospinal tract inhibit?

flexors

Do fibers of the vestibulospinal tract cross?

NO

At what cord levels would you find the vestibulospinal tract?

All cord levels

What is the main source of influence for the vestibulospinal tract?

cerebellum

Where does the vestibulospinal tract originate?

lateral vestibular nucleus (Deiters) in MO

What is special about the origination of the vestibulospinal tract?

only descending tract to originate in nucleus of MO

What are the two reticulospinal tracts?

pontine (medial) and medullary (lateral)

In which funiculus does the pontine (medial) reticulospinal tract run?

anterior funiculus

In which funiculus does the medullary (lateral) reticulospinal tract run?

lateral funiculus

What is the origin of the pontine (medial) reticulospinal tract?

pons tegmentum

What is the origin of the medullary (lateral) reticulospinal tract?

MO

What is the function of both reticulospinal tracts?

maintain heart, BP, respiratory rates/rhythms

Do the reticulospinal tracts cross?

mostly no

What is the general origin for the reticulospinal tracts?

reticular formation

Where do the reticulospinal tracts terminate?

all cord levels in medial ventral horn

Which rexed lamina do the reticulopinal tracts terminate in?

intermediolateral cells of RL 7

What type of fibers make up the fasciculus proprius? Origin and termination?

spinospinal; originate in cord and terminate in cord

In what direction on the cord do the fibers of fasciculus proprius and the dorsolateral tract travel?

up or down

What is the function of fasciculus proprius?

coordination of spinal reflexes

Which fibers are the first to be myelinated in the fetus?

fasciculus proprius

Where is the dorsolateral tract (of Lissauer) located?

between RL 1 and the posterior lateral sulcus of the cord

Describe the fibers of the dorsolateral tract (of Lissauer)

small in diameter, collateral fibers off posterior root axons

Where does the dorsolateral tract (of Lissauer) synapse?

gray horns, RL 2

Which two descending tracts are influenced by the cerebrum?

Anterior and lateral corticospinal

In what funiculus does the tract Gracilis travel?

medial aspect of dorsal funiculus

Which modalities does Gracilis recognize?

vibratory, 2 pt touch discrimination, proprioception

In what way does Gracilis travel, ipsilateral or contralateral?

ipsilateral

If a spinal lesion impacted Gracilis, would the symptoms be contralateral or ipsilateral?

ipsilateral

How many neurons are involved in Gracilis?

3

Which neuron crosses over in Gracilis? Where?

2nd neuron, internal arcuate fibers in MO

At what cord levels is Gracilis present? At what levels does it receive input?

all cord levels, T5/T6 and below

From what part of the body does Gracilis receive information?

lower extremities

Where do each of the neurons in Gracilis synapse?

1: nucleus gracilis in MO

2: VPL thalamus

3: posterior central gyrus

What is unique about Gracilis and Cuneatus?

only ascending tracts that DO NOT synapse in spinal cord

Which test would indicate an issue with Gracilis and maybe Cuneatus?

Romberg's

In what funiculus does the tract Cuneatus travel?

lateral aspect of dorsal funiculus

Which modalities does Cuneatus recognize?

vibratory, 2 pt touch discrimination, proprioception

In what way does Cuneatus travel, ipsilateral or contralateral?

Ipsilateral

If a spinal lesion impacted Cuneatus, would the symptoms be contralateral or ipsilateral?

Ipsilateral

Which neuron crosses over in Cuneatus? Where?

2nd neuron, internal arcuate fibers in MO

Which cord levels does Cuneatus occupy? Which levels does it receive info from?

upper cord levels, T5/T6 and above

From what part of the body does Cuneatus receive information?

upper extremities

How many neurons are involved in Cuneatus?

3