CNS Exam 2 - Unit 4 (spinal cord and ascending tracts)

How many neurons in the spinal cord?

100 million

At what level does the spinal cord occupy 75% of the vertebral canal?

C5-C6

What is the superior boundary of the spinal cord? (general and specific)

foramen magnum

superior most ventral rootlet of the first cervical spine

What is the inferior boundary of the spinal cord? At what levels?

conus medullaris L1-L2

The Bell Magendie Law states that:

Dorsal _____ contain ______ fibers

Ventral _____ contain ______ fibers

Dorsal roots contain sensory (afferent) fibers

Ventral roots contain motor (efferent) fibers

T/F? Bell Magendie Law is concerning the rami?

False - the roots

Roots, rootlets, nerves, and rami are all ______ structures

PNS

______ exits between occiput and atlas

C1

C4 exits at IVF between _____ and ______

C3 and C4

C8 exits at IVF between _____ and _____

C7 and T1

Which nerve exits between C5 and C6?

C6

T1 exits at IVF between _____ and _____

T1 and T2

Where does T12 exit between?

T12 and L1

L1 exits IVF between ____ and ____

L1 and L2

L5 exits between _____ and _____

L5 and S1

S1-S4 exit where?

dorsal/ventral sacral foramina

S5 is the exception and exits where? What nerve also exits here?

sacral hiatus, coccygeal nerve

During the first 3 months of embryonic development, what is the relationship between the spinal cord and vertebral column?

they are the same length

T/F? The spinal cord grows faster than the vertebral column

False - vertebral column grows faster

By adulthood, Co1 cord level is found at what level? What does it form?

L1-L2, conus medullaris (tapering end of cord)

Roots of lumbar/sacral/coccygeal nerves for the _______ in the ________

cauda equina, lumbar cistern

Rexed lamina is made up of ______ matter

gray

Spinal tracts are made up of ______ matter

white

The dorsal horns receive what kind of info?

sensory afferent (from DRG to CNS)

The lateral horns are present which of the following cord levels?

Specify which levels carry what kind of info?

T1-L2 sympathetic

S2-S4 parasympathetic

The lateral horns consist of what kind of neurons?

preganglionic autonomic neurons

Which rexed lamina is present in the lateral horns?

RL 7

The ventral horns receive what kind of info?

motor efferent info (from CNS to muscle)

The gray matter has a dense concentration of _________ and _________

neuron cell bodies and capillary beds

Gray matter has thick __________ that are ______ near cell bodies creating many synaptic areas

dendritic mats, unmyelinated

The posterior horns (or RL 1-6) are associated with _______ information

sensory

The anterior horns (or RL 7-10) are associated with ______ information

motor

What is one important thing regarding RL I?

posterior horn forms a thin cap over it

RL II is known as the reception center for what? It is also called __________

pain

substantia gelatinosa

What 2 spinal tracts synapse in RL II?

lateral spinothalamic and dorsolateral tract of lissauer

RL III and IV contain the _________

nucleus proprius

T/F? RL III and IV are associated with pain?

False! light touch and deep pressure

(pain is RL II)

Which spinal tract synapses in RL III and IV?

anterior spinothalamic tract

RL V has ________ formation in the ______ area only

reticular formation, cervical area only

T/F? RL V is found in ALL cord levels

True

RL V contains cell bodies that send axons into which tracts? Does this make them contralateral or ipsilateral?

BOTH spinothalamic tracts

Contralateral

Which RL is missing at some cord levels?

RL VI

Which RL is the most anterior aspect of the dorsal (posterior) horn?

RL VI

Which RL is the most posterior aspect of the ventral (anterior) horn?

RL VII

What ascending structure is found in RL VII? What cord levels is it present at?

nucleus dorsalis (Clarke's)

C8-L3

The intermediolateral nucleus is found in which RL? What cord levels? What kind of neurons?

RL VII

T1-T12

preganglionic sympathetic neurons

T/F? There is NO distinct horn at L1-L2 and S2-S4

True

RL VII contains what structure at S2-S4? What kind of neurons are contained?

sacral parsympathetic nucleus

preganglionic parasympathetic neurons

Which RL is the medial aspect of the anterior horn?

RL VIII

Which RL is also referred to as the "somatic motor horn"

RL IX

RL IX has what kind of neurons? What is special about them?

class A alpha motor neurons

largest/faster conducting motor neurons in our bodies

T/F? Class A alpha motor neurons in RL IX are the largest and fastest conducting neurons in our BODY

False! They are the largest fastest MOTOR, not in the whole body

Which RL surrounds the central canal?

RL X

Which RL contains anterior and posterior gray commissures that connect equivalent structures?

RL X

What is the difference between funiculus and fasciculi?

1 funiculus contains multiple fasciculi

White matter has a dense concentration of ___________ covered by what?

neuron fibers (myelinated) covered by interfasciular oligodendrocytes

T/F? Blood vessels are more dense in white matter than in gray?

False - less dense

Bundles of functionally related axons are called ________

fasciculi (tracts)

What holds fasciculi together?

NCAMs (nerve cell adhesion molecules)

T/F? Tracts are observable by general staining techniques

False - NOT observable

What are the 6 ascending tracts?

gracilis

cuneatus

lateral spinothalamic

anterior spinothalamic

anterior spincerebellar

posterior spinocerebellar

Tracts gracillis and cuneatus make up what? Their cell bodies are where?

posterior column, cell bodies in DRG

Tracts gracillis and cuneatus BOTH carry what?

2 point touch

Vibratory sensations

Kinesthetic sensation (conscious-proprioception)

Tracts gracillis and cuneatus travel in which funiculus?

posterior (dorsal)

(hint: because they make up the posterior column)

T/F? Gracilis is present at ALL cord levels

True!

T/F? Cuneatus is present at ALL cord levels?

False - T5 or T6 and up only

Which tract carries vibratory sensation from the hand?

cuneatus

Which tract carries kinesthetic information from the feet?

gracilis

Where do fibers synapse in tract gracilis?

nucleus gracilis of MO

Where do fibers synapse inn tract cuneatus?

nucleus cuneatus of MO

T/F? Romberg's test is cerebellar test

False! testing posterior column

T/F? Romberg's test should be performed with eyes closed

True! identify proprioceptive problems

Tracts gracilis and cuneatus are a ? neuron pathway. Where does it initiate?

3 neuron pathway, DRG

In tracts gracilis and cuneatus, how does neuron cross to the other side of the MO? Where does it travel in next?

internal arcuate fibers, medial lemniscus

In tracts gracilis and cuneatus, where does the neuron pathway end?

VPL of thalamus to the posterior central gyrus

Which tract carries right sided kinesthetic proprioception?

left medial lemniscus

(or right cuneatus)

The left medial lemniscus carries info from what side of the cord and where?

right side of cord, right side of body

If someone has a lesion on the left medial lemniscus, what function is affected?

right sided dysfunction (2 pt. touch, kinesthetic, vibratory sensation)

The posterior column tracts are ipsilateral or contralateral? What about their pathway?

ipsilateral tract (starts and synapses in MO on same side THEN crosses over)

contralateral pathway (cross over via internal arcuate fibers)

BOTH lateral and anterior spinothalamic tracts are present in what cord levels?

All!

Lateral and anterior spinothalamic are named because of?

the funiculus they travel in (lateral in lateral, anterior in anterior)

Together, the lateral and anterior spinothalamic tracts are called what?

anterolateral system

Cell bodies of lateral and anterior spinothalamic tract are found where?

gray horn of cord

The lateral spinothalamic carries _____ and _______ information and it crosses slow or fast?

pain and temperature, fast

The lateral spinothalamic tract is associated with which RL?

RL II substantia gelatinosa (pain!)

The anterior spinothalamic carries _____ and _____ information and it cross over slow or fast?

light touch and deep pressure, slow

The anterior spinothalamic tract is associated with which RL?

RL III and IV nucleus proprius

Describe the 3 neuron pathway of the anterior and lateral spinothalamic tracts?

1. DRG

2. RL 2 (lateral) or RL III or IV (anterior)

3. VPL of thalamus

Anterior and lateral spinothalamic tracts are contralateral or ipsilateral?

contralateral

(ex: left side of cord carries right sided info)

The left lateral spinothalamic tract carries what type of information?

right sided pain and temperature

A patient has a lesion on the right anterior spinothalamic tract, what function is lost?

left sided light touch and deep pressure

Analgesia is?

loss of pain sensation

Thermoanesthesia is?

loss of temperature

If a patient has analgesia or thermoanesthesia, which tract is involved?

lateral spinothalamic

A patient shows up with right sided analgesia, what is wrong?

left lateral spinothalamic problem, loss of pain

How are anterior and posterior spinocerebellar tracts named? Why is this significant?

for their relationship to each other, because BOTH are in lateral funiculus

T/F? Anterior and posterior spinocerebellar tracts deal with conscious information

False! subconscious because we are going to cerebellum NOT thalamus

Do fibers cross in the anterior spinocerebellar tract?

yes - TWICE!!

What cord levels in anterior spinocerebellar tract found?

ALL

Where does anterior spinocerebellar tract terminate?

superior cerebellar peduncle