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Neuroanatomy > Introduction to Neuroanatomy > Flashcards

Introduction to Neuroanatomy Flashcards

1
Q

What is the diencephalon made up of?

A
  • Thalamus
  • Hypothalamus
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2
Q

What are the 3 sections of the brain?

A
  1. Forebrain
  2. Midbrain
  3. Hindbrain
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3
Q

What are the 2 parts which makes up the forebrain?

A
  1. Diencephalon
  2. Cerebral Hemispheres
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4
Q

What makes up the brainstem?

A
  1. Midbrain
  2. Pons
  3. Medulla
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5
Q

What are the different ventricles?

A
  • 2x Lateral Ventricle
  • Third Venitrcle
  • Fourth Ventricle

Circulation of CSF –> called Hydrocephalus

NB: There is no such thing as a second ventricle

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6
Q

What is the equivalent of a ‘nerve’ from the PNS in the CNS?

What is the equivalent of a ‘ganglion’ found in the PNS in the CNS?

A
  • A nerve is called a ‘tract’ in the CNS
  • A ganglion is called a ‘nucleus’ in the CNS

Ganglion = Nucleus –> these are a GROUP of NEURONAL CELL BODIES

NB: Synapses are always one way

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7
Q

Which is inhibitory and which is excitatory between;

  • Glutamate
  • GABA
A

Glutamate –> EXCITATORY (+)

GABA –> INHIBITORY (-)

Glutamate is the most common excitatory neurotransmitter in the body

Glutamate –> is also what kills the neurones during old age due to excitotoxicity (too much)

Glutamate will INCREASE the CHANCES of a NEURONE being TRIGGERED (post-synaptic)

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8
Q

What does a neurone projecting somewhere mean?

A

A neurone ‘projecting’ to somewhere is the same as a neurone ‘sending an axon’ to somewhere

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9
Q

What is meant by a collateral?

A

Collateral - this is a branch of an axon

Dendrites –> these RECEIVE INFORMATION

Axons –> MOST have COLLATERALS which BRANCH therefore sending SIGNALS to 2 or MORE PLACES

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10
Q

Briefly describe the development of the neural system

A
  1. Neural plate epithelium –> FOLDS
  2. This forms a GROOVE (becomes invaginated)
  3. The GROOVE then forms a NEURAL TUBE leaving NEURAL CRESTS and becoming DISCONNECTED from the EPITHELIUM

Neural Tube –> forms the CNS

Neural Crest –> forms the PNS (glial cells too)

NB: Neural Crests from from the EDGES

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11
Q

What causes Anencephaly and Sina Bifida?

A
  • When the neural tube does not close
  • Should be closed in the 1st Month
  • Folic Acid needs to be taken BEFORE pregnancy is confirmed to reduce risk (not helpful during pregnancy)
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12
Q

What does the Neural Tube of the embryo form?

A
  • Forms the CNS
  • Rostral Head –> expands to form the brain
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13
Q

Which part of the neural tube expands to form the head?

What 4 parts can this bit be split into?

A

Rostral (Head End)

  • Forebrain Vesicle
  • Midbrain Vesicle
  • Hindbrain Vesicle
  • Spinal Cord

Brain vesicles at rostral (head) end of the neural tube

NB: It is ‘Vesicle’ and not ‘Ventricle’

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14
Q

There are 2 outgrowths from the forebrain vesicle. What are they?

A
  • Telencephalon (with 2 outgrowths itself)
  • Diencephalon (original forebrain)
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15
Q

What are the 2 outgrowths from the telencephalon?

A
  • These are the cerebral hemispheres

(Think of it like tele has 2 antennas)

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16
Q

What is does the original forebrain vesicle become (other than outgrowths/telencephalone)?

A
  • Diencephalon (hypothalamus & thalamus)
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17
Q

Where is the lateral ventricle found?

A
  • There is one in each cerebral hemisphere
  • Lateral ventricle extends into each part of the hemispheres
  • It opens into the 3rd ventricle via the Interventricular Foreamen
  • Seen on a Median Sagital Sections (because it is within the hemispheres)

They each connect to the Third Vesicle via an Intraventricular Foramen

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18
Q

Where is the third ventricle found?

A
  • Found in the diencephalon (including hypothalamus & thalamus)
  • Found in between THALAMUS & HYPOTHALAMUS

Diencephalon –> ANYTHING which has ‘Thalamus’ in it is part of this

Diencephalon –> part of the FOREBRAIN

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19
Q

What is a ventricle?

A

This is a fluid-filled structure which contains Cerebral Spinal Fluid (CSF)

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20
Q

In a summary, what are the different parts of the adult brain and their function?

A
  • Brainstem (including pons & midbrain & medulla oblongata)
  • Medulla = Medulla Oblongata
  • Pons –> is SWOLLEN & BULKY compared to Medulla
    *
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21
Q

Give a summary of the pons

A
  • Swollen
  • More bulky than the Medulla
  • Intimately linked to the cerebellum on the back of it
  • Pons –> linked to cerebellum via middle peduncle
  • Above it is the midbrain (from the midbrain vesicle)

NB: Midbrain is derived from the midbrain vesicle

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22
Q

What does the Cerebellum do?

A
  • Coordination of Movement (prime function)
  • Other things (balance & posture)
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23
Q

Summary of the brainstem

A

Brainstem is in charge of:

  • Heart Rate
  • Breathing
  • Blood Pressure
  • Most Main functions of life
  • It also gives 10 of the 12 cranial nerves (therefore without brain stem we would be brain dead)
  • Brainstem –> CONTINUOUS with the SPINAL CORD
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24
Q

Describe CSF exit circulation.

A
  1. CSF enters subarachnoid space
  2. CSF goes to superior sagital sinus
  3. Superior sagital sinus goes around the top of the brain
  4. It leaves via the Arachnoid Villi (granulations) and drains into the blood vessel called Superior Sagital Sinus
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25
Q

What is the 4th Ventricle?

A
  • Found between Cerebellum & Brainstem (pons)
  • The 4th Ventricle has a median & lateral aperture
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26
Q

Where is CSF made?

A
  • CSF is mainy made in the Lateral Ventricle
  • It then goes via the Interventricular Foramen to the 3rd Ventricle
  • It then goes down a tube called the cereberal aquaduct to the 4th Ventricle
  • Made by Choroid Plexuses largely in Lateral Ventricle
  • Lateral Ventricle –> found in both Cerebral Hemispheres
    *
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27
Q

Where does the CSF exit?

A
  • CSF goes to the 4th Ventricle
  • CSF goes to the Subarachnoid Spaces
  • CSF then exits via Arachnoid Villi/Granulations in the Superior Sagital Sinus
  • Some CSF will leak out to the cranial spinal section & beyond
  • This provides the CSF for the spinal cord
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28
Q

What is special about the Superior Sagittal Sinus?

A

It is the main vessel for the cerebral cortex drainage

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29
Q

Importance of CSF functionally?

A
  • Important for the protection of the brain
  • CSF flows around the brain
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30
Q

What happens if there is a blocked aqueduct?

Who does this usually occur to?

A
  • Stenosis of the Cerebral Aqueduct can occur in babies (born this way)
  • CSF continues to be produced in the Lateral Ventricles (and other ventricles)
  • This causes ventricles to expand
  • Inability to flow down the aqueduct to the 4th ventricle
  • Inability to go to the subarachnoid space
  • This causes hydrocephalus
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31
Q

What is the condition that cerebral aqueduct stenosis can cause?

A
  • Hydrocephalus (swelling of brain ventricles)
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32
Q

What must you be careful when doing surgery from behind?

A
  • Superior Sagital Sinus (largest near the back)
  • Therefore damage can occur here
  • However operations from the back do not have as much CSF than when approaching from the cerebellum direction (below)
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33
Q

Hydrocephalus

Which ventricles would swell if aqueduct is blocked?

A
  • Predominantely Lateral Ventricles (main ones that form CSF)
  • Occurs due to Stenosis of Cerebral Aqueduct
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34
Q

What occurs in Hydrocephalus?

A
  1. Stenosis of Cerebral Aqueduct –> causing blockage
  2. CSF continues to be produced in lateral ventricles (predominantely)
  3. Cannot flow down aqueduct
  4. Cannot reach the sub-arachnoid space
  5. Causes lateral ventricles to swell up
  6. Causing brain to get squashed from the inside

There is no space in the extra-cranial cavity –> therefore brain tissue is pushed out against skull bone

  • Dark Spaces on Axial MRI –> shows the Ventricles
  • Lateral Ventricle –> shown as L-FISSURE
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35
Q

What is the solution for hydrocephalus?
What does it involve?

A
  • Neurosurgery
  • Plastic Tube called a shunt is placed into lateral ventricle
  • This tube goes down to peritoneal cavity
  • This allows CSF to drain into peritoneal cavity

It is important that this surgery is done soon after birth to prevent brain damage problems

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36
Q

What are the cerebellar peduncles and what do they do?

A
  • Found on either side of the midline (para-sagittal)
  • Not seen in sagittal (midline sections)
  • Connect cerebellum and parts of the brainstem via 3 peduncles
  • Peduncle is like a ‘stalk-like’ structure
  • There is a superior, middle & inferior peduncle

Para-Sagital: Found on either side of the midline

Neurones go TO & FROM the brainstem & cerebellum via the peduncles

NB: Middle peduncle has 20 million axons going through it between the pons & cerebellum

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37
Q

Where are the superior & inferior colliculus located and what are their general functions?

A
  • Found in the midbrain
  • Superior Colliculus –> Eye Movement
  • Inferior Colliclus –> Hearin
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38
Q

Which peduncle is linked to which part of the brainstem?

A
  • Superior Cerebellar Peduncle –> connects MIDBRAIN & CEREBELLUM
  • Middle Cerebellar Peduncle –> connects PONS & CEREBELLUM
  • Inferior Cerebellar Peduncle –> connects MEDULLA & CEREBELLUM

NB: Pons is a bit swollen and has its back in contact with cerebellum

The floor of the 4th ventricle on the brainstem is diamond-shaped

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39
Q

What are the layers of the meninges that cover the brain & spinal cord?

A
  • Dura (outside) –> very thick
  • Arachnoid (middle) –> attached to the inside of dura
  • Pia (inside) –> quite thin

Dura & Arachnoid –> has no/little space –> it is just ‘potential space’ if something goes wrong (middle meningeal bleed)

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40
Q

What is the denticulate ligament?

A
  • Sits between the ARACHNOID & PIA MATTER
  • Between these two layers the Subarachnoid Space is formed
  • Keeps the PIA DURA in place
  • Subarachnoid space contains CSF
  • CNS floats in CSF
  • Arteries supplying the CNS –> are in the SUBARACHNOID SPACE –> which are surrounded by CSF
    *
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41
Q

What is the subarachnoid space and why is it important?

A
  • Space between PIA MATER & ARACHNOID LAYER
  • Has lots of space for Spinal Nerves
  • Contains CSF (similar composition to water + salts)
  • Arteries supplying the Spinal cord are found in the subarachnoid space –> therefore bleeding occurs in the subarachnoid space into the CSF
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42
Q

Where is the dentrospinal artery found and what does it do?

A
  • Found in the Subarachnoid Space
  • Supplies the spinal cord
  • If it bleeds –> goes into the CSF
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43
Q

What happens if there is too much loss of CSF?

A
  • Loss of Protection (CSF needed for brain & spinal cord to be surrounded by to float in & keep them alive - content)
  • Spinal cord would collapse on itself –> the structure would cave in as it needs something to float in

CSF is soft and allows brain to sit in it

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44
Q

What happens if there is a middle meningeal bleed?

A
  • Found between the Dura & Arachnoid
  • There is no real space here but simply ‘potential space’
  • Blood is found here if there is a bleed (usually nothing here)
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45
Q

What happens if there is bleeding of arteries supplying the spinal cord?

A
  • These arteries are found in the subarachnoid space
  • Therefore bleeding will cause blood to go into CSF
  • This causes murky CSF
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46
Q

Myelination of spinal cord. What is myelinated and how does it appear?

A
  • Grey Matter –> contains Neural Cell Bodies (mainly)
  • White Matter –> contains Myelinated Cell Axons (mainly)

Grey Matter –> is not stained but rather the myelin of oligendrocytes (CNS) surrounding the axons in the white matter are.

47
Q

Why is white matter most abundant in the cervical cord and least in the sacral cord?

A

This is because nearer to the top there is a lot of axons which have come into the spinal cord by now. Therefore, there is going to be a lot of axons in the ascending & desending tracts making white matter a lot more here.

Sacral Region: Most axons would have either been given off by then or very few (just from lower reaches of body) have been inputted therefore little ascending & descending tracts in white matter here.

48
Q

What does the dorsal horn & root contain?

A

Dorsal Horn & Root –> contains SOMATOSENSORY

49
Q

What does the ventral horn & root contain?

A

Ventral Horn & Root –> contains MOTOR NEURONES

50
Q

What is the central canal and why can it be helpful?

Where did it come from?

A
  • Middle of Spinal Cord –> is the CENTRAL CANAL
  • This does not have CSF in it
  • Embryonic remnants from what used to be the neural tube
  • Find stem cells here –> however they do not grow neurones if someone damages their CNS (spinal cord part)
51
Q

What is lateral & ventral white matter?

A
  • These are the ascending & descending tracts (depending on where abouts in the white matter)
  • There are no physical barriers/boundaries between them
52
Q

What is the distribution of the ventral (anterior) spinal artery? (important)

Are strokes of this artery common?

Which parts of the spinal cord are affected?

A
  • Not common but they do occur

Stroke (lesion of artery) can cause loss of blood to:

  1. Great Descending Motor Tracts –> therefore PARALYSES for THAT LEVEL & BELOW
  2. Ascending Pain Pathways –> LOSS of PAIN SENSATION (somatosensory)

Loss of Blood supply leads to death & destruction of the areas

53
Q

What are radicular arteries and why are they important?

A
  • Supply the spinal arteries (including ventral spinal artery)
  • Run along the spinal roots (thus called radicular)

Blockages of these can cause problems for spinal arteries and have similar effect as a stroke in the ventral (anterior) spinal artery (i assume)

54
Q

What is special about the Left T10 level in terms of blood supply?

A
  • This spinal artery is particularly large
  • Called Adamkiewicz
  • Can be used as a landmark
  • Need to ensure it is not damaged in surgery
55
Q

What is grey matter in the spinal cord divided into?

A
  • Divided into Laminae of Rexed
  • These are laminae form I-VI (6) found in the dorsal horn
  • Dorsal Horn –> mainly somatosensory
56
Q

Which layers does the superficial dorsal horn include and what somatosensory function is involved here?

A
  • Superfiical Dorsal Horn –> includes Lamina I & II
  • These laminae are important for Pain (nociception)
57
Q

What is another name for Lamina II and what is found there?

A
  • Substantia Gelatinosa
  • Contains lots of small neurones
  • Found in Superficial Dorsal Horn
58
Q

Why is the cerebral cortex important in pain?

A
  • If you do not have cerebral cortex –> you cannot conceptualise pain –> so you cannot feel it (perceive it)
59
Q

What are nociceptors?

A
  • Detection of Noxious Stimuli
  • This occurs all over the body
  • This is not the same as pain

Pain is a construct of the cerebral cortex –> whereas nociception is the pain stimuli –> which is conducted back to the brain and interpreted as ‘pain’

60
Q

What is found in Lamina IX?

Explain the distribution? (e.g. medial & lateral parts)

A
  • Lamina 9 (XI)
  • These are Motor Neurones
  • Most Medial Motor Neurones –> supply TRUNK MUSCLES
  • Most Lateral Motor Neurones –> supply EXTREMITIES (hands & feet)

Axons that LEAVE the VENTRAL ROOT –> go into the SPINAL NERVE then head DORSALLY down the DORSAL RAMUS (mixed nerve) to the BACK MUSCLES (e.g. erector spinae)

61
Q

Where are pre-ganglionic sympathetic neurones found?

  • Lamina?
  • Parts of Spinal Cord?
A
  • Found in the Lateral Horn
  • Found in Lamina VII (7)
  • Only found in Thoraco-Lumbar Parts
62
Q

What is a Lower Motor Neurone Lesion?

How can this occur?

What are examples of nerve injury which can cause a LMNL?

A
  • Injury to Peripheral Nerves
  • This can be caused by poliomyelitis (epidemics occur)

Can occur due to:

  1. The death of the cell body
  2. Peripheral Damage to Axon (along its course) at any part
63
Q

What does Poliomyelitis do?

A
  • Virus
  • Epidemics can occur
  • Virus kills the motor neurones causing paralysis if enough neurones are killed

Virus is usually found in the gut during normal health

64
Q

How can the body fix PNS damage?

A
  • Damage to PNS Nerves
  • Any surviving motor neurones –> can sprout –> to innervate target & take over (from the ones that died)
65
Q

What is the problem with successfully regenerated nerves?

A
  • They fatigue earlier in life (problems arise earlier in life)
66
Q

What is a motor unit made up of?

A
  1. Muscle Fibres
  2. Nerves (the somatosensory unit & axon)
67
Q

What does a LMNL (Lower Motor Neurone Lesion) cause?

  • What type of paralysis?
A
  • Flaccid Paralysis
  • Rapid Muscle Wasting
  • Fibrillation
  • Fasciculation

Flaccid Paralysis: If any muscle does not contract it will waste away –> therefore you need electrical stimulation to stop them wasting away

Fasciculation: Little parts of muscle will twitch this is a common sign of LMNL

NB: Poliomyelilitis can cause LMNL

68
Q

What is a common sign of LMNL?

A

Fasciculation (twitching)

69
Q

Where does damage have to occur to be classed as a LMNL?

A
  1. Death of Cell Body
  2. Injury of Axon –> anywhere along its course
70
Q

What happens when peripheral nerve is damaged?

A
  • Distal part of axon will die (whether motor or sensory)
  • Surviving axons –> will sprout from injury site
  • They will grow distally to try and find a target which they can stimulate
  • Axons regenerate along course of pre-existing fibres looking for something to innervate

If they find their target then regeneration is successful and patient will get better (regain control)

71
Q

What happens when CNS nerve is damaged?

A
  • Axons cannot regenerate
  • Therefore there is no recovery
  • Noone knows why not
    *
72
Q

What happens if damage is close to cell body?

A
  • If close enough then cell body may die
  • Otherwise –> axons regenerate
73
Q

What happens to muscles that are not innervated?

A
  • muscles that are not innervated –> cannot contract –> they are flaccid
  • Muscles that do not contract –> waste away

Electrical Stimulation –> can STOP them WASTING AWAY

LMNL –> causes muscles to TWITCH & FIBRILLATE

74
Q

What is the problem with regeneration?

A
  • Innervation is not as good as it was before
75
Q

How can we help peripheral nerves regenerate?

A
  • Repair by suturing (stich nerves together)
  • Axons can regenerate across the lesion & down the distal stump
  • The damaged nerves are stitched up together again –> however axons will not join up again
  • However they will line up so that the proximal stump can regenerate
  • New regenerated axons can follow the pre-existing fibre down its path to where the distal dead neurone was going –> to find its distal target

NB: Axons do not join up but regenerate from the nerve stump (where damage is)

76
Q

Problem with suturing?

A
  • Only 50% of patients with repaired peripheral nerves report useful degree of functional recovery
  • However there is regeneration of axons in nearly every case (but some lost along the way)
  • Neuropathic pain –> this is a consequence of a failed functional regeneration

Theory: Axons are lost on their way down to regenerate the target they should be innervating (may not be correct)

77
Q

Which tracts carry voluntary motor neurones?

  • Where do they arise from?
  • Where do they end?
A
  • Corticospinal (Lateral) Tracts
  • Descending Motor instructions are carried by corticospinal tract
  • Arise from the cerebral cortex
  • They cross the spinal cord
  • End in Spinal Cord
    *
78
Q

Is brain control ipsilateral or contralateral?

A
  • Each side of the brain –> controls the other side of the body
  • Each side of the brain –> receives sensory info from the other side of the body
  • Thus sensory & motor tracts in the brain come from contralateral side (decussate)
  • The information DECUSSATES (crosses the midline)
79
Q

What does ipsilateral & contralateral mean?

A

Ipsilateral –> SAME SIDE

Contralateral –> OPPOSITE SIDE

80
Q

What is the path of the corticospinal tract?

What does the corticospinal tract do?

  • What is its function?
  • What is it called in the spinal cord (after decussation)?

Where does the decussation occur?

A
  • It is the main motor tract
  • Called the Lateral Corticospinal Tract in the spinal cord after decussation
  • Decussation occurs in the LOWEST PART of the MEDULLA (brainstem)
  • Includes voluntary movement
  • Cell of Origin –> came from the CONTRALATERAL SIDE to the MOTOR ORGAN it CONTROLS

Corticospinal tract needed to widdle your fingers

81
Q

What is an Upper Motor Neurone Lesion?

How can it occur?

A
  • This means control from the brain is lost –> however everything below is still intact
  • There is NO CENTRAL BRAIN CONTROL
  • Occurs due to: SPINAL CORD INJURY or STROKE or BRAIN INJURY
    *
82
Q

What happens to degenerated corticospinal tract?

A
  • Replaced by astrocytes (glial cells)
83
Q
  • What are the signs of UMNL?
A

Can occur due to SPINAL INJURY / STROKE / BRAIN DAMAGE

  • Spastic Paralysis
  • Little Muscle Wasting
  • Babinsky Sign
84
Q

What is spastic reflex?

  • When does it occur
A
  • Occurs in UMNL (loss of brain input/control)
  • Contract spontaneously all the time
  • Occurs due to reflexes of the muscle spindle
  • No brain control therefore muscles contract on its own
  • This means there is no wasting
  • You get babinsky reflex (no inhibition from brain)
  • Muscles cannot be voluntarily moved (due to lost cortical connection)

Spinal Reflexes –> STILL WORK in UMNL –> they are acting ALL the TIME –> there is NO MUSCLE WASTING –> due to these ELECTRICAL STIMULATIONS from REFLEXES

85
Q

Will a baby dorsiflex or plantar flex when its foot is stroked?

Why?

A
  • Baby –> DORSIFELXION

This is called the BABINSKI REFLEX

  • This is NOT become of an UMNL (obviously)
  • Corticospinal Tract has not been myelinated in babies yet
  • Usually these supress the dorsiflexion in adults and cause plantarflexion
  • Seen until the age of 2
  • Usually corticospinal tract supresses dorsiflexion however here it does not becuase it is not myelinated (not to do with UMNL)
86
Q

Will an adult dorsiflex or plantar flex when its foot is stroked?

Why?

A
  • See this when a patient has an UPPER MOTOR NEURONE LESION
87
Q

What is the babinski sign?

A
  • Dorsiflexion (not normal) when you stroke a foot
  • Should be plantarflexing

It is a sign of either:

  1. Baby below 2
  2. UMBL
88
Q

When do we see the Babinski reflex in adults?

A
89
Q

Why is the corticospinal tract important in the context of the babinski reflex?

A
  • Usually there is a signal that goes down the LATERAL CORTICOPSINAL TRACT
  • This usually supresses the dorsiflexion
  • Babies however do not have myelinated corticospinal tract –> thus they do not have this supression to dorsiflexion
  • This means they do dorsiflexion

It causes SUPRESSION of DORSIFLEXION when the FOOT is STROKED

Non-Myelinated Corticospinal Tract –> will NOT be able to SUPRESS BABINSKI SIGN

90
Q

Where do the corticospinal tracts arise from?

Does it pass down the ventral or dorsal part of the brainstem?

Where does it decussate?

A
  • Cerebral Cortex
  • Near ventral surface of brainstem
  • Decussates on the anterior surface of the Medulla (brainstem)
  • After decussation it forms the corticospinal tract in the spinal cord

It goes down the FOREBRAIN then down the BRAINSTEM then it crosses over at the VENTRAL PART of the MEDULLA

91
Q

Here is a section of the upper midbrain

What is being pointed at?

A

Superior Colliculus –> important for EYE MOVEMENTS

92
Q

Section through Lower Pons

A
93
Q

What does the basilar artery supply?

A

Basilar Artery –> supplies the PONS

Basilar Artery Branches:

  • They ONLY supply the MOTOR BUNDLES in PONS
  • They do NOT SUPPLY the SENSORY BUNDLES
94
Q

What happens if a branch of the basilar artery is blocked & why?

A
  • Basilar Artery –> supplies the CORTICOSPINAL TRACTS in PONS
  • Blocked –> causes LOCKED IN SYNDROME

This is because they would LOSE BLOOD SUPPLY to the MOTOR BUNDLES but NOT the SENSORY BUNDLES

95
Q

What is locked in syndrome?

A

Sensory Tracts –> INTACT

Motor Tracts –> LOST

96
Q

What forms the pyramids in the open medulla?

A
  • Corticospinal Tracts
97
Q

What is the open medulla?

A
  • This is the top (rostral) part of the medulla
  • Open –> because it has ‘opened up’ to the 4th ventricle
  • There is no central canal
98
Q

What is the closed medulla?

A
  • Bottom (caudal) part of the medulla
  • Contains a central canal
  • It has still not ‘opened up’ to the 4th ventricle
99
Q

What does selective damage to the pyramids (rare) do?

A
  • Corticospinal tracts travel in the pyramids
  • These neurones go from the cerebral cortex (cell body in cortex) to the brainstem
  • They go down to spinal cord and control motor neurones
  • they bring about voluntary movements

Corticospinal Tract –> where cerebral cortex can produce voluntary movements

Causes DESTRUCTION of the CORTICOSPINAL TRACT

100
Q

What are the 2 types of strokes?

A
  1. Haemorrhage (blood leaking out somewhere where it shouldn’t)
  2. Occlusion (thrombus/embolism in the blood vessel)
101
Q

What is the difference between a thrombus and an embolism?

A
  • Thrombus –> NON-MOVING CLOT
  • Embolism –> MOVING CLOT
102
Q

What do the aqueduct and central canal have in common?

A
  • They both open up to the 4th ventricle

Central Canal: Goes up to the medulla and opens up in the rostral region into the 4th ventricle

103
Q

How does the corticospinal tract travel through the pons?

A
  • It is broken up as bundles in the pons
  • Travels as one in the pyramids in the medulla
104
Q

What does the inferior cerebellar peduncle connect?

A

Connection between CEREBELLUM & BRAINSTEM (medulla)

(There are 2 other peduncles)

105
Q

How does the corticospinal tract travel in the pons & medulla?

A
  • Pons –> BUNDLES
  • Medulla –> COMES TOGETHER –> form LARGE BUNDLES called the PYRAMIDS (pyramidal tract)

Pyramids –> contains only the corticospinal tract

106
Q

What is the landmark of the open medulla?

A

Olives

107
Q

What happens if someone has a lesion of the corticospinal tract?

A
  • After Surgery Recovery
  • Patients begins to return voluntary movement commands –> despite not having corticospinal tract
  • They can do nearly all the actions as before
  • However –> the one feature they lose is precise control of the hands & fingers
  • They now have clumsy hands (lose accurate finger control)

This is because accurate finger control was solely controlled by the corticospinal tract (cannot be taken over)

108
Q

Does the closed medulla contain a central canal or not?

A
  • Yes it does
  • It has not‘opened up’ yet
  • Brainstem central canal is continuous with central canal in spinal cord
  • Closed Medulla –> has no 4th ventricle dorsal to it yet
  • Open medulla –> has a 4th ventricle dorsal to it
109
Q

What happens in the lowest part of the medulla?

A
  • Lowest Part of the Medulla –> is just before spinal cord begins
  • Corticospinal Axons –> cross the midline (decussation of pyramids)
  • Ventral Surface –> where CORTICOSPINAL TRACT is found
110
Q

How does the decussation appear?

A
  • Bottom of the Pyramids: There is an obscurity as the bundles of axons in the corticospinal tract cross over in the lowest part of the medulla
  • They partially fill in the ventral fissure in the ventral medullary surface
  • Cross over to contralateral side (one motor side controls contralateral side)
111
Q

Labelled picture of the brainstem

A
112
Q

What is the alternative motor pathway to the corticospinal tract?

What can it do?

What cant it do?

Where is it found in the spinal cord?

A
  • Rubrospinal Tract
  • It can voluntary control movements too (another voluntary motor pathway)
  • it cannot do accurate movements of the fingers
  • It overlaps the descending corticospinal tract
  • Both tracts are dorsal to the denticulate ligaments

It is another pathway –> where the cerebral cortex can control voluntary motor neurones –> but it needs an extra synapse in the red nucleus

113
Q

What is the rubrospinal tract pathway?

A
  1. Goes from the forebrain to the red nucleus (which has motor functions)
  2. Axon leaves the red nucleus to cross the midline at the level of the red nucleus
  3. Descends the spinal tract
  4. Synapses at interneurones/motorneurones
  5. Interneurones go to motor neurones –> which control muscle

It originates from the cerebral cortex allowing you to make voluntary movements

114
Q

What are the locations of the corticospinal tract & rubrospinal tract in the spinal cord?

A
  • Corticospinal Tract –> runs in the DORSAL-LATERAL WHITE COLUMN
  • Rubrospinal Tract –> OVERLAPS the CORTICOSPINAL TRACT –> it is SLIGHTLY ANTERIOR

Neuroanatomy (7 decks)

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