Spinal Cord & Nerves Flashcards
Where does the spinal cord run from and to before becoming conus medullaris
Atlas -> L1
Where is the conus medularis?
L1
Where is the cauda equina?
L2
What is the function of the meninges in the spinal cord?
Anchorage & protection
What does pia mater thicken to become?
Denticulate ligament
Where is the epidural space found?
Between the dura and vertebrae
What does the pia mater become when it gets stringy?
Filum terminale
What are the four regions of the spinal cord?
Cervical (C1-8)
Thoracic (T1-12)
Lumbar (L1-5)
Sacral (S1-5)
C0
What do spinal nerves do?
Connect the periphery to the spinal cord
What are ventral nerves involved with?
Efferent communication (sensory info in)
What are dorsal nerves involved with?
Afferent communication (motor info out)
What type of matter is found in the inner part of the spinal cord?
Grey matter
What type of matter is found in the outer part of the spinal cord?
White matter
In the GREY MATTER of the spinal cord - what are the following involved in?
- Dorsal horn
- Lateral horn
- Ventral horn
Dorsal horn = sensory input
Lateral horn = pre-ganglionic SS neurons
Ventral horn = motor output
What are lots of neurons in grey matter called?
Laminae
What is information from the outside called?
Exteroception
What is information from the inside called?
Proprioception
What are bundles of axons in WM of spinal cord called?
Tracts
Which info is the dorsal column of the spinal cord responsible for?
Proprioception & light touch
Name three ascending tracts of the spinal cord.
Dorsal column
Spinocerebellar column
Spinothalamic column
Which ascending tract is responsible for proprioception & light touch?
Dorsal column
Which ascending tract is responsible for proprioception?
Spinocerebellar
Which ascending tract is responsible for pain and temperature sensation?
Spinothalamic
What is another name for the dorsal tract?
Tract of Lissauer
Where do asending nerves enter the spinal column?
Through the dorsal tract (tract of lissauer)
Do dorsal column nerves ascend on the same side or contralateral side?
Same side
Where is the cell body of a first order neuron of the dorsal column found?
In the dorsal root ganglion (outside the spinal cord)
What is the name of the collection of nerves from the arm?
Cuneate fascilius
What is the name for the collection of nerves from the leg?
Gracile facilius
Where do the first order neurons in the dorsal column synapse?
In the nucleus cuneatus or nucleus facilius.
Which neuron in the dorsal column crosses the midline?
The second order neuron
Where abouts does the dorsal column cross the midline?
In the medulla
Describe the pathway of the dorsal column tract.
1st order neuron
Enters through tract of Lissauer
Ascends same side
Synapses in nucleus fascilius or nucleus cuneatus with second order neuron.
Crosses midline in medula
Ascends to the thalamus
Synapses in thalamus with 3rd order neuron
Travels to the somatosensory cortex
What is the name for the place where the 2nd order neuron crosses the midline in the medulla?
Medial lamniscus
How does unilateral loss of a dorsal column neuron present?
Loss of procioception / VS / discriminative touch on one side. Loss will be same side below the lesion.
What things can cause unilateral loss of dorsal column nerves?
MS
Low B12
NO misuse
How does bilateral loss of dorsal column neurons present?
Severe ataxia
Where is the 2nd order neuron found in the spinothalamic tract?
In the dorsal horn (of the spinal cord)
Where do the neurons cross the midline in the spinothalamic tract?
In the dorsal horn
Describe the pathway of the spinothalamic tract.
1st order enters via tract of Lissauer
Synapses with 2nd order in dorsal horn
Crosses midline
Ascends in either anterior or lateral spinothalamic tracts into thalamus
Synapses with 3rd order neuron in thalamus
Passes through internal capsule to the somatosensory cortex
How does damage to the spinothalamic tract present clinically?
Loss of pain / temp / crude touch
Will loss of sensation be on the same side or contralateral side in the spinothalamic tract?
Contralateral side
What illness can cause loss of sensation to the spinothalamic tract?
Syringomyelia
Which is syringomyelia
Syrinx in spinal cord (fluid filled cyst) - expands and affects arms, legs and then lower down - bilateral loss of pain and temp. BUT keep lighter touch & proporioception
Will the lesion be on the same side or contralateral side to the symptoms in the spinothalamic tract?
Contralateral side
Which are the two tracts of the spinocerebellar tract?
Posterior tract
Anterior tract
Which part of the spinocerebellar tract is involved with information from muscle spindles & organs?
Posterior tract
Which part of the spinocerebellar tract is involved with information from interneurons?
Anterior spinocerebellar tract
What does the spinocerebellar tract control?
Unconscious proprioception
Smooth muscle control
How many neurons are involved in the spinocerebellar tract and why?
Only 2 (1st and 2nd order)
For quicker transmission of signal
Describe the path of the nerves in the spinocerebellar tract
1st order neuron enters through dorsal root
Synapses with the second order neurone
Ascends through the lateral border of the cord to the cerebellum, thalamus & motor cortex
Name two descending tracts in the spinal cord
Corticospinal tract
Extrapyramidal tract
Which descending tract controls voluntary movement?
Corticospinal tract
Which descending tract controls involuntary movement?
Extrapyramidal tracts
How many neurons are involved in the corticospinal tract? What are they?
2
Upper motor neuron
Lower motor neuron
Where do upper motor neurons travel from and to?
From cerebral cortex –> ventral horn.
Where do the 2 neurons of the corticospinal tract synapse?
Ventral horn
Where do the lower motor neurons travel from and to?
From the ventral horn –> peripheral muscle
Where do the UMNs cross the midline in the corticospinal tract?
80% cross in the pyramids of the medulla
20% dont cross - continue straight down in the anterior CST
What are cell bodies of lower motor neurons called?
Anterior horn cells
What type of motor neurons control voluntary muscle?
Αlpha motor neurons
What type of motor neurons control muscle spindles?
Gamma motor neurons
In which part of the ventral horn are the flexor muscle neurons found?
Middle
In which part of the ventral horn are extensor muscle neurons found?
Outside
If a lesion occurs above the medulla in the corticospinal tract, which side of the body is affected?
Opposite (80%)
If a lesion occurs below the medulla in the corticospinal tract, which side of the body is affected?
Same (80%)
What are the symptoms of an upper motor neuron problem?
Parents away (hyper)
Spasticity
Brisk reflexes
Weakness
No wasting
What can damage an upper motor neuron?
Stroke, cord injury, compression
What are the symptoms of a lower motor neuron problem?
Dead children (depression)
Flaccid paralysis
No reflexes
Muscle atrophy
Which illness causes degeneration of the anterior horn cell?
Spinal muscular atrophy
Which illness causes the immune system to attack the nerves incorrectly following a viral infection?
Guillain-Barre syndrome
Which illness affects both the upper and lower motor neurons progressively, causing wasting, vesticulations, stiffness & brisk reflexes?
Motor Neuron Disease
What do extrapyramidal tracts control?
Posture
Involuntary movement
What is the path of extrapyramidal tracts?
They start in the brainstem and descend, but dont pass through the pyramids of the medulla - down to the ventral horn.
Which extrapyramidal tract starts in the red nucleus of the brain AND is responsible for actions of flexors and extensors?
Rubrospinal tract
Which extrapyramidal tract starts in the superior colliculus AND is responsible for postural movement in response to visual stimuli?
Tectospinal tract
Which extrapyramidal tract is responsible for stabilisation when the head is tilted?
Vestibulospinal tract
Which syndrome will have damage to the cord and present as
- reduced pain & temp on opposite side
- lower motor neuron paralysis & atrophy on SAME side
- reduced vibration, proprioception & 2 point sensation on SAME side?
Brown-Sequard Syndrome
