Spinal Tract Pathways Flashcards

0
Q

What information is conveyed by the spinothalamic tract?

A

Non discriminatory touch, temperature and pain

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1
Q

Name all of the sensory tracts.

A
  1. Spinothalamic
  2. Dorsal Column / Medial Leminiscal
  3. Chief Sensory Tract
  4. Spinal Tract V
  5. Spinocerebellar
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3
Q

What information is conveyed by the dorsal column / medial leminiscal tract?

A

Discriminatory touch, vibration and conscious proprioception

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4
Q

What information is conveyed by the chief sensory tract?

A

Discriminatory touch, vibration and conscious proprioception

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5
Q

What information is conveyed by the spinal tract V?

A

Non discriminatory touch, temperature and pain

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6
Q

What information is conveyed by the spinocerebellar tract?

A

Unconscious proprioception

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7
Q

Name all of the motor tracts.

A
  1. Corticospinal tract (pyramidal)
  2. Corticobulbar tract
  3. Vestibulospinal tract (extra pyramidal)
  4. Reticulospinal tract (extra pyramidal)
  5. Rubrospinal tract (extra pyramidal)
  6. Tectospinal tract (extra pyramidal)
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8
Q

What is the function of the vestibulospinal tract?

A

maintenance of posture by innervating extension muscle groups responding to gravity

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9
Q

What is the function of the reticulospinal tract?

A
  1. Motor function - selectively inhibits/excites muscle groups to ensure correct tone and correct force depending on the movement e.g walking. Ensures fluidity and smoothness of muscle.
  2. Sympathetic outflow to the paravertebral chain
  3. Pain modulation
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10
Q

Describe how motor information is conveyed through the reticulospinal tract.

A
  1. Caudal pontine reticular nucleus and oral pontine reticular nucleus extend axons through the medial reticulospinal tract (bilateral) and the gigantocellular nucleus extends axons through the lateral reticulospinal tract (ipsilateral)
  2. Lateral reticulospinal tract neurons inhibit cortically induced movement of axial extensor muscles
  3. Medial reticulospinal tract neurons facilitate cortically induced movement of extensor ‘anti-gravity’ muscles
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11
Q

Describe the journey of sympathetic outflow through the reticulospinal tract.

A
  1. Nuclei within the hypothalamus extend axons carrying sympathetic information through the dorsal longnitudinal fasiculus to the reticular formation to synapse.
  2. Neurons from the reticular formation extend through the lateral reticulospinal tract (ipsilateral)
  3. These synapse at the intermediolateral nucleus. Then there is outflow to the sympathetic chain.
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12
Q

What is the function of the rubrospinal tract?

A

Fine motor control of flexors mainly of the hand and arms.

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13
Q

Describe the how pain modulation occurs via the reticulospinal tract.

A
  1. PAG nuclei extend axons to the reticular formation. These then synapses at the raphe nucleus within the reticular formation.
  2. Neurons extend through the lateral reticulospinal tract (ipsilateral tract) and synapse at the intermediolateral tract.
  3. Interneuron then synapses at neurons entering the spinothalamic tract (non-discriminatory touch, temperature and pain) and modulate sensory pain information
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14
Q

Where does the rubrospinal tract originate?

A

The red nucleus at the midbrain at the level of the superior colliculus

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15
Q

Describe the journey of the rubrospinal tract.

A

The rubrospinal tract closely resembles the corticospinal tract due the cortical input. This is the only extra-pyramidal tract to do so.

  1. The motor cortex inputs to the red nucleus (the corticospinal tract iis parallel to the rubrospinal tract, there is a close association)
  2. The dentate nucleus of the cerebellum also input to the red nucleus. Fibres exit the cerebellum via the superior cerebellar peduncle.
  3. From the red nucleus, there is immediate decussation.
  4. The fibers pass through the lateral funiculus (into white mater) and pass into the grey matter where it synapses with lower motor neurons.
  5. These lower motor neurons innervate flexors and extensors but mainly flexors for fine motor control.
  6. This terminates mainly at the cervical spinal levels for extra dexterity of the arms and hands
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16
Q

What is the function of the tectospinal tract?

A

Reflex movements in response to bright lights and loud noises

17
Q

Where does the tectospinal tract originate?

A
  1. The superior colliculus is where the tract starts and has inputs from the retina and visual cortex
  2. This is where visual reflexes are relayed to
  3. Neurons originating from the inferior colliculus joins the tectospinal tract. This is where auditory reflex information comes from.
  4. There is immediate decussation
  5. Synapse with lower motor neurons at all cervical levels for reflex movements collaterally
18
Q

Describe the journey of sensory information through the spinothalamic tract (non discriminatory touch, tempreature and pain).

A
  1. 1st order neuron comes in through the dorsal root (cell body is in the dorsal root ganglion) and synapses in the laminae of the dorsal horn. The particular laminae depends on the modality of sensory information.
  2. 2nd order neuron carries on through the grey mater and decussates at the anterior white commissure.
  3. The neuron ascends on the contralateral side through the lateral funiculus. This ascends through the brain stem and to the ventral posterior lateral (VPL) nucleus of the thalamus to synapse.
  4. The 3rd order neuron then passes through the internal capsule and then through the corona radiata to the primary sensory cortex and association sensory cortex.
19
Q

What are the consequences of a lesion to each type of neuron in the spinothalamic tract?

A

1st order: Ipsilateral deficit
2nd order: Contralateral deficit
3rd order: Contralateral deficit

21
Q

Explain syringomyelia and its affect on the spinothalamic tract.

A
  1. This is where a syrinx (a cyst/cavity) that forms in the spinal cord and expands into the anterior white commissure.
  2. As a result there is a deficit of non discriminatory touch, pain and temperature.
22
Q

Where does the vestibulospinal tract originate?

A
  1. Nuclei within the vestibular apparatus.
  2. Axons travel through the vestibulocochlear nerve to vestibular nuclei within the pons at about the level of the cerebral peduncle.
23
Q

Describe the journey of the vestibulospinal nerve.

A

-

24
Q

Describe the journey of sensory information through the dorsal column / medial leminiscal pathway (discriminatory touch, vibrations and conscious proprioception)

A
  1. The first order neuron enters through the dorsal root (the cell body is in the dorsal root ganglion)
  2. The first order neuron continues as it ascends either through the fasiculus cuneatus (above T6) or the fasiculus gracilis (below T6).
  3. The neuron then synapses at the nucleus gracilis or cuneatus (corresponding to the fasiculus) at the medulla. The nuclei can be seen on the posterior aspect of the medulla.
  4. The 2nd order neuron immediatly decussates to the contralateral sides and are now called lateral arcuate fibres as they pass laterally
  5. As the lateral arcuate fibres ascend the pathway is referred to as the medial leminiscal pathway. These neurons synapse at the ventral posterior lateral nucleus of the thalamus.
  6. The 3rd order neurons then pass through the internal capsule, cross the corona radiata to terminate at the primary/association sensory cortex.
25
Q

What are the consequences of a lesion to each type of neuron in the dorsal column / medial leminiscal pathway?

A

1st order: ipsilateral. Note, this includes not only the peripherals but also the spine
2nd order: contralateral
3rd order: contralateral