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Neuroscience 2.0 > Lateral & Medial Descending pathway & Motor Organisation of Spinal cord > Flashcards

Lateral & Medial Descending pathway & Motor Organisation of Spinal cord Flashcards

1
Q

What are the tracts located in the Lateral funiculus?

A

Lat. corticospinal, rubrospinal, lat. Reticulospinal
- Fine voluntary movement, Distal muscles

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2
Q

What are the tracts in the anterior ( medial ) funiculus ?

A

Vestibulospinal, reticulospinal, medial (anterior) corticospinal, tectospinal.

  • Postural and reflex movement, Proximal and axial muscles
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3
Q

Which tracts modify segmental reflex activity?

A

Supraspinal tracts

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4
Q

Which tract regulates posture and balance and facilitates Aa motor neurons of the postural ( antigravity ) extensor muscles?

A

Vestibulospinal tract

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5
Q

Which tract originates from the superior colliculus ?

A

Tectospinal tract

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6
Q

True or False? The tectospinal tract is confined to lumbo-sacral segments of the spinal cord.

A

FALSE!! It is confined to the Cervical segments of the spinal cord.

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7
Q

What is the function of the Tectospinal tract?

A

It controls head and movement

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8
Q

Which medial activation tracts innervate proximal limbs and trunk extensors ( both upper & lower limb) ?

A

Medial reticulospinal & Lateral Vestibulospinal

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9
Q

Which medial activation tract innervate the Head and neck region?

A

Medial vestibulospinal and Tectospinal tract .

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10
Q

Fill in the blanks. “ ___________ innervates the innervates trunk and proximal limb muscles in upper limb.”

A

Medial corticospinal tract

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11
Q

What is the major role of the medial pathways?

A

The major role of the medial pathways is to regulate posture and balance, by acting mainly on the more proximal and axial antigravity musculature.

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12
Q

Which tract plays a significant part in decorticate rigidity?

A

Rubrospinal tract

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13
Q

Fill in the blanks. “The lateral reticulospinal tract descends in the ____________ column and inhibit __________ while it facilitates __________-.”

A

The lateral reticulospinal tract descends in the anterolateral column
inhibit extensor and facilitate flexor motoneurones - targeting the Ag more than the Aa motoneurones.

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14
Q

Where does the corticobulbar tract originate?

A

From the facial region of the motor cortex.

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15
Q

Which Cranial nerve controls eye movements?

A

CN III, IV, and VI

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16
Q

Which cranial nerves control Cranial, facial , pharyngeal and laryngeal muscles ?

A

CN V,VII, IX, and X

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17
Q

Which cranial nerves supply some superficial muscles of the back and neck ?

A

CN XI

18
Q

Which cranial nerve supplies the intrinsic and extrinsic muscles of the tongue?

A

CN XII

19
Q

What is the major function of the Lateral activation system?

A

The major function of the lateral system is to
over-ride the postural set (inhibit anti-gravity muscles) in order to promote the integrated, but independent and finely controlled, dexterous use of the muscles of the distal appendages, to carry out a highly variable repertoire of movements.

20
Q

What happens during the recovery of a transection of the spinal cord?

A

1) Development of hypersensitivity in the denervated neurones below the lesion.

(2) Sprouting of intact nerve terminals below the lesion to make new functional contacts.

21
Q

During the recovery of a transection of the spinal cord, why do reflexes become hyperactive or altered?

A

This is as a result of:

(a) loss of descending modulatory control or
(b) newly formed synaptic contacts, and
(c) denervation hypersensitivity.

22
Q

What does the Medial Reticular Extensor inhibitory area?

A

This area inhibits mainly the g-motor neurones, and to a lesser extent the a -motor neurones, of the extensor muscles.

23
Q

Which nuclei is Extensory inhibitory?

A

Reticular nuclei

24
Q

Which nuclei is Extensor Facilitatory?

A

Pontine nuclei

25
Q

Fill in the blanks. “ The ___________ drives the rigidity which is released from control by higher centers.”

A

Vestibular system

26
Q

What are the causes of Decerebrate ?

A

Primary lesions, such as infarction, hemorrhage, or tumor. Other causes include metabolic encephalopathy, head injury, and brain stem compression associated with increased intracranial pressure

27
Q

Fill in the blanks. “ Decerebrate posture indicates ____________.”

A

Upper brain stem damage.

28
Q

Fill in the blanks. “ Lesion of the vestibular system will __________.”

A

Abolish speciosity and lead to Hypotonia

29
Q

What is the function of the Vestibular nuclei?

A

This selectively control the excitatory signals to the different antigravity M. to maintain equilibrium in response to signals from the vestibular apparatus.

30
Q

What is the Inhibitory area?

A

Medullary reticular system

31
Q

What is Decortication?

A

Destruction of the cerebral cortex leaving the red nucleus and basal ganglia intact.

32
Q

What is the site of origin of descending fibres?

A

The motor cortex

33
Q

What is the basic unit of a reflex action called?

A

Reflex arc

34
Q

What is the reflex arc composed of?

A
  • A sensory organ
  • An afferent neuron
  • One or more synapses( Interneurons ) in spinal cord or brain
  • An efferent neuron
  • An effector
35
Q

What is the name given to a sense organ that monitors length of muscle and how fast muscles change in length?

A

Muscle spindle

36
Q

What type of muscle fibres are found in the muscle spindle?

A

Ia and II

37
Q

What are the structures that the muscle spindle are composed of?

A

Intrafusal muscle fibres
Afferent fibres
Gamma motor neurons

38
Q

Fill in the blanks.” Alpha motor neurons supplies _________ fibres.”

A

Extrafusal fibres

39
Q

Fill in the blanks. “ ____________ supplies contractile peripheral part of intrafusal fibers. “

A

Gamma motor neurons

40
Q

Where does alpha motor nerves originate from?

A

Rexed lamina IX

41
Q
A

Neuroscience 2.0 (29 decks)

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