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Neuro anatomy 2 > Motor II > Flashcards

Motor II Flashcards

1
Q

Origin and termination of Corticotectal tract

A
  • Origin = occipital lobe (visual association cortex = areas 18 and 19)
  • Termination:

–> oculomotor accessory nuclei = control reflex movements of eyes

–> superior colliculus = gives rise to tectospinal tract and associated with reflex movements

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2
Q

origin and termination of Tectospinal tract

A
  • Origin = superior colliculus
  • Termination = C and T spinal cord levels
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3
Q

what is the function of the Tectospinal tract

A
  • associated with reflex movements of the eyes, neck (head) and upper thorax in response to auditory, vestibular, or cutaneous stimuli
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4
Q

describe Corticorubral tract

A
  • origin = sensorimotor cortex
  • termination = red nucleus of midbrain
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5
Q

describe Rubrospinal tract

A
  • Origin = red nucleus
  • Crosses in the MIDBRAIN and descends to the upper spinal cord
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6
Q

Function of rubrospinal tract

A
  • controls the movement of HAND and DIGITS by:
    1) facilitating motor neurons that innvervate distal flexor muscles of UL
    2) inhibitor motor neurons that innervate the distal extensor muscles of UL
  • Supplements the function of (more important) corticospinal tract
  • more important in primates for grasping branches
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7
Q

what is the result of Rubrospinal tract lesion

A
  • will result in UMN signs
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8
Q

What stimualtes the reticulospinal system?

A

IPSILATERAL:

–> descending cortical projections (corticoreticular fibers)

–> input from the cerebellum and vestibular nuclei (influence muscle tone)

–> ascending somatosensory projections (spinoreticular fibers) relaying nociception

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9
Q

Describe corticoreticular fibers

A
  • Origin = sensorimotor cortex
  • descend with corticonuclear and corticospinal tract fibers
  • Termination = IPSILATERAL reticular formation (pons and medulla)
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10
Q

describe MEDIAL (pontine) reticulospinal tract

A
  • Origin = pontine nuclei
  • descends IPSILATERAL down the anterior funiculus and synapse in gray matter with interneurons and gamma motor neurons
  • Termiantion = at ALL spinal cord levels
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11
Q

describe the function of the medial (pontine) reticulospinal tract

A

EXCITATORY INFLUENCE on motoneurons that innervate PARAVERTEBRAL and LIMB EXTENSORS

  • Simultaneously inhibitory to the flexors

**LESION = UMN signs**

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12
Q

describe Lateral (medullary) reticulospinal tract

A
  • Origin = medullary nucleus
  • Descends IPSILATERALLY down the anterior funiculus and synapses in gray matter with interneurons
  • Terminates at ALL spinal cord levels
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13
Q

function of lateral (medullary) reticulospinal tract

A
  • INHIBITORY influence on motorneuron that innervate the paravertebral and limb extensors
  • Simultaneously EXCITATORY to the flexors

**Opposite of medial reticulospinal tract**

** LESION = UMN signs**

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14
Q

describe the role of both reticulospinal tracts

A
  • Terminate on interneuons that synapse with alpha and gamma motor neurons that INNERVATE ANTIGRAVITY MUSCLES (paravertebral and proximal limb muscles - NOT fingers)
  • modulate muscle tone and posutre maintenance via commands that arise from basal ganglia and verebellum
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15
Q

Describe medial vestibulospinal tract

A
  • Origin = medial and inferior vestibular nuclei
  • termination - BILATERALLY at cervical and upper thoracic spinal cord levels
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16
Q

function of medial vestibulospinal tract

A
  • innervate neck muscles
  • maintain equilibrium (balance) in response to vestibular input
  • control head movement to keep an image on the retina
17
Q

Describe lateral vestibular nucleus

A
  • Origin = Lateral vestibular nucleus (receives inputs from vestibular apparatus)
  • termination = IPSILATERALLY at ALL spinal cord levels (interneurons mostly and some alpha motor)
18
Q

Function of lateral vestibular nucleus

A
  • EXCITATORY to antigravity muscles (trunk paravertebral and proximal limb extensor muscles
  • simultaenously inhibit LMS’s that innervate limb flexor muscles
  • Function = maintenance of posture and balance
19
Q

what tracts belong to ventromedial (anteromedial) group

A
  • Anterior corticospinal tract
  • medial and lateral vestibulospinal tracts
  • medial and lateral reticulospinal tracts
  • tectospinal tract

** Muscles of AXIAL (trunk), PROXIMAL LIMB (girdle) inorder to MAINTAIN BALANCE as postural adjustments are made

20
Q

Lateral group tracts

A
  • lateral corticospinal tract
  • rubrospinal tract (not very important in humans)

** Tracts influence mostly DISTAL MUSCLES OF LIMBS (muscles that control digits)**

21
Q

Cortical Group tracts

A
  • consists ONLY of axons of the LATERAL CORTICOSPINAL TRACT which termiante on LOWER MOTOR NEURONS (but not interneurons) that innervate DISTAL MUSCLES OF LIMBS, especially muscles of hand

–> axons mediate distinct, fractionated movements of the digits (PLAYING PIANO)

22
Q

describe the order of muscle innervation from medial to lateral

A
  • TSAFH

–> trunk

–> shoulder

–> arm

–> forearm

–> hand

23
Q

describe Brown-sequard syndrome

A
  • Results following HEMISECTION of SPINAL CORD

–> LOSS of discriminative sense AT or BELOW level of lesion IPSILATERALLY (FG/FC ascend ipsilaterally)

–> LOSS of reflex activity invovling level of lesion IPSILATERALLY

–> UMN signs BELOW lesion IPSILATERALLY

–> LMN lesion signs AT level of lesion, IPSILATERALLY

–> Loss of PAIN and TEMP 2 segments BELOW lesion CONTRALATERALLY

24
Q

describe polyomyelitis

A
  • Viral infection of spinal cord

–> Affects LMN causing LMN signs

25
Q

describe Combine systems disease (subacute combined degeneration, Posterolateral sclerosis)

A
  • Deficiency in VITAMIN B12 intake or metabolism
  • DORSAL FUNICULUS (FG,FC) DEGENERATION = Loss of discriminitive touch, 2 point discrimination, vibratory sense, proprioception
  • LATERAL FUNICULUS Degeneration (motor fibers of corticospinal tract) = UMN signs = babinski sign, hyperreflexia, muscle weakness, spasticity
26
Q

Anterior spinal artery

A
  • supplies anterior 2/3 of spinal cord = anterior and lateral funiculi and most of gray matter
27
Q

posterior spinal artery (2)

A
  • 2 posterior spinal arteries supply posterior 1/3 of spinal cord = dorsal funiculi and posterior part of dorsal horn
28
Q

Radicular and medullary arteries

A
  • spinal branches of segmental arteries branch into:

–> radicular arteries = spinal nerve roots

–> medullary arteries = spinal cord

29
Q

what level of spinal cord is most susceptible to damage from interruption of blood flow

A
  • CERVICAL LEVELS

–> cervical region is supplied ONLY by anterior and posterior spinal arteries without contribution of the RADICULAR ARTERIES ANASTOMOSES

30
Q

Anterior spinal artery syndrome

A
  • OCCLUSION by thrombus or compression causes:

–> damage to anterolateral system/pathway = loss of pain and temp

–> damage to anterior horn cells = LMN weakness

–> large lesion affected lateral corticospinal tracts = UMN signs

–> damage descending pathways = control sphincter function and causing incontinence

31
Q

Posterior spinal artery syndrome

A
  • Occlusion or compression of one or both posterior spinal arteries

–> Lesion of posterior white columns = LOSS of proprioception (position sense from muscles and joints), loss of vibratory sense and loss of tactile (fine touch) discrimination)

Neuro anatomy 2 (10 decks)

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