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Neuro Exam I > Anatomical Basis of Movement Disorders > Flashcards

Anatomical Basis of Movement Disorders Flashcards

1
Q

what is the position of the caudate nucleus with respect ot the

  • thalamus?
  • lateral ventricles?
A

caudate nucleus is a strucutre that moves in a horizantal plane, an caudally, runs in between the lateral vencticles (superior structure) and thalamus (inferior structure)

  • the tail of the caudate nucleus is bilaterally:
    • is along the superolateral surface of thalamus
    • along the deep (inferior) surface fo the lateral ventricles
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2
Q

what is the caudate nucleus?

what are its important anatomic relations?

A
  • an anteroinferior (rostral) expansion of the caudate nucleus
  • anatomic relations: to the more lateral putamen
    • inferior portion: is fused to the lateral putamen
    • superior portion: is separated from putamen by the anterior limb of the internal capsule
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3
Q

what is the amydala?

where is it located?

A
  • the inferior tip of the caudate nucleus
  • in the temporal lobe
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4
Q

what is the striatum?

A

a combination of the caudate nucleus + putamen

  • seen in the anteiror part of brain
  • superiorly are separated by the IC (anterior crus), inferiorly are directly fused
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5
Q

what is the lentiform nucleus?

A

combination of putamen + globus pallidus

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6
Q
  • what is the putamen?
  • what borders it laterally & mediallly?
A
  • the most lateral component of the basal ganglia:
  • borders:
    • its medial surface is
      • fused to head of the _caudate nucleu_s (superiorly)
      • fused to globus pallidus (inferiorly)
    • its lateral surface is: fused to the external capsule - i..e, the insula (thin sheet of axons)
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7
Q

what is the external capsule?

what are its key anatomic relations?

A
  • the insula: a thin sheet of axons
  • forms the lateral border of the putamen
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8
Q

what is the subthalamic nucleus?

what are its anatomic relations?

A
  • a small disc shaped body in the forebrain
  • anatomic relations:
    • inferior to the thalamus
    • thus, at the vertical level of the midbrain
      • medial to the IC (like the thalamus), and thus separated from the tegmentum by the external IC that covers it
      • lateral to the red nucleus
      • dorsal to the substantia nigra
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9
Q

the substantia nigra

  • is bordered by what structures dorsally?
  • is histologically divided into what sections?
A
  • bordered dorsally by the
    • red nucleus (medially)
    • subthalamic nucleus (laterally)
  • histologically divided into the:
    • substantia nigra pars compacta: neurons dense region
    • substasntia nigra pars reticula: neuron sparse region
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10
Q

the basal ganglia

  • recieves its main input frrom?
  • provides its main output to?
A
  • main input from: cerebral cortex
  • main output to: thalamus
    • which coordinates to the brain stem: the brainstem have no direct connections with the spinal cord*
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11
Q

the input (afferent) signals to the basal ganglia

  • come from where?
  • by which fibers?
  • carrying which specific signals?
  • arrive at what region?
A
  • come from: cerebral cortex (largely motor cortex)
  • carried by: corticostriate fibers
  • signals: glutamate (exctiroy)
  • arrive at: the striatum (caudate nucleus + putamen)
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12
Q

the output (efferent) fibers from the basal ganglia

  • originate where?
  • travel via which fibers?
  • carrying which specific signals?
  • arrive at what region?
A
  • originate in: globus pallidus interna
  • travel via the:
    • ansa lensicarus: travel inferior to posterior crus of IC
    • lenticarus fasciulus: travel perpendicular to posterior crus of IC
  • carrying: GABAnergic (inhibitory)
  • arrive at: the VA & VL (motor nuclei) of the thalamus
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13
Q

the ansa lenticarus and lenticular fasiculus

  • travel how?
  • merge to form what tract? where?
A
  • travel from globuls pallidus interna -> thalamus (VA & VL)
    • ansa lenticaris: courses inferior to posterior crus of IC
    • lenticular fasiculus: courses perpendicular to (through) posterior crus of IC
  • merge to form the pallidothalamic tract (thalamic fasciculus) once medial to the posterior crus - i.e., once in the thalamus
    • ansa lenticaris: courses inferior to posterior crus of IC
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14
Q

outline the direct pathway of the neural circuitry of the basal ganglia.

what is the ultimate consequence of the direct pathway?

A
  1. corticostriate fibers send glutamic (excitory) signals to striatum [afferent]
  2. stiatum internus, activated, sends GABAnergic (inhibitory) neurons to to globus pallidus internus
  3. the globus pallidus internus, inhibited, cannot sent GABA (inhibitor) neurons to the thalamus VA & VL [efferent]
  4. uninhibited VA & VL -> increased motor activity (disinhibition)
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15
Q

outline the indirect pathway of the neural circuitry of the basal ganglia.

what is the ultimate consequence of the direct pathway?

A
  1. corticostriate fibers send glutamic (excitory) signals to striatum [afferent]
  2. intermediate steps:
    • stiatum internus: uninhibited, sends GABA neurons to globus pallidus externus
    • globus pallidus: inhibited, cannot send GABA neurons to subthalamic nucleus
    • subthalamic nucleus: unihibited, sends sends glutamic globus pallidus internus
  3. the globus pallidus internus, unhibited, sends GABA (inhibitor) neurons to the thalamus VA & VL [efferent]
  4. inhibited VA & VL -> decreased motor activity (inhibition)
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16
Q

what signals are the same in the direct & indirect basal ganglia neural circuitry?

which steps lead to the different results of each path?

A
  • afferents to basal ganglia: always glu (excitatory)
  • efferents from basal ganglia: always GABA (inhibitory)
  • efferents from thalamus: always glu (excitatory)

direct pathway: striatum -> GABA -> globus internus -> no GABA -> VA & VL disnihibited -> increased motor cortex activity

indirect pathway: striatum -> GABA -> globus externus -> no GABA -> subthalamic nucleus -> glu -> globus internus -> GABA -> VA & VL inhibited -> decreased motor cortex activity

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17
Q

draw out the basal ganglia - thalamus - motor cortrex circuit

A
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18
Q

what is dyskinesia?

A

abnormal timing of movement

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19
Q

excessive activity of each basal ganglia pathway would lead to which type of dyskinsesia?

A
  • indirect pathway: hypokinesia (parkinsons)
  • direct pathway: hyperkinesia (huntingtons chorea)
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20
Q

hemibalismus

  • definition
  • cause
  • presentation
A
  • defintion: type of dyskinesia
  • cause: subthalamic nucleus disruption (indirect pathway)
    • leading to impaired disinhibition of thalamus & increased motor activity
  • presentation: violent, uncontolled motor activity on side of body contralateral to disruption
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21
Q

review the important anatomic relations of the infeior olivary nucleus:

A
  • medially: medial lemniscus
  • ventromedially: medullary pyramid
    • separated by ventrolateral sulcus
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22
Q

how does the hypoglossal nerve travel through the medulla?

A
  • travels ventolaterally in between the:
    • inferior olivary nucleus & medial lemniscus
    • inferior olivary nucleus & medullary pyramids
23
Q

list the afferents that feed into the inferior olivary nucleus

A
  • spinoolivary tract (dorsal root ganglion)
  • central tegmental (red nucleus)
  • corticoolivary tract (cerebral cortex)
  • cerebroolivary tract (cerebelloolivary)
24
Q

the spinoolivary tract

  • travels in what direction?
  • originates where?
  • synapse where?
  • dessucates where?
  • move where after reaching the inferior olive?
A
  • ascending tract (sensory)
  • path:
    • originates in dorsal root ganglion (1st order nueonrs)
    • 1st order neurons synapse in dorsal root (2nd order neurons)
    • 2nd order neurons
      • dessucate while moving to to ventral funiculus
      • ascend through the ventrl funiculus
      • synapse onto inferior olivary nucleus (3rd order neurons)
  • after reaching inferior olive: 3rd order neurons move to inferior cerebellar peduncle (main inferior olivary output0
25
the central tegmental tract * travels how? * originates where? * moves where after going ot the inferior olivary nculeus?
* are descending fibers * originates: **red nucleus**. * **parvocellular portion, specifically:** * **rostral portion** * **small cells** * **densely packed** * after reaching inferior olive: dessucate on the way to travel through _inferior cerebellar peduncle_ [main olivary afferent]
26
which olivary afferent carries "feedback" fibers
cerebroolivary tract
27
the inferior olivary efferents * carry what fibers? * travel how? * dessucate where? * contribute to?
* carried by: **climbing fibers** * travel through: **the inferior cerebellar peduncle** * dessucate in: **the medulla** * contribute to: **all three functional circuits within the cerebellum** * **​**pontocerebellum * spinocerebellum * vestibulocerebellum
28
damage to the inferior olives would lead to what defects? why?
* b/c it would disrupt efferents to the inferior cerebellar peduncle, which contributing to all cerebellar circuits: * ataxia * balance impairment * motor learning
29
the corticospinal tracts divides into * what two descending tracts? * how do they travel? * where & how do they synapse?
* forms the lateral & ventral corticospinal tracts * lateral corticospinal tracts: synapse onto LMNs in _lateral ventral horn_ * ventral corticospinal tracts: syanpse onto LMNs in _medial ventral horn_
30
the red nucleus is divided into what regions? by what anatomical landmarks? that differ how?
* divided into **rostral (superior)** and **caudal (inferior)** portions _by an imaginary line between the superior & inferior colliculus_ of the tectum: * **parvocellular portion** * rostral * small cells * densely packed * **magnocellular portion** * caudal * large cells * loosely packed
31
describe how features of the tegmentum line with horizantally with the superior & inferior colliculi
* the colliculi line up with the red nuclei - superior cerebellar peduncle junction * red nuclei (most rostral) - superior colliculi * suprior cerebellar peduncle - superior colliculi
32
what are the afferents that go into the red nucleus?
* corticorubral tract * cerebellorubral tract
33
the corticorubral tract * originates where? * travels how? * goes where?
red nucleus afferent * originates: **primary motor cortex (precentral gyrus) + premotor cortices** * travels through: the **posterior crus of the IC** (like the corticorubral tract) * goes to: red nucleus
34
the cerebellorubral tract * originates where? * travels how? * dessucate where? * goes where?
red nucleus afferent * originates: **dentate nucleus** (deep cerebellar nuclei) * travels: **through superior cerebellar peduncle** * dessucate: **at the red nucleus surface** * goes to: **red nucleus**
35
rubrospinal tract * originates where? * travels how? * dessucates where? * goes where?
red nucleus efferent * originates: **red nucleus** (tegmentum) * **magnocellular portion** * caudal * large cells * loosely packed * travels: * through tegmentum - and _dessucates here_ * enters spinal cord - descends _thru lateral funiculus_ * go to: neurons that innervate the upper limb
36
the rubrospinal tract has what actions?
upper limb: * flexor excitation * extensor inhibition
37
the rubrospinal tract travels near what other major tract?
desends through the lateral lemniscus near the lateral corticospinal tract (dessucated)
38
rubroolivary tract * originates where? * travels how? * goes where?
red nucleus efferent / inferior olive afferent - i.e., central tegmental tracgt * originates in: **red nucleus** * **parvocellular segment:** * rostral * small cells * tightly packed * travels through: **central tegmental tract** * goes to: inferior olive
39
mollaret's triangle * is formed by what features? * clinical relevance?
* features * dentate nucleus (arbor vitae of cerebellum) * red nucleus (tegmentum) * inferior olivary bodies (medulla) * clinical: lesions in this region can lead to **palatal myoclonus - contraction of the soft palate**
40
lesions to the red nucleus can lead to?
possibly, a rubral tremor (damage to tracts on either side of the red nucleus a more common cause)
41
what key tracts involve the magnocellular and parvocellular regions of the red nucleus?
* magnocellular: **rubrospinal trac**t (red nucleus efferent) arises here * parvocellular: **ruboolivary / central tegmental tract** (red nucleus efferent, inferior olivary afferent) arises here
42
lateral (medullary) reticulospinal tract * originates where? * travels how? * goes where? * mediates what?
* originates: reticular formation - **gigantocellular nucleus** * travels: descends through the **lateral funiculus** * mediates: 1. weak flexion 2. inhibition of extension of lower limb & trunk (opposite of lateral vestibulospinal tract)
43
lateral vesibulospinal tract * originates from? * travels how? * mediates what?
* originates: **vestibular nucleus** * travels: in the _ventral funiculus_ * mediates: * excitation of extensors * inhibition of flexors - trunks & legs (opposite of lateral reticulospinal tract)
44
what tracts make up the lateral motor system?
* lateral corticospinal * lateral reticulospinal * rubrospinal
45
medial vesitubulospinal tract * originates where? * travels how? * mediates what?
* originates: medial vestibular nucleus * travels: through the medial funiculus, only to the _level of the neck_ * mediates: **movements of head & neck**
46
medial reticulospinal tract * origin * pathway * mediates
* origin: caudal and oral pontine nuclei (reticular formation) * pathway: descents in ventral funiculus * mediates: * inhibition of flexors * excitation of trunk + lower limbs
47
list each descending tract that innervate the legs. indicate how each tract excites / inhibits muscle groups
* lateral corticospinal - excites everything * lateral vestibulospinal - excites extensors + inhibits flexors * pontine reticulospinal tract - excites extensors + inhibits flexors
48
which lower leg tracts excite the extensors while inhibiting the flexors?
* lateral vestibuospinal * pontine reticulospinal
49
how does damage to the lateral corticospinal tract affect the legs? why?
* **excess leg extension** * w/out the lateral corticospinal, the legs are only innervated by the lateral vesitbulospinal & pontine reticulospinal, which both **_excite the extensors_ + inhibit the flexors**
50
list each descending tract innervates the arms indicate how each tract excites / inhibits individual muscle groups
* lateral corticospinal: excite everything * rubrospinal: excites flexors + inhibit extensors * medullary reticulospinal: excites flexors + inhibits extensors
51
which two arms tract excite the flexors + inhibit the extensors?
* rubrospinal * medullary reticulospinal
52
how does damage to the corticospinal tract affect the arms? why?
* **excess arm flexion** * **​**w/out the lateral corticospinal, the arms are only innervated by the rubrospinal & medullary reticulospinal which both **_excite the flexors_ + inhibit the extensors**
53
**decorticate posture** * is caused by? * presents as?
* cause: damage to the corticospinal tract * presents as: * lower limb extension * upper limb flexion
54
decerebrate posture * is caused by * presents as
* cause: damage to BOTH the _corticospinal tract_ & _rubrospinal tract_ * presentation: * lower limb extension * upper limb mixed: * wrist flexion, but * elbow extension

Neuro Exam I (15 decks)

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