Nervous System Part 4 Flashcards

1
Q

Motor structures found deep within the cerebral cortex (subcortical structures).
-Important for inhibitory and excitatory effects
-Complement the cerebral cortex in producing motor actions/activity

A

Basal Ganglia

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2
Q

Subcortical motor nuclei that are interconnected with the cerebral cortex, thalamus, and brainstem. All must work together in a coordinated fashion to produce normal movement.

A

Basal Ganglia

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3
Q

Consists of myelinated axons/fibers that originate up in motor areas of the cerebral cortex, which are funneled down into the brainstem.
-Also have fibers running from the thalamus projecting to the cerebral cortex.

A

Internal Capsule

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4
Q

Not a Basal Ganglia structure.
-Gives rise to the Rubro-spinal Tract Pathway
-Doesn’t function for very long in life. Very primitive.
-Goes to lower thoracic segments and goes away once we build up more prominent pathways
-Valuable to newborns and that’s it

A

Red Nucleus

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5
Q

Regulate movement along with the Cerebral Cortex

Automatic Action Motor Selection and Initiation:
-Help initiate a specific motor task (Ex: reaching and grabbing something)
-Integration of motor commands to perform the task. Have to have several systems together to carry out complete motor tasks.
Can be inhibitory (-) or excitatory (+).

A

Basal Ganglia

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6
Q

Excitatory impulses are initiated from the Cerebral Cortex onto the Caudate Nucleus and Putamen. Then, the Putamen exercises an excitatory control over the Globus Pallidus, which projects it up to the Thalamus and then the Cerebral Cortex.
The Cerebral Cortex can exert excitatory or inhibitory stimuli on the Putamen. (circular diagram).
-Inhibitory signals can follow this same pathway.

A

Motor System of the Basal Ganglia

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7
Q

Projects inhibitory signals to the Caudate Nuleus and the Putamen in exchange for them sending back down an excitatory impulse.
-Issues here = Dyskinesia (Parkinson’s)

A

Substantia Nigra

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8
Q

Projects an inhibitory signal to the Globus Pallidus in exchange for it sending back down an excitatory impulse.
-Issues here = Dyskinesia (Hemiballismus)

A

Subthalamic Nucleus

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9
Q

Muscles are firing at will all the time. Subtle form of writhing movements, or can be explosive limb movements.

A

Hemiballismus

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10
Q

Unwanted muscle activity because inhibition has been taken off of the basal ganglia and Excitatory signals are unmatched. Now have excitatory signals pouring into the nervous system and delivered out to the muscles to make them contract at unwanted times.

A

Dyskinesias (lesions in Substantia Nigra or Subthalamic nucleus)

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11
Q

Motor Cortex of Cerebral Cortex projects to cerebellum (via the Pons) and basal ganglia.
-Both cerebellum and basal ganglia send feedback via the Thalamus to the Motor Cortex.
-Cerebellum = Excitatory feedback
-Basal Ganglia = Inhibitory Feedback

Final output is determined by which system is dominating.

A

Basal Ganglia/Cerebellum Influence on the Cerebral Cortex

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12
Q

Loss of the substantia nigra or subthalamic nucleus loses our inhibitory feedback, making the whole cerebral cortex be fueled by excitatory impulses, causing dyskinesias

A

Loss of Basal Ganglia

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13
Q

Balance between these two opposing systems allows for smooth, coordinated movement to carry out functional tasks.
-Structures must be connected together in a normal fashion to share information with each other for muscles to work together without excessive dyskinetic movement

A

Basal Ganglia and Cerebellum

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14
Q

Problem with Basal Ganglia. Excessive movement

A

Dyskinesia

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15
Q

Problem with Cerebellum. Extraneous movement. Have intentional tremors: occur only when you’re trying to do something
-Ex: Friedrich’s Ataxia
-Results from dysfunction or failure of pathways to form properly that carry information from the spinal cord to the Cerebellum (Anterior lobe)
-Cerebellum cannot tell the Cerebral Cortex to contract muscles synergistically.
-Alcohol related (FAS)

A

Dysynergia

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16
Q

Alcohol use during the 1st trimester (during neural tube fomration)
-Negative effects on CNS & Cerebellum = dysynergia
-Small eye openings, smooth philtrum, thin upper lip
-Effects on CN development

A

Fetal Alcohol Syndrome

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17
Q

Congenital Condition that produces serious disordered movement patterns, enough that the person is disabled.
Swaying while walking (truncal ataxia) and widespread gait (limb ataxia). Dysynergia.

A

Friedrich’s Ataxia

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18
Q

S/Sx:
-Tremor, head bobbing, stooped posture, mask-like face, muscle rigidity (lead pipe), distal extremity tremor at rest (tremor goes away when trying to accomplish a task)
-Dyskinesia

A

Parkinson’s Disease

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19
Q

Inherited disorder in which basal ganglia (and cerebral cortex) undergo severe degeneration.
-Fatal, prolonged disease
-Every muscle is trying to contract at once in different directions - get flailing extremities and unsteady gait

A

Huntington’s Chorea

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20
Q

Coverings of the Brain and Spinal Cord.
A trilaminar sac (3 layers)
-Spinal and Cranial ___ are continuous with each other
-Protect CNS from Mechanical Injury

A

Meninges

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21
Q

Layer of meninges found just deep to the inner table of the skull.
-Very durable
-Thick, fibrous layer

A

Dura Mater

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22
Q

Layer of meninges deep to the Dura Mater.
-Spiderweb appearance

A

Arachnoid Mater

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23
Q

Layer of meninges applied very tightly to the brain itself, following the convulsions into the gyri.

A

Pia Mater

24
Q

Contains CSF, located between the Arachnoid Mater and the Pia Mater

A

Subarachnoid Space

25
Q

CSF is produced in the ventricles by this. CSF has a pathway through all ventricles and ends up in the Subarachnoid Space, containing the CNS within the skull/spinal column as if laying on a water bed.

A

Choroid Plexus

26
Q

A potential space, not usually a space but can be one if the Dura Mater and Arachnoid Mater are separated

A

Subdural Space

27
Q

Superficial Cerebral Veins are visible on top of the brain and drain the cerebral cortex. Eventually, they collect on the top of the head and drain into the Superior Sagittal Sinus.

A

Intracranial Venous Structures

28
Q

Lie mostly in the Subarachnoid space. Lesion = Subarachnoid hemorrhage.
Pierce the Arachnoid membrane JUST before draining into the Superior Sagittal Sinus. Come to lie in the Subdural space, which is where they terminate and drain into the Superior Sagittal Sinus.

A

Superficial Cerebral Veins

29
Q

Blood accumulates on either side of the Superior Sagittal Sinus and the meninges as they make the fold into the median longitudinal fissure.
-Due to trauma on the top of the head (Shaking syndrome in babies)
-Have to evacuate blood before it puts too much pressure on cerebral cortex
-Inc pressure = tonsillar herniations
-Typically a venous herniation, so can take several days to show serious symptoms

A

Subdural Hematoma

30
Q

A potential space located in the cranium, between the dura mater and the inner table of the skull.
Location of the Middle Meningeal Artery and its Anterior and Posterior branches.

A

Epidural Space

31
Q

A viable space filled with fat found in the Vertebral Column, where epidural blocks/injections occur.

A

Epidural Space (different from cranial one)

32
Q

A horizontal modification of the Dura Mater that overlies the posterior cranial fossa and cerebellum.

A

Tentorium Cerebelli

33
Q

A modification of dura mater than lies within the Median Longitudinal Fissure (crevice that exists between the two cerebral hemispheres)
-Sickle shaped
-Attaches rostrally to the Crista Galli
-Top is Superior Sagittal Sinus
-Bottom (free edge) is Inferior Sagittal Sinus

A

Falx Cerebri

34
Q

Dura mater that lies between the two cerebellar hemispheres, dividing them from each other

A

Falx Cerebelli

35
Q

Neurons and glial cells require oxygen, so has to be delivered to them somehow. Also need venous structures to bring blood back down to be recirculated.

A

CNS Circulation

36
Q

Made up by two systems:
1) Anterior (Carotid)
2) Posterior (Vertebral)
Both of these meet up together to form the Circle of Willis
-Anastomotic connections ensure a fail safe mechanisms to keep blood in important areas just in case we lose circulation to a different part.

A

Extracranial Circulation

37
Q

Accomplished by the Common Carotid Arteries. After the bifurcation (occurs at C4 - Larynx), can see CC split into External (runs anteriorly -lots of branches) and Internal (runs posteriorly - no branches) Carotid Arteries

A

Anterior Circulation

38
Q

-Two vertebral Arteries enter the Foramen Magnum, then these converge to form the Basilar Artery (runs up surface of basis pontis).
-Basilar artery bifurcates into two posterior cerebral arteries that have branches coming off - the posterior communicating arteries.
-Post. communicating arteries join up with the internal carotid arteries.
-From the internal carotid arteries comes the middle cerebral arteries and the anterior cerebral arteries.
-Anterior cerebral arteries are joined by a very small segment called the anterior communicating artery.

A

Intracranial Arterial Structures

39
Q

Anterior and Posterior circulations converge at this point, and arterial supply to higher centers is largely due to this and its branches.

A

Circle of Willis

40
Q

Comes off of the Internal Carotid Artery at the Circle of Willis and runs laterally, right through the Lateral Fissure.
-Has several branches (Lenticulostriate branches).
-Very important: Supplies blood flow to subcortical structures. Once it leaves the lateral fissure, it supplies blood and O2 to the lateral aspect of the cerebral cortex.
-MOST COMMON ARTERY INVOLVED IN STROKES

A

Middle Cerebral Artery

41
Q

Supplies blood flow to the:
1) Internal Capsule (White strip - cluster of myelinated axons rising up in the motor areas of the cerebral cortex and being bundled up to carry motor influence down through brainstem and ultimately to spinal cord.)

2) External to internal capsule are some of the basal ganglia structures. Most lateral one is the Putamen, medial one is globus pallidus.

A

Lenticulostriate branches of the Middle Cerebral Artery

42
Q

Runs right up through the median longitudinal fissure

A

Anterior Cerebral Artery

43
Q

Formed by the split/bifurcation of the Basilar Artery

A

Posterior Cerebral Artery

44
Q

Converge to form the Basilar Artery

A

Vertebral Arteries

45
Q

A branch off of the Vertebral Artery that supplies the lower brainstem, medulla (respiratory center), and posterior inferior cerebellar surface.
Lesion = Ventilator
-Occlusion/ Hemorrhage here causes Wallenberg’s Syndrome (brainstem stroke - generally bilateral outcomes)

A

Posterior Inferior Cerebellar Artery (PICA)

46
Q

A branch off of the Basilar Artery that supplies the Middle Brain Stem and the Anterior Inferior Cerebellar surface

A

Anterior Inferior Cerebellar Artery (AICA)

47
Q

Very small artery that accompanies the Vestibulocochlear Nerve (CN VIII) and the Facial Nerve (CN VII) as they enter the Internal Acoustic Meatus.
-Supplies blood and O2 to the inner ear

A

Labyrinthe Artery

48
Q

Small arteries coming off of the Basilar Artery that supply the Basis Pontis

A

Pontine Arteries

49
Q

Split off of the Basilar Artery right before it bifurcates into the Posterior Cerebral Arteries.
-Supply the upper brainstem and superior surface of the cerebellum

A

Superior Cerebellar Arteries

50
Q

Basilar Artery Bifurcates into these

A

Posterior Cerebral Arteries

51
Q

Emerges from the Pontomedullary groove (groove that separates the pons and the medulla).
-Surrounded by two arteries:
1) Anterior Inferior Cerebellar Artery (inferiorly)
2) Labyrinthine Artery (Superior and Rostrally)

A

Abducens Nerve (CN VI)

52
Q

Emerges from a deep impression between the cerebral peduncles (interpeduncular fossa) and goes on to work in the orbit.
-Surrounded by two arteries:
1) Superior Cerebellar Artery (Inferiorly)
2) Posterior Cerebral Artery (Rostrally)
Compressed during Uncal herniation due to the Temporal Lobe shifting medially. Results in pupil dilation

A

Oculomotor Nerve (CN III)

53
Q

Supplies the:
-Posterior portion of the Cerebral Cortex
-Medial/Lateral Occipital Lobe (via the median longitudinal fissure)
-Inferior Surface of the Temporal Lobe (the parahippocampus, inferior temporal gyrus, and the hippocampus)

A

Posterior Cerebral Artery

54
Q

-Calcarine Branch (runs in the Calcarine sulcus)
-Lesion in this branch causes loss of the primary visual cortex (Cortical Blindness)

A

Posterior Cerebral Artery

55
Q

Runs laterally off of the Internal Carotid Artery and passes between the Lateral fissure. Has branches that supply the lateral side of frontal, parietal, and temporal lobes, as well as internal structures such as basal ganglia and internal capsule.

Occlusion/hemorrhage Affects:
-Motor Speech Area (Pars Opercularis and Triangularis)
-Wernicke’s Area (supramarginal gyrus + Superior temporal gyrus)
-Rest of cerebral cortex following homuncular pattern

A

Middle Cerebral Artery

56
Q

Completes the anterior portion of the Circle of Willis, following the contour of the Corpus Callosum.
-Supplies the medial side of frontal and parietal lobes
-Strokes/occlusions generally experience contralateral loss of lower limb function (Homunuclus)

A

Anterior Cerebral Artery