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Anatomy (MPAS) > Lecture 3: Nervous system II > Flashcards

Lecture 3: Nervous system II Flashcards

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1
Q

What is the ventricular system?

A

4 fluid-filled cavities (~150 ml) within the
brain

2 lateral ventricles connected to midline 3rd ventricle (level of diencephalon) by inter- ventricular foramina (foramina of Monro)

3rd ventricle connected to 4th ventricle by the midline cerebral aqueduct (level of midbrain)

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2
Q

Floor and roof of 4th ventricle

A

floor is pons/medulla

roof is cerebellum

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3
Q

Flow of CSF in ventricular system

A

2 lateral ventricles into midline 3rd ventricle which drains into 4th ventricle via cerebral aqueduct (narrowest part of icv system)

4th ventricle drains into sub-arachnoid space of cranial cavity median aperture and 2 lateral apertures.

Circulates around brain and spinal cord

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4
Q

What produces the CSF? How much?

A

Choroid plexus (highly vascular tissue found within ventricles)

500 ml per day (volume of subarachnoid space is only 150 ml)

Constantly produced

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5
Q

What is the CSF?

A

clear fluid derived from plasma of

the highly vascularized choroid plexus

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6
Q

What does choroid plexus look like?

A

appears as tufts of material in all 4 ventricles (suspended within CSF of ventricles)

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7
Q

What is choroid plexus made of?

A

specialized epithelial cells that determine which solutes enter the CSF and which don’t

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8
Q

Where is CSF absorbed?

A

Absorbed into blood through arachnoid granulations in venous sinuses

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9
Q

What happens if production of CSF is higher than absorption?

A

Hydrocephalus

Also happens if CSF accumulates in the ventricles

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10
Q

CSF functions

A
  1. Provides protection: provides buoyancy of brain within cranium
  2. Maintains constancy of environment for brain tissue (provides nutrients & ions)
  3. Removes cellular waste products – CSF eventually goes to venous blood
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11
Q

Composition of CSF

A

relatively constant

change is indication of pathological process (examined by lumbar puncture; lumbar cistern is at base of spinal cord)

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12
Q

What drains the CSF from the subarachnoid space into the venous sinuses?

A

Arachnoid villi (tufts of arachnoid that extend through dura into venous sinus)

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13
Q

Where are the arachnoid villi most numerous?

A

superior sagittal sinus and are seen as arachnoid granulations

(see figure)

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14
Q

What supplies brain oxygen?

A

internal carotid (anterior) and vertebral arteries (posterior)

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15
Q

What part of brain do the internal carotids oxygenate?

A

telencephalon (ant., med., & lat.) and diencephalon

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16
Q

What part of brain do the vertebral arteries oxygenate?

A

posterior & inferior parts of telencephalon (occipital and inferior part of temporal lobes)

brainstem

cerebellum

cervicalspinal cord

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17
Q

Major branches of internal carotid

A
  1. Posterior communicating artery (connects anterior and posterior circulation)
  2. Anterior cerebral artery (medial and superior surfaces of frontal and parietal lobes)
  3. Middle cerebral artery (lateral cortical and subcortical)

(see figure)

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18
Q

What connects the anterior cerebral arteries?

A

Anterior communicating

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19
Q

What does occlusion of the anterior cerebral artery cause?

A

sensory and motor deficits of the contralateral body (lower limbs)

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20
Q

What parts of brain are supplied by the middle cerebral artery?

A

large portion of motor and pre-motor areas in frontal lobe

large area in parietal lobe

superior surface, and anterior pole of temporal lobe

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21
Q

What does occlusion of the middle cerebral artery cause?

A

sensory and motor deficits of the contralateral body (trunk upper limbs, head/face)

language deficits

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22
Q

What do the vertebral arteries form?

A

Basilar artery

Basilar artery ascends along the pons before splitting into posterior cerebral arteries (left and right)

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23
Q

What parts of the brain to the posterior cerebrals supply

A

Occipital lobe

Inferior surface of temporal lobe

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24
Q

What connects the posterior cerebral to the anterior cerebral?

A

Posterior communicating artery

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25
What do the vertebral arteries supply before forming the basilar artery?
Cervical spinal cord via the anterior spinal artery
26
Anterior spinal artery
Midline artery Descends along the anterior medial sulcus of the medulla and the spinal cord (see figure)
27
Components of the circle of Willis
1. Ant. Cerebral, 2. Ant. communicating, 3. Ant. cerebral, 4. Internal carotid 5. Post. communicating, 6. Post. cerebral, 7. Post. communicating, 8. Internal carotid
28
What is the advantage of the circle of Willis?
Allows the other blood vessels to provide blood in case of blockage CNS is very metabolically active Requires uninterrupted blood flow, otherwise neurons will diw
29
Stroke
occurs when blood supply to the brain is interrupted Loss of consciousness, electrical activity ceases, irreversible damage
30
Ischemic stroke
Occlusion of vessel
31
Hemorrhagic stroke
more commonly involves smaller vessels under chronic hypertension also subarachnoid hemorrhage (due to aneurysms)
32
What is a sinus?
a channel carrying venous blood All venous blood in the brain drains into a venous sinus (several venous sinuses in the cranial cavity) Convey venous blood from brain to internal jugular veins
33
Sinus vs vein
functionally similar to a vein but has a different structure
34
Pressure of sinuses vs arteries
Sinuses have low pressure compared to arteries
35
What are the three midline sinuses that carry the bulk of the brain's venous blood?
1. Superior sagittal sinus: superior margin of falx cerebri 2. Inferior sagittal sinus: inferior margin of falx and flows into: 3. Straight Sinus: junction of cerebral falx and cerebellar tentorium (see figure)
36
What are the major paired sinuses?
1. Transverse sinus 2. Inferior Petrosal Sinus 3. Sigmoid sinus: joins with inferior petrosal to form internal jugular vein (see figure)
37
Blood flow through venous sinuses from superficial cerebral veins
Superficial cerebral veins drain into Superior sagittal sinus which flows into the Confluence, then Transverse, then Sigmoid, then Internal Jugular The internal jugular vein drains the blood from the brain and returns it to heart
38
Blood flow through venous sinuses from deep cerebral veins
Deep cerebral veins drain into the Inferior sagittal sinus to form the Straight sinus into transverse sinus, then Sigmoid, then Internal Jugular The internal jugular vein drains the blood from the brain and returns it to heart
39
What are the cranial nerves
12 pairs of nerves that arise from the brain and innervate head & neck (mainly), but also thorax & abdomen Nerves may be efferent (i.e., a motor nerve), afferent (i.e., a sensory nerve), or mixed (both sensory and motor fibres)
40
Which nerves arise from the midbrain?
III, IV
41
Which nerves arise from the pons?
V, VI, VII, VIII
42
Which nerves arise from the medulla?
IX, X, XI, & XII
43
12 cranial nerves
``` I. Olfactory II. Optic III. Occulomotor IV. Trochlear V. Trigeminal VI. Abducens VII. Facial VIII. Vestibulocochlear IX. Glossopharyngeal X. Vagus XI. (Spinal) Accessory XII. Hypoglossal ``` Oh Once One Takes The Anatomy Final Very Good Vacations Are Heavenly
44
CNI
Olfactory n. Carries olfactory information from olfactory epithelium through the foramina of cribiform plate
45
CNII
Optic n. Carries visual information from retina through the optic canal
46
CN VIII
Vestibulocochlear n. Carries balance and hearing from inner ear (cochlea and vestibular apparatus) through the internal auditory meatus
47
Sensory nerves:
I, II, VIII
48
Cranial nerves: motor
3 nerves for extra-ocular muscles (enter orbit through superior orbital fissure): III, IV, VI XI, XII
49
CN III
Occulomotor n. innervates 4 of the 6 extrinsic muscles of eye, and intrinsic muscles (iris and ciliary body/lens)
50
CN IV
Trochlear n. innervates superior oblique (pulls eye down when adducted)
51
CN VI
Abducens n. innervates lateral rectus (abducts the eye)
52
What is diplopia?
Double vision
53
CN XI
Spinal Accessory n. innervates the sternocleidomastiod (rotates the head) & trapezius muscles (shrugs the shoulders).
54
CN XII
Hypoglossal n. innervates the intrinsic and extrinsic muscles of tongue. (sticking out your tongue)
55
Where do CN XI and CN XII exit cranium?
CN XI exits cranium via jugular foramen while CN XII exits via hypoglossal canal
56
Mixed cranial nerves
V, VII, IX, X
57
CN V
Trigeminal n.. 3 branches V1, V2, V3 V1 (Ophthalmic n. - Sup. Orb. Fiss.) – Somatosensory from cornea, nose, and forehead. V2 (Maxillary n. - f. rotundum) – Somatosensory from maxilla, upper lip & teeth, hard palate. V3 (Mandibular n. - f. ovale) Somato-sensory mandible, lower lip & teeth, ant. 2/3 tongue; Motor to muscles of mastication
58
CN VII
Facial n. (Internal Aud. Meatus) Sensory – Taste: Ant. 2/3 of Tongue Motor – Muscles of facial expression Motor (Visceral) - All glands (salivary) of face/oral cavity except parotid gland
59
CN IX
Glossopharyngeal n. (Jugular f.) Sensory – Taste and somatosensation: Post. 1/3 of Tongue Motor – Assist in swallowing Motor (Visceral) – Parotid gland
60
CN X
Vagus n. (Jugular f.) Sensory – Taste: Epiglottis; Visceral sensory from resp. tract and viscera Motor – Swallowing (vomiting) Motor (Visceral) – Respiratory tract, heart, and esophagus, stomach, intestines
61
How to remember function of cranial nerves
``` I. Olfactory (S) II. Optic (S) III. Occulomot. (M) IV. Trochlear (M) V. Trigeminal (B) VI. Abducens (M) VII. Facial (B) VIII. Vestibulocochlear (S) IX. Glossopharyngeal (B) X. Vagus (B) XI. (Spinal) Accessory (M) XII. Hypoglossal (M) ``` Some Say Marry Money, But My Brother Says Big Brains Matter More

Anatomy (MPAS) (22 decks)

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