Chapter 14 - The Brain and Cranial Nerves Flashcards

1
Q

What is The Development of the Nervous System?

A

The development of the nervous system begins with a thickening of the Ectoderm called the Neural Tube

Prosencephalon (forebrain):
1- Make Telencephalon, make Cerebrum, make Lateral Ventricles
2- Make Diencephalon, make Thalamus, Hypothalamus, and Epithalamus, make Third Ventricle

Mesencephalon (midbrain):
Make Mesencephalon, make Midbrain, make Aqueduct of the Midbrain between Third and Fourth Ventricles

Rhombencephalon (Hindbrain):
1- Make Metencephalon, make Pons and Cerebellum, make Upper Part of Fourth Ventricle
2- Myelencephalon, make Medulla Oblongata, make Lower Part of Fourth Ventricle

All ventricles form CSF from up to down
(Lateral Ventricles to Third Ventricle to Fourth Ventricle)

(If path blocked, CSF accumulates, Brain gets bigger but skull doesn’t, need surgery to fix)

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2
Q

What are the Principle Parts of the Brain?

A

1- Cerebrum

2- Diencephalon:
Thalamus
Hypothalamus
Pineal Gland (part of Epithalamus)

3- Brainstem:
Midbrain
Pons
Medulla Oblongata

4- Cerebellum

5- Spinal Cord

6- Pituitary Gland

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3
Q

What is Brain Protection?

A

Brain is protected by:

1- Cranial bones

2- Cranial Meninges:
Pia Mater
Arachnoid Mater
Dura Mater (Cranial Dura is composed of 2 layers: Periosteal and Meningeal layers)

Epidural Space between Bone and Dura
Subdural Space between Dura and Arachnoid
Subarachnoid Space between Arachnoid and Pia

3- CSF

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4
Q

What are the Structures around the Superior Sagittal Sinus?

A

Skin
Parietal Bones

Epidural Space
Dura Matter (Periosteal layer then Meningeal layer)
Subdural Space
Arachnoid Matter
Subarachnoid Space
Pia Mater

Arachnoid Villus (extends from Arachnoid Matter into sinus)

Cerebral Cortex

Falx Cerebri (inferior to Superior Sagittal Sinus, where Dura Matter of both hemispheres meet)

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5
Q

What is Blood Flow to the Brain?

A

Blood flows to the Brain via the Vertebral and Carotid Arteries
And flows back to the Heart via the Jugular Veins

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6
Q

What is Homoculus?

A

Picture of self in Brain

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7
Q

What is Importance of Blood Flow to the Brain?

A

The Brain utilizes about 20% of the body’s oxygen supply

Any interruption of the oxygen supply can result in weakening, permanent damage, or death of Brain cells

Glucose deficiency may produce mental confusion, dizziness, convulsions, and unconsciousness

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8
Q

What is Blood-Brain Barrier (BBB)?

A

The BBB protects Brain cells from harmful substances and pathogens by serving as a selective barrier to prevent passage of substances from blood to Brain

BBB can prevent entry of therapeutic drugs

Injury to Brain may cause a breakdown of the BBB, permitting passage of normally restricted substances into Brain tissue

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9
Q

What is CSF?

A

CSF is a liquid that protects Brain and Spinal Cord against chemical and physical injuries
CSF carries oxygen, glucose, and other important substances from blood to nervous tissue cells

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10
Q

What are Ventricles and the Choroid Plexus?

A

Ventricles of the Brain contain CSF

Choroid Plexuses make CSF

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11
Q

How are Ventricles Organized?

A

1- Two Lateral Ventricles:
Separated by Septum Pellucidum

2- Third Ventricle:
Inferior to Lateral Ventricles
Interventricular Foramen connects Lateral Ventricles to Third Ventricle

3- Fourth Ventricle:
Inferior to Third Ventricle
Aqueduct of the Midbrain connects Third Ventricle to Fourth Ventricle

4- Below the Fourth Ventricle:
Lateral Aperture (between Pons and Medulla Oblongata)
Median Aperture (Posterior of Medulla Oblongata)
Central Canal (in Spinal Cord)

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12
Q

What is Choroid Plexus made of?

A

Choroid Plexus inside Ventricles

Blood capillary of Choroid Plexus
Capillary Endothelium around it
Pia Matter around it
Ependymal Cells with Tight Junctions around it

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13
Q

What is CSF Flow?

A

1- Lateral Ventricles’ Choroid Plexus make CSF into Lateral Ventricles

2- CSF goes to Third Ventricle through Interventricular Foramen
Third Ventricle’s Choroid Plexus makes CSF into Third Ventricle

3- CSF goes to Fourth Ventricle through Aqueduct of the Midbrain (Cerebral Aqueduct)
Fourth Ventricle’s Choroid Plexus make CSF into Fourth Ventricle

4- CSF goes to Subarachnoid Space through Lateral and Median Apertures

5- CSF goes to Arachnoid Villi of Dural Venous Sinuses

6- CSF goes into Venous Blood

7- Venous Blood goes to Heart and Lungs

8- Arterial Blood goes from Heart to each Choroid Plexus in each Ventricle

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14
Q

What is Tentorium Cerebelli?

A

Separate Cerebrum from Cerebellum on each hemisphere

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15
Q

What is Septum Pellucidum?

A

Separates both Lateral Ventricles

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16
Q

What is Corpus Callosum?

A

Superior to Lateral Ventricles

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17
Q

What is Brainstem?

A

Brainstem is composed of the:

1- Medulla Oblongata
2- Pons
3- Midbrain

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18
Q

What is Medulla Oblongata?

A

Medulla Oblongata: CN8-12
Continuous with the superior aspect of the Spinal Cord
Contains portions of both Motor and Sensory Tracts

1- Cranial Nerves:
Vestibulocochlear Nerve VIII (8) - (balance, ears)
Glossopharyngeal Nerve XI (9)
Vagus Nerve X (10)
Accessory Nerve XI (11)
Hypoglossal Nerve XII (12)

2- Structural regions:
Pyramids
Inferior Olivary Nuclei

3- Functional Regions:
Heart Rate
Respiratory Rate
Vasoconstriction
Swallowing
Coughing
Vomiting
Sneezing
Hiccupping

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19
Q

What is Pons?

A

Pons: 5-8
Located superior to Medulla Oblongata
Links parts of Brain with one another by way of Tracts

1- Cranial Nerves:
Trigeminal Nerve V (5)
Abducens Nerve VI (6)
Facial Nerve VII (7)
Vestibular Branch of Vestibulocochlear Nerve VIII (8) - (balance)

2- Functional Regions:
Relays nerve impulses related to voluntary skeletal muscle movements from Cerebrum to Cerebellum
Pneumotaxic and Apneustic Areas (control of respiration)

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20
Q

What is Midbrain?

A

Midbrain: 3-4
Located superior to Medulla Oblongata
Extends from Pons to Diencephalon

1- Cranial Nerves:
Oculomotor Nerve III (3)
Trochlear Nerve IV (4)

2- Structural Regions:
Cerebral Peduncles
Corpora Quadrigemina
Substantia Nigra (if damaged, Parkinson’s Disease, resting tremors)
Red Nuclei
Medial Lemniscus

3- Functional Regions:
Conveys motor impulses from Cerebrum to Cerebellum and Spinal Cord
Sends sensory impulses from Spinal Cord to Thalamus
Regulates auditory and visual reflexes

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21
Q

What is Reticular Formation?

A

Reticular Formation:
Helps regulate muscles tone
Alerts Cortex to incoming sensory signals
Responsible for maintaining consciousness and awakening from sleep

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22
Q

What is Cerebellum?

A

Cerebellum:
Occupies inferior and posterior aspects of Cranial Cavity
Consists of 2 Hemispheres and a Central Vermis

Functions:
Coordination of skeletal muscle contractions
Maintenance of normal muscle tone, posture, and balance

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23
Q

What are the Structures of the Cerebellum?

A

Anterior Lobe
Posterior Lobe
Vermis (separates hemispheres)

Cerebellar Superior Peduncle
Cerebellar Middle Peduncle
Cerebellar Inferior Peduncle

Flocculonodular Lobe

Folia (foliage looking)
Arbor Vitae (White Matter)
Cerebellar Cortex (Gray Matter)

24
Q

What is Diencephalon?

A

Diencephalon composed of the:

1- Thalamus
2- Hypothalamus
3- Epithalamus

25
What is Thalamus?
Pain Center Thalamus: Located superior to Midbrain Contains Nuclei that serve as relay stations for all sensory impulses (except smell) to the Cerebral Cortex Structures: Interthalamic Adhesion Inferior to Central Sulcus (motor area anterior, sensory area posterior)
26
What are the Thalamus's Nuclei?
Reticular Medial Interthalamic Adhesion Midline Anterior Internal Medullary Lamina Intralaminar Ventral Anterior Lateral Dorsal Ventral Lateral Ventral Posterior Lateral Posterior Pulvinar Lateral Geniculate Medial Geniculate
27
What is Hypothalamus?
Hypothalamus: Inferior to Thalamus Has 4 major regions Controls many body activities One of major regulators of homeostasis
28
What are the Structures of the Hypothalamus?
Posterior Hypothalamic Nucleus Mammillary Body Dorsomedial Nucleus Ventromedial Nucleus Arcuate Nucleus Paraventricular Nucleus Anterior Hypothalamic Nucleus Supraoptic Nucleus Medial Preoptic Nucleus Lateral Preoptic Nucleus Suprachiasmatic Nucleus
29
What is Epithalamus?
Epithalamus: Superior and posterior to Thalamus Contains Pineal Gland Pineal gland secrets Melatonin Habenular Nuclei involved in olfaction
30
What is Circumventricular Organs (CVOs) of the Diencephalon?
CVO: Parts of the Diencephalon Monitor chemical changes in blood because they lack BBB - CVOs include a portion of the: Hypothalamus Pineal Gland Pituitary Gland CVOs coordinate homeostatic activities of the Endocrine and Nervous Systems
31
What is Cerebrum?
Cerebral Cortex composed of Gray Matter which contains billions of neurons Gyri, Fissures, and Sulci can be identified on the Cortex Deep to Cortex is White Matter composed of Tracts of neurons that connect parts of the Brain to each other and the Spinal Cord Corpus Callosum: Bundle of White Matter Tracts that connect right and left hemispheres of Cerebrum
32
What are some of the Cerebral Cortex Markings?
Frontal Lobe Parietal Lobe Occipital Lobe Longitudinal Fissure (separate right and left hemispheres) Precentral Gyrus Central Sulcus Postcentral Gyrus
33
What are the Lobes of the Cerebrum?
Cerebrum divided into the: 1- Frontal Lobe 2- Parietal Lobe 3- Temporal Lobe 4- Occipital Lobe 5- Insula (deep at intersection of Frontal, Parietal, and Temporal Lobes) Parieto-Occipital Sulcus Transverse Fissure (between Occipital and Temporal Lobes and Cerebellum) Lateral Cerebral Sulcus (between Frontal and Temporal Lobes)
34
What are the Basal Nuclei of the Cerebrum?
Basal Nuclei are paired masses of Gray Matter in each Cerebral Hemisphere Basal Nuclei: 1- Caudate Nucleus 2- Putamen 3- Globus Pallidus Help initiate and terminate movements Suppress unwanted movements Regulate muscle tone
35
What is Limbic System?
Limbic System found in Cerebral Hemispheres and Diencephalon Promotes range of emotions: Pleasure Pain Docility Affection Fear Anger
36
What is Functional Organization of the Cerebral Cortex?
Specific types of sensory, motor, and integrative signals are processed in certain regions of the Cerebral Cortex There are: 1- Sensory Areas 2- Motor Areas 3- Association Areas
37
What are some Functional Areas of the Cerebrum?
Primary Auditory Area Prefrontal Cortex Broca's Speech Area (motor speech area) Frontal Eye Field Area Premotor Area Primary Motor Area (precentral Gyrus) Central Sulcus Primary Somatosensory Area (Postcentral Gyrus) Somatosensory Association Area Common Integrative Area Wernicke's Area (speech interpretation, then sent to Broca's Speech Area) Visual Association Area Primary Visual Area
38
What is Hemisphere Lateralization?
Functional differences in right and left hemispheres
39
What is Right Hemisphere Functions?
Receive somatic sensory signals from and controls muscles on left side of body Music/Art Space/Pattern perception Recognition of faces and emotional content of facial expression Generate emotional content of language Generate mental images to compare spatial relationships Identify and discriminate among odors Patient with damage to right hemisphere that correspond to Broca's and Wernicke's areas in left hemisphere speak in monotonous voice, having lost ability to impart emotional inflections to what they say
40
What is Left Hemisphere Functions?
Receive somatic sensory signals from and control muscles on right side of body Reasoning Numerical and scientific skills Ability to use and understand sign language Spoken and written language Persons with damage in left hemisphere often exhibit Aphasia (hard to understand speak read write)
41
What are Brain Waves?
Brain waves indicate electrical activity of the Cerebral Cortex Presented on an EEG For awake: 1- Alpha 2- Beta For sleep: 3- Theta 4- Delta
42
What are Cranial Nerves?
Olfactory Nerve I (1) Optic Nerve II (2) Oculomotor Nerve III (3) Trochlear Nerve IV (4) Trigeminal Nerve V (5) Abducens Nerve VI (6) Facial Nerve VII (7) Vestibulocochlear Nerve VIII (8) Glossopharyngeal Nerve IX (9) Vagus Nerve X (10) Accessory Nerve XI (11) Hypoglossal Nerve XII (12)
43
What is Olfactory Nerve (CN I)?
Special Sensory: Olfaction (smell)
44
What is Optic Nerve (CN II)?
Special Sensory: Vision
45
What is Oculomotor Nerve (CN III)?
Motor Somatic: Movement of eyeballs and upper eyelids Motor Autonomic: Adjusts Lens for near vision Constricts Pupil
46
What is Trochlear Nerve (CN IV)?
Motor Somatic: Movement of eyeballs
47
What is Trigeminal Nerve (CN V)?
Mixed Sensory: Touch, Pain, Thermal sensation from scalp, face, and oral cavity (including teeth and anterior 2/3 of tongue) Motor (branchial): Chewing Controls middle ear muscles
48
What is Abducens Nerve (CN VI)?
Motor Somatic: Movement of eyeballs
49
What is Facial Nerve (CN VII)?
Mixed Sensory: Taste from anterior 2/3 of tongue Touch, Pain, Thermal sensation from skin in external ear canal Motor (branchial): Control of muscles of facial expression and middle ear muscle Motor Autonomic: Secretion of tears and saliva
50
What is Vestibulocochlear Nerve (CN VIII)?
Special Sensory: Hearing and equilibrium
51
What is Glossopharyngeal Nerve (CN IX)?
Mixed Sensory: Taste from posterior 1/3 of tongue Proprioception in some swallowing muscles Monitor BP and oxygen and CO2 levels in blood Touch, Pain, Thermal sensation from skin of external ear and upper pharynx Motor (branchial): Assists in swallowing Motor Autonomic: Secretion of saliva
52
What is Vagus Nerve (CN X)?
Mixed Sensory: Taste from epiglottis Proprioception from throat and voice box muscles Monitor BP and oxygen and CO2 levels in blood Touch, Pain, Thermal sensation from skin of external ear Sensation from thoracic and abdominal organs Motor (branchial): Swallowing Vocalization Coughing Motor Autonomic: Motility and secretion of GI organs Constriction of respiratory passageways Decreases HR
53
What is Accessory Nerve (CN XI)?
Motor (branchial): Movement of head and pectoral girdle Sternocleidomastoid muscle
54
What is Hypoglossal Nerve (CN XII)?
Motor Somatic: Speech Manipulation of food Swallowing
55
What is Development of Brain and Cranial Nerves?
During the 3rd week of gestation, Ectoderm thickens, forming Neural Plate Neural Plate folds inward and forms the Longitudinal Groove On either side of the Longitudinal Groove, the raised edges are the Neural Folds Eventually the Neural Folds meet to form the Neural Tube
56
How does Aging affect Nervous System?
Aging can result in: Loos of neurons Diminished capacity for sending nerve impulses to and from Brain Diminished ability to process information Decreased conduction velocity Slowing of voluntary motor movements Increased reflex time Degenerative changes in vision, hearing, sight, taste, smell, touch, and balance
57
What are some Brain Disorders?
Cerebrovascular Accident (Stroke) Transient Ischemic Attack (TIA) Alzheimer's Disease (type of Dementia, CNS disease)