Chapter 14 - Brain & Cranial Nerves Flashcards

1
Q

Development of brain

Three to four-week embryo:

A

forebrain (prosencephalon)

midbrain (mesencephalon)

hindbrain (rhombencephalon)

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2
Q

**Development of Brain **

5-week embryo

A

telencephalon (cerebrum)

diencephalon (thalamus, hypothalamus & epithalamus)

mesencephalon (midbrain)

metencephalon (**pons & **cerebellum)

myelencephalon (medulla oblongata).

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3
Q

Forebrain

Midbrain

Hindbrain

A

**Forebrain - **Cerebrum & Diecephalon (3)

**Midbrain **& cebral aqueduct

**Hindbrain - **pons & cerebellum + medulla

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4
Q

Brain stem

consists of?

A

continuation of spinal cord

consists of medulla oblongato, pons & midbrain

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5
Q

second largest part of the brain.

posterior to brain stem

A

Cerebellum

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6
Q

Diencephalon

A

superior to brain stem

gives rise to thalamus, hypothalamus & epithalamus

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7
Q

largest part of brain

A

cerebrum

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8
Q

cranial meninges

A

**dura mater - **2 layers (perieosteal & meningeal)

arachnoid mater

pia mater

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9
Q

(3) extensions of the dura mater separate parts of the brain:

A

**1) falx cerebri - **seperate the 2 cerebral hemispheres

**2) falx cerebelli - **seperate the 2 cerebellar hemispheres

**3) tentorium cerebelli - **seperate cerebrum from cerebellum

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10
Q

Extensions of the Dura Mater: Brain Blood Flow and the Blood-Brain Barrier

Brain receives approximately _____% of the total blood supply.
Internal __ & __ arteries carry blood to brain.
Internal _____veins return blood from the brain.

Blood-brain barrier (BBB) protects brain from?

A

20%

internal **carotid & vertebral **arteries - blood to brain

internal **jugular **veins return blood from brain

harmful substances.

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11
Q

Cerebrospinal Fluid (CSF)

A

clear, colourless fluid that protects CNS from chemical & physical injuries, absorbs shock, helps transport nutrients & wastes from blood & nervous tissue

circulates through cavities in brain (**ventricles) & spinal cord (central canal) **& in subarachnoid space

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12
Q

Ventricles

(3) & cerebral aqueduct

A

CSF-filled cavities within the brain.

** 1 lateral ventricles - **in each hemisphere seperated byb septum pellucidum

**third ventricle - **along midline superior to hypothalamus

**cerebral aqueduct - **midbrain

fourth ventricle - between brain stem & cerebellum

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13
Q

CSF formation & circulation

A

formed in **choroid plexuses **of **lateral ventricles → **interventricular foramina → third ventricle → cerebral aqueduct (midbrain)→ 4rth ventricle → median aperture/lateral apertures (2) → subarachnoid space →central canal

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14
Q

Choroid plexus

A

networks of capillaries in the walls of the
ventricles.

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15
Q

Ventricles are lined by __ cells

A

ependymal

plasma is drawn from **choroid plexuses **through ependymal cells into ventricles to produce CSF

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16
Q

CSF is reabsorbed into blood by?

A

arachnoid villi - extensions of arachnoid that project into dural venous sinuses (sugerior sagittal sinnus)

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17
Q

Brain Stem (medulla, pons & midbrain) and Reticular Formation

Medulla Oblongata

A

continous with superior spinal cord

white matter tract contains all sensory & motor tracts between spinal cord & other parts of brain

white matter bulges on anterior - **pyramids **formed by large corticospinal tracts that pass from cerebrum to spinal cord

  • common site of decussation of tracts - crossing over
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18
Q

**Centers of the Medulla Oblongata **

A

Vital centers:

**cardiovascular **

**respiratory **

also includes centers for vomiting, swallowing, sneezing, coughing and **hiccupping. **

houses 5 pairs of cranial nerves (VIII-XII)

portion of 3rd ventricle found here

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19
Q

**Midbrain (mesencephalon) **

A

Extends from the pons to the **diencephalon. **
Part of the ventricle found here- **cerebral aqueduct - **connects 3rd & 4rth ventricle

anterior part contains **cerebral peduncles **

posterior part - **tectum **

superior colliculli, inferior colliculi & substantia nigra

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20
Q

**Cerebral Peduncles - **paired bundles of axons in anterior part of midbrain

consists of?

**Tectum **

A

axons of the corticospinal, corticopontine and
corticobulbar tracts.

Tectum- situated posteriorly and contains 4 rounded elevations: 2
superior ones called superior colliculi and 2 inferior ones called inferior colliculi

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21
Q

Midbrain:

Substantia Nigra

A

large area with dark pigments. Help control subconscious muscle activities.

Loss of neurons here is associated with Parkinson disease.

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22
Q

Redc Nucleus of Midbrain

A

: Help control voluntary movements of the limbs

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23
Q

Midbrain contains cranial nerves….

A

III-IV

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24
Q

Reticular Formation

A

Extends from upper part of spinal cord, throughout brain stem & into
lower part of diencephalon.

25
Part of the reticular formation called the **Reticular activating System (RAS) **consists of?
consists of sensory axons that project to the cerebral cortex S helps maintain consciousness.
26
**Cerebellum ** vermis **anterior & posterior **lobes **flocculonodular **lobe **cerebellar cortex** **arbor vitae**
2nd largest part of brain central constricted area = **vermis** **anterior** and **posterior** lobes control **subconscious** aspects of skeletal movement. **flocculonodular** lobe - equilibrium & balance **cerebellar cortex** - gray matter in form of parallel folds called **folia** **arbor vitae - **tracts of white matter
27
**Cerebellar peduncles **
3 pairs - **superior, middle & inferior ** attach cerebellum to brain stem functions:** coordinate movements, regulate posture & balance**
28
Thalamus
**intermediate mass **joins right & left sides of thalamus (7) major nuclei: **anterior, medial, lateral, ventral, intralaminar, midline, reticular** major relay station for most impulse reaching primary sensory areas transmits info from cerebellum & basal nuclei to primary motor area
29
Hypothalamus
inferior to **thalamus ** consists of **mammillary body, median eminence, infundibulum, and # of nuclei. **
30
Functions of the **Hypothalamus**
Control of the **ANS** production of **hormones** regulation of **emotion** & **behavioral** patterns, **eating** & **drinking**, body temp, **circadian** rhythms
31
Epithalamus
small region superior to **thalamus ** consists of **pineal gland **that secretes **melatonin **which induces sleep
32
Cerebrum
seat of intelligence **cerebral cortex - **gray matter **Gyri ** **Sulci ** **longitudinal fissure** **cerebral hemispheres**
33
Cerebrum ## Footnote **Gyri ** **Sulci ** **longitudinal fissure** **cerebral hemispheres**
**Gyri **- folds of cortical region **Sulci - **shallow grooves between folds **longitudinal fissure - **seperates cerebrum into right & left halves (contains **falx cerebri**) **cerebral hemispheres- **connected internally by **corpus callosum **
34
Lobes of the cerebrum (4)
frontal parietal temporal occipital
35
**Cerebral white matter **consists of ?
myelinated axons in (3) types of tracts 1) **association ** **2) commissural ** **3) projection **
36
myelinated axons in (3) tracts of **cerebral white matter**
1) **association - **axons conduct nerve impulses between **gyri **in same hemisphere 2) **commissural - **axons conduct nerve impulses to corresponding gyri in opposite hemisphere 3 groups - **corpus callosum, anterior & posterior commissure** 3) **projection - **axons conduct nerve impulses from cerebrum to lower CNS (thalamus, brain stem & spinal cord)
37
Basal Nuclei
(3) **nuclei** (masses of gray matter) deep within each cerebral hemisphere **LENTIFORM NUCLEUS: ** ***globus pallidus - **lateral to thalamus * ***putamen - **closer to cerebral cortex* **CAUDATE NUCLEUS ** ***corpus striatum** = caudate + lentiform*
38
Basal Nuclei functions
Help **initiate** and **terminate movements**, **suppress** unwanted movements & **regulate** muscle tone.
39
Limbic system
A ring of structures on **inner border of cerebrum** and **floor of diencephalon** * emotional brain - governs emotional aspects of behavior* * also involved in **olfaction & memory***
40
Components of the **limbic system **
**Limbic lobe - **cingulate, parahippocampal gyrus & hippocampus ## Footnote **dentate gyrus** **amygdala ** **septal nuclei ** **mammillary bodies** **anterior & medial nucleus ** **olfactory bulbs **
41
Functional Organization of the Cerebral Cortex: **Sensory Areas ** **(5) **
Primary **somatosensory** area- Primary **visual** area- Primary **auditory** area- Primary **gustatory** area- Primary **olfactory** area-
42
**Cerebrum ** central sulcus precentral gyrus postcentral gyrus
**central sulcus **- seperates frontal & parietal lobes **precentral gyrus - frontal: **primary motor area **postcentral gyrus - parietal: **primary somatosensory area
43
1. Primary **somatosensory** area- ___ gyrus. 2. Primary **visual** area- \_\_\_\_\_\_\_\_\_\_\_\_lobe. 3. Primary **auditory** area- \_\_\_\_\_\_\_\_\_\_\_\_lobe. 4. Primary **gustatory** area- base of the __ gyrus. 5. Primary **olfactory** area- \_\_\_\_\_\_\_\_\_\_\_\_lobe
1. **postcentral** gyrus 2. **occipital** 3. **temporal** 4. **postcentral **gyrus 5. **temporal**
44
Functional Organization of Cerebral Cortex: **Motor Areas **
**primary motor area - **precentral gyrus **Broca's speech area - **left cerebral hemisphere *(speech production) *
45
Functional Organization of the Cerebral Cortex: **Association **Areas
* *Somatosensory association area**- behind 1° somatosensory area. * *Visual association area**- occipital lobe. * *Auditory association area-** temporal lobe. * *Wernick's area**- left temporal & parietal lobes (*speech comprehension)* * * Prefrontal cortex-** anterior portion of frontal lobe.
46
Cranial Nerves
12 pairs sensory, motor & mixed name & roman numberic number to identify
47
Olfactory (I) Nerve
**Sensory** nerve. Sense of **smell**. **Olfactory cells** converge to become **olfactory nerve **that end in **olfactory bulb**.
48
Optic (II) Nerve
**sensory** **vision ** **ganglion cells **in retina join to form **optic nerve **
49
Oculomotor (III) Nerve
motor cranial originates in **midbrain ** supply extrinsic **eye muscles** to control movement of eye & upper eyelid
50
Trochlear (IV) Nerve
**motor cranial nerve** **smallest ** originate in **midbrain** controls movement of eyeball
51
**Trigeminal (V) nerve**
largest cranial nerve **mixed ** (3) branches: **ophthalmic, maxillary & mandibular ** deal with sensation of touch, pain & temperature. **motor axons **supply muscles of **mastication**
52
Abducens (VI) Nerve
motor cranial originates in **pons** cause **abduction **of the eyeball (**lateral rotation**)
53
Facial (VII) Nerve
mixed cranial **sensory** portion - from taste buds of anterior 2/3 of tongue **motor - **arises from pons & deal with facial expression
54
Vestibulocochlear (VIII) Nerve
sensory cranial originates in **inner ear** **vestibular branch - **impulses for equilibrium **cochlear branch - **impulses for hearing
55
Glossopharyngeal (IX) Nerve
mixed cranial **sensory: **taste buds of posterior 1/3 of tongue **motor: **arise from medulla & deals with release of saliva
56
Vagus (X) Nerve
mixed cranial distributed from **head & neck **into **thorax & abdomen** **sensory: **sensations - proprioception & stretching **motor - **arise from medulla & supply muscles of pharynx, larynx & soft palate that are involved **swallowing & vocalization**
57
Accessory (XI) Nerve
**Motor cranial** nerve. Divided into **cranial accessory** and **spinal** **accessory** nerves. Supplies **sternocleidomastoid & trapezius **muscles to coordinate head movements.
58
Hypoglossal (XII) Nerve
motor cranial conduct nerve impulses for **speech & swallowing**
59