A&p Final The Brain

Front 1

BLOOD SUPPLY

Back 1

- receives 20% of blood
- flow to brain via: INTERNAL CAROTID AND VERTEBRAL ARTERIES.
- Blood can be shifted from one brain regulator to another
- Glucose: E substrate neuron that metabolizes for ATP... but is not stored in brain so needs constant blood supply.

Front 2

BBB: Blood Brain Barrier

Back 2

Regulates substance exchange between BLOOD & BRAIN
-Formed by : ASTROCYTES + TIGHT JUNCTION between capillary endothelial calls and cap. BM..
- permeable to lipid soluble and carrier transported subs.
- BBB is the reason why some meds are hard to administer in brain
- can be damaged by inflammation and trauma.

Front 3

CSF: Cerebrospinal fluid

liquid that surrounds CNS

Back 3

Functions:
1. Mechanical protections:
-shock absorbing,
-buoyancy: effective weight of brain way less than the actual weight.
2. Homeostatic function:
- must maintain CSF pH bc it affects pulmonary ventilation, blood flow.
- also deals with transporting hormones.
3. Circulation:
- acts as a medium for exchange of nut. & waste products b/w blood and Nervous tissue.

Front 4

Blood- CSF barrier

Back 4

by tight junction between the ependymal cells
This decreases harmful materials from blood into CSF.

Front 5

CSF circulation

Back 5

Ventricles: 4 CSF filled chambers in brain (continous).
2 are lateral: large, one for each cerebral hemisphere
1 is 3rd ventricle: midsagittal plane; inferior to corpus collosum
1 is 4th ventricle: smal triangle shaped; between pons and cerebellum.
Process:
LV > intervent. foraminia > 3rd. > Cerebral aqueduct > 4th
> central canal> apertures (lateral (to subarachnoid) or median) >subarachnoid space> arachnoid villi (allow CSF to enter bloodstream bc it is protrudes to...) > dural venous sinuses> blood> LV

Front 6

Clinical

Back 6

Normal: CSF production rate = CSF reabsorption rate
BUT:
If ^ CSF prod. or low reabs. (caused by obstruction (blockage)) ---> HYDROCEPHALUS (water in head)

HYDROCEPHALUS: high pressure due to high CSF in ventricle
In childhood: enlarged head
In adult: venticular dilation and compressed brain tis.

Front 7

Clinical cont'd

Back 7

Concussion: temp loss of consciousness bc of blow to head

CONTUSION: brain bruise
SUBDURAL HEMATOMA: bleeding into subdural space, not as rapid - this is why they tell people not to sleep

EPIDURAL HEMATOMA: FAST; bleed bw dura & skull; usually middle meningeal a. bleed.
MENINGITIS: by bacterial or viral infection; lumbar puncture is the diagnosis.

Front 8

The Brain Stem

Back 8

- medulla, pons, and midbrain
- bw s.c and diencephalon
- produces programmed behaviors for survival
- pathway for fiber tracts bw s.c and cerebrum

Front 9

MEDULLA

Back 9

- superior part of s.c but wider
- starts from foramen magnum and extends to pons.
- contains motor and sensory tract.
-has last 5 cranial nerve nuclei (VIII, IX, X, XI, XII)
-contains medullary "centers" = neurons controlling heart rate, respiration, bv diameter, coughing, swallowing, vomiting

Front 10

"Pyramids" of medulla

Back 10

-2 large columns of motor neuron tracts on ventral anterior surface
- they are separated by anterior median fissure
- has CORTICOSPINAL TRACTS: control voluntary limb movement

Front 11

Decussation of pyramids

Back 11

Look at previous image

at junction of medulla with the s.c
where 90% of corticospinal axon cross with message from cerebrum to s.c

EACH SIDE OF BRAIN CONTROLS VOLUNTARY MOVEMENT ON OPPOSITE SIDE OF BODY... everything has crossed over at s.c

Front 12

"OLIVES"

Back 12

- oval like structure lateral to the pyramids
- contains "inferior olivary nuclei"
responsible for sending axon to cerebellum.

Front 13

Pons... the bridge

Back 13

- pontine nuclei= synaptic RELAY STATION bw cerebrum and cerebellum
- coordination of voluntary motor output.
- has Ascending/sensory ( stimulus to PNS TO CNS) and DESCENDING/motor tracts

- helps control breathing using: pneumotaxic and apenustic (promotes inhalation) areas. (antagonize each other)
Cranial nerve nuclei: V, VI VII, VIII

Front 14

Midbrain
(mesencephalon)

Back 14

b/w pons and diencephalon
contains cerebral aqueduct (plays a part in CSF circulation).

-made up of cerebral peduncles, substantia nigra, tegmentum, and tectum

Front 15

Cerebral peduncles

Back 15

- ventral surface of midbrain
- contain corticospinal, coticopontine, and corticobulbar motor neuron tracts

CORTI-...

Front 16

Substantia nigra (XS) (seen only when cross section the midbrain)

Back 16

- black nucleus bw peduncles and tegmentum
- dark bc if high level of melanin DOPAMINE
- motor center containing dopamine neurons that extend to the basal nuclei > thus help with controling muscles activity.

PARKINSON DISEASE: caused loss of neuron association/ loss of dopamine

Front 17

Tegmentum (XS)

Back 17

- has red nucleus ---> rubrospinal tract origination. (motor control pathway)
- receives axons from cerebrum and cerebellum--> some movement coordination.

Front 18

Tectum

Back 18

- dorsal part of midbrain
- corpora quadrigemina
4 rounded bodies (colliculi) in the tectum:
Superior Collicili: Upper pair; some optic tract input > VISUAL REFLEXES
INFERIOR COLLICULI: lower pain; AUDITORY REFLEXES

Cranial nerve of mid brain : III and IV

Front 19

Reticular formation

Back 19

arrangement of white and gray matter from upper s.c to BS to inferior diencephalon
- neurons have both ascending (sensory) and descending (motor) functions:
1. Somatic motor control: muscle tone regulation
2. Autonomic input: parasympathetic and sympathetic
3. arousal:
ascending fibers activate the cerebral cortex

Front 20

RAS: Reticular activating system

Back 20

regulates arousal and sleep-wake transition
- prevents sensory overload
Damage can cause coma.

NO input from olfactory receptors.

Front 21

Cerebellum

Back 21

posterior to medulla and pons (seperated by 4th ventricle)
- highly folded... thus higher surface area
- Tentorium cerebelli causes lower pressure on cerebellum bc it separates the cerebellum from occipital.

Vermis: connects the two hemisphere of cerebellum at a central area
Cerebellar cortex: superficial gray mater, has folds called folia, separated by grooves (sulci)
Arbor vitae: tracts of white matter, deep of gray matter.

Front 22

Cerebellar connection ( 3 paired tracts)

Back 22

1. Superior cerebellar peduncles - axons connecting to midbrain and thalamus
2. Middle cerebellar peduncles - pons connection
3. Inferior cerebellar peduncles - medulla connection

Front 23

Cerebellar Function

Back 23

checks and compares if the muscle is doing what it is told by the cerebral cortex, corrects it otherwise

Damage= uncoordinated movements (ATAXIA) and low muscle tone.
How to test: finger to nose and heel to shin test.

Front 24

Diencephalon (2nd division of forebrain)

Back 24

- superior to BS midbrain
surrounded by cerebral hemisphere
surrounds the 3rd ventricle.

Thalamus, hypothalamus, and epithalamus.

Front 25

Thalamus ( must cut the brain to see)

Back 25

80% of diecephalon
-2 oval masses of cell bodies (each organized as 7 groups of nuclei)
-intermediate mass: neuron bridge connecting the oval masses (passes through the 3rd ventricle)
-each mass "embedded" in a cerebral hemisphere, underlies cortex, and lateral ventricle, and each mass is bound laterally by an "internal capsule"

Front 26

Internal capsule

Back 26

White matter connecting thalamus with cerebral cortex

Front 27

Thalamus function

Back 27

GATEWAY to cerebral cortex
MAJOR RELAY startion for most SENSORY input
nuclei integrate sensory, motor, emotions, and learning

Information that reaches thalamus doesn't need to reach the cerebral cortex (thus won't reach conscious level)
so thalamus decides what reaches cerebral cortex.
For example: when you are studying, you see bunch of things around you, but you don't concentrate on that because thalamus won't let it reach the conscious level.

Front 28

Hypothalamus (HT)

Back 28

- inferior to thalamus
- extends from the anterior "optic chiasm" to the posterior "mammillary bodies" (visible in ventral view)
-infundibulum = attaches the pituitary to the HT
-merges into midbrain of brain stem
-composed of many nuclei organized into 4 main regions (preoptic, supraoptic, tuberal, and mammillary)

Front 29

HT function

Back 29

ANS control
hormone production
regulation of emotion and behavior (heart of limbic system)
regulation of eating and drinking
control of body temp
sleep wake cycle regulation... regulation of circadian rhythms and consciousness.

Front 30

Epithalamus

Back 30

dorsal part of dienecephalon
thin roof over 3rd ventricle
has pineal gland

also has habenula : relay system for limbic system (emotional responses to odor).

Front 31

Pineal gland

Back 31

in epithalamus
a midline marker, makes melatonin , which induces sleep. HIGH in teens
regulate circadian rhythms (sleep)

Front 32

Circumventricular organs

Back 32

- at the walls of 3rd ventricle
BBB is absent
allow brains to monitor and respond to blood composition
BUT may be the entry sites for pathogens into brain (HIV)

Front 33

CEREBRUM

Back 33

-seat of intelligence
-right and left hemispheres
-cerebral cortex, cerebral white matter, and basal nuclei

Front 34

Cerebral Cortex

Back 34

-outer surface of gray matter
-contains billions of neuron
-folding of cortex - increased surface area (a large part of cortex is not visible because hidden in the fissures and sulci)
-pattern variation from one brain to another BUT some are constant enough to serve as landmarks --> lobes (frontal, parietal, occipital, temporal, and insula)

Front 35

Anatomy of cerebral cortex

Back 35

Gyrus: fold on surface of cortex, separated by grooves
Fissures... Deep grooves
Sulci... Shallow grooves

Front 36

Separation

Back 36

Longitudinal fissure: rt and lt hemisphere division
Central sulcus: 90deg to L.F. Frontal and parietal division
Parieto occipital sulcus: seperates parietal and occipital lobes
Transverse cerebral fissure: separates cerebral hemisphere from cerebellum

Front 37

Function of each lobes

Back 37

Frontal: motor! Motivation, judgement, aggression, decision making (most developed in human).
Parietal: sensory info processing, like feeling pain
Occipital: visual info
Temporal: hearing, learning and memory, emotion, visual recog
Insula: deep inside in lateral fissure

Front 38

Cerebral white matter

Back 38

Myelinated axon tracts
Association tracts: connect area of cerebral cortex in the same Hemisphere
Commissural tracts: Connect area of cerebral cortex in the opposite hemisphere (Transfer learned information from one hemisphere to another)
Projection tracts: Descending and ascending tract.
Internal capsule Has both ascending and descending axon

Front 39

Basal nuclei (not ganglia bc It's located in the central nervous system not PNS)

Back 39

3 nuclei deep within each hemisphere
1. Globus pallidus: lateral to thalamus
2. Putamen: lateral to GP
P + GP = lentiform nucleus
3. Caudate: C shaped ( head body and tail); + putamen= corpus striatum
Substantia nigra and subthalamic nuclei Are functionally linked to basal nuclei

Front 40

Function of BN

Back 40

Control subconscious skeletal muscle contraction
Regulate muscle tone
Facilitate some muscle contraction while inhibiting others thus Fine motor control
Damage can cause muscular rigidity And termors... Parkinson's disease
Other roles: Involved in attention and memory planning and act with limbic system... Dysfunction of both can cause psychiatric disorder

Front 41

Limbic system (Oldest component of cerebrum)

Back 41

Surrounds thalamus and corpus callosum
Cingulate gyrus, Hippocampus, Dentate gyrus, septal nuclei, olfactory bulb, Mammillary bodies, Fornix, And amygdala

Involved in emotional responses memory and smell

Front 42

Clinical notes

Back 42

Lesion or rumors can can emotional disturbance: Such as uncontrollable laughter or cry
Temporal lobe tumor can cause aggression or memory loss
Psychosomatic illness : LS connects to HT > Emotion induced illness.... Thus stress causes sickness
Amnesia is lesion in hippocampus

Korsakoff's syndrome: Amnesia caused by vitamin B12 (thiamine) Deficiency...due to alcoholism or starvation... This affects the limbic system structures

Front 43

Generalization about cortex

Back 43

1. Three functional areas
2. Each hemisphere is concerned with opposite side of the body
3. Some lateralization (Control by one hemisphere or the other)

Front 44

Functional areas: 1deg Motor area

Back 44

Precentral gyrus ( of frontal lobe)
-Control skeletal muscle
Somatotopy: Corresponding between groups of neurons in the gyrus and muscle on the opposite side of the body (contralateral)
- broca's speech area : Located in frontal lobe near lateral sulcus
- motor homunculus is Disproportional. High area means finer control.... Mouth and hand

Front 45

2. Sensory areas

Back 45

1deg Somatosensory area
Postcentral gyrus (Parietal lobe)
Receives general sensory information such as temperature touch pressure pain from opposite side of the body
Also: somatotopy: Sensory homunculus

Front 46

Special sensory areas

Back 46

information sent somewhere other than somatosensory area
1. 1° visual area - posterior occipital lobe
2. 1° auditory area - superior temporal lobe
3. 1° gustatory area - taste, base of postcentral gyrus in parietal lobe
4. 1°olfactory area (smell) medial temporal lobe

Front 47

3. Association areas

Back 47

All areas of the cortex had except the primary (1deg)
Surrounds the sensory and the motor areas
Processes and Interpret info

Front 48

Premotor area = motor Association area

Back 48

Anterior to primary motor area
It's where the voluntary muscle contraction is initiated.... Causes muscles to contract in sequence which is based on learned events

Front 49

Somatosensory association area

Back 49

Posterior to primary sensory area in parietal lobe
Receives input from primary sensory area
Remembers object which means allows determination of objects space and texture
Determination of body position

Front 50

Visual association area

Back 50

At occipital lobe
Posterior to somatosensory areas
Allows identification of objects that you see
Facial recognition is part of inferior temporal lobe

Front 51

Auditory Association area

Back 51

Part of the temporal lobe
Allows us to realize whether sound is this speech music or just noise

Front 52

Frontal association area

Back 52

Aka Prefrontal Area
Intellectual activities such as judgment

Front 53

Hemispheric lateralization

Back 53

Functionally asymmetrical
Both Hemisphere share performance of many function but they're also specialize
Left hemisphere: speech grammar problem-solving reasoning analytical
Right hemisphere processing information in more integrated way such as imagination, artistic, recognize complex visual and music patterns

Front 54

Characterization of left and right Hemisphere

Back 54

Cerebral dominance : the left hemisphere dominance for language which is 97%

Unilateral inattention: Lesion of inferior parietal lobe
Ignores the stimuli coming from contralateral side of the body or the opposite side of the body

Lateralization develops with age and it's more distinct in male so they have a harder time speaking after getting a stroke

Front 55

Language

Back 55

Broca's: Generates motor program causing muscles to produce speech
Wernicke's: Recognizes spoken and written language. Damage can cause fluent aphasia (word salad) (Language defect hard time understanding)

Front 56

Affective language area

Back 56

Gives emotion to speech
Damage can cause aprosodia : Flat emotionless speech

Front 57

Brain waves

Back 57

Action potential of brain neurons
Recorded by electrode on scalp... Recording is called EEG.... Helps the diagnosis of brain disorder and studies normal brain function. Example: Epileptic seizure

Front 58

Cranial nerves

Back 58

Nerve fiber: Axon of Single neuron
Nerve: Structure made up of a collection of Axon in PNS
Connective tissue covering the nerves: Endoneurium, perineurium, and Epineurium.

Nerve fiber classifications: afferent: receptor to CNS
Efferent: CNS to effector

Front 59

Classification of nerves

Back 59

mixed nerve : contain both sensory (afferent) fibers and motor (efferent) fibers

Sensory (1,2,8)
Motor (3,4, 6, 11, 12)

Front 60

Mnemonic of 12 pairs of cranial nerves

Back 60

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