The Brain

define rostral

toward the forehead

define caudal

toward spinal cord

detail gray matter of the brain

the seat of neurosomas, dendrites, and synapses

-dull because of little myelin

-Forms surface layer (cortex) over cerebrum and cerebellum

detail white matter of brain

bundles of axons

-deep to gray matter

-Composed of tracts, or bundles of axons, that connect one part of the
brain to another, and to the spinal cord

what are the two layers of the dura mater

outer periosteal and inner meningeal

detail the outer periosteal

equivalent to
periosteum of cranial bones

define periosteum

The periosteum is a dense, fibrous membrane that covers most bones, supplying blood, sensation, and the ability to grow and repair bone tissue.

detail the inner meningeal layer of the dura mater

continues
into vertebral canal and forms
dural sheath around spinal cord

detail dural sinuses

separates the outer and inner layer
-Collect blood circulating through brain

detail the dura mater

Pressed closely against cranial bones

detail arachnoid membrane

Transparent membrane over brain surface

-Subarachnoid space separates it from pia mater below

detail the pia mater

Very thin membrane that follows contours of brain, even dipping into sulci

-need microscope to see

name the ventricles of the brain

(2) lateral ventricle, third ventricle, and fourth ventricle

detail the ventricles of the brain

Filled with CSF

-Lined with ependymal cells

-Continuous with the central canal
of the spinal cord

what is the chorochoid plexus

Spongy mass of blood capillaries on the floor of each ventricle

what is CSF

Surrounds the brain and bathes its external surface

how much CSF does he brain produce and absorb a day

500 mL/day

how much CSF is normally present in the body at once

100-160 mL

where is CSF produced

Production begins with filtration of blood plasma through capillaries of the brain

what are the roles of ependymal cells in ventricles

help modify the filtrate

detail the flow of CSF

CSF continually flows through and around the CNS

-CSF secreted in lateral ventricles flows through intervertebral
foramina into third ventricle

-CSF is reabsorbed by arachnoid granulation

what are the functions of CSF

buoyancy, protection, and chemical stability

how does CSF help chemical stability

Flow of CSF rinses away metabolic wastes from nervous tissue and
homeostatically regulates its chemical environment

detail the brain blood barrier system

Regulates what substances can get from bloodstream into
tissue fluid of the brain

what are the two major brain barrier systems

brain-CSF barrier and blood-brain barrier

detail the blood brain barrier

Protects blood capillaries throughout brain tissue

-Anything leaving the blood must pass through the endothelisl cells, and
not between them
-exclude harmful substances from passing
to the brain tissue while allowing necessary ones to pass

detail blood CSF barrier

-Protects brain at the choroid plexus
-Forms tight junctions between the ependymal cells

what can get through the bran barrier system

-Highly permeable to water, glucose, and lipid-soluble
substances (O, CO2, alcohol, caffeine, nitcotine, anesthetics)

-Slightly permeable to Na+, Cl-, K+, and waste produce of urea and
creatinine

Circumventricular organs (CVOs):

no brain barrier sysem

whaat are some CVOs

Portions of third and fourth ventricles
○ Allow blood direct access to the brain
○ Enables the brain to monitor and respond to fluctuations in blood
glucose, pH, osmolarity, and other variables
○ CVOs afford a route for invasation by HIV

function of the medulla oblongata

All nerve fibers connecting the brain to the rest of the body
pass through the medulla

-Decussation of motor neurons for the muscles below the neck
occurs here within the corticospinal tract

what are the important nuclei in the medulla oblongota

Cuneate and gracile fasciculi

Inferior olivary nucleus

detail cuneate and gracile fasciculi

First-order neurons synapse here with second-order neurons

detail inferior olivary nucleus

Major relay center for signals going from different levels of the brain to the
cerebellum

What parts of the reticular formation are associated with the medulla

pons

what is reticular formation

Loose web of gray matter that runs
vertically through all levels of the
brainstem

What is the function of reticular formation

-somatic motor control
-Cardiovascular control
- Pain modulation
- Sleep and consciousness
- Habituation

what’s the function of the pons

-Relay center (Primarily)

-Site of the beginning or end of
several cranial nerves

which nuclei of the reticular formation is associated with the pons

Contains nuclei associated with
sleep, respiration, and posture

what is the function of the midbrain

Has two cranial nerves that control
eye movement that originate here

what are the four buldges in the midbrain called

corpora quadrigemina

detail the superior colliculi of the midbrain

Function in visual attention, tracking moving objects, and some reflexes

detail the inferior colliculi

Receives signals from the inner ear and relays them to other parts of the brain, especially the thalamus

what is the function of the cerebellum

-Important for motor coordination and locomotor ability

-Recent studies have revealed several sensory, linguistic, emotional,
and other nonmotor functions

What are the components of the forebrain?

dicephalon and telencephalon

detail the dicephalon

three parts
■ Encloses third ventricle
■ Most rostral part of the
brainstem

detail the telencephalon

Develops chiefly into the cerebrum

what’s the function of the thalamus

Plays key role in motor control

• Relays signals from cerebellum to cerebrum

Provides feedback loops between cerebral cortex and basal nuclei

-Involved in memory and emotion

what’s the limbic system

complex structure that include some cerebral cortex of
the temporal and frontal lobe; and some of the anterior thalamic nuclei

detail the hypothalamus

A major control center of autonomic nervous system and endocrine system

-plays essential role in
homeostatic regulation of all
body systems

what are the functions of the hypothalamus

• Hormone secretion

-Growth, metabolism, stress, reproduction, labor contraction, lactation,
water conservation

• Autonomic effects

-Influence heart rate, BP, gastrointestinal secretions/motility

• Thermoregulation

• Food and water intake

• Sleep and circadian rhythms

• Memory

• Emotional behavior and s*xual response

What is the function of the epithalamus

Very small mass of tissue
composed of

pineal gland and habenula

function of pineal gland

Endocrine gland that
releases melatonin

function of habenula

Relay from the limbic system to the midbrain

What are the main tracts of the cerebrum

Projection tracts, Commissural tracts, and association tracts

what are the tracts of the cerebrum made of

white matter

function of projection tracts in cerebrum

Connects higher and lower parts of the brain and spinal
cord

function of commissural tracts

Connects the hemispheres

function of association tracts

Connects different regions within the same hemisphere

what are basal nuclei

Masses of gray matter buried in white matter

what are the main function of basal nuclei

Masses of gray matter buried in white matter

what is the cerebral cortex

Many of the “higher” order functions of the brain occur “on” the cortex

what neurons are involved in cerebral cortex

sleep, memory, cognition, emotion, sensation, motor control,
language

What is an EEG

Measures electrical activity (brain waves) of the cortex

-Helps in diagnosis of degenerative brain diseases, metabolic abnormalities, brain tumors, etc.

what is sleep

temporary state of unconsciousness

What is dreaming?

Occurs during both REM and non-REM sleep

-Parasympathetic nervous system is very active

what is cognition

ental action or process of
acquiring knowledge and
understanding through thought,
experience, and the sense

what is memory

Hippocampus of limbic system is important as a memory
forming center

Detail the somatosensory regions of the cortex

The general senses from the body

-Touch, pressure, stretch, movement, heat,
cold, pain

Detail the motor regions of the cortex

Multiple points in the cortex control one
muscle

What are the 2 major areas that are associated with language?

Wernicke’s area and Broca’s area

function of Wernicke’s area

sensory speech area

function of Broca’s area

motor speech area

what’s aphasia

A language deficit from lesions to hemisphere with Wernicke
and Broca areas

detail nonfluent (broca’s) aphasia

-Lesion in Broca area

-Slow speech, difficulty in choosing words, using words that only
approximate the correct word

detail fluent (wernike’s area)

-Lesion in Wernicke's area

-speech normal and excessive, but uses senseless jargon

-Cannot comprehend written and spoken words

detail Anomic aphasia

Can speak normally and understand speech, but cannot identify written
words or pictures

What is cerebral lateralization?

the difference in the structure and function of the cerebral hemispheres

describe the left hemisphere

usually the categorical hemisphere

-specialized for spoken and written language
- Sequential and analytical reasoning (math and science)

describe the right hemisphere

usually the representational hemisphere
- Perceives information in a more integrated way
- Seat of imagination and insight
- Musical and artistic skill
- Perception of patterns and spatial relationships
- Comparison of sights, sounds, smells, and taste