Chapter 14 Brain

Mesencephalon (midbrain)

-processing of visual and auditory data -generation of reflexive somatic motor responses -maintenance of consciousness

anatomy of cerebellum

1. arbor vitae a sagittal section through the cerebellum reveals gray matter on the periphery with white matter shaped like a tree 2. connections to the brain stem a. superior cerebellar peduncles b. middle cerebellar peduncles c. inferior cerebellar peduncles

three major types of fibers or tracts in the brain

1. commissural tracts 2. association tracts 3. projection tracts

gray matter areas of the brain such as the cortex are areas that control specific functions. What are some of the important areas of the cortex?

1. motor control 2. sensory control

functions of the hypothalamus

1. temperature control 2. control of osmotic pressure (how much water and salt is in the blood) 3. feeding center 4. control of the autonomic nervous system 5. control of the pituitary gland 6. synthesis of some hormones directly 7. role in emotion and memory as part of the limbic system 8. role in sense of smell 9. feedback with pineal gland to determine day-night cycle

how many ventricles are there? name them.

4 lateral (2) third fourth

pons

A brain structure that relays information from the cerebellum to the rest of the brain

Are sensory tracts ascending or descending?

All Sensory tracts are ascending

what do commissural tracts connect?

Axons running from left to right

what role does the cerebellum play in proprioception?

Because sensation is delayed, real-time movement control requires not just sensing, but also predicting limb position, a function hypothesized for the cerebellum. Such cerebellar predictions could contribute to perception of limb position (i.e., proprioception), particularly when a person actively moves the limb

what happens in a stroke?

Blood is prevented from reaching areas of the cerebrum. Depending on the location and extent of reduced blood flow, signs and symptoms may include loss of movement (paralysis), loss of speech (aphasia), weakness, and changes in sensation.

homeostasis and CSF

CSF is produced continuously. It is important that there is a balance between the production of CSF by the choroid plexus and absorption of CSF into the superior sagittal sinus

Broca's area

Controls language expression - an area of the frontal lobe, usually in the left hemisphere, that directs the muscle movements involved in speech.

why might damage to the medulla oblongata be a fatal brain injury

If your medulla oblongata becomes damaged, it can lead to respiratory failure, paralysis, or loss of sensation.

why might a bad odor elicit such a strong emotional response

Odors take a direct route to the limbic system, including the amygdala and the hippocampus, the regions related to emotion and memory. "The olfactory signals very quickly get to the limbic system,"

which four cranial nerves carry autonomic impulses

Optic nerve. Oculomotor nerve. Short ciliary nerve (parasympathetic nervous system) Trochlear nerve. Trigeminal nerve (ophthalmic branch) Abducens nerve. Facial nerve. Long ciliary nerve (sympathetic nervous system)

by definition, nerve is a bundle of axons in the ___. these nerves begin or end in the brain, but the nerve is part of the ___.

PNS PNS

diseases involving basal nuclei include

Parkinson's disease (lack of dopamine)

why is the autonomic nervous system affected by emotions?

Positive emotions also result in altered autonomic nervous system activity, characterized by increased parasympathetic nervous system activity, whereas negative emotions (e.g., anger) result in parasympathetic withdrawal and sympathetic activity

what are the two major arteries that bring oxygen to the brain?

The brain receives blood from two sources: the internal carotid arteries, which arise at the point in the neck where the common carotid arteries bifurcate, and the vertebral arteries

what is meant by the direct motor (pyramidal motor) system?

The direct pathway, sometimes known as the direct pathway of movement, is a neural pathway within the central nervous system (CNS) through the basal ganglia which facilitates the initiation and execution of voluntary movement.

what specifically is controlled by the post central gyrus?

The postcentral gyrus (gyrus behind the central sulcus) constitutes the somatosensory cortex (Areas 1, 2, 3). This is where the whole opposite half of the body's sensory inputs (general sensations of touch, pain, temperature, etc.) is registered.

Identify the post central gyrus. which lobe is it located?

The postcentral gyrus contains the primary somatosensory cortex, a significant brain region responsible for proprioception.[1] This region perceives various somatic sensations from the body, including touch, pressure, temperature, and pain PARIETAL LOBE

Identify the pre-central gyrus. which lobe is it located?

The precentral gyrus is the anatomical location of the primary motor cortex and is responsible for the control of voluntary movement. FRONTAL LOBE

why is increased intracranial pressure such a concern?

The pressure can damage the brain or spinal cord by pressing on important structures and by restricting blood flow into the brain.

basic functions of cerebrum

Thinking, consciousness, sensory perception, motor movement

cranial nerve nuclei

VIII, IX, X, XI, XII

epidural hematoma

a hematoma located between the dura matter and the cranium

Tracts of the mesencephalon

a. cerebral peduncles: ventral bulges where the voluntary motor tracts (pyramidal tracts) are located b. sensory tracts must also pass through midbrain c. the midbrain is connected by cerebellar peduncles to the cerebrum

the brain can be divided into four main regions

a. cerebrum (cerebral hemisphere) b. diencephalon c. cerebellum d. brain stem

flow of cerebrospinal fluid

a. choroid plexus b. brain ventricles c. superior sagittal sinus

nuclei of mesencephalon

a. corpora quadrigemina (located on the dorsal side=tectum) i. superior colliculi: reflex centers for vision ii. interior colliculi: reflex centers for hearing b. substantia nigra i. inhibits basal nuclei activity ii. dopamine synthesis iii. Parkinson's disease (decrease in dopamine) may result from damage to the substantial nigra c. red nucleus: motor function such as muscle tone d. reticular activating center: role in wakefulness and sleep e. cranial nerve nuclei: III, IV

reticular activating center

a. sensory input into the RAS triggers arousal b. key activating center location: midbrain c. neurotransmitters i. serotonin: sleep ii. norepinephrine: arousal

functions of the thalamus

a. sensory relay station: the thalamus is where "crude" sense is interpreted (touch, pain, temperature). almost all sensory inout to the brain synapses int the thalamus including vision and auditory impulses b. part of the thalamus plays a role in memory and emotions (limbic system) c. part of the thalamus plays a role in motor function

neurotransmitters:

acetylcholine (excitatory), dopamine (inhibitory)

what is meant by the blood-csf barrier?

aid in the protection of what gets in the brain

ganglia (singular ganglion)

areas in the PNS where neuron cell bodies are found

which cells create the blood-brain barrier

astrocytes

arachnoid villi

at some places the arachnoid will protrude through the dura matter into the superior sagittal sinus

what is located in white matter?

axons and myelin

what do projection tracts connect?

axons from high to low brain centers

basic functions of cerebellum

balance, equilibrium, coordination

subdural space

beneath the dura matter is a space called the subdural space. clinical significance= subdural hematoma

vasomotor center

blood vessel diameter

nerve

bundle of axons in PNS

tract

bundle of axons in the CNS

What are tracts?

bundles of axons in the CNS

bundles of axons in the white matter=

bundles of fibers or tracts tracts are made up of axons of neurons (also sometimes called fibers)

what is located in gray matter?

cell bodies, dendrites, and synapses of neurons

sensory travts travel through the medulla oblongata to the thalamus and post central gyrus. they may also travel to the cerebellum to give information about body position (via the ___ ___)

cerebellar peduncles

which areas are connected by these peduncles?

cerebellum and brain stem

the gray matter on the periphery of the cerebral hemispheres is called the ___ ___.

cerebral cortex

the reticular formation is a network of neurons located in all three parts of the brainstem. it filters sensory information going to the ___ and some ___ motor impulses ***nuclei of medulla oblongata

cerebrum descending

where is csf made?

choroid plexus in ventricles

What is cerebrospinal fluid (CSF)?

clear watery fluid that fills the space between the arachnoid membrane and the pia mater.

what are nuclei?

clusters of cell bodies in the CNS

subdural hematoma

collection of blood under the dura mater

what do association tracts connect?

connect different regions of the cerebral cortex within the same hemisphere

mammillary bodies

connections to the hippocampus via the fornix (part of the limbic system)

brain stem

connects the diencephalon, cerebral hemispheres, and cerebellum with the spinal cord. much of the brain stem consists of tracts, but there are very important nuclei as well

cardiac center (reticular formation)

controls the heart rate

decussation of pyramids

crossover of corticospinal tracts; descending voluntary tracts cross here

what is a brain ventricle?

csf fills large open structures called ventricles, the ventricles keep the brain buoyant and cushioned

what specifically is controlled by the primary motor cortex?

direction of movement

what is the purpose of the superior sagittal sinus?

drains the lateral aspects of the anterior cerebral hemispheres

falx cerebri

dura matter extends into the longitudinal fissure of the brain and attaches to the skull at the crista galli of the ethmoid bone **separates hemispheres

cingulate gyrus

emotions

which cranial nerve sends fibers to muscles that cause facial expressions

facial

which cranial nerve causes tears

facial #7

amygdala

fear/fight or flight

fornix

fibers that link parts of the limbic system

Pia matter

fine collagen and elastic fibers that extend into the crevices (sulci) of the brain

arachnoid

fine collagen and elastic fibers that form a "spider web" of tissue

where is the pre central gyrus located? (primary motor cortex)

frontal lobe

gustatory cortex

frontal lobe/insula

besides water, what is found in csf?

glucose, ions (Na+, Cl-, Mg++) plasma-like fluid (less protein, more Na++)

what is located more towards the periphery of the cerebrum: gray or white matter?

gray

will the basal nuclei be white or gray matter?

gray

nucleus

gray area in the CNS where neuron cell bodies are found

intermediate mass (also called inter thalamic adhesion)

gray matter connecting two thalami

what does the cerebral cortex consist of?

gray matter: cell bodies, unmyelinated axons, dendrites, and synapses

central sulcus

groove between frontal and parietal lobes

what is the purpose of csf?

helps protect the brain and the spinal cord from sudden impact or injury

basic functions of diencephalon

hormonal control, control of smooth muscle, temperature regulation, etc.

the diencephalon is located deep inside the brain superior to the brain stem. it consists of three parts: ___ ___ and ___. the largest part of the epithalamus is the ___ ___.

hypothalamus thalamus epithalamus pineal body

blood-brain barrier

in addition to being bathed by CSF inside and out to maintain a healthy environment for the brain, there is also a blood-brain barrier to ensure that the environment in the brain is controlled

epithalamus

includes the pineal body (gland) makes melatonin works with hypothalamus to regulate sleep-wake patterns

how would Parkinson's disease be treated?

increase dopamine

what is the danger of hydrocephalus?

it can develop damage to brain tissue due to the pressure caused by excess CSF

what is meant by the motor homunculus?

it is an exaggerated map of areas in the precentral gyrus corresponding to number of neurons that lead to each specific body part

longitudinal fissure

large crevice between the right and left cerebral hemispheres

wernike's area

largely in the parietal lobe, this area is responsible for general interpretation of what is seen and heard

speech and motor control are usually more developed on one side of the brain than the other (dominant hemisphere) for 95 percent of people the ___ is dominant over the ___

left right

right hemisphere

left hand control, music/artistic skills, spatial relationships, insight

tracts of pons

major sensory and motor tracts connection to the cerebellum via cerebellar peduncles

many of these centers above are vital centers located in the ___ ___

medulla oblongata

hippocampus

memory

emotional behavior is strongly related to

memory autonomic nervous system hormones eating habits smell

both the brain and the spinal cord are covered by layers of tissues collectively called the ___.

meninges. the singular of meninges is meninx

medulla oblongata

most inferior portion of the brain stem

abducens (VI)

motor fibers to the lateral muscle of the eye

trochlear (IV)

motor fibers to the superior oblique muscle of the eye

what is a pyramidal cell?

motor neurons in the precentral gyrus

accessory (XI)

motor to sternocleidomastoid and trapezius muscles

hypoglossal (XII)

motor to tongue muscles

If the nerve ends in the CNS will it be sensory or motor?

motor?

what happens in the pre central gyrus?

much of the frontal lobe contains the premotor cortex for learned motor skills the right primary cortex controls motor function on the left side, and the left primary cortex controls motor function on the right side of the body

what is the significance of the somatosensory homunculus?

much of the parietal lobe is called association cortex. its function is to integrate sensory input sensory input of the right side of the body will travel to the left post central gyrus, and sensory input on the left side of the body will travel to the right post central gyrus

functions of cerebellum

muscle coordination and equilibrium loss of coordination leads to ataxia

the right and left brain are ___ ___.

not identical

which are gray matter?

nuclei that control specific functions

visual cortex

occipital lobe

what types of substances can pass through the blood-brain barrier?

only water, certain gases (O2) and lipid soluble substances

cerebral cortex

outer portion of the cerebrum

where is the post central gyrus located (primary somatosensory cortex)?

parietal lobe

dura matter is a fibrous connective tissue that has a superficial and deep layer. the superficial layer of dura matter is fused to the ___ of the skull. the deep layer is connected to the superficial layer and extends into the ___ ___ of the brain and cerebellum. this causes a separation between the superficial and deep layers where large veins (called venous sinuses) are located

periosteum longitudinal fissure

what is the function of the choroid plexus?

produce csf via ependymal cells that line the ventricles of the brain

breathing center

rate of breathing

functions of basal nuclei

regulate motor movements 1. involved in semi-automatic movement patterns (gesturing, walking, etc.) also function in subconscious motor movement (muscle tone) 2. the basal nuclei also influence other subconscious motor centers (for example, those in the brain stem)

nuclei of pons

reticular formation (throughout brainstem) brain stem cranial nerve: V, VI, VII, VIII

what are gyri? (singular is gyrus)

ridges of the brain

left hemisphere

right hand control, speech, numerical/reasoning skills

What is proprioception?

sense of body position and movement

olfactory (I)

sense of smell to the brain the olfactory nerves end in the olfactory bulbs that were observed on the models and sheep brains

cranial nerves I, II, and VIII are almost entirely ___. III, IV, VI, XI, and XII are almost entirely ___. the others are a mixture of sensory and motor (V, VII, IX, X)

sensory motor

what is the somatosensory homunculus?

sensory caricature of the body on the gyrus that represents the # of sensory neurons coming from each area of the body

Vestibulocochlear (VIII)

sensory from the internal ear for balance (vestibular part) and hearing (cochlear part)

trigeminal (V)

sensory: face sensation of touch (also pain motor: masseter muscle

vagus (X)

sensory: taste motor: swallowing, voice muscles, autonomic fibers to many abdominal organs such as heart, lung, liver, stomach, intestines, etc

facial (VII)

sensory: taste Motor: lacrimal (tear) gland, salivary glands, skeletal facial muscles

Glossopharyngeal (IX)

sensory: taste motor: salivary gland and muscles of the pharynx (swallowing)

if the nerve begins in the CNS will it be sensory or motor

sensory?

what are sulci? (singular is sulcus)

shallow grooves in the brain

reticular formation

sleep pattern/consciousness/arousal

what is the choroid plexus?

spongy mass of blood capillaries on the floor of each ventricle

the basal nuclei work together with the premotor cortex and cerebellum to coordinate muscle function. The ___ ___ works with the basal nuclei through the production of dopamine

substantia nigra

CSF flows from the 4th ventricles into the subarachnoid space. It then flows around the brain and spinal cord. It is absorbed into the ___ ___ ___ through extensions called ___ ___.

superior sagittal sinus arachnoid villi

what large vein is located in the longitudinal fissure

superior sagittal sinus?

ocular motor (III)

supplies motor fibers to four of the extrinsic muscles that move the eye also important are motor fibers to the muscle that constricts the pupil as well as the muscle that controls the shape of the lens for near and far vision

auditory cortex

temporal lobe

olfactory cortex

temporal lobes

which ventricles are connected by the mesencephalic (cerebral) aqueduct?

the 3rd and 4th

hypothalamus

the hypothalamus plays a major role in homeostasis of body functions, because it contains centers that link the autonomic, limbic, and endocrine systems 1. consists of many nuclei controlling specific body functions

what happens if more fluid is made than absorbed in the superior sagittal sinus?

there becomes too much fluid in/on the brain=hydrocephalus

basal nuclei (ganglia)

these nuclei are located within the CNS (brain) however, in a clinical setting, the nuclei are frequently called basal ganglia. remember that a ganglion is the word for a collection of neuron cell bodies outside of the CNS EXAMPLES: putamen, globus pallidus, caudate nucleus

reticular formation

this is a diverse group of nuclei in the brain stem. The reticular activating center helps control the level of activity of the brain. Other parts of the reticular formation are involved in skeletal muscle control, autonomic functions (heart and blood vessels) and pain modulation

limbic system

this is a diverse group of structures of the brain (cerebrum and diencephalon) that play a role in emotional behavior and motivation

superior sagittal sinus

this is a large vein that is located in the longitudinal tissue of the brain between two layers of dura matter. CSF will ultimately flow into this vein and be carried away with the blood ***note- the word "sinus" can have several meanings. It is a membrane-lined space within a flat bone of the skull. It can also refer to a vein that lacks smooth muscle in its wall

which are white matter?

tracts

what would be the signs of Parkinson's disease?

tremors, loss of smell, faulty muscle tone, abnormal galt

which cranial nerve helps with chewing

trigeminal

typically how many somatic motor neurons are there in a motor pathway?

two

thalamus

two oval masses of gray matter 1. the thalamus contains over 10 nuclei each nucleus integrates a specific function

subarachnoid space

underneath the arachnoid is the subarachnoid space. there is a watery fluid in this space called cerebrospinal fluid

which cranial nerve slows down the heart rate

vagus #10

are the pyramids located on the ventral or dorsal side of the medulla oblongata

ventral

which cranial nerve helps with balance

vestibulocochlear #8

optic (II)

vision from the retina the optic nerve travels from the retina to the thalamus of the brain. some of the fibers cross over in the optic chiasma.

basic functions of brain stem

vital centers such as breathing and blood pressure

what type of impulses are carried by tracts that travel through the pyramids of the medulla oblongata? **these are the tracts of the medulla oblongata

voluntary motor, and sensory tracts?

swallowing center

vomiting center, coughing sneezing, etc.

why are emotions and memory connected? where is the connection?

when we get emotional, the amygdala in our brain is stimulated and our bodies often secrete adrenaline. Somehow, these two processes work on the hippocampus, which is the centre of memory function, and our memories for that time period are sharpened.

would tracts be white or gray matter

white

is choroid plexus found in every ventricle of the brain

yes? resides in Pia matter which lines all ventricles of the brain