THE B

RAIN &

CRANIAL

NERVES

SARAH CRON IN

MATT HAWK IN

S

TYLER P L AS

MAR ISSA KRAMER

The adult human brain contains about 98% of the body’s neural tissue. A typical brain weighs about 1.4kgThe brain of a male is usually about 10% larger than that of a female. No correlation lies between brain size and intelligence.

MAJOR PARTS OF THE BRAINCerebrum

Divided into two hemispheres covered by the neural cortex.

It is the largest part of the brain, contains the majority of the cranial nerves, and the “speech center” that regulates patterns of breathing and vocalization needed for normal speech.

CerebellumSecond largest part of the brain, covered by the cerebral cortex.

Adjusts the postural muscles, allows you to perform the same movements over and over, programs and fine-tunes movements controlled at the conscious and subconscious levels

MAJOR PARTS OF THE BRAINDiencephalon

Composed of the left and right thalamus.Plays an active part in motor commands, and integrating conscious and subconscious sensory information.

HypothalamusThe floor of the Diencephalon Contains centers involved with emotions , autonomic functions, and hormone production.

Brain StemContains a variety if important processing centers and nuclei that relay information headed to or from the cerebrum.

MesencephalonHeadquarters of the reticular activating system, processing of visual and auditory data, and maintenance of consciousness.

PonsConnects the cerebellum to the brain stem. Contain sensory and motor nuclei for four cranial nerves

Medulla Oblongata Connects the brain and spinal cord.

CEREBELLUM

• Coordinates complex

somatic motor patterns• Adjusts output of other

somatic motor centers

in brain and spinal cord

MEDULLA OBLONGATA

Relays sensory information to thalamus

and to other portions of the brain stem Autonomic centers for regulation of visceral

function (cardiovascular, respiratory, and

digestive system activities)

CEREBRUM

• Conscious thought processes, intellectual functions

• Memory storage and processing• Conscious and subconscious regulation

of skeletal muscle contractions

MESENCEPHALON

• Processing of visual

and auditory data• Generation of reflexive

somatic motor responses • Maintenance of

consciousness

DIENCEPHALON

HYPOTHALAMUS

• Centers controlling

emotions, autonomic

functions, and hormone

production

THALAMUS

• Relay and processing centers for sensory and motor information

Brain stem

Gyri

Sulci

Fissures

Spinal cord

Left cerebralhemisphere

•

•

PONS

• Relays sensory

information to cerebellum

and thalamus • Subconscious somatic and visceral motor centers

BREAKDOWN• The CNS begins as a hollow cylinder

known as the neural tube.• This tube has a fluid filled internal

cavity, called the neurocoel.• Three areas enlarge rapidly through

expansion of neurocel. • Enlargment creates 3 prominent

divisions called primary brain vessicels.

3 DIVISIONS OF PRIMARY BRAIN VESICLES• Prosencephalon: – “Forebrain”•Telencephalon•Diencephalon

• Mensencephlon: - “Midbrain”• Rhombncephalon: - “ Hindbrain”• Mentencephalon• Mylencephalon

VENTRICLES OF THE BRAIN• During development, the neurocel,

diencephalon, metencephalon, and medulla oblongota expand to form chambers called ventricles.

• Each cerebral hemisphere contains a large lateral ventricle.

• The ventricle in the decephalon is called the third ventricle.

• The fourth ventricle lies between the pons and the cerebellum.

• The ventricles are filled with cerebrospinal fluid.

(a) (b)

Pons

Medulla oblongata

Spinal cord

Mesencephalic aqueduct

Central canal

Lateral ventricles

Interventricular foramen

Fourth ventricle

Cerebral hemispheres

Cerebellum

Third ventricle

THE CRANIAL MENINGESMade up of three layers:• Cranial Dura Mater

Outer fibrous layer: Fused to periosteum of cranial bones Inner fibrous layer

• Cranial Arachnoid Mater• Arachnoid membrane

• Pia Mater• Sticks to the surface of

the brain

DURAL FOLDS

• Provide stabilization and support to the brain. • Dural Sinuses•Large collecting veins located within dural folds.

THREE MAIN FOLDS

• Three large main folds:• Falx Cerebri- injects between the cerebral hemispheres.• Tentorium Cerebelli- seperates and protects the cerebral hemispheres• Falx Cerebelli- divides the two cerebellar hemispheres along the midsagittal line.

PROTECTIVE FUNCTION OF CRANIAL MENINGES• Cranial bone provides mechanical

protection, like a car. • The fibrous dual folds act like seat

belts, holding the brain in position.

• The cerebrospinal fluid acts like an airbag cushioning the brain against sudden jolts and shocks.

CEREBRAL SPINAL FLUID• Cushions the brain• Supports the brain• Transports nutrients, chemical messengers, and waste

products.• The choroid plexus consists of specialized ependymal cells

and permeable capillaries involved in the production of CSF.• The ependymal cells secrete CSF into the ventricles and

remove waste from CSF.• The CSF circulates from the choroid plexus through the

ventricles and fills the central canal of the spinal cord.

BLOOD SUPPLY TO THE BRAIN• Arterial blood reaches the brain through internal

carotid arteries and the vertebral arteries.• Most of the venous blood leaves the brain

through internal jugular veins.• Cerebrovascular Diseases are cardiovascular

disorders that interfere with the normal blood supply to the brain.

• A stroke occurs when blood supply to a portion of the brain is cut off.

MEDULLA OBLONGATA

• Continuous with the spinal cord.• All communication between the brain and spinal cord

involves tracts that ascend or descend through this.• Contain three groups of nuclei:• Nuclei controlling visceral activities• Reflex centers here receive input from cranial nerves

• Sensory and Motor Nuclei of Cranial Nerves• These cranial nerves provide motor commands to muscles of the pharynx, neck, back, and visceral organs of the thoracic and peritoneal cavities.

Relay Stations along Sensory & Motor PathwaysThe nucleus gracilis and he nucleus cuneatus pass somatic sensory information to the thalamus.

The olivary nuceli relay information to the cerebellar cortex.

THE PONS • Contains four groups of components:• 1. Sensory and Motor Nuclei of Cranial

Nerves •These CN innervate the jaw muscles, anterior face surface, the lateral rectus, and the sense organs of the inner ear.

2. Nuceli Involved with the Control of Respiration Two respirtory centers: the apneustic

and pneumotaxic centers These centers modify the activity of

the respitory rythmic center of the Medulla Oblongota.

THE PONS• 3. Nuceli and Tracts that Process and

Relay Information Heading to or from the Cerebrum

4. Ascending, Descending, and Transverse Tracts Transverse fibers are axons that link nuclei of the pons with the cerebellar hemisphere of the opposite side.

THE CEREBELLUM• Automatic processing center functions:

1. Adjusting the postural muscles of the body coordinates rapid, automatic adjustments that maintain balance and equilibrium.2. Programming and fine-tuning movements3. Refines learned movement patterns

THE MESENCEPHALON• Also known as the midbrain• Processes visual and auditory data

with the use of corpora quadrigemina, which are pairs of sensory nuceli.

• Maintains consciousness.• Maintains generation of the reflexive

somatic motor responses.

THE DIENCEPHALON• Plays a vital role in integrating conscious and

unconscious sensory information and motor commands. • The pineal gland, located in the top posterior end of the

diencephalon, secretes the hormone melatonin, which is important for regulation of the day and reproductive functions.

THALAMUS• The thalamus is the final relay point for

all the information that travels to the primary sensory cortex. It acts as a filter.

• All sensory information not regarding smell enters the thalamus.

• The thalamic nuclei deal primarily with the relay of sensory information to the basal nuclei and cerebral cortex.

HYPOTHALAMUS• Located just below the thalamus. • Controls the following functions:1. Hunger2. Thirst3. Sexual behavior4. Body’s reactions to changes in temperature

LIMBIC SYSTEM • Located in the core of the forebrain between the cerebrum and the

diencephalon• Limbic System Functions:

1. Establishing emotional states2. Linking the conscious, intellectual functions of the cerebral cortex with the unconscious and autonomic functions of the brain stem3. Facilitating memory storage and retrieval

• The amygdaloid plays a role in the regulation of your heart rate and is responsible for the “flight or fight” response.

• The hippocampus is important for learning and the storage and retrieval of long term memories.

THE CEREBRUM• Divided into two hemispheres, separated by a

longitudinal fissure.• Each hemisphere is divided into lobes, or regions • The central sulcus divided the anterior front lobe

and the posterior parietal lobe.• The lateral sulcus separates the frontal lobe from

the temporal lobe. • The parieto-occipital sulcus separates the parietal

lobe from the occipital love.

(b)

Precentralgyrus

Centralsulcus

Postcentralgyrus

PARIETAL LOBE

TEMPORAL LOBE

OCCIPITAL LOBE

Cerebellum

Medulla oblongataPons

Lateralsulcus

FRONTAL LOBE

Lateral view

(c)

Precentralgyrus

Centralsulcus

Postcentral gyrus

PARIETAL LOBE

TEMPORAL LOBE

OCCIPITAL LOBE

Cerebellum

Medulla oblongata

Pons

FRONTAL LOBE

Cingulategyrus

Midsaggital section

Parieto-occipital sulcus

• Each cerebral hemisphere receives sensory information from, and sends motor commands to, the opposite side of the body.

• The two hemispheres have different functions, even though they look identical

• The correspondence between a specific function and a specific region of the cerebral cortex is imprecise.

WHITE MATTER• The interior of the cerebrum.• Association fibers, commissural fibers,

and projection fibers all make up white matter.

• These all serve the function of connecting the hemispheres and other parts around the brain.

BASAL NUCELI• Masses of gray matter that lie within each

hemisphere deep to the floor of the lateral ventricle.

• Involved with subconscious control of skeletal muscle tone and the coordination o learned movement patterns.

• Once a movement is underway, the basal nuclei provide the general pattern and rhythm.

• They set your body position.• Ex. Walking

MOTOR AND SENSORY AREAS OF THE CORTEX• Neurons of the primary motor cortex direct

voluntary movements by controlling somatic motor neurons in the brain stem and spinal cord

• The somatic sensory association area monitors activity in the primary sensory cortex.

• The prefrontal cortex of the frontal lobe coordinated information relayed from he association areas of the entire cortex.

Writing

Auditorycortex

(right ear)

LEFTHEMISPHERE

RIGHT HEMISPHERE

Generalinterpretive

center(language andmathematical

calculation)

LEFT HAND

Prefrontal cortex

Visual cortex(right visual field)

Visual cortex (left visual field)

Spatial visualization and analysis

Auditory cortex (left ear)

Analysis by touch

Anterior commissure

RIGHT HAND

Prefrontalcortex

Speechcenter C

ORPUSCALLOSUM

• A printed report of the electrical activity of the brain is called an electroenephalogram(EEG).

• Three types of brain waves:•Alpha•Beta• Theta

• A seizure us a temporary cerebral disorder accompanied by abnormal movements, unusual sensations, and inappropriate behavior.

NERVES• The Oculomotor Nerves- Eye

movement • The Abducens Nerves- Eye Movement• The Trigeminal Nerves- Mixed

sensory and motor to face• The Facial Nerves- Mixed sensory and

motor to face • The Vestibulocochlear Nerves-

Balance and Equilibrium, Hearing• The Glossopharyngeal Nerves-

Mixed sensory and motor to head and neck

NERVES • The Vagus Nerves- Mixed Sensory

and Motor widely distributed throughout the thorax and abdomen

• The Accessory Nerves- Motor to muscles of the neck and upper back

• The Hypoglossal Nerves- Motor tongue movement

OVERALL FUNCTIONS OF THE BRAINAttention and thought, voluntary movement,

decision–making, and language. processes intentional awareness of the environment, manipulating objects, representing numbers, learning and attention, perception, face recognition, object recognition, memory acquisition, understanding language, and emotional reactions. Basically your entire life and more.

OCCUPATIONS• Neurological Surgeon An M.D. who performs surgery on the nervous system

(brain, spinal, nerves).• NeuropsychologistStudies brain/behavior relationships especially

cognitive function.• PsychiatristM.D. who diagnoses and treats mental disorders.• Neurologist An M.D. who diagnoses and treats disorders of the

nervous system.