CH 10- Objectives

• 1. Give the location and functions of the 4 main divisions of the brain

• 2. Name and locate the subdivisions of the brainstem• 3. Name and describe the 3 meninges• 4. Cite the function of CSF and describe where this fluid is

formed• 5. Cite one function of the cerebral cortex in each lobe of

the cerebrum• 6.Cite the names of the cranial nerves, #s 1,2,7,8,10• 7. Describe several methods used to image the brain• List some disorders that involve the brain or the cranial

nerves

The Brain & Spinal Cord

B&S CHAPTER 10

The Human Brain

• Is highly developed

• Is an intricate mass of soft tissue

• Weighs about 3 lbs

What does the brain look like?

• Besides having the 3 meninges:

• dura, arachnoid, pia…

• There is another covering over the brain though, it’s called the cerebral cortex

What does the brain look like?

• It appears to be gray in color due to it’s covering called cerebral cortex. This cortex is made up of:

• 1. Sulci (salsie)or grooves and folds throughout it• 2. Gyri or elevations throughout it

• (Sulci & Gyri A.K.A cerebral cortex)

• These elevated and grooved areas give the brain surface area and bulk and are very important (will discuss it later)

Sulci & Gyri give the brain surface area which means it fills up the

space

• SULCI – grooves & folds

• GYRI – elevations throughout

Gray matter versus white matter

• Gray matter – nerve tissue composed mainly of cell bodies of neurons. Found in the CNS in the cerebral cortex, basal ganglia, and nuclei of the brain

• White matter – the white substance of the spinal cord and brain consisting of nerve fibers being myelinated and unmyelinated

Basal Ganglia – Gray Matter

• Basal ganglia is found in gray matter of the brain and looks like 4 masses of gray area

• Basal ganglia are complex in function

• Basal ganglia regulate body movement and facial expressions

Protection

• The brain is protected by the:

• Skull

• Meninges

• CSF

Skull

• Made of bones, provides protection

• strong from calcium and phosphorus

Meninges

• Are the 3 membranes that cover the brain and spinal cord, they are:

• Dura mater

• Arachnoid mater

• Pia mater

Meninges

• 1. Dura mater is the external covering of the brain, contains tough, dense, fibrous , connective tissue with lots of blood vessels, dura mater is the thickest and toughest of all 3 membranes, found just under the skull bone

• 2. Arachnoid mater is the middle layer of the membrane. It looks like a fine cob-web of fluid filled spaces, it allows room for the CSF to move

• 3. Pia mater - internal layer, this layer covers the brain itself and is attached to the nervous tissue of the brain, has lots of blood vessels, and is held together by fine areolar connective tissue. The blood supply of the brain is carried by this pia mater

Spaces in between…

• The space between the arachnoid and the pia mater is filled with CSF that is produced within the ventricles of the brain

• This fluid acts as a shock absorber and a source of nutrients for the brain

Meninges

The Brain is divided into 3 parts:

• 1. Cerebrum

• 2. Cerebellum

• 3. Brainstem

Cerebrum

• The largest and highest part of the brain, it holds the nerve center and controls sensory & motor activities

• It occupies the whole upper part of the skull

• It weighs about 2 lbs

• Gray matter covers the upper and lower surface of the cerebrum

The Cerebrum

• The cerebrum controls conscious thought, judgment, memory, reasoning and will power

• The awesome degree of development of the cerebrum makes the human the most intelligent of all animals

The Cerebrum

• Is divided into 2 hemispheres, RIGHT & LEFT

• In the middle of the 2 hemispheres, down deep, is corpus callosum. This band of white matter bridges the 2 hemispheres together allowing communication between the centers of each hemisphere

Right & Left Hemispheres of the Cerebrum

Each of the Right & Left hemispheres are further divided

into 4 uneven lobes • Each side of the cerebral hemisphere has 4

uneven lobes that controls different types of functions, the 4 lobes are :

• 1. Frontal• 2. Parietal• 3. Temporal• 4. Occipital

Frontal Lobe

• 1. Controls the motor functions in humans• 2. Motor area controls voluntary muscles• 3. Cells in the R hemisphere control the L side of

the body• 4. Cells in the L hemisphere control the R side of

the body• 5. What happens in a R sided stroke pt= L side

paralysis• 6. Frontal lobe also includes 2 areas of speech

control

Parietal Lobe

• This part of the brain receives and interprets nerve impulses from the sensory receptors for pain, touch, heat and cold

• It helps us in determination of distances, sizes and shapes (spatial ability)

Temporal Lobe

• Contains the auditory area in the upper part of this lobe

• The back of this lobe is where olfactory or smell center is

Occipital Lobe

• Is located over the cerebellum, controls eyesight

• It’s the visual area of the brain

Covering of the Cerebral Hemisphere

• As discussed earlier, the bulk, folds and grooves of the brain is known as the cerebral cortex

• as stated earlier…

• The outer nervous tissue of the cerebral hemisphere is gray matter known as cerebral cortex, this is the sulci and gyri

Cerebral Cortex

• Is a thin layer of gray matter that is highly evolved and is responsible for conscious thought, reasoning and abstract mental functions

• Specific functions are localized in the cortex of different lobes

Moving downward into the brain for a moment…

• You’ll find the limbic system

The Limbic System

• Lies along the border between the cerebrum and the diencephalon

• This limbic system is involved in emotional states and behavior and governs wakefulness and sleep

• The hippocampus is here (shaped like a sea-horse). Hippocampus is responsible for learning and long-term memory

Moving even deeper down into the brain…

Diencephalon

• This is the area between the cerebral hemispheres and the brain stem

• Di = 2, there are 2 major structures here:

• 1. Thalamus• 2. Hypothalamus

Thalamus

• It’s located deep inside of the cerebral hemispheres

• It acts as a relay for (sensory) incoming and outgoing nerve impulses and relays them to the appropriate area of the cerebral cortex

• Damage to this area results in an increased ability to distinguish pain, or total LOC

Hypothalamus

• Lies below the thalamus hypo = below• Remember, the hypothalamus calls the pituitary

and directs it to do things

• Hypothalamus does 6 things:• 1. Regulates the parasympathetic and sympathetic

systems of the autonomic nervous system• 2. Controls BP by constricting or dilating blood

vessels and the beating of the heart

Hypothalamus

• Influences the following:

• 3. Temperature

• 4. Water balance

• 5. Sleep

• 6. appetite

Moving to the back lowest end of the brain…

The Cerebellum

• Controls all body functions that have to do with skeletal muscles such as:

• Balance• Muscle tone• Coordination

• Removal of or injury to the cerebellum results in motor impairment

The Cerebellum

• Is located below the cerebrum, towards the back of the brain, and is connected to the brain stem and spinal cord and to the underside of the cerebrum

• • It is composed of 2 hemispheres or wings R&L

• The word cerebellum means “little brain”

The Cerebellum

• The cerebellum communicates with the rest of the central nervous system

• The cerebellum has gray matter on the outside and white matter on the inside

• The cerebellum receives incoming messages regarding movement within joints, muscle tone, and tightness of ligaments and tendons

DID YOU KNOW…

• Why does the Physician ask you to place your finger on the tip of your nose?

• Placing a finger on your nose is a diagnostic test for cerebellar function. The cerebellum normally coordinates and smoothes out skeletal muscle activity. In attempting to touch an object, a pt with cerebellar dysfunction may overshoot, first to one side and then to the next

Moving slightly forward and underneath from the Cerebellum

is the Brainstem

•The stem-like part of the

brain that connects the

cerebral hemispheres with

the spinal cord

•This is where the respiratory

center is located

Brainstem

• Is made up of 3 parts:

• 1. midbrain

• 2. pons

• 3. Medulla

• The brainstem extends down from the medulla some refer to the whole extension (midbrain, pons, medulla) as the stem

• This is where the respiratory center is located

Pons

• Contains myelinated nerve fibers

• Helps connect the 2 halves of the cerebellum to the brainstem and connects the cerebrum with the spinal cord

• Cranial nerves 5-8 originate in the pons

Medulla

• It appears white because it contains myelinated fibers

• It regulates HR, breathing, BP and other reflexes such as coughing, sneezing, swallowing and vomiting

The brainstem

• Pons, medulla and spinal cord are located at the bottom of this picture

Ventricles of the brain

• The brain contains 4 lined cavities called ventricles.

• Each of the 4 ventricles contains a rich network of blood vessels

• The 4 ventricles are filled with CSF

• CSF is formed from the choroid plexus

Choroid Plexus

• Is a vascular network within the ventricles

• When filtration of blood and cellular secretions occurs, CSF is formed

Problems with the ventricles:

• These ventricles can overfill causing increased intercranial pressure. Pts have shunts placed in their ventricles to take the extra CSF on out of the brain to the peritoneal area to be dumped then reabsorbed

• Or• If a pt has a spinal leak, and the fluid “goes away”,

the pt will have horrible headaches. Blood patch can be placed to stop the leak

CSF

• Cerebral spinal fluid

• This fluid is usually clear and contains nutrients that the brain uses

• CSF serves as a liquid shock absorber protecting the delicate brain and spinal cord

Hydrocephalus

• Increased accumulation of CSF within the ventricles of the brain

• Causes vary, can result in interference of normal circulation due to blockage or narrowing of the foramina. Fluid can’t flow freely

• Other causes are developmental anomalies, infection, injury or brain tumors

Signs & Symptoms of Hydrocephalus in children

• Head becomes globular shaped

• The face becomes disproportionately small with eyes hidden in sockets and turned upward

• In children, sutures of the skull become separated, fontanels bulge and cranial bone becomes thin from the pressure, there is some room for the brain to grow from the fluid

Signs & Symptoms of Hydrocephalus in adults

• Headache

• Vomiting

• Choked vertebral discs

• Atrophy of the optic nerve

• Mental disturbances

• In adults, there is no room for the brain to expand from too much fluid

Treatment

• Placement of a shunt into the brain

Hydrocephalus

Other Problems that can occur in the brain

• CVA

• Hematoma

• Neurological diseases such as Alzheimers or Parkinson’s disease

• Cerebral Palsy

• Epilepsy/seizures

• Tumors known as gliomas

CVA – Cerebral Vascular Accident

• Blood clot (Thrombus) blocks blood flow to the brain, depriving blood and O2 to the brain

• Many impairments can occur

• Remember, if the stroke started on the L, you’ll see R sided impairment

Treatment of Cerebral Vascular Accident

• Treatment includes Thrombolytics (clot busters)– Streptokinase

– Urokinase

– Given IV

– Side Effect-Bleeding, blood is too thin, can be dangerous

F.Y.I

• Streptokinase – an enzyme produced by certain strains of hemolytic streptococci, used to dissolve clots

• Urokinase – an enzyme obtained from human urine, used experimentally for dissolving venous thrombi and pulmonary emboli.

• These meds are given IV

Other maintenance medication after a stroke

• Plain old fashion Aspirin. Usually 80mg/day = 1 tiny aspirin is sufficient

• Plavix – taken P.O.

• CANNOT take aspirin and Plavix together, will make blood too thin, possible hemorrhage can occur

Epidural space

• Epi – means upon or over

• Dura – that outer most covering of the brain

• You have a large amount of blood in the outer most covering of the brain, if injured, this pushes on the skull = pain and lots of pressure

• Epidural Hematoma

Dura Mater

Dura Mater Removed and Subdural Hematoma revealed

Parkinson’s Disease

• Progressive condition

• Tremors, rigidity of limbs and joints, slow movement, impaired balance

• Neurotransmitter – dopamine, cell death causes faulty production of dopamine

• TREATMENT – dopamine replacement

Parkinsons Disease

• Rigidity• Tremors• Slowness• Meds include

L-dopa/levadopa and Sinemet

Alzheimer’s

• There is an unusual protein build up in and around neurons in the 2 parts of the brain that control memory which is also known as cerebral cortex degeneration

• When neurons die, people loose their capacity to remember and their ability to do everyday tasks

• Physical damage to brain and other parts of the CNS can also kill or disable neurons

Medication used to treat Alzheimer’s

• Aricept

Cerebral Palsy (CP)

• Is an “umbrella” term for a group of nonprogressive, but often changing, motor impairment syndromes secondary to lesions or abnormalities of the brain arising in the early stages of development

• The primary cause of CP is not always trauma or stress at birth or hypoxia

• Most people think CP always causes seizures or developmental delay, not true

Cerebral Palsy

• CP is classified by the extremities involved and the type of neurological dysfunction. CP causes different things to be affected:

• Spastic CP• Hypotonic CP – flaccid tone• Dystonic CP – stiff and rigid body with

intermittent jerking• Athetotic CP – snake-like spasms in upper body

Epilepsy

• A recurrent jerking and spasming periodic sudden attacks of the cerebrum, marked by sudden, brief attacks of altered consciousness, motor activity or sensory phenomena.

• Convulsive seizures are the most common form of attack.

• Not all recurrent seizure patterns are d/t epilepsy, can be d/t gliomas or other tumors or brain abnormalities or fever

Types of seizures

• Simple Partial Seizure

• Partial Seizure

• Complex Partial Seizure

• Tonic Clonic or Grand Mal or Generalized

• Absence Seizure or Petit mal

Status Epilepticus

A series of Grand Mal seizures that may occur when the pt is awake and active or during sleep and consciousness is not completely regained between attacks

This means the brain is continually firing, this becomes a medical emergency

Pt may have to be put in a Phenobarbitol coma to make seizures stop

Maintenance Meds for Epilepsy

• Depakote

• Phenobarbitol

• Trileptal

• Tegretol

• Neurontin

• There are others but these are seen most

Tumors - Glioma

• Tumors can arise from the tissues that surround and protect the brain, there are tumors called:

• gliomas, astrocytomas, neuroblastomas• Some tumors are malignant and others are

benign• Benign tumors can cause pressure in areas

that can cause one’s death

Imaging of the brain

• CT Scan (computed tomography) -

• Provides multiple 3-D x-rays and pictures from different angles simultaneously. Pt may need sedation. A mild “whirring” sound is heard

CT Scan

• A computed tomography (CT) scan uses x-rays to make detailed pictures of structures inside of the body.

• The CT scanner sends X-rays through the body area being studied. Each rotation of the scanner takes less than a second and provides a picture of a thin slice of the organ or area.

• All of the pictures are saved as a group on a computer. They also can be printed.

CT Scan

• An iodine dye (contrast) is often used to make structures and organs easier to see on the CT pictures. The dye may be used to check blood flow, find tumors, and look for other problems. For some types of CT scans you drink the dye. CT pictures may be taken before and after the dye is used.

• A CT scan can be used to study all parts of your body, such as the chest, belly, pelvis, or an arm or leg. It can take pictures of body organs.

• It also can study blood vessels, bones, and the spinal cord.

MRI structural.gif

• Magnetic resonance imaging.

• MRI gives more views in 2 and 3-D of the brain without having to use dye or x-rays

PET Scan

• Positron Emission Tomography

• Nuclear Medicine-type test which means radioactive particles known as “tracers” are used

• Pt is given an injection of a sugar compound tagged to a tracer and the brain is scanned to detect areas of alteration

Cranial Nerves

• 12 pairs

• These are numbered according to their connection with the brain

• They are numbered using Roman Numerals

Cranial Nerves to know

• Nerve #• #1 olfactory – smell• #2 optic nerve – see• #7 facial nerve – facial expression muscles• #8 auditory nerve – hearing• #10 Vagus nerve – longest cranial nerve, supplies

most of the nerves in the thoracic and abdominal cavities and the larynx and pharynx, will make you faint if you bear down d/t a decrease in HR

# 10 – Vagus Nerve

• Vagus nerve is a mixed nerve having sensory and motor affects

• If a patient is having supraventricular tachycardia, they can bear down as in a bowel movement, and slow the heart rate down

• Seizure activity can be stopped by stimulating the vagal nerve through a vagal nerve stimulator

Disorders involving the cranial nerves

• Bell’s Palsy – a facial paralysis caused by damage to the 7th cranial nerve

• It’s usually paralyzed on one side of the face

• Distortion of the face d/t one-sided paralysis

Neuralgia (nu-RAL-je-ah)

• Severe spasmodic, nerve pain

• Affects the 5th cranial nerve

• The pain involved comes faster and harder

• Treatment includes microsurgery or high-frequency current

(EEG) Electroencephalogram

• Instrument that detects brain waves

EEG Reading

Quadraplegic

• Paralysis of all 4 extremities

Paraplegic

• Paralysis of the lower portion of the body and lower legs

Aging of the nervous system

• As we grow older, the brain begins to decrease in size and weight due to loss of cells

• These losses cause a decrease in the synapses and neurotransmitters

• The speed of processing information decreases, especially for recent events

The End