Lecture 3 the Brain

Cerebral Cortex

outer region of the cerebrum, containing sheets of nerve cells; gray matter of the brain

Angiogram of CW

this is normal vasculature. I am sharing this with you to demonstrate the clinical significance of having to learn this material. Do you see the CW in the middle of this picture and the arterial branches around it?

Flow of CSF

The CSF from lateral ventricles flow through interventricular foramen (foramen of Monro) to third ventricle to cerebral aqueduct (aqueduct of Sylvius)-to fourth ventricle to foramen of Luschka (laterally) & foramen of Magendie (medial) and into the subarachnoid space surrounding the brain and spinal cord.

Menings

Three layers of connective tissue: 1.)Dura Mater(Outermost layer) 2.)Arachnoid(Middle Layer) 3.)Pia Mater(Innermost Layer) membrane that protect the brain and spinal cord

Sulci

Valleys of the brain(nervous tissue folds)

12 Cranial Nerves

1-olfactory, 2-optic, 3-oculomotor, 4-trochlear, 5- trigeminal, 6- abducens, 7- facial, 8-vestibulocochlear, 9-glossopharyngeal, 10-vagus, 11-accessory, 12- hypoglossal

Sensory and Motor Homunculus

Body parts whose movements are more important, occupy more space in the brain

Electroencephalogram (EEG)

An amplified recording of the waves of electrical activity that sweep across the brain's surface. These waves are measured by electrodes placed on the scalp. Used to diagnose certain brain dysfunctions like seizures,narcolepsy, sleep disorders, psychiatric illnesses and determine brain death.

falx cerebri

An extension fo the dura mater, separating the left and right cerebral hemisphere.

tentorium cerebelli

An extension of the dura mater as well, separating the cerebrum from the cerebellum

Ventricles

Are chambers inside the brain where CSF is made and allows the CSF to circulate throughout the CNS ** Know where the CSF is produced and its function.

Circle of Willis

Arterial network of blood supply to the brain.

Periosteum

Beneath the skin, the membrane over the skull ,beneath the skull are the three meninges layers

Summary

Brain stem(Midbrain, Pons, Medulla Oblangat)-Functoins maintainer sort info and basic functions of life Cerebellum-Motor control/memory Thalamus-sorts info Hypothalamus-homeostasis Posterior Pituitary-below hypothalamus Cerebrum-corpus collusam -allows hemis to connectbelow cerebrum is basal ganglia-motor control cerebral cortex-frontal(boss functions),parital(sensation), occipital(vision),temporal,speech,hearing,memory). Somatosensory cortex and motor cortex receive and send messages.

Cerebrovascular Accident (stroke)

Caused by blockage of blood flow to the brain. If not treated early can become permanent injury to the brain. Indications: Loss of strength and sensation in one-half of the body, slurred speech,visual disturbance,loss of sensation and weakness on one side of the face, confusion. Diagnosis: non-contrast CT scan, MRI, carotid duplex, echocardiogram. Treatment: Made by identify cause, generally embolism, therefore we use clot busting agents and blood thinners.

Ventricles

Chambers inside the brain , they have choroid plexus which procure Cerebrospinal fluid CSF

Brain Stem

Connects the brain and the diencephalon with the spinal cord and is comprised of -Midbrain -Pons -Medulla Oblongata

Diencephalon

Consist of the Thalamus and the Hypothalamus.

Choroid plexus

Consist of tightly adhered epithelial cells which separates the systemic blood circulation from the CNS circulation. **Choroid plexus and arachnoid membrane comprise the Blood Brain Barrier (BBB)

Parietal Lobe

Controls sensory functions of our body so that we become aware of our surroundings. Sensory info from our body is sent to primary sensory area of the parietal lobe for processing.

Parkinson's Disease(No cure at this time)

Degenerative Disease of the brain, some are genetically predisposed.underlying problem with Parkinson's is low levels of dopamine Indications : Bradykinesia (slow body movement), cogwheel rigidity,postural instability and resting tremor. Diagnosis: Based on clinical presentation Treatment: With Sinemet(med that supplies dopamine to the CNS);reduces disease progression No cure at this time

Alzheimer Disease (No cure at this time)

Degenerative disease of the brain.Some are genetically predisposed.underlying problem with Alzheimer is that the level of acetylcholine in the brain is gradually depleting. Indications: Memory loss, decline in thinking abilities, personality changes and can become demented and psychotic. Diagnosis: Made using mental status examination, laboratory work ups, CT and MRI. Treatment: Using anticholinesterase inhibitors like rivastigmine,tacrine can reduce disease progression. No cure at this time.

Transportation of Fluid by villi

Depending on the region of the brain where absorption took place, the fluid travels from the superior sagittal sinus, inferior sagittal sinus, straight sinus, transverse sinus, sigmoid sinus and then into the jugular vein where it is mixes with the systemic circulation. And that is it!!!

EEG waves

EEG shows alpha and beta waves; see what these waves look like. Normal sleep consists of stage 1, 2, 3, 4, and rapid eye movement (REM) sleep; each stage has a characteristic wave pattern; see what they look like below. Stage 1 or light sleep has theta waves, stage 2 has sleep spindle and K-complexes, stage 3 and 4 are deep sleep and consist of delta waves, and REM shows a "sawtooth" pattern on EEG.

Frontal lobe

Gives us identity ,personality and is involved in thought processes and abstract thinking. Controls motor functions of our body, it controls body movement, mediated by the primary motor area . Also responsible for producing speech-motor speech in an area known as the Broca's area ** Frontal lobe has nerve pathways of the visual field leading to the occipital lobe. Orientation to person, place, and time, as well as, concentration, problem solving, and making judgments are essential functions of the frontal lobe. Injury to this part of brain will result in deficit of the functions as described.

Encephalitis

Inflammation and infection of the brain. Bacteria can cause it but most likely are viruses like Herpes Simplex, Varicella, West Nile, H1N1 virus. Indication: Presents itself like meningitis Diagnosis:via spinal tap or lumbar punter to evaluate CSF, CT scan prior to spinal tap to rule out elevated intracerebral pressure. Treatment: antibiotics for bacteria and antiviral medicine for virus.

Blood Brain Barrier (BBB)

Integral part of protecting the brain from all elements.

Corpus Callosum

Internally Connects the left and right hemisphere of the brain creating a bridge to allow the hemispheres to talk. ** Locate the Corpus Callosum

Temporal Lobe

Involved in our abilities to smell, hear and understand languages/ speech. It carries visual neuronal Pathways from our eyes to the occipital lobe

frontal / coronal cut of the brain.

Locate the temporal lobe and you can find the amygdala, hippocampus, and mamillary bodies.

Pons CN5-8

Located in the middle of the brain stem; it links the neuronal connection from the cerebellum(the hind brain) to the cerebrum and spinal cord and projects cranial nerves 5-8

Wernicke's speech area

Located on the dominant side of the temporal lobe, is responsible for our ability to understand language. **As we hear a language, the information is processed by the auditory centers of the temporal lobe, then we understand the language, which is processed by the Wernicke's area of the temporal lobe, then, we produce speech, which is processed by the Broca's area of the frontal lobe; and this is how we learn to communicate by listening first , then speaking

medulla oblongata CN9-12

Located on the inferior aspect of the brain stem; is have neuronal centers that control respiration and heart rate; ** Where the motor nerves from the brain crossover(decussate) That's how the right hemi controls the left side of the body and left hemi the right. ** cranial nerves #9, 10, 11, and 12 are projected at the level of medulla oblongata.

Cranial Nerves (CN)1&2

Located on the inferior aspect of the frontal lobe

Midbrain. CN3&4

Located on the superior aspect of the brain stem;it has neuronal pathways for controlling reflexes involving the eyes. Cranial nerves #3 and #4 project at the level of the midbrain

Lambic system

Located within and adjacent to the medial surface of the temporal lobe. Includes olfactory tract (sense of smell),fornix,cingulated gyrus, and mamillary bodies 3 Main Parts 1. The Amygdala - responsible for emotional responses 2. Hippocampus - responsible for memory formation 3. Reticular Activating System (RAS) - responsible for alertness and focus ** all 3 work together if emotion is trigger (1) it stimulates (3) to bring focus and forms memories (2)

sleep architecture in Adults

People who are depressed often complain of insomnia and sleep disruption. These individuals experience repeated nighttime awakenings and waking too early. Elderly people have repeated nighttime awakenings and reduced stage 3, 4 and REM sleep.

Thalamus (neuronal signal Post office )

Relay station where all the nervous signals get sorted and directed to appropriate regions within the brain. ** Located subcortical(beneath the cortex)

Absorption of CSF

Removal of metabolic waste products from the brain . Arachnoid villi are contained within the sinuses;this I is where the CSF is absorbed. Fluid absorbed by these villi is transported into sinuses.

Cerebellum (Hind Brain)

Resides in the posterior inferior aspect within the cranium. 3 Main Functions 1. Coordination of voluntary Muscles 2. Maintain posture and balance 3. Maintenance of muscle tone. Has two Cerebellar hemis cinnected at the midline by the Vermis

Hypothalamus(Below Thalamus) Maintains Homeostasis.

Sensor of the body, it senses everything from body temp,pH,Blood pressure,heart rate,respiratory rate,oxygen level in blood and Controls these functions by releasing hormones into the nervous system

Lateral Sulcus

Separates temporal lobe from parietal and frontal lobes.

cerebrospinal fluid (CSF)

Specialized fluid that protects the CNS from concussive shock. It is contained in the subarachnoid space around the brain and spinal cord.Produced by the choroid plexus inside the ventricles of the brain. General Info Function: Supports,cushions and protects CNS; transports hormones and nutrients and hormone-releasing factor; removes metabolic waste products via absorption. CSF glucose - should be 50-75mg/dL Protein- should be 15-50mg/dl CSF pressure-should be 80-100mm H20 -elevated CSF pressure can indicate brain tumors or meningitis.

Lobes Functions

The central sulcus is an important landmark as it separates the primary motor area of the frontal lobe from the primary sensory area of the parietal lobe. Locate the lateral fissure or sulcus, and you can see that the lateral sulcus separates the motor speech area of the frontal lobe from the auditory regions and speech comprehension region of the temporal lobe. There is no sulcus or fissure separating the occipital lobe from the other lobes.

Lobes of the brain

The cerebral hemispheres are further divided into lobes, for example, there are the: 1.)frontal lobes (on the anterior), 2.) parietal lobes (at the top), 3.) occipital lobes (at the back) 4.)temporal lobes (on the sides of the ear). Each of these lobes has particular function in our body.

Gyri

The hills of the brain(nervous Tissue folds)

occiptal lobe

The occipital lobe has its own set of sophisticated neuronal pathways for processing and interpreting visual signals from our eyes. This lobe is ultimately responsible for our vision and that's it!!!!

Parietal Cortex

Where the brain determines the origin of sensory signals coming from the body;fingers,hand,belly,face,legs,hips,etc.

subarachnoid space

a space in the meninges beneath the arachnoid membrane and above the pia mater that contains the cerebrospinal fluid

The brain is divided into two halves called:

hemispheres Left and Right Between is the Longitudinal Fissure

Meningitis

inflammation of the meninges;caused by bacteria or virus. Indications: Fever, headache,stiff neck,photophobia,nausea /vomitting and altered mental state. 'Diagnosed -via spinal tap or lumbar punter to evaluate CSF, CT scan prior to spinal tap to rule out elevated intracerebral pressure Treatment: based on etiology; antibiotics for bacteria and antiviral medicine for virus.

Longitudinal Fissure

separates the left and right hemispheres of the brain.

Subdural space

space between dura mater and arachnoid mater