Presentation on theme: "THE BRAIN & CRANIAL NERVES SARAH CRONIN MATT HAWKINS TYLER PLAS MARISSA KRAMER."— Presentation transcript:
THE BRAIN & CRANIAL NERVES SARAH CRONIN MATT HAWKINS TYLER PLAS MARISSA KRAMER
The adult human brain contains about 98% of the body’s neural tissue. A typical brain weighs about 1.4kg The 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 BRAIN Cerebrum 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. Cerebellum Second 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 BRAIN Diencephalon Composed of the left and right thalamus. Plays an active part in motor commands, and integrating conscious and subconscious sensory information. Hypothalamus The floor of the Diencephalon Contains centers involved with emotions, autonomic functions, and hormone production.
Brain Stem Contains a variety if important processing centers and nuclei that relay information headed to or from the cerebrum. Mesencephalon Headquarters of the reticular activating system, processing of visual and auditory data, and maintenance of consciousness. Pons Connects 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 cerebral hemisphere 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.
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.
THE CRANIAL MENINGES Made 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 Pathways The 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 movements 3. 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.Hunger 2.Thirst 3.Sexual behavior 4.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 states 2. Linking the conscious, intellectual functions of the cerebral cortex with the unconscious and autonomic functions of the brain stem 3. 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.
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 Auditory cortex (right ear) LEFT HEMISPHERE RIGHT HEMISPHERE General interpretive center (language and mathematical 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 Prefrontal cortex Speech center C O R P U S C A L L O S U M
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 BRAIN Attention 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). Neuropsychologist Studies brain/behavior relationships especially cognitive function. Psychiatrist M.D. who diagnoses and treats mental disorders. Neurologist An M.D. who diagnoses and treats disorders of the nervous system.