Anatomic and Physiologic Overview PDF

Anatomic and Physiologic Overview - connects the pons and the cerebellum with the cerebral hemispheres 2 major parts of Nervous system: CNS & PNS...

Anatomic and Physiologic Overview - connects the pons and the cerebellum with the cerebral hemispheres 2 major parts of Nervous system: CNS & PNS - contains sensory and motor pathways and serves as the center for auditory and visual reflexes Cells of the nervous system - Cranial nerves involved: Cranial 3 and 4 - Dendrites: branch-type structures Pons - Cell body: - is situated in front of the cerebellum between the midbrain and the medulla - Axon: a long projection that carries electrical impulses away from the cell body - contains motor and sensory pathways, regulate respiration - Cranial nerves involved: Cranial nerves V through VIII Major Neurotransmitters Medulla - Acetylcholine: stimulation of vagal nerve - Cranial nerves involved: Cranial nerves IX through XII - Serotonin: control mood and sleep - Reflex centers for respiration, blood pressure, heart rate, coughing, vomiting, swallowing, and - Dopamine: behavior and fine movement sneezing - Norepinephrine: affects mood and overall activity Cerebellum - Gamma-aminobutyric acid (GABA): Inhibitory - posterior to the midbrain and pons, and below the occipital lobe - Enkephalin, Endorphin: pleasurable sensation, inhibits pain transmission - Functions: controls fine movement, balance, and position (postural) sense of proprioception The CNS Brain Structures Protecting the Brain - Divided into 3 major parts: cerebrum, brain stem, cerebellum Major Bones: frontal, temporal, parietal, occipital, and sphenoid bones. Cerebrum Meninges: fibrous connective tissues that cover the brain and spinal cord - Gyri outside surface of the hemispheres has a wrinkled appearance Layers of Meninges - Longitudinal Fissure separates the cerebrum into the right and left hemispheres - Dura Mater (outermost layer): tough, thick, inelastic, fibrous, and gray; Major extension: falx - Corpus callosum: a thick collection of nerve fibers that connects the two hemispheres of the cerebri, tentorium brain, is responsible for the transmission of information from one side of the brain to the other - Herniation: excess pressure occurs in the cranial cavity, brain tissue may be - Gray matter: external or outer portion of the hemispheres compressed against these dural folds or displaced - White matter: innermost layer and is composed of myelinated nerve fibers and neuroglia - Arachnoid: (middle membrane) an extremely thin, delicate membrane that closely resembles cells a spider web 4 Lobes - Subarachnoid: has cerebrospinal fluid (CSF) in the space 1. Frontal lobe: functions are concentration, abstract thought, information storage or memory, and - Arachnoid villi: are unique finger-like projections that absorb CSF into the venous motor function system 2. Parietal lobe: analyzes sensory information and relays the interpretation of this information to other - Increased size of ventricles: communicating hydrocephalus cortical areas - Pia mater: the innermost, thin, transparent layer that hugs the brain closely and extends into 3. Temporal lobe: contains the auditory receptive areas and plays a role in memory of sound and every fold of the brain’s surface understanding of language and music 4. Occipital lobe: responsible for visual interpretation and memory CSF - a clear and colorless fluid that is produced in the choroid plexus of the ventricles and Hypothalamus circulates around the surface of the brain and the spinal cord - an important role in the endocrine system because it regulates the pituitary secretion of - 4 ventricles: the right and left lateral and the third and fourth ventricles hormones s that influence metabolism, reproduction, stress response, and urine production - Interventricular foramen: foramen of Monro - is the site of the hunger center - Blockage of the flow of CSF anywhere in the ventricular system: Obstructive - temperature regulation by promoting vasoconstriction or vasodilation hydrocephalus - regulate the sleep–wake cycle, blood pressure, aggressive and sexual behavior, and emotional response Cerebral Circulation - controls and regulates the ANS Arteries - Optic chiasm ((the point at which the two optic tracts cross) & mammillary bodies (involved in - Frequent sites of aneurysm: bifurcations along the circle of Willis olfactory reflexes and emotional response to odors) - Aneurysms are outpouchings of the blood vessel due to vessel wall weakness Brain Stem (consist of midbrain, pons, medulla oblongata) Midbrain Blood Brain Barrier  - is formed by the endothelial cells of the brain’s capillaries, which form continuous tight - regulates the activities of internal organs such as the heart, lungs, blood vessels, digestive junctions, creating a barrier to macromolecules and many compounds organs, and glands Spinal Cord - Maintenance and restoration of internal homeostasis - is continuous with the medulla, extending from the cerebral hemispheres and serving as the Major Divisions: SNS (fight or flight response) & PNS (controls visceral function) connection between the brain and the periphery SNS - Conus medullaris: terminal end of spinal cord - Main neurotransmitter: epinephrine - cauda equina: are the nerve roots that extend beyond the conus PNS Spinal Tracts - functions as the dominant controller for most visceral functions; - fast-conducting myelinated fibers form bundles: tracts - Primary neurotransmitter: acetylcholine 6 ascending tracts Coordination of movement - fasciculus cuneatus and gracilis: sensations of deep touch, pressure, vibration, position, - Flaccidity: lack of muscle tone; preceded by abnormal posturing in a patient with cerebral and passive motion injury - anterior and posterior spinocerebellar tracts: conduct sensory impulse - Athetosis: movement of a slow, squirming, writhing, twisting type - anterior and lateral spinothalamic tracts: responsible for conduction of pain, temperature, - Chorea: marked by spasmodic, purposeless, irregular, uncoordinated motions of the trunk proprioception, fine touch, and vibratory sense and the extremities 8 Descending Tracts anterior and lateral corticospinal tracts Assessment of the NERVOUS SYSTEM ○ conduct motor impulses - Health History three vestibulospinal tracts - Past Health, Family, social history ○ descend uncrossed and are involved in some autonomic functions & involuntary Common symptoms muscle control - Pain: unpleasant sensory perception and emotional experience associated with actual or corticobulbar tract potential tissue damage ○ conducts impulses responsible for voluntary head and facial muscle movement - Seizures: are the result of abnormal electrical discharges in the cerebral cortex rubrospinal and reticulospinal tracts - Dizziness & Vertigo: Dizziness is an abnormal sensation of imbalance or movement; Vertigo, ○ conduct impulses involved with involuntary muscle movement. or the illusion of movement in which the individual or the surroundings are sensed as moving Vertebral Column - Visual Disturbances: 7 cervical, 12 thoracic, and 5 lumbar vertebrae,sacrum, coccyx - Muscle Weakness: common manifestation of neurologic disease - Abnormal Sensation: a neurologic manifestation of both central and peripheral nervous PNS system disease Cranial Nerves 1. Olfactory Physical Assessment 2. Optic 5 components of neurologic assessment: 3. Oculomotor 1. consciousness and cognition 4. Trochlear - 5. Trigeminal 2. Cranial Nerves 6. Abducens 3. Motor system 7. Facial 4. Sensory System 8. Acoustic 5. Reflexes 9. Glossopharyngeal 10. Vagus 11. Spinal accessory 12. Hypoglossal Spinal Nerves - 31 pairs: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal ANS