Neurologic Function: CNS and PNS

Anatomy and Physiology of the Neurologic Function

• The nervous system has two parts: the CNS and PNS
• The CNS acts like the integrating and command center
• The PNS consists of nerves outside the CNS, extending from the brain and spinal cord.
• Spinal nerves carry impulses to and from the spinal cord.
• Cranial nerves carry impulses to and from the brain
• Cranial nerves serve as a communication line.
• They carry impulses from sensory receptors to the CNS to the appropriate glands and muscle and are split into sensory and motor divisions.

Organization of the Nervous System

• The central nervous system (CNS) consists of the brain and spinal cord
• The peripheral nervous system (PNS) consists of cranial and spinal nerves.
• Sensory (afferent) nerves carry information from sense organs to the CNS
• Motor (efferent) nerves carry impulses from the CNS to muscles and glands.
• The somatic nervous system controls voluntary movements by activating skeletal muscles
• The autonomic nervous system controls involuntary responses by influencing organs, glands, and smooth muscle.
• The sympathetic division prepares the body for stress or energetic activity, triggering "fight or flight" responses.
• The parasympathetic division dominates during rest, directing maintenance activities and promoting "rest and rumination."

Spinal Nerves

• Spinal nerves emerge from different regions of the spinal cord, innervating specific areas of the body.
• Cervical nerves (C1-C8) serve neck muscles, the diaphragm, deltoid, wrist, triceps and fingers.
• Thoracic nerves (T1-T12) innervate intercostals and abdominals.
• Lumbar nerves (L1-L5) serve the hips, quadriceps, hamstrings, knee and foot
• Sacral nerves (S2-S4) control bowel and bladder function
• Sacral nerves affect penile erection and ejaculation.

Functions of the Nervous System

• It maintains body homeostasis.
• It controls motor, sensory, autonomic, cognitive, and behavioral activities.
• It activates sensation, mental functioning and emotional response, muscles, and glands.
• 10 million sensory neurons send information about the internal and external environment to the brain
• 500,000 motor neurons control the muscles and glands.
• The brain contains more than 20 billion nerve cells that link the sensory to motor response.

Sensory Neurons

• Carry sensory impulses from sensory organs to the central nervous system

Motor Neurons

• Carry motor impulses from the central nervous system to specific effectors.

Neurons (Nerve Cells)

• Neurons are the functional unit of the brain
• Neurons respond to stimulus.
• Neurons are specialized cells to transmit messages (nerve impulses and compose of cell body.

Cell Body (Soma)

• Supports neuron life

Dendrites

• Conduct impulses to the cell body
• Dendrites are a branch-type structure with synapses that receive electrochemical messages.

Axons

• Conduct impulses away from the cell body.
• Neurons may have hundreds of dendrites depending on their types
• Each neuron has only one axon which arises from a cone-like region called the axon hillock

Types of Neuroglia or Glial Cell

• They support nutrition, insulation, and help with signal transmission in the nervous system.
• Astrocytes support, regulate ions in the CNS
• Microglial cells defend the CNS
• Ependymal cells line cavities in the CNS
• Oligodendrocytes wrap and insulate to form the myelin sheath in the CNS
• Satellite cells surround neuron cell bodies in the PNS
• Schwann cells insulate and help form the myelin sheath in the PNS

Nervous Tissue: Structure and Function

• Nerve cell bodies occurring in clusters are called Neuroglia simply called Glial Cell
• They support, protect, and nourish neurons.
• A cluster of cell bodies with the same function is called a center
• An example of a center is a respiratory center.

Axons and Nerve Impulses

• Axonal terminals are separated from the next neuron by a gap
• the gap between adjacent neurons is a synaptic cleft.
• A junction between nerves is a synapse.
• Axonal terminals contain tiny vesicles or membranous sacs that contain neurotransmitters

What Happens at the Synapse

• The neuron releases a neurotransmitter to transmit the signal from one neuron to another across the synapse
• Neurotransmitters act as chemical messengers from one neuron to another.

Neurotransmitters

• Neurotransmitters communicate messages from one neuron to another or from a neuron to a specific target tissue.
• Neurotransmitters are manufactured and stored in synaptic vesicles.
• Neurotransmitters enable conduction of impulses across the synaptic cleft.

Major Neurotransmitters

• Acetylcholine is usually excitatory; parasympathetic effects sometimes restrain
• Serotonin helps control mood and sleep and inhibits pain pathways.
• Dopamine affects behavior, attention, emotions, and fine movement.
• Norepinephrine affects mood and overall activity
• Gamma-aminobutyric acid is an excitatory amino acid.
• Enkephalins, endorphins provide pleasurable sensations and inhibits pain transmission

Hippocampus

• A complex brain structure embedded in the temporal lobe which plays a major role in learning and memory.

Ventral Tegmental Area

• Located in the midbrain and controls diverse behavioral repertoire.

Neural synapse

• Brain functions are modulated through activity at neurotransmitter receptor sites
• These functions include memory and cognitive processes

Neurologic disorders due an imbalance in neurotransmitters

• Huntington’s disease stems from a lack of GABA and acetylcholine.
• Epilepsy comes from low serotonin levels
• Parkinson's disease develops from a decrease in dopamine

Types of Receptors

• Direct receptors cause passage of ions when opened.
• Direct receptors can be excitatory or inhibitory
• Direct receptors are rapid acting and measured in milliseconds
• Indirect receptors affect metabolic processes in the cell, taking from seconds to hours to occur

Receptor Sites

• Receptor sites are often the target for medications either block or stimulate neurotransmitters at receptor sites
• They provide relief from symptoms and are the sites for action of addictive drugs.

Cerebrum

• Cerebrum is more than half the brain mass.
• Cerebrum consists of two hemispheres incompletely separated by the longitudinal fissure.
• Sulcus separates the cerebrum into right and left hemispheres joined by the corpus callosum
• Corpus callosum transmits information from one side of the brain to the other.
• Sensation, memory, and learning discrimination are transferred.
• Outside surface of hemispheres - wrinkled appearance from folded layers called gyri, increase brain surface area.
• Gray matter - external or outer portion, cerebral cortex, billions of neurons/cell bodies, giving gray appearance.
• White matter makes up the innermost layer; support tissue connects parts of the brain.
• Surface lobes of the cerebrum are the Frontal, Parietal, Occipital and Temporal lobe.

Frontal Lobe

• Largest lobe responsible for concentration, abstract thought, information storage or memory, and motor function.
• Contains critical Broca's area used for motor control of speech.
• Responsible for an individuals affect, judgment, personality, and inhibitions.

Parietal Lobe

• Location of the Somatic sensory area posterior to the central sulcus

Sensory Lobe

• Contains the primary sensory cortex
• Primary sensory cortex, analyzes sensory information and relays interpretation to the thalamus and other cortical areas.
• Essential part for individual's body orientation in space/spatial relations.

Occipital Lobe

• Containes the visual area and is responsable for visual interpretation.

Temporal Lobe

• Contains the auditory area
• Contains a vital area called the interpretive area that provides integration of somatization, visual and auditory areas
• Plays the most dominant role of any area of the cortex in cerebration.

Cerebral Special Senses

• Gustatory (taste), visual, auditory, and olfactory areas are all specialized senses within the cerebrum.

Sensory Pathways

• The Sensory pathways are crossed pathways which means the left side of the sensory cortex receives impulses from the right side and vice versa

Right Cerebral Cortex

• Holistic, intuitive, conceptual, and synthesizing NON-VERBAL

Left Cerebral Cortex

• Logical, analyzer, mathematical, technical VERBAL

Right Limbic

• Interpersonal, emotional, artistic, symbolic

Left Limbic

• Controlled, conservative, planner, organizer and administrator.

The Brain in Whole

• RH controls spatial, holistic and intuitive
• LH controlled through language, math, analytical, and sequential processes

Information Transferred by Corpus Callosum

• Right-handed people and some left-handed people have LH cerebral dominance for verbal, arithmetical, calculating, and analytic functions.
• The non-dominant hemisphere is responsible for geometric, spatial, visual, pattern, and musical functions.

Basal Ganglia

• Masses of nuclei located deep in the cerebral hemispheres.
• Responsible for controlling fine motor movements of the hands and lower extremities.

Thalamus

• Acts as a relay station for all sensation except smell.
• All memory, sensation, and pain impulses pass through this section of the brain. (Pleasant or unpleasant)

Hypothalamus

• Located anterior and inferior to the thalamus.
• Infundibulum of the hypothalamus connects it to the posterior pituitary gland.
• Important role in the endocrine system because it regulates the pituitary secretion of hormones that influence metabolism, reproduction, stress response, and urine production.
• Works with the pituitary to maintain fluid balance and temperature regulation by promoting vasoconstriction or vasodilatation.
• The mammillary bodies serve as a reflex center involved in olfaction bulge from the floor of the hypothalamus posterior to the pituitary gland.
• Limbic System or "emotional visceral brain"; Site of the hunger center and is involved in appetite control.
• Contains centers that regulate the sleep-wake cycle, bloop pressure, aggressive and sexual behavior
• Center emotional responses (ie, blushing, rage, depression, panic, and fear). The hypothalamus also controls and regulates the autonomic nervous system.

Pituitary Gland

• Located in the Sella turcica (bony structure) connected to the hypothalamus.
• A common site for brain tumors in adults;
• Detected by physical signs and symptoms that can be traced to the pituitary like hormonal imbalance visual disturbances secondary to pressure on the optic chiasm.

Topography of the Cortex

• Posterior portion of each hemisphere ie the occipital lobe is devoted to visual perception.
• Lateral region or temporal lobe incorporates the auditory center.
• Midcentral zone or parietal zone is posterior to the fissure of Rolando, and is concerned with sensation
• Anterior portions are concerned with frontal eye field voluntary muscle movements.
• Large area behind forehead contains association pathways determine emotional attitudes/responses and contribute to formation of thought processes.
• Damage in the frontal lobe affects a person's personality, basic attitudes, sense of humor and propriety, self-restraint, and motivations,.

Brain Stem

• Parts of the Brain stem are the Midbrain, Pons and Medulla oblongata.

Midbrain

• It contains sensory and motor pathways; serves as the center for auditory and visual reflexes.
• Cranial nerves III and IV originate in the midbrain.

Pons

• Situated in front of the cerebellum between the midbrain/medulla ;acts as a bridge between halves of cerebellum and the medulla and the cerebrum.
• Cranial nerves V through VIII connect to the brain in the pons; contains motor and sensory pathways.
• Portions of the pons also control the heart, respiration, and blood pressure.

Medulla Oblongata

• Contains motor fibers from the brain to the spinal cord and sensory fibers from the spinal cord to the brain;
• Cranial nerves IX through XII connect to the brain in the medulla.
• Contains important control centers that regulate vital visceral activities like the heart rate, blood pressure, breathing, swallowing and vomiting.

Tentorium Cerebelli

• Separates from the cerebral hemispheres

Cerebelli

• It has both excitatory and inhibitory actions and is responsible for coordination of movement.
• Controls fine movement, balance, position sense, and integration of sensory input.

Structures Protecting the Brain

• They include the Scalp and skin, Skull and vertebral column and also Meninges.

Meninges

• Fibrous connective tissues that cover the brain and spinal cord) provide protection, support, and nourishment to them.
• 3 Layers of the meninges consisting of the Dura, Arachnoid and Pia mater

Dura Mater

• Outer most layer ("means tough or hard mother") that covers the brain and the spinal cord.
• Tough, thick, inelastic, fibrous, and gray layer with four extensions (Falx cerebri, Tentorium, Falx cerebelli and Diaphragm sellae)

Arachnoid Layer

• The middle membrane with a spider-like appearance, middle membrane, thin, delicate membrane.
• Appears white as lack blood supply with the choroid and has arachnoid
• The Choroid plexus produces the CSF , absorbed by the arachnoid villi.
• Subdural space is between dura/arachnoid layer, subarachnoid space is between arachnoid/pia layers.
• Subarachnoid contains the CSF.

Pia Mater

• Innermost layer (“gentle mother”) that surrounds the brain and extends into every fold of the brain's surface.

Cerebrospinal Fluid Characteristics

• Clear and colorless fluid with a specific gravity of 1.007, produced in ventricles, circulated around brain/ spinal cord.
• Ventricular and subarachnoid system contains approximately 125-150 mL of fluid (15-25 mL each lateral ventricle).
• Composition is similar to other extracellular fluids, concentrations of the various constituents differ.
• Laboratory report for color, gravity, protein count, WBC, glucose, other electrolytes may be tested for WBC and Lactate if needed
• Cerebral circulation receives 15% of cardiac output or 750 mL/minute.
• Brain doesn't store nutrients; high metabolic demand needs high blood flow.
• Blood pathway unique because arteries fill up/ veins drain down.
• Brain lacks collateral blood flow which may causes tissueirreversible damage.

Circle of Willis

• Ring of arteries at base of brain surrounding pituitary gland, connecting vertebral and internal carotid arterial chains

Arteries

• 2 internal carotid and 2 vertebral arteries/extensive system of branches supply blood to the brain.
• ICA supplies much of anterior circulation of brain.
• VA branch from SAA; flows upward on either side of cervical vertebrae; enters cranium through foramen magnum.
• At brain stem level VA join to become basilar artery, divides to form two branches of posterior cerebral arteries.
• Vertebrobasilar arteries supply most of posterior circulation of brain.

Veins

• Venous drainage for brain doesn't follow arterial circulation patterns.
• Veins reach brain's surface, join larger veins, cross subarachnoid space, empty into dural sinuses within tough dura mater.
• Network carries venous outflow/empties into the internal jugular vein; returns to heart.
• Cerebral veins/sinuses don't have valves for backward flow/depend on gravity/blood pressure.

Spinal Cord

• Approximately 18 inches (45 cm) long from the brain stem
• Provides 2-way conduction pathway to/from the brain and the Major reflex center which Enclosed vertebrae extends from foramen magnum of skull from lumbar vertebra/ends below ribs.

Vertebral Column

• Bones of vertebral serving Support, extent From the skull/supports Weight consist of 26 irregular bones separated by intervertebral disks normal curvature that consists of CONCAVE AND CONVEX .

Peripheral Nervous System

• Nerve is a bundle of neuron fibers/nerves
• Contains both the cranial/spinal and autonomic nerves
• Classified by direction in which they transmit impulses. Mixed nerves are both sensory and motor fibers
• Afferent sensory carry impulses toward CNS
• Efferent motor carry impulses away from CNS
• 12 pairs of nerves that mostly serve head/neck - only 1 pair that extends the thoracic abdominal cavity
• 3 entirely sensory I, II, VIII
• 4 are mixed V, VII, IX, and X – both sensory and motor functions
• 5 are motor III, IV, VI, XI, and XII

Spinal Nerves

• Spinal cord is composed of 31 pairs
• 8 Cervical, 12 Thoracic, 5 Lumbar, 5 Sacral, 1 Coccygeal spinal nerves
• Each has a ventral and dorsal root, roots are motor/transmit impulses from trunk.
• Fibers are either somatic/visceral: Visceral fibers control cardiac/glandular secretions, digestion, lubrication, hormones.

Autonomic Nervous System

• ANS regulates internal organs like heart, lungs, vessels, digestive organs, glands.
• Its maintenance/restoration helps internal homeostasis.

Divisions of the Autonomic Nervous System

• Sympathetic increases excitatory responses including "fight or flight"
• Parasympathetic controls visceral functions.
• Regulated by centers in the spinal cord, brain stem, and hypothalamus. The autonomic system involves two motor neurons arranged in series.

ANS Anatomy

• Sympathetic originates T₁ through L2 of Lumbar regions.
• Parasympathetic originates brain stem and S through S4 of Sacral region
• PNSFibers are PURPLE, SF are Green. Solid are preganglionic/Dash line.

Autonomic Response

• Response that is triggered by unusual stimulus
• Its takes over to increase activities
• Sympathetic is the "Fight or flight" which is termed the "E" division - Exercise, Excitement, Emergency and Embarrassment

Sympathetic Nervous system

• Critical actions for survival that are upregulated is Tachycardia, Output Bronchodilation, Mydriasis Gluconeogenesi Diaphoresi Hypertensio
• NC actions that are for survival downgraded is Salivation, Lacrimatio Digestion, Defecatio Uninatio

Parasympathetic

• Controls digestion and is called the "resting-and-digesting" system, more active when body rests.
• Conserves energy, maintains body functions," and promotes Rest and digest.

Computed Tomography

• Scanning is a computer-based nuclear imaging technique that produces images of actual organ functioning.
• Permits measurement of bloodflow, tissuer composition, and the measurement the activity of specific brain areas
• Used in the diagnosis of a brain condition that detects changes in glucose use showing density differences
• With/without intravenous contrast material then the head with face still by lying.
• Noninvasive and Painless

Nursing Interventions

• Preparation with patient Monitoring by providing patient instructions.
• The patient must be assessed before CT with constrast for shellfish allergies, for monitor client , with possible need for line use etc..

Positron Emission Tomography (PET)

• PET show metabolic changes (Alzheimer/locate/therapy-effects/vascular diseases
• Prepare pt; include injection and inhalation

Resonance Imaging (MRI)

• Uses magnetic field =images; potent identifies earlier, better than tests Can provides changes within Is/diagnosis mult/scler
• Pt with metal device can't- risk of severe damage/death due to magnetized items- loud tapping of coils during

Cerebral Angiography

• Angiography as minimally test for iodine (material to produce in brain vessels: vessels catheter

Nursing Interventions For Patient with AngioGram

• If some pts, experience major/minor from embolized thrombi,hemorrhage- deficit/change in senses
• Should hydrated with more clear liquids to void before, and remains immobile expect for temp -metallic taste/signs+symp/ altered

Myelography

• Myelgraphy: x/ spinal through lumbar puncture- agent spaceOutline-tumors cysts lesions
• Water-more Side Effects
• Prepare Pt by using medications such blood thinner, to prevent lengthy test
• Untoward- head, fever -photo/light Seiz,chemical=Bacterial

Transcranial Doppler Sonography

• Noninvasive- vessels of intracranial are assessed. - Vasospasm or alters- stroke. - Prepare pt: head is soluble;bedside

Electroencephalography (EEG)

• Recording for electricity activity to dx/evalu:disorders/coma/tumor;infection
• For baseline avoid stimulating. - Test light/ seizure

Evoked Potential Studies

• With electrodes, stimulus and the pt. look @ visual stimulus that used to to cord, function of deMylination

Lumbar Puncture

• Carried by fluid (CSF pressure tests/antibiotics) subarachnoid 3-4-5the.
• Fluid (should clear= colorless for the pressure in tests (glucose tests, lab)
• Lying with severe a few days= headache. / epidural

###Other Complications

• Hemi, Hema

Electromyography (EMG)

• Diagnostic for nerve/cell ,but motor+ cause contraction that translate into specialist test
• Check before/ after= allergies, that the result will interfere/Tell for food/that warn discomfort muscle - plate .

Examinations For Motor system

• Size and strength to walk across then inspect for atro/movement muscle

Muscle Strength Testing

• Flex to resist test
• Grading is five points; to weak

Balance test by coordination

• Cerebellar is the test and it involves upper point coordination through symmetry and for heel , to run then the ataxia is incoordination and swaying and some is also

Reflex Examing

• Reflex is an invol motor and tested deep/the cutaneous responses then grade the responses using the 4+, which it may interpreted can determine it's

Nervous System Disorders

• The nervous system disorders has the potential at a part of the time of the life (mild, self-limits, threatening)

Health History

• The initial systematic inter and for relying to question the history is through that the details included all symptoms and signals.

Disease/Influenced

• Genetics and are associated with a assessment, that are similar and also with for age/onset child. learning to genetic/Duchenne's to help muscle intacr

Abnormal Sensations

• Numbness, abnormal, loss are all manifestations
• • All of the senses like auditory to know that cerebral then cause these disturbances like mental with integrative

• Impact-Imposes pt to live with community: report, observe-to the cranial and its function will impact

Brain Injuries

• It's defined, that's located at front, or side at an injury which leads to symptoms+effects/aids, to help at time of: prevent from aspiration,protecting

• Neurologic - assess resp rate is the indicator of pt’s, it can be pt in any pos/to also the fluids are restrict and may occur with coma/ the patients need emotional

MARALIT