Neurologic Function and Nervous System Overview

• Neurologic function involves receiving stimuli, communicating information, processing information for responses, and transmitting information to control body actions.

Nervous System Division:

• The nervous system divides into the peripheral nervous system (PNS) and the central nervous system (CNS).
• The PNS consists of cranial nerves and spinal nerves.
• The PNS relays information to and from the CNS.

Neurons:

• Neurons, composed of axons, dendrites, and cell bodies, are nerve cells.
• Axons transmit impulses away from the cell body.
• Dendrites transmit impulses toward the cell body.

Myelin Sheath:

• The myelin sheath is interrupted by nodes of Ranvier.
• Impulses conduct from node to node, increasing conduction velocity via a "jumping effect".

Synapse:

• The synapse is the small gap between the axon of one neuron and the dendrites or cell body of the next neuron.
• Synapses ensure one-way transmission of impulses through a chemical process.

Neurotransmitters:

• Excitatory neurotransmitters include acetylcholine, norepinephrine, dopamine, and serotonin.
• Inhibitory neurotransmitters include gamma-aminobutyric acid (GABA) found in brain tissue and glycine in the spinal cord.

Neuron Types:

• Sensory neurons carry impulses from receptors to the CNS (afferent).
• Interneurons are found entirely within the CNS and integrate sensory and motor impulses.

Nerve Impulses:

• Nerve impulses are action potentials that carry information along the neuron membrane.
• Neurons at rest have abundant Na+ ions outside the cell and abundant K+ ions and negatively charged ions inside.

Action Potential Sequence:

• Polarization: The neuron membrane has a positive charge outside and a negative charge inside, maintained by sodium and potassium pumps.
• Depolarization: Stimuli alter the membrane potential, opening voltage-regulated sodium channels and allowing Na+ influx, making the inside more positive.
• Repolarization: Voltage-regulated potassium channels open, allowing K+ efflux, making the outside more positive; sodium ions return outside, and potassium ions return inside via pumps.

Brain:

• The brain is composed of approximately 100 billion neurons and trillions of synapses.
• Major brain parts include the medulla, pons, midbrain (brain stem), cerebellum, diencephalon, and cerebrum.
• Ventricles are four cavities within the brain, each containing a choroid plexus that forms cerebrospinal fluid from blood plasma.
• Meninges line the brain.
• The brain is marked by surface gyri (folds) and sulci (grooves).

Cerebrum:

• The cerebrum, the largest brain part, divides into left and right hemispheres by the falx cerebri.
• Hemispheres are marked with gyri and sulci and are connected internally by the corpus callosum.
• Each hemisphere subdivides into frontal, parietal, occipital, and temporal lobes.
• The fissure of Rolando (central sulcus) separates the frontal and parietal lobes.
• The sylvian fissure separates the frontal and temporal lobes.

Lobe Functions:

• Frontal Lobe: conceptualization, abstraction, motor ability, judgment formation, and writing ability.
• Parietal Lobe: sensory function interpretation, body part recognition, and left/right discrimination.
• Temporal Lobe: memory storage and auditory stimuli integration.
• Occipital Lobe: visual center and understanding of written materials.

Speech:

• Speech functionality is the dominant hemisphere of the brain,.
• Broca's area (left frontal lobe) is the motor (expressive) speech center, enabling clear speech and gestures.
• Wernicke's area (temporal lobe) is the auditory speech center, enabling language understanding.

Aphasia:

• Aphasia is the inability to understand or make language.
• Motor Aphasia (Broca's Area): inability to speak and make gestures.
• Auditory Aphasia (Wernicke's Area): inability to receive and understand language.
• Global Aphasia: affects both motor and auditory abilities.

Basal Ganglia:

• Basal ganglia (gray matter) structures within the cerebrum include the caudate nucleus, putamen, and globus pallidus.
• It functions as part of the extrapyramidal system (EPS), responsible for postural adjustments and gross volitional movements.

Brainstem Structures:

• Brainstem structures include the diencephalon, midbrain, pons, and medulla.

Diencephalon:

• The diencephalon includes the thalamus, epithalamus, subthalamus, and hypothalamus.
• The thalamus, superior to the hypothalamus and inferior to the cerebrum, serves as the end station for all sensory impulses.

Epithalamus:

• The epithalamus contains the pineal body (an endocrine gland, thought to retard sexual development and growth).

Subthalamus:

• The subthalamus receives fibers from the globus pallidus (part of the afferent descending pathway).

Hypothalamus:

• The hypothalamus regulates body temperature, food intake, autonomic nervous system functioning, emotional responses, and body rhythms.

Midbrain:

• The midbrain extends from the pons to the hypothalamus, integrating visual and auditory reflexes.

Pons:

• The pons, bulging anteriorly from the upper medulla, contains two respiratory centers for normal breathing rhythms, connecting cranial nerves V and VIII.

Medulla:

• Medulla extends, anterior to the cerebellum, from the spinal cord to the pons.
• It contains cardiac, vasomotor, and respiratory centers.

The Reticular Formation (Reticular Activating System):

• Respiratory, cardiovascular, afferent and motor systems have their centers in the reticular formation.
• Reticular formation is the system's core of tissue.

Cerebellum:

• Situated inferior to the occipital lobes of the cerebrum, the cerebellum functions in spatial orientation, truncal equilibrium, antigravity muscle control, and volitional movement checking.
• It uses information from the inner ears to regulate equilibrium.

Blood Supply:

• The brain receives blood supply from the internal carotid arteries and vertebral arteries.

Blood-Brain Barrier:

• The blood-brain barrier is formed by capillaries which limits substance movement from blood to brain tissues.

Cerebrospinal Fluid (CSF):

• The choroid plexus produces CSF from blood plasma at 18 mL/hr.
• Approximately 500 mL of CSF is secreted each day, with only 120 mL in the ventricular system at any one time.
• CSF functions include providing cushioning, nourishment, metabolite removal, and ICP regulation.

Spinal Cord:

• The spinal cord is an elongated cylindrical structure, approximately 1.8 cm thick and 45 cm long.
• Beginning as a medulla oblongata continuation, it serves three principal functions: conduction, locomotion, and reflexes.
• The spinal cord gives rise to 31 pairs of spinal nerves divided into cervical, thoracic, lumbar, and sacral regions.
• Reflexes involves a specific, stereotyped motor response to an adequate sensory stimulus.

Cord Tissue

• The spinal cord consists of gray and white matter.

Gray Matter

• Gray matter, containing somas, dendrites, and proximal axons, presents a butterfly or H shape in cross-sections.
• Contains sparse myelin.
• Functions in synaptic contact.

White Matter

• White matter, myelinated axons arranged in tracts or fasciculi, carries signals within the CNS.
• Has abundant myelin.
• The spinal cord has ascending (sensory) and descending (motor) tracts.

Spinal Cord Columns:

• The posterior/dorsal white column carries sensory impulses.
• The lateral white column carries sensory reflexes.
• The anterior/ventral white column carries voluntary movements.

Meninges:

• The meninges protects the CNS. From superficial to deep, they are the dura mater, arachnoid mater, and pia mater.

Peripheral Nervous System (PNS)

• The PNS is the nervous system outside the CNS composed of sensory, motor, and mixed nerves, classified as cranial or spinal nerves.

Cranial Nerves

• Cranial nerves, numbered I to XII, emerge directly from the brain and brainstem.

Spinal Nerves:

• There are thirty-one pairs of spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal.
• Beginning with L3 to S5, spinal nerves form cauda equina.
• Phrenic (C3-C5): innervates the diaphragm.
• Radial (C5-C8, T1): innervates the muscles of the posterior arm, forearm, hand, thumb, and first two fingers
• Median (C5-C8, T1): innervates the anterior arm, forearm, and hand.
• Ulnar (C8, T1): innervates the medial arm, forearm, hand, little finger and ring finger.
• Intercostal (T2-T12): innervates the intercostal muscles.
• Femoral(L2-L4): innervates the thigh, medial leg and foot.
• Sciatic (L4-S3): innervates the thigh, leg and foot.

PNS Divisions

• Somatic (SNS): innervates skeletal muscles, with acetylcholine as the major neurotransmitter.
• Autonomic (ANS): controls glands, cardiac muscle, and smooth muscle.
• Primary ANS targets are the viscera of the thoracic and abdominal cavities.
• Subsystems are sympathetic and parasympathetic divisions.
• Sympathetic (adrenergic) division: norepinephrine is the major neurotransmitter, operates in "fight or flight" situations.
• Parasympathetic (cholinergic) division: acetylcholine is the major neurotransmitter

Diagnostic Evaluation

• Diagnostic evaluation ranges from Skull films, to Spinal films, to CT Scans,.

Skull Films

• X-rays.
• Remove metallic items from the hair..

Spine Films

• X-rays.
• Remove metallic objects.

CT Scan

• Multiple beam X-rays.
• Remove metallic objects from hair.
• Maintain absolute stills.
• NPO 4-6 hours if contrast is used.
• Observe for reactions to contrast..

Electroencephalography (EEG)

• Measures electrical impulses.
• Shampoo hair.
• Avoid all stimulants.
• Wash hair after.

Electromyography (EMG)

• Measures electrical activities in muscles.
• Detects NM's with accuracy.

Brain Scan

• Detects brain tumors.
• Tell client the risks.

Cerebral Angiography

• Visulalizes extracranial and intracranial components.

Nursing Implications (Before Procedure)

• Explain the procedure.

Spinal Tap

• Inserts a needle into the subarachnoid space.

Nursing Considerations (After)

• Flat to stop spinal effects.

Myelogram

• Detects disc compression in spinal cord.
• Requires Lumbar puncture.

Brain Imaging (MRI)

• Uses magnetic waves.
• Remove all meatalic devices.

Pneumoencephalography

• Uses air to act as medium.

CVA's

Goals.

• All must have accurate goals set.

CSF Tests

• Drains fluid.
• Spinal lab shows any abnormalities.

Drug Therapy

• Controls different functions in the body.

Magenic Resonance Imaging (MRI)

• Obtains metal history..

Ventriculography

• Air inside.

Altered LOC (Levels of Consciousness)

DEFINITION

• Defined as being unresponsive to and stimuli.

Altered LOC

LEVELS..

• Different levels of conciousness on a scale.
• From the most conscious to complete comatose levels of concious.

Alert or Conscious

• Attends to the environment

Complications or Consequences

• All sorts all related to conciousness

Risk for safety

• Fall risk.

Medical Management

• Different support methods for breathing.

Assess

• Responsiviness.

Protecting the Patient.

• Pad rails to prevent injury.

Maintaining Skin

• Constant assessment is needed.

Meninges.

• Protective covering.

Meeting the families.

• Support is needed.

ICP (Intricranial Pressure)

HIGH ICP

• The amount that measures fluid on and around your brain

Causes

• Bleeding onto the brain.
• High stroke.

Brain volume

• Brain is connected to volume.

Diuretics

• Osmotics are needed such as Manitol .

Coid compress

• Uses to remove inflammation.

Intercranioal surgery

Introduction.

• There are cases when neurosurgery is needed.

ICP( Intracranial Pressure)

• Used to treat if any problem is to occur..

What happenss?

• Pressure increase on brain , thus causing issues

Complications during procedures.

• Can range from all types .

Nursing Diagnosis.

• High risk at all times for infection. Ineffective Cerebral Tissue Perfusion Interventions.

Intercranial Adaptive Capacity

• High bp is needed.

Inter cranial surgery

Types and components.

Neurological assessments.

• Need to do all the time.

Medications

• Sedatives need to be given..

Surgical and medical managements .

Post op needed.

Skull

Anatomy.

Functions of Central Nervous System

• Composed mainly of 12 cranial components.

Assessment

• Important to do at all times. Glasgow Coma Scale
• The way to measure alertness.

Stroke (What is It)

• Disrupted flow to the brain.

Different Types

• Each has their own set of treatments.

Hemorrhaagic and ischemic

• Clots are most frequent .

Time is impoprtant

What it is essential.

Stroke Treatment

• Medical or surgical .
• To give support. 34 - 39 - What is MS(Multiple Sclerosis)
• Affects sensory and all system functions.

Damage.

• Damage at all times can occcur.

Immune.

• Autoimmune can trigger everything.

Types of MS

• All need to be treatable.

Treatment.

• To reduce the reoccurance.