Neurology: Nervous System Medical Terminology Study Guide

Neurology and the Nervous System

Introduction to Neurology

Neurology is the medical specialty focused on the study, diagnosis, and treatment of the nervous system. It encompasses laboratory and diagnostic tests, medical and surgical procedures, and pharmacological interventions for nervous system diseases.

• Neurology: The study of nerves and the nervous system.

• Practitioners: Neurologists use various tests and procedures to treat nervous system disorders.

• Key Medical Terminology:

  • neur/o-: means nerve

  • -logy: means study of

Anatomy of the Nervous System

Overview of Nervous System Structure

The nervous system is a complex, widespread body system consisting of the brain, spinal cord, and cranial and spinal nerves. It serves as the pathway for nerve impulses throughout the body.

• Central Nervous System (CNS): Brain and spinal cord

• Peripheral Nervous System (PNS): Cranial and spinal nerves and their branches

• Autonomic Nervous System: Controls involuntary functions (heart muscle, smooth muscle, glands)

• Somatic Nervous System: Controls voluntary skeletal muscle movements

• Divisions:

  • Parasympathetic Division: "Rest and digest"

  • Sympathetic Division: "Active and alert" or "Fight or flight"

Anatomy of the Brain

Major Structures of the Brain

The brain is the largest part of the CNS, located in the cranium and composed of several key structures:

• Cerebrum: Largest structure, divided into four lobes (frontal, parietal, temporal, occipital) and two hemispheres

• Ventricles: Four connected cavities filled with cerebrospinal fluid (CSF)

• Thalamus: Relay station for sensory information

• Hypothalamus: Regulates temperature, hunger, thirst, emotions

• Hippocampus: Transfers short-term memory to long-term memory

• Amygdaloid bodies: Interprets facial expressions, links visual images to memory

• Brainstem: Connects brain and spinal cord (midbrain, pons, medulla oblongata)

• Cerebellum: Maintains balance and coordinates movements

• Meninges: Three membrane layers surrounding the brain

Lobes of the Cerebrum

Each lobe of the cerebrum is named after the cranial bone above it and has specialized functions:

• Frontal Lobe: Conscious thought, intelligence, prediction, motor control, speech, taste analysis

• Parietal Lobe: Touch, temperature, vibration, pain analysis (somatosensory area)

• Temporal Lobe: Hearing (auditory cortex), smell (olfactory cortex)

• Occipital Lobe: Vision analysis (visual cortex), 3D vision

Brain Hemispheres and Functions

The cerebrum is divided into right and left hemispheres, connected by the corpus callosum. Each hemisphere processes information from the opposite side of the body.

• Left Hemisphere: Memories, language, reasoning, problem solving

• Right Hemisphere: Environmental analysis, emotion, recognition, artistic abilities

Gyri, Sulci, and Ventricles

The surface of the cerebrum contains folds (gyri) and grooves (sulci). The gray matter forms the outer layer, while white matter lies beneath.

• Ventricles: Lined with ependymal cells, produce and circulate CSF

• CSF: Cushions and protects the brain

Midline Structures of the Brain

Key midline structures include the thalamus, hypothalamus, midbrain, pons, medulla oblongata, and cerebellum.

• Thalamus: Sensory relay station

• Hypothalamus: Regulates autonomic functions and emotions

• Midbrain: Maintains consciousness, coordinates reflexes

• Pons: Relays impulses

• Medulla Oblongata: Regulates respiration and heart rate

• Cerebellum: Balance and movement coordination

Meninges

The meninges are three protective membrane layers around the brain:

• Dura Mater: Tough, fibrous outer layer

• Arachnoid: Cushioning middle layer, surrounds CSF-filled subarachnoid space

• Pia Mater: Thin, delicate inner layer with blood vessels

Anatomy of the Spinal Cord

Structure and Protection

The spinal cord is a long, narrow column of tissue beginning at the medulla oblongata and traveling through the spinal canal. It is protected by vertebrae, epidural space, and meningeal layers.

• Central Canal: Lined with ependymal cells, produces CSF

• Gray Matter: Cell bodies

• White Matter: Axons bundled into tracts

• Ascending Tracts: Sensory information to the brain

• Descending Tracts: Motor commands from the brain

Anatomy of the Cranial and Spinal Nerves

Cranial Nerves

There are twelve pairs of cranial nerves, each with specific sensory and motor functions.

• Olfactory: Smell

• Optic: Vision

• Oculomotor, Trochlear, Abducens: Eye movement

• Trigeminal: Facial sensation, chewing

• Facial: Taste, tear and saliva secretion

• Vestibulocochlear: Hearing, balance

• Glossopharyngeal: Taste, blood pressure, swallowing

• Vagus: Taste, heart, bronchial, GI muscle control

• Accessory: Swallowing, speech, neck movement

• Hypoglossal: Tongue movement

Spinal Nerves

There are thirty-one pairs of spinal nerves, named for their adjacent vertebrae. Each nerve has dorsal (sensory) and ventral (motor) roots.

• Dorsal Roots: Receive sensory information (afferent)

• Ventral Roots: Send motor commands (efferent)

• Reflex: Rapid, involuntary muscle reaction controlled by the spinal cord

Divisions of the Nervous System

Autonomic Nervous System

Controls involuntary movements of cardiac and smooth muscle. Divided into:

• Parasympathetic Division: Active during rest, uses acetylcholine, decreases heart rate, increases digestion

• Sympathetic Division: Active during stress, uses norepinephrine, increases alertness, heart rate, and metabolism

Somatic Nervous System

Controls voluntary movements of skeletal muscles, driven by conscious thought.

Anatomy and Physiology of Neurons and Neuroglia

Neurons

Neurons are individual cells that conduct electrical impulses, forming the functional unit of the nervous system.

• Dendrites: Receive impulses

• Cell Body: Contains nucleus, produces neurotransmitters

• Axon: Transmits impulses, may be covered in myelin

Neuroglia

Neuroglia are supportive cells that do not conduct impulses. Five types:

• Astrocytes: Form blood-brain barrier

• Ependymal Cells: Produce CSF

• Microglia: Consume dead tissue and pathogens

• Oligodendroglia: Produce myelin in CNS

• Schwann Cells: Produce myelin in PNS

Neurotransmitters

Neurotransmitters are chemicals that transmit impulses across synapses.

• Acetylcholine: Parasympathetic division

• Dopamine: Brain

• Endorphins: Brain neuromodulator

• Epinephrine: Adrenal hormone

• Norepinephrine: Sympathetic division

• Serotonin: Brain and spinal cord

Common Nervous System Diseases and Disorders

Brain Tumors

Abnormal growths in the brain, can be benign or malignant. Diagnosis often involves imaging and biopsy.

Astrocytoma

A cancerous tumor arising from astrocytes, a type of neuroglia.

Cerebral Palsy

A disorder affecting movement and muscle tone, often seen in children.

Cerebrovascular Accident (Stroke)

Occurs when blood flow to the brain is disrupted, causing paralysis on the opposite side of the body.

• Hemorrhagic: Due to bleeding

• Embolic: Due to blockage

Concussion

A mild traumatic brain injury, often resulting in temporary loss of function.

Down Syndrome

A genetic disorder characterized by distinctive physical features and intellectual disability.

Dyslexia

A learning disorder affecting reading and writing abilities.

Epilepsy

A disorder characterized by recurrent seizures, diagnosed by EEG.

Subdural Hematoma

Bleeding beneath the dura mater, often after trauma.

Migraine

Severe headache often triggered by various factors.

Alzheimer Disease

A progressive neurodegenerative disorder, seen as decreased metabolic activity in PET scans.

Spinal Cord Diseases

Meningomyelocele

A congenital defect where meninges and spinal cord protrude outside the body.

Radiculopathy

Pathology of nerve roots, often due to herniated disk pressing on the sciatic nerve.

Spinal Cord Injury

Injury level and completeness determine extent of paralysis (paraplegia or quadriplegia).

Nerve Diseases

Bell Palsy

Paralysis of the facial nerve, causing drooping of facial muscles.

Paresthesias

Abnormal sensations such as burning, tingling, numbness, or crawling feelings.

Laboratory, Diagnostic, and Radiologic Procedures

Arteriogram

Imaging of arteries using injected dye to detect blockages or aneurysms.

Doppler Carotid Ultrasonography

Ultrasound imaging combined with Doppler technology to assess blood flow in carotid arteries.

Electroencephalography (EEG)

Recording of electrical impulses of brainwaves to diagnose seizure disorders.

Polysomnography

Sleep study recording EEG, eye movements, muscle activity, heartbeat, and respirations.

Medical Procedures

Babinski Sign

A positive Babinski sign indicates abnormal neurological function, seen as extension of the great toe and fanning of other toes.

Lumbar Puncture

Procedure to obtain cerebrospinal fluid from the lumbar area for diagnostic purposes.

Summary Table: Divisions of the Nervous System

Division	Main Function	Key Structures
Central Nervous System	Integrates and processes information	Brain, spinal cord
Peripheral Nervous System	Transmits signals between CNS and body	Cranial and spinal nerves
Autonomic Nervous System	Controls involuntary functions	Heart, smooth muscle, glands
Somatic Nervous System	Controls voluntary movements	Skeletal muscles
Parasympathetic Division	Rest and digest	Acetylcholine
Sympathetic Division	Fight or flight	Norepinephrine

Key Equations and Concepts

• Neuronal Transmission: $\text{Impulse transmission: Dendrite} \rightarrow \text{Cell Body} \rightarrow \text{Axon} \rightarrow \text{Synapse}$

• Reflex Arc: $\text{Sensory Input (Dorsal Root)} \rightarrow \text{Spinal Cord} \rightarrow \text{Motor Output (Ventral Root)}$

Conclusion

This study guide provides a comprehensive overview of the nervous system, its anatomy, physiology, common diseases, and diagnostic procedures. Understanding these concepts is essential for proficiency in medical terminology and clinical practice related to neurology.