Introduction to Neurology Basics

Neurophysiology 1: An Introduction to Functional Neuroanatomy

• Neurophysiology 1 is an introduction to functional neuroanatomy.
• The course covers ten topics.

Overview - 10 Topics

• The overview consists of ten topics covering various aspects of neuroanatomy and neurophysiology.
• These topics include functional neuroanatomy, neuronal support, neurotransmitters, consciousness, sleep, pain, lower motor neurons (LMNs), spinal reflexes, upper motor neurons (UMNs), and cranial nerves.
• The topics further include the neuroexamination, descending/ascending pathways, and special senses such as hearing, vestibular sense, vision, taste, and smell.

Neurology: Functional Neuroanatomy

• Neurology is the study of functional neuroanatomy.
• Functional neuroanatomy focuses on the physiology of neurons, their chemical impulses, and collective behavior.
• Neuroanatomy encompasses the anatomy of the brain, spinal cord, peripheral nervous system, and sensory systems.
• Neurology aims to diagnose and treat diseases.
• Accurate diagnosis requires understanding how the nervous system components manifest during disease, injury, or degeneration. This involves more than just clinical pathways and imaging which only reveal a fraction of the story.

Nervous System Function

• The nervous system collects sensory information (internal and external).
• It integrates this information to formulate a response plan.
• The system either changes the environment or maintains it consistently.
• Collecting sensory information and generating motor output are functions of the peripheral nervous system (PNS).
• Integrating this information is a function of the central nervous system (CNS).

Nervous System Function (Continued)

• The nervous system functions in a complex and integrated manner.
• Functions include controlling movement, posture, thoughts, cognition, learning, memory, emotions, the special senses (sight, hearing, smell, taste, touch, proprioception) and regulating homeostasis.

Neuroanatomy

• Neuroanatomy focuses on the structure of the nervous system.

Nervous System Divisions

• The nervous system divides into the central nervous system (CNS) and peripheral nervous system (PNS).
• The CNS comprises the brain and spinal cord.
• The PNS includes spinal nerves and cranial nerves.

Embryology

• Ectoderm, mesoderm, and endoderm give rise to different structures in the nervous system during development.
• The neural tube and neural crest are significant derivatives of the ectoderm.
• The notochord, a mesoderm structure, has a role in early development and later degenerates.

Central Nervous System (CNS)

• The central nervous system (CNS) is primarily composed of the brain and spinal cord.
• The brain can be divided in 7 major parts:
  • Telencephalon (cerebral hemispheres)
  • Diencephalon (epithalamus, thalamus, hypothalamus)
  • Midbrain
  • Pons
  • Medulla
  • Cerebellum
  • Spinal Cord.

Telencephalon

• The telencephalon is the part of the forebrain, containing the cerebral cortex and deeper structures.
• The cerebral cortex is composed of four main lobes: Frontal, Parietal, Occipital, and Temporal.
• Subcortical structures including the basal ganglia are also an important part of the telencephalon.

Subcortical Structures of the Telencephalon

• Basal Ganglia: A group of structures, playing a critical role in motor control, but also associated with reward and cognition; consisting of the corpus striatum (largest component), lenticular nuclei (putamen and globus pallidus), subthalamic nuclei and substantia nigra; responsible for initiating and controlling movements.
• Hippocampus: Involved in memory and learning; part of the limbic system.

Cerebral Cortex Function

• The cerebral cortex has six layers, developing from the dorsal telencephalon (sensory in origin). It acts as a crucial link between sensory and motor functions.
• It's the location of specific regionalisation of motor and sensory input; controls coordination of motor output, learning, memory and emotions.
• This layer integrates and modulates complex inputs from all brain areas.

Basal Ganglia Function

• Basal ganglia mainly control motor functions.
• They act as gatekeepers for initiation of movement, selecting and inhibiting actions.
• They also play a significant role in reward-related processes and higher-order cognitive functions like planning

Basal Ganglia Communication

• Input and output to basal ganglia involve communication between these areas using two major pathways (inhibitory and excitatory).

Diseases

• Diseases affecting basal ganglia often reveal their function, including those caused by poisoning (e.g., in horses) and human diseases like Parkinson's and Huntington's diseases.

Diencephalon

• The diencephalon consists of the epithalamus, thalamus, and hypothalamus.

Epithalamus

• The epithalamus connects the limbic system to other parts of the brain.

Thalamus Function

• The thalamus is a paired structure that relays sensory and motor signals to other parts of the brain.
• It regulates consciousness and alertness.
• It receives sensory information from various parts of the body (except olfactory information).
• Sensory information from various modalities relay through distinct thalamic nuclei except olfactory information.

Hypothalamus Function

• The hypothalamus regulates homeostasis, the neuroendocrine system, and behavioral responses like hunger, thirst & temperature regulation.
• It interacts with the limbic system, and regulates the circadian rhythm.

Midbrain, Pons, and Medulla

• The midbrain, pons, and medulla, collectively known as the brainstem, are crucial for life-sustaining functions like regulating cardiovascular and respiratory systems.

Midbrain Function

• The midbrain is involved in connecting the cerebrum with the spinal cord and plays essential roles in motor control, sensory processing, and cranial nerves.

Pons Function

• The pons is between the midbrain and medulla; controls various functions including motor control and sensory processing. Plays a role in cranial nerves, as well as relay of information to the cerebellum.

Medulla Oblongata Function

• The medulla is located at the base of the brain; has multiple important functional centers relating to heart, lungs and digestion. It's important for regulation of life-sustaining functions through cardiac and respiratory regulation, relaying sensory information and controlling several cranial nerves.
• The medulla is also involved in transmission and regulation for various life-sustaining processes.

Brainstem Functions

• The brainstem, which includes the midbrain, pons, and medulla, plays a crucial role in important functions including relay of information to the cerebellum, regulation of movement, control of visceral and autonomic functions, consciousness, cranial nerves, arousal, pain regulation and relaying sensory information.

Cerebellum

• The cerebellum (the "little brain") is situated below the cerebrum and plays a pivotal role in coordinating movements.
• It co-ordinates movements and maintains posture and balance.
• It also contributes to motor learning.

Spinal Cord

• The spinal cord is a vital component of the CNS and conducts information between the brain and the peripheral nerves.
• It spans from the brainstem to the lower back and terminates as the cauda equina; forms important segments allowing for segmental arrangement and branching out of spinal nerves.
• The spinal cord facilitates communication between the brain and peripheral nerves; vital for sensory and motor functions.

Spinal Cord Tracts

• Spinal cord tracts transmit sensory and motor information.
• These tracts are categorized and have specific functions depending on the pathway (e.g., ascending vs descending).

Peripheral Nervous System

• The peripheral nervous system (PNS) carries information to and from the CNS.
• The PNS includes spinal nerves and cranial nerves, and contains sensory (afferent) and motor (efferent) systems.
• Classifying by direction (afferent/efferent) and function (somatic/autonomic) provides further insight into particular nerve systems.

Spinal Nerves

• Paired spinal nerves innervate various parts of the body, including muscles (myotomes) and skin (dermatomes).

Cranial Nerves

• Cranial nerves are nerves originating from the brain stem and are essential for sensory and motor innervation of the face, head and neck regions. This includes a range of functions that may involve olfactory and visual stimuli, eye movement, and other sensory and motor functions.

Sensory Systems

• The sensory systems of the PNS carry signals to the CNS.
• These signals relay information regarding external or internal environments.
• Sensory systems can be classified as somatic or visceral, and further specialized by specific stimuli detected (e.g., general or special).

Motor Systems

• The motor systems of the PNS carry signals from the CNS.

This quiz covers fundamental concepts in neurology, exploring the major branches of study, the importance of functional anatomy, and the roles of different brain structures. Test your knowledge on the brain's organization and its implications for clinical practice.