Introduction to Neuroanatomy

Introduction to Neuroanatomy

• The nervous system is a complex network of cells and tissues controlling bodily functions.
• Aristotle (335 BC) incorrectly believed the heart held mental processes, while the brain regulated heat dissipation.
• Learning objectives for neuroanatomy lectures include describing nervous system organization, identifying components of the central nervous system (CNS) and peripheral nervous system (PNS), understanding CNS regional functions, understanding how structure dictates function, and developing basic drawing and labeling skills for nervous system portions.

Lecture Objectives

• Students will develop a comprehensive understanding of the organization of the nervous system.
• Students will identify and differentiate the critical roles of the central nervous system (CNS) including brain and spinal cord and the peripheral nervous system (PNS).
• The CNS regions and their associated functions are important for comprehension in the course
• The anatomy and localization of brain regions impacts its function.
• Students will learn the essentials for drawing and labeling various components of the nervous system.

Terms & Directions

• Anatomical directional terms aid in precise descriptions of location in the body, such as ipsilateral, contralateral, bilateral, proximal, distal, superior, inferior, medial, lateral and planes.

Terminology

• Included terminology includes elements like CNS (central nervous system), PNS (peripheral nervous system), white matter, gray matter, tracts, nuclei, ganglia, ventricle, and specific structures like the olive, pyramids (both terms related to the brain), geniculate, putamen, subdural, epidural, cavernous sinus, ophthalmic, arachnoid, choroid plexus & dura sinus.

• Other terms pertain to regions/structures of the brain - Teleencephalon, Diencephalon, Midbrain, Mesencephalon, Dorsal columns, Subcortical white matter, Basal ganglia, Hypothalamus, Epithalamus

• Terms include Ipsilateral/Contralateral/Bilateral, Proximal/Distal, Superior/Inferior, Medial/Lateral, and horizontal, coronal (frontal), and sagittal planes.

Directional Terms

• Directional terms above the midbrain: Anterior = Rostral, Posterior = Caudal, Superior = Dorsal, Inferior = Ventral.
• Directional terms below the midbrain: Anterior = Ventral, Posterior = Dorsal, Superior = Rostral, Inferior = Caudal.

Development to Adult Brain Structures

• Covers the intricate developmental progression from initial structures (prosencephalon, mesencephalon, rhombencephalon), to the formations of the telencephalon, diencephalon, mesencephalon, metencephalon, and myelencephalon.
• Explicates the origins of different components from these embryonic phases to the formation of the adult brain: telencephalon, midbrain, pons, and medulla
• Identifies the spinal cord as a major developmental component

Nervous System

• The nervous system is structured and functional.
• Separate components include central (CNS), peripheral (PNS), autonomic (involuntary), and somatic (voluntary) divisions and subsystems.

Functional Divisions/Directions

• The afferent division carries sensory information from the peripheral nervous system (PNS) to the central nervous system (CNS).
• The efferent division transmits motor commands from the CNS to the PNS, targeting muscles and glands.

Spinal Cord and Peripheral Nerves

• Diagram of spinal cord and peripheral nerves.

Parts and Pieces

• A generic title

Brain

• A structural element of the nervous system.

Cerebral Cortex

• Composed of frontal, parietal, temporal, and occipital lobes.
• Sulci are crevices/grooves, fissures are deep sulci, and gyri are bumps/rises in the brain.

Six Major Regions of the Brain

• The brain is divided into six major regions including Cerebrum, Cerebellum, Diencephalon, Mesencephalon (midbrain), Pons, and Medulla oblongata.

Primary Sensory and Motor Areas

• Primary motor cortex is located in the precentral gyrus, controlling contralateral body movement.
• Primary sensory cortex, in the postcentral gyrus, receives contralateral sensory information.
• Visual, occipital, auditory, and temporal cortical regions are specified, with functions mapping along or near significant cerebral structures like calcarine and Sylvian fissures.
• Cortical homunculus - a topological ("map") representation of the body's areas on the primary somatosensory and motor cortex.

Topographical Organization

• Cortical homunculus - a useful tool to represent the body's anatomical divisions on the brain.

Why do the features look weird??

• The body regions in the cortical homunculus (a representation of the body on the brain) are in proportion to the surface area of the cortex dedicated to their function, which explains the disproportionate size of different body parts. Larger body parts have a larger brain function allocation.

Topographical Organization

• Body regions within the brain's cortex are proportionally mapped with hands and faces receiving more brain mass.

Map of our brain

• Shows a simplified map of the brain with sensory and motor regions.

Association Cortex

• Unimodal and heteromodal association cortices are components of the brain.
• These provide a function analysis. Associated with specific modalities or multiple modalities. Key functions are integration and processing.
• Mental status exam can be used to test these areas.

Limbic System

• The limbic system is a complex set of interconnected brain structures including the orbital frontal gyri, temporal pole, parahippocampal gyrus, hippocampus, amygdala, and uncus.
• Critical to various functions including memory, emotions, and motivation.
• The term describes a complex structure.

Brainstem

• The brainstem comprises several key structures: midbrain, pons, and medulla oblongata responsible for critical functions.

Brainstem and Cranial Nerves

• Illustrates relationships among brainstem components, their anatomical landmarks, and cranial nerves.

Spinal Cord

• Important for conveying info, and its components (gray and white matter, dorsal and ventral horns, neuronal pathways are detailed).

Typical Cross-Section of the Spinal Cord

• The composition of the spinal cord (with gray and white matter, different sections of the cord, and spinal nerve connections) is depicted.

Peripheral Nervous System

• Organization and structure of the peripheral nervous system are presented.

Gray Matter and White Matter

• Describes the sectional anatomy of the spinal cord's components: gray and white matter and their organization. It also defines how projections arise in the gray matter.