NG

Neuroanatomy Lecture Notes

Objectives of Neuroanatomy

  • Objective 1: Explain the difference between white and gray matter.

  • Objective 2: List the names for a bundle of myelinated axons that travel together in the central nervous system (CNS).

  • Objective 3: List the functions of the peripheral nervous system, the spinal region, the brainstem, and cerebellum.

  • Objective 4: Describe the location and function of the structures that comprise the diencephalon.

  • Objective 5: Identify the lobes of the cerebral hemisphere and the sulci that form clear boundaries between lobes.

  • Objective 6: Identify the white matter and gray matter structures in the cerebral hemispheres.

  • Objective 7: Identify the ventricles and the layers of the meninges.

  • Objective 8: Describe the blood supply of the brain.

Introduction to Neuroanatomy

  • Three Anatomical Planes: Imaginary lines through the nervous system.

    • Sagittal Plane: Divides a structure into right and left portions.

    • Midsagittal Plane: Evenly divides a structure into right and left portions, being equal.

    • Horizontal Plane (Transverse Plane): Divides a structure into upper and lower portions.

    • Coronal Plane (Frontal Plane): Divides a structure into anterior (front) and posterior (back) portions.

Directional Terminology

  • Anterior or Ventral: Relates to the front or belly side of the body.

  • Posterior or Dorsal: Relates to the back side of the body.

  • Superior: Refers to structures that are above or higher than others.

  • Inferior: Refers to structures that are below or lower than others.

  • Medial: Closer to the midline of the body.

  • Lateral: Farther away from the midline of the body.

  • Rostral: Closer to the head.

  • Caudal: Closer to the tail or the end of the body.

Divisions of the Nervous System

  • Central Nervous System (CNS): Includes the brain and spinal cord.

  • Peripheral Nervous System (PNS): Includes the somatic nervous system and autonomic nervous system.

    • Somatic Nervous System: Involves sensory axons, motor axons, sensory endings, and glial cells.

    • Autonomic Nervous System: Composed of entire neurons, sensory endings, synapses, ganglia, and glial cells.

Cellular-Level Neuroanatomy

  • Gray Matter Areas of the CNS:

    • Composed of cell bodies and dendrites.

    • Main function involves the integration of information.

  • White Matter:

    • Composed of axons and myelin.

    • Major function is to convey information.

  • Bundle of Myelinated Axons: Named based on context (e.g., tract, lemniscus, fasciculus, column, peduncle, capsule).

Peripheral Nervous System

  • Afferent Axons: Carry information toward the CNS.

  • Efferent Axons: Carry information away from the CNS.

Cranial Nerves

  • Total: Twelve pairs of cranial nerves emerge from or enter the brain.

  • Classification: Numbered according to the site of attachment to the brain (anterior to posterior):

    • Sensory Nerves:

    • Olfactory (I), Optic (II), Vestibulocochlear (VIII)

    • Motor Nerves:

    • Oculomotor (III), Trochlear (IV), Abducens (VI), Accessory (XI), Hypoglossal (XII)

    • Mixed Nerves (both sensory and motor):

    • Trigeminal (V), Facial (VII), Glossopharyngeal (IX), Vagus (X)

Central Nervous System: Structure Overview

  • Three Major Regions:

    • Spinal Region

    • Brainstem and Cerebellar Region

    • Cerebrum

Spinal Region

  • Cross-section of the Spinal Cord:

    • Gray matter forms an "H" shape, surrounded by white matter.

    • Gray Matter Components:

    • Interneurons

    • Endings of sensory neurons

    • Cell bodies of neurons

    • White Matter Components:

    • Composed of axons and myelin.

  • Two Main Functions of the Spinal Region:

    1. Convey information between peripheral structures and the brain.

    2. Process information locally.

Brainstem and Cerebellum

  • Cerebellum:

    • Composed of two large cerebellar hemispheres and a midline vermis.

    • Connects to the posterior brainstem via large bundles of fibers known as peduncles.

    • Primary function is coordinating movements.

Cerebrum and Diencephalon

  • Diencephalon Structures:

    1. Thalamus

    2. Hypothalamus (inferior to the thalamus)

    3. Epithalamus (posterosuperior to the thalamus)

    4. Subthalamus (inferolateral to the thalamus)

  • Cerebral Hemispheres:- divided by the longitudinal fissure.

    • The surfaces of the cerebral hemispheres are marked by:

    • Gyri: Rounded elevations.

    • Sulci: Grooves.

Cerebral Structures

  • Cerebral Cortex:

    • The outer surface of the hemispheres where sensory, motor and memory information is processed.

    • Site for reasoning, language, nonverbal communication, intelligence, and personality.

  • White Matter Beneath the Cortex:

    • Contains axons connecting the cerebral cortex with other CNS regions.

    • Notable bundles include:

    • Corpus Callosum: Connects left and right cerebral hemispheres.

    • Internal Capsule: Major pathway for information passing to and from the cortex.

  • Lobes of Cerebral Hemispheres: Six lobes exist in each hemisphere:

    1. Frontal

    2. Parietal

    3. Temporal

    4. Occipital

    5. Limbic

    6. Insular

Insula and Areas of Gray Matter

  • Basal Ganglia:

    • Involves components like caudate, putamen, and globus pallidus.

    • Functions include control over movement, social behavior, and emotions.

  • Additional Gray Matter Areas:

    • Amygdala: Involved in emotions and motivation.

    • Hippocampus: Processes memory for facts.

Cerebrospinal Fluid System

  • Cerebrospinal Fluid (CSF):

    • Circulates from brain cavities to the surface of the CNS and is reabsorbed into the venous blood system.

  • Meninges:

    • Three protective membranes covering the CNS structures:

    • Dura Mater (outer layer)

    • Arachnoid Mater (middle layer)

    • Pia Mater (inner layer)

Blood Supply

  • Brain Blood Supply:

    • Two main arterial sources:

    • Internal Carotid Arteries

    • Vertebral Arteries

  • Circle of Willis: A critical arterial structure providing collateral circulation to the brain.

References

  • Cleveland Clinic (2022a). Cerebellum. Retrieved from https://my.clevelandclinic.org/health/body/23418-cerebellum

  • Cleveland Clinic (2022b). Meninges. Retrieved from https://my.clevelandclinic.org/health/articles/22266-meninges

  • Gutman, S.A. (2017). Quick reference neuroscience for rehabilitation professionals: The essential neurologic principles underlying rehabilitation practice (3rd ed.). Slack Inc.

  • Lundy-Ekman, L. (2023). Neuroscience: Fundamentals for rehabilitation (6th ed.). Elsevier.

  • Michigan State University (2021). Anatomical Terminology: Foundations of Neuroscience. Retrieved from https://openbooks.lib.msu.edu/neuroscience/chapter/anatomical-terminology/