Gross Brain Overview: Part II Basic Neuroscience James H. Baños, Ph.D.

Overview Organization Organization Morphology Morphology Developmental/Evolutionary Developmental/Evolutionary Cytoarchitectural Cytoarchitectural 3-D Orientation to Internal Structures 3-D Orientation to Internal Structures

How do we organize and characterize different parts of the brain? How do we organize and characterize different parts of the brain?

Morphology Morphology Developmental/Evolutionary Origins Developmental/Evolutionary Origins Cytoarchitecture Cytoarchitecture Function Function

Morphology: External Features

Frog Rat Cat Monkey Human What’s changing?

Sulci - The “valleys” on the surface of the brain Sulci - The “valleys” on the surface of the brain Gyri - The “Hills” Gyri - The “Hills”

The term “gyrus” is sometimes used broadly and doesn’t always refer to a single well-defined ridge on the surface of the brain. The distinctions between large gyri are sometimes better seen in coronal sections.

Hemispheres Longitudinal Fissure

Lobes Central (Rolandic) Sulcus Lateral (Sylvian) fissure Parieto-occipital fissure

Lobes Frontal Parietal Temporal Occipital Cingulate Gyrus “Limbic Lobe”

Brain Stem Thalamus Hypothalamus Midbrain Pons Medulla

Cerebellum: Superior Aspect Ant 2 Hemispheres Vermis

Cerebellum: Posterior Aspect Hemisphere Vermis Posterior Lobe Anterior Lobe Primary Fissure

Cerebellum: Mid-Saggital Anterior Vermis Posterior Vermis

Developmental and Evolutionary Origins: The “Cephalons”

Developmental Origins Areas of the Brain can be characterized by the embryonic origins of the tissue. Nervous system begins as a tube that differentiates into three vessicles: Prosencephalon Mesencephalon Rhombencephalon Three Vessicle Stage

Developmental Origins Prosencephalon differentiates: Telencephalon -- beginnings of hemispheres Diencephalon Rhombencehphalon differentiates Metencephalon Meyelencephalon We use this terminology to describe the parts of the brain that develop from these vessicles Five Vessicle Stage

Developmental Origins

Organization Telencephalon Telencephalon Cortex Cortex Basal Ganglia Basal Ganglia Limbic System Limbic System Hippocampus Hippocampus

Organization Diencephalon Diencephalon Thalamus Thalamus Hypothalamus Hypothalamus

Organization Mesencephalon Mesencephalon Midbrain Midbrain

Organization Metencephalon Metencephalon Cerebellum Cerebellum Pons Pons

Organization Myelencephalon Myelencephalon Medulla Medulla

Cytoarchitectural Organization

Brodmann’s Areas

Internal Structure

Major Internal Structures Ventricular System Ventricular System Amygdala (helpful landmark) Amygdala (helpful landmark) Thalamus/Hypothalamus/brain stem Thalamus/Hypothalamus/brain stem Basal Ganglia Basal Ganglia Caudate Nucleus Caudate Nucleus Putamen Putamen Globus Pallidus Globus Pallidus Hippocampal formation Hippocampal formation Hippocampus Hippocampus Fimbria Fimbria Fornix Fornix Major white matter landmarks Major white matter landmarks Corpus callosum Corpus callosum Internal capsule Internal capsule

Evolution and Development Frog Rat Cat Monkey Human

Evolution and Development Frog Rat Cat Monkey Human ?

Evolution and Development Ventricles Basal Ganglia Hippocampus

Evolution and Development Why not the thalamus?

The Ventricular System

Ventricles Lateral Ventricles Third Ventricle Fourth Ventricle

Ventricles Ventricles are connected (communicate) Ventricles are connected (communicate) Intraventricular Foramina (of Monroe) Intraventricular Foramina (of Monroe) Lateral Ventricles to Third Ventricle Lateral Ventricles to Third Ventricle Wide, oval hole Wide, oval hole Cerebral Aqueduct (of Sylvius) Cerebral Aqueduct (of Sylvius) Third Ventricle to Fourth Third Ventricle to Fourth Long, thin channel Long, thin channel Foramen of Magendie Foramen of Magendie Median aperture -- Fourth ventricle to subarachnoid space Median aperture -- Fourth ventricle to subarachnoid space Foramina of Luschka Foramina of Luschka Lateral apertures -- Fourth ventricle to subarachnoid space Lateral apertures -- Fourth ventricle to subarachnoid space

Ventricles Foramen of Monroe Aqueduct of Sylvius Foramina of Luschka Foramen of Magendie

Ventricles

Choroid Plexus and CSF Choroid Plexus Choroid Plexus Spongy tissue located in the ventricles Spongy tissue located in the ventricles Rich capillary bed Rich capillary bed Pia Mater Pia Mater Choroid endothelial cells Choroid endothelial cells Produces CSF Produces CSF About.35 ml per minute About.35 ml per minute Total volume ml Total volume ml

Choroid Plexus

CSF Flow Lateral ventricles Lateral ventricles Foramina of Monroe Foramina of Monroe 3rd ventricle 3rd ventricle Aqueduct of Sylvius Aqueduct of Sylvius 4th Ventricle 4th Ventricle Foramen of Magendie/foramina of Lushka Foramen of Magendie/foramina of Lushka Subarachnoid Space Subarachnoid Space Arachnoid granulations (absorption) Arachnoid granulations (absorption) Superior sagittal sinus Superior sagittal sinus

CSF Flow

CSF Absorption CSF flows to the dorsal surface of the brain, where arachnoid granulations form a one-way valve and let the excess CSF enter the veinous drainage of the superior sagittal sinus CSF flows to the dorsal surface of the brain, where arachnoid granulations form a one-way valve and let the excess CSF enter the veinous drainage of the superior sagittal sinus

CSF Absorption

Arachnoid Granulations

Ventricular System plus Amygdala

Ventricular System plus Thalamus

Ventricles, Brainstem, and Thalamus

Basal Ganglia -- Caudate Nucleus Basal Ganglia Basal Ganglia Caudate Nucleus Caudate Nucleus Putamen Putamen Globus Pallidus Globus Pallidus Sometimes Amygdala Sometimes Amygdala

Basal Ganglia -- Caudate Nucleus

Basal Ganglia -- Putamen & Globus Pallidus

Basal Ganglia

Hippocampus Hippocampal formation Hippocampal formation Fimbria Fimbria Fornix Fornix Anterior Commissure Anterior Commissure Amygdala Amygdala

Hippocampus

Hippocampus

Coming up… Circulation and Stroke Circulation and Stroke Development Development Spinal cord Spinal cord Basic Spinal Pathways Basic Spinal Pathways