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Cerebrum (Cerebral Hemispheres)

Notes

Cerebrum (Cerebral Hemispheres)

Sections




Summary

Key Terms

  • Cerebral cortex
    • Relatively thin shell of neuronal tissue
    • Outer, cellular gray matter of the brain
  • Subcortical white matter
    • Inner to the cerebral cortex
    • Forms a dense core of connection fibers (thicker than the cerebral cortex)
    • Comprises underlying axons
  • Cerebrospinal fluid
    • Center of cerebrum
    • Forms pockets of fluid deep in the brain
    • Assists the meninges in nourishing and supporting the nervous system with essential nutrients and metabolites.
  • Brainstem
    • Basic seat of life
    • Contains cranial nerve nuclei and other essential neuronal populations and fiber tracts
    • Controls and carries the most primitive, most vital of our functions
  • Cerebellum
    • Fundamental for balance and motor coordination

Cerebral Lobes

See: Cerebral Lobes

  • Frontal (superior/anterior)
    • Comprises a large portion of the brain
    • Responsible for cognitive functions, such as language production and organizational skills, motor planning and initiation, and volitional eye movements
  • Parietal (superior/posterior)
    • Responsible for sensory processing and spatial orientation
  • Temporal (inferior)
    • Responsible for language comprehension and visual identification
    • Stores visual, auditory, olfactory, and other forms of information
  • Occipital (posterior)
    • Primarily known for visual reception and processing
  • Limbic (medial)
    • Known for its role in memory, which localizes posteriorly, and emotional processing, which localizes anteriorly
  • Corpus callosum
    • Major white matter pathway
  • Hippocampus
    • Major memory-processing center
  • Amygdala
    • Seat of emotional and behavioral processing
  • Fissures and Sulci:
    • Fissures: alter the contour of the cerebral ventricles (Sylvian fissure)
    • Sulci: indent the outer surface of the brain (central sulcus): extends from the apex of the brain to the Sylvian fissure

Cortical Gyri

Delineated segments of cerebrum

  • Precentral gyrus
    • Primary motor cortex which lies anterior to the [central sulcus: initiates movement

Clinical Correlation: Stroke: Precentral Gyrus

Cerebral Cortical Histology

Clinical Challenge Question

With the overview information you've learned in this tutorial, you should be able to answer this clinical challenge question. Note that the answer explanation does provide additional information on the topic, beyond the scope of this tutorial but that information isn't necessary to answer the question, itself.

Full Text

Overview

Here, we will learn about the cerebrum.

  • Start a table. Denote the following:

Cerebrum

  • The cerebrum comprises the bilateral cerebral hemispheres. It sits above the brainstem and cerebellum.
    • The brain constitutes the cerebrum, brainstem, and cerebellum.
  • Now, draw a coronal section through the brain, so we can study the cerebral cortex and subcortical white matter.

Cerebral Cortex

  • Draw an inner layer and label the space between the layers as the cerebral cortex, which is a relatively thin shell of neuronal tissue.
    • Denote that the cerebral cortex is the outer, cellular gray matter of the brain.

Subcortical White Matter

  • Now, draw the subcortical white matter inner to the cerebral cortex, which forms a dense core of connection fibers – much thicker than the cerebral cortex.
    • Denote that it comprises the underlying axons.

CSF

  • Next, draw the cerebrospinal fluid system within the center of the cerebrum; this system forms pockets of fluid deep in the brain.
    • Denote that the cerebrospinal fluid assists the meninges in nourishing and supporting the nervous system with essential nutrients and metabolites.

Brainstem

  • Next, draw the brainstem, below the brain; it's the basic seat of life.
  • Denote that the brainstem contains cranial nerve nuclei and other essential neuronal populations and fiber tracts, as such it controls and carries the most primitive, most vital of our functions.

Cerebellum

  • Now, on the posterior aspect of the brainstem, draw the leafy hemispheres of the cerebellum, which pack the cerebellum into a small nook within the posterior skull base (the posterior fossa).
    • Denote that the cerebellum is fundamental for balance and motor coordination; it's a learning organ, which presumably relates to the adaptive ability of our balance center.

Cerebrum: Lateral View

Lateral Aspect of the Cerebrum

  • Now, draw a lateral view of the cerebrum.
    • Denote that we'll learn the cerebral lobes, which constitute the bulk of brain matter.
  • Show them as follows:
  • Superior/anterior is the frontal lobe; it comprises a large portion of the brain.
    • Denote that it's responsible for cognitive functions, such as language production and organizational skills; motor planning and initiation, and volitional eye movements; thus, the frontal lobe both generates and governs many discrete and important higher level actions.
  • Superior/posterior is the parietal lobe.
    • Denote that it's responsible for sensory processing and spatial orientation; it guides us through our environment.
  • Inferior is the temporal lobe.
    • Denote that it's responsible for language comprehension and visual identification; it stores visual, auditory, olfactory, and other forms of information.
  • Posterior is the occipital lobe.
    • Denote that it's primarily known for visual reception and processing; even a large occipital stroke will mostly only manifest with vision loss because of this area's dedication to vision.

Cerebrum: Medial View

Medial Aspect of the Cerebrum

  • Next, draw the medial aspect the cerebrum, so we can inspect regions that are hidden in lateral view.
  • As reference points, draw the corpus callosum, a major white matter connection pathway.
  • And the cingulate sulcus above it.
  • Shade the lobes of the brain as follows:
    • Superior/anterior is the frontal lobe.
    • Superior/posterior is the parietal lobe.
    • Inferior is the temporal lobe.
    • And posterior is the occipital lobe.
    • Central is the limbic lobe. Denote that it is best known for its role in memory, which localizes posteriorly, and emotional processing, which localizes anteriorly.

Fissures & Sulci

Fissures & Sulci

Next, let's address fissures and sulci.

  • Denote that invaginations exist along the brain as deep fissures, which alter the contour of the cerebral ventricles and shallow sulci, which merely indent the outer surface of the brain.

In the lateral hemisphere diagram, label two key invaginations:

  • The Sylvian fissure (aka the lateral sulcus).
  • The central sulcus, which extends from the apex of the brain to the Sylvian fissure.

Key Gyri

Definition

Next, denote that cortical gyri are delineated segments of cerebrum; they anatomically defined areas with discrete functions.

Precentral Gyrus

  • Show that the precentral gyrus, which is the primary motor cortex (aka area), lies anterior to the central sulcus (within the frontal lobe); it initiates movement.

Postcentral Gyrus

  • Then, show that the postcentral gyrus, which is the primary sensory cortex (aka area), lies posterior to the central sulcus (within the parietal lobe); it is the initial cortical reception site for sensation.