Brain Internal Structure Quiz

Internal Structure of the Brain

• Cross-section reveals gray and white matter.
• Gray matter consists of cell bodies, primarily located in the cortex and in structures known as nuclei or ganglia.
• White matter contains myelinated fibers and is located beneath the cortex.

Key Structures in Gray Matter

• Caudate nucleus
• Lentiform nucleus
• Thalamus
• Internal capsule runs between gray matter structures.

Overview of White Matter

• Underlies the cerebral cortex.
• Composed of nerve fibers that are predominantly myelinated, neuroglia, and blood vessels.
• Nerve fibers can originate or terminate within the cortex.

Classification of Nerve Fibers

• Association fibers: Connect different parts of the same hemisphere.
• Projection fibers: Extend between the cortex and subcortical regions.
• Commissural fibers: Connect corresponding regions of both hemispheres.

Association Fibers

• Short association fibers connect adjacent gyri and lie just beneath the gray cortex.
• Long association fibers connect distant gyri throughout the white matter.

Specific Long Association Fibers

• Superior longitudinal fasciculus: Links frontal, parietal, temporal, and occipital lobes.
• Uncinate fasciculus: Connects frontal lobe to the temporal lobe, involved in behavioral regulation.
• Cingulum: Connects frontal and parietal lobes to the temporal gyrus and para-hippocampal gyrus.
• Inferior longitudinal fasciculus: Connects occipital lobe to the temporal pole, aiding in visual recognition.

Language Centers

• Broca's area: Located in the left frontal cortex, controls language production.
• Wernicke's area: Found in the posterior temporal lobe, analyzes and orders words for speech.

Commissural Fibers

• Corpus Callosum: Main commissural fiber connecting the two cerebral hemispheres; located in the median longitudinal fissure.
• Anterior commissure: Connects olfactory bulbs and interconnects frontal and parietal lobes.
• Hippocampal commissure: Connects the left and right hippocampus.
• Posterior commissure: Links visual relay nuclei in the midbrain.

Normal Function and Clinical Significance

• Internal capsule: Pathway for cortico-spinal, cortico-bulbar, and thalamocortical projections.
• Damage to specific brain areas can lead to:
  • Object agnosia and prosopagnosia with lesions in the inferior longitudinal fasciculus.
  • Split-brain syndrome from corpus callosum damage, where each hemisphere can function independently.
  • Posterior disconnection syndrome from splenium damage, resulting in inability to comprehend written language while being able to speak and write normally.

Quiz Questions

• Types of fibers in the corpus callosum are commissural fibers.
• Fibers connecting different gyri in the same hemisphere are classified as association fibers.
• Fibers connecting the cortex with subcortical areas are projection fibers.
• The internal capsule contains projection fibers.
• Cortico-spinal fibers are found in the posterior limb of the internal capsule.
• Hippocampal commissure connects the hippocampi of both hemispheres.

This quiz explores the internal structure of the brain, focusing on the distinction between gray and white matter. It covers the locations and functions of key nuclei, including the caudate nucleus and thalamus. Test your knowledge of brain anatomy and its components.