Lecture Notes on Neuroanatomy

Introduction

• Apologies for being in scrubs; busy schedule with surgeries and lecture.
• Aim: Simplify neuroanatomy, focusing on brain anatomy.

Brain Development

• The brain develops from a simple tube into a complex organ.
• Features gyri, sulci, and complex folding patterns.

Brain Regions

• Cerebral Hemisphere: Largest portion, 83% of brain mass.
  • Covers diencephalon and midbrain, located above cerebellum.
  • Pattern of gyri and sulci characterizes different functional areas.

Lobes of the Brain

• Frontal Lobe: Separated from parietal lobe by central sulcus.
• Temporal Lobe: Separated from frontal by lateral or sylvian fissure.
• Occipital Lobe: Defined by preoccipital notch.
• Transverse Fissure: Divides supratentorial and infratentorial spaces.

Brain Views

• Lateral View: Shows frontal, parietal, occipital lobes, and central sulcus.
• Medial View: Frontal and parietal lobes separated by paracentral lobule.
• Ventral Surface: Characteristic temporal lobe gyri and sulci.

Historical Background

• Brodmann's Areas: Early subdivision of brain into 52 cortical areas based on cell types.
  • Important for understanding functional areas despite appearing random.

Functional Brain Anatomy

• Prefrontal Cortex: Complex behavior, cognitive processing, personality.
• Motor Areas: Includes primary motor cortex (Brodmann area 4), premotor areas.
• Sensory Areas: Primary somatosensory cortex with somatotopic organization.

Association Areas

• Prefrontal Cortex: Higher cognitive processing, executive functions.
• Premotor Area: Planning and selecting motor plans.
• Frontal Eye Field: Complex motor function for eye movement.
• Broca's Area: Speech area near motor function for mouth and hand.

Sensory Processing

• Primary Sensory Cortex: Somatotopic organization similar to motor cortex.
• Association Areas: Integrate inputs from various sensory modalities.

Visual Processing

• Primary Visual Cortex: Located in occipital lobe, along calcarine sulcus.
• Dorsal Stream: "Where" pathway for spatial location.
• Ventral Stream: "What" pathway for object recognition.

White Matter

• Commissures: Connect left and right hemispheres (e.g., corpus callosum).
• Association Fibers: Within one hemisphere.
• Projection Fibers: Input-output pathways of the brain.

Deep Brain Structures

• Basal Forebrain Nuclei: Important for acetylcholine transmission.
• Basal Ganglia: Involved in motor processing, affected in diseases like Parkinson's.

Thalamus and Hypothalamus

• Thalamus: Sensory relay station, modulated by deep brain stimulation.
• Hypothalamus: Autonomic functions, hormone control, emotional responses.

Brain Stem

• Divisions: Midbrain, pons, medulla.
• Functions: Automatic, reflexive behaviors, origins of cranial nerves.

Cerebellum

• Functions: Coordination of movement, sensory input processing.
• Structure: Folia and fissures, mediates axial and appendicular coordination.

Conclusion

• Neuroanatomy overview simplified yet complex, highlighting key structures and functions.