Gross Brain Anatomy

Understanding the physical structure of the brain is the prerequisite for all functional neuroscience. The human brain is a highly folded mass of tissue weighing approximately 1.3 to 1.4 kilograms, floating in cerebrospinal fluid within the skull.

The Cerebral Cortex

The outermost layer of the brain, the cortex, is highly convoluted to maximize surface area within the cranial vault. It is heavily populated by neuronal somas (gray matter). It is traditionally divided into four primary lobes:

Frontal Lobe: Executive function, motor control (primary motor cortex), and speech production (Broca's area). Read more on cognitive control.
Parietal Lobe: Somatosensory processing, spatial navigation, and proprioception.
Temporal Lobe: Auditory processing, memory formation (hippocampal integration), and language comprehension (Wernicke's area).
Occipital Lobe: Primary and secondary visual processing.

Subcortical Structures & The Limbic System

Deep to the cortex lies white matter (myelinated axons) and distinct gray matter nuclei that are crucial for survival, memory, and emotion.

Structure	Primary Function	Associated Neurotransmitter System
Hippocampus	Declarative memory consolidation, spatial memory	Glutamate, ACh
Amygdala	Emotional valence, fear conditioning	Glutamate, GABA, Serotonin
Basal Ganglia	Action selection, reward processing, motor habituation	Dopamine
Thalamus	Sensory relay station (except olfaction)	Various

The Brainstem and Cerebellum

The evolutionary oldest parts of the brain manage vital autonomic functions. The brainstem (midbrain, pons, medulla) regulates heart rate, respiration, and sleep/wake cycles (Circadian rhythms). The cerebellum, containing over half the brain's neurons despite its small size, is critical for motor coordination and precision.

Interactive Atlas Reference

While we provide textual explanations, spatial understanding requires 3D visualization. We recommend referencing the Allen Brain Atlas for detailed stereotaxic coordinates.

Common Mistakes in Anatomical Studies

Assuming strict localization: While regions specialize (e.g., visual cortex), complex behaviors require distributed network activation. Plasticity can shift these functions, especially after injury.
Ignoring white matter: The connectivity (fasciculi) between regions is just as vital as the regions themselves. DTI (Diffusion Tensor Imaging) is the primary method used to study these tracts.

Internal Links for Further Reading

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