What are the major regions and structures of the brain and their functions?

Anatomy of the Brain

The brain is organized into distinct structural and functional regions that work together to control vital functions, sensory processing, motor control, cognition, and consciousness.

Major Brain Regions and Their Functions

Cerebrum

The cerebrum is the largest and most complex brain structure, responsible for higher-order cognitive functions, sensory processing, and voluntary motor control. 1

• The cerebral cortex contains specialized functional areas including the frontal, temporal, parietal, and occipital lobes, each serving distinct roles in cognition, sensation, and motor function 2
• The dorsolateral prefrontal cortex (DLPFC) manages executive functions including working memory, planning, and cognitive flexibility 2
• The medial prefrontal cortex is involved in cognitive control and self-referential processing 2
• The anterior cingulate cortex participates in salience detection, emotional processing, and pain perception 2
• The posterior cingulate cortex and precuneus are involved in self-referential processing and default mode network activity 2
• The primary and secondary somatosensory cortices process tactile and proprioceptive information 2
• The insular cortex (insula) integrates sensory information with emotional and autonomic responses, playing a key role in interoception and pain processing 2

Subcortical Structures

• The thalamus serves as a critical relay station for sensory information ascending to the cortex and is essential for conscious pain perception through thalamocortical connections 2, 3
• The striatum (including caudate nucleus and putamen) receives glutamatergic and dopaminergic inputs and participates in cognitive and reward systems, as well as habitual responding 2
• The amygdala processes emotional stimuli and fear responses, with connections to autonomic control systems 2, 4
• The hippocampus is critical for memory formation and spatial navigation, demonstrating strong theta-band neural oscillations that encode spatial information 2, 4
• The hypothalamus regulates autonomic function and homeostasis 2, 4

Brainstem

The brainstem connects the cerebral hemispheres with the spinal cord and cerebellum, controlling basic vital functions including breathing, heartbeat, blood pressure, consciousness, and sleep. 5

• The brainstem consists of four parts: diencephalon, mesencephalon (midbrain), pons, and medulla oblongata 5
• It is organized in three laminae: the tectum (containing the quadrigeminal plate), tegmentum (containing cranial nerve nuclei and ascending sensory tracts), and basis (containing descending motor pathways) 5
• The brainstem contains critical structures including the periaqueductal grey and rostroventral medulla, which modulate pain processing 2
• Cranial nerve nuclei are arranged systematically from medial to lateral based on function: somatic motor, visceral motor, visceral sensory, and somatic sensory 5
• The brainstem houses the reticular formation, which regulates arousal and consciousness 5
• Brainstem serotonergic systems play crucial roles in coordinating respiratory, arousal, and autonomic functions 2

Cerebellum

The cerebellum resides in the posterior cranial fossa dorsal to the brainstem and is critically involved in motor control, motor learning, and increasingly recognized nonmotor cognitive and affective functions. 6

• The cerebellum consists of two lateral hemispheres connected by the vermis 7
• It has diverse connections to the cerebrum, brainstem, and spinal cord, with output projections to motor nuclei, cerebral cortex, and basal ganglia 8
• The cerebellar cortex is divided into distinct functional compartments with highly regular neuronal arrays sharing the same basic microcircuitry 6
• The cerebellum receives blood supply from three main arteries: the superior cerebellar artery (SCA), anterior inferior cerebellar artery (AICA), and posterior inferior cerebellar artery (PICA) 7

Functional Brain Networks

• The brain operates through intrinsic networks including the default mode network, salience network, and somatosensory network, which subserve homeostatic, attentional, cognitive, emotional, executive, and sensory functions 2
• Thalamocortical connections and intact cortical structures are essential for conscious perception and subjective experience 3
• The limbic system (including limbic cortex, hypothalamus, amygdala, and hippocampus) has reciprocal connections with the brainstem and regulates autonomic function, particularly in response to emotional stimuli 2

Clinical Relevance

• The blood-brain barrier regulates substance movement between bloodstream and neural tissue, protecting the central nervous system 4
• Understanding precise anatomical localization is crucial for neurological diagnosis, particularly when interpreting advanced neuroimaging 5
• Different brain regions show specific vulnerability to various pathological processes, with regional patterns varying by disease stage and symptom characteristics 2