Dr Chi
Member
- Dec 20, 2016
- 15
- 16
The brain is a complex organ responsible for cognition, movement, sensation, and autonomic functions. It is divided into major regions, each with distinct roles and clinical significance.
1. Major Divisions of the Brain
A. Cerebrum (Higher Functions)
• Largest part, divided into two hemispheres connected by the corpus callosum
• Controls voluntary movement, sensory processing, language, and memory
Lobes of the Cerebrum
1. Frontal Lobe → Motor control, decision-making, speech (Broca’s area)
• Lesions: Paralysis, personality changes, Broca’s aphasia
2. Parietal Lobe → Sensory processing, spatial awareness
• Lesions: Sensory loss, neglect syndrome
3. Temporal Lobe → Hearing, memory, language (Wernicke’s area)
• Lesions: Wernicke’s aphasia, memory loss
4. Occipital Lobe → Vision
• Lesions: Visual field defects (hemianopia)
B. Diencephalon (Core of the Brain)
1. Thalamus → Sensory relay center (except smell)
• Lesions: Sensory loss, thalamic pain syndrome
2. Hypothalamus → Controls hormones, hunger, temperature, sleep
• Lesions: Hormonal imbalances, diabetes insipidus
C. Brainstem (Vital Functions)
• Midbrain → Eye movements, reflexes (Lesions: Parkinson’s disease)
• Pons → Respiratory control, cranial nerve relay (Lesions: Locked-in syndrome)
• Medulla → Controls heart rate, respiration (Lesions: Fatal brainstem strokes)
D. Cerebellum (Coordination & Balance)
• Controls fine motor movements and posture
• Lesions: Ataxia (unsteady gait), intention tremors
2. Ventricular System & CSF Circulation
• Four ventricles produce cerebrospinal fluid (CSF)
• Clinical Relevance: Obstruction causes hydrocephalus, leading to increased intracranial pressure (ICP)
3. Blood Supply of the Brain
A. Circle of Willis
• Major arteries: ACA, MCA, PCA
• Stroke syndromes:
1. ACA Stroke → Leg weakness, personality changes
2. MCA Stroke → Face/arm weakness, aphasia, neglect
3. PCA Stroke → Visual defects (homonymous hemianopia)
4. Basilar Artery Stroke → Brainstem dysfunction, locked-in syndrome
4. Common Brain Disorders
1. Traumatic Brain Injury (TBI) → Concussions, hemorrhages
2. Stroke (Ischemic/Hemorrhagic) → Sudden neurological deficits
3. Brain Tumors → Symptoms vary by location
4. Neurodegenerative Diseases → Alzheimer’s (hippocampus), Parkinson’s (midbrain)
5. Hydrocephalus → CSF accumulation, increased ICP
1. Major Divisions of the Brain
A. Cerebrum (Higher Functions)
• Largest part, divided into two hemispheres connected by the corpus callosum
• Controls voluntary movement, sensory processing, language, and memory
Lobes of the Cerebrum
1. Frontal Lobe → Motor control, decision-making, speech (Broca’s area)
• Lesions: Paralysis, personality changes, Broca’s aphasia
2. Parietal Lobe → Sensory processing, spatial awareness
• Lesions: Sensory loss, neglect syndrome
3. Temporal Lobe → Hearing, memory, language (Wernicke’s area)
• Lesions: Wernicke’s aphasia, memory loss
4. Occipital Lobe → Vision
• Lesions: Visual field defects (hemianopia)
B. Diencephalon (Core of the Brain)
1. Thalamus → Sensory relay center (except smell)
• Lesions: Sensory loss, thalamic pain syndrome
2. Hypothalamus → Controls hormones, hunger, temperature, sleep
• Lesions: Hormonal imbalances, diabetes insipidus
C. Brainstem (Vital Functions)
• Midbrain → Eye movements, reflexes (Lesions: Parkinson’s disease)
• Pons → Respiratory control, cranial nerve relay (Lesions: Locked-in syndrome)
• Medulla → Controls heart rate, respiration (Lesions: Fatal brainstem strokes)
D. Cerebellum (Coordination & Balance)
• Controls fine motor movements and posture
• Lesions: Ataxia (unsteady gait), intention tremors
2. Ventricular System & CSF Circulation
• Four ventricles produce cerebrospinal fluid (CSF)
• Clinical Relevance: Obstruction causes hydrocephalus, leading to increased intracranial pressure (ICP)
3. Blood Supply of the Brain
A. Circle of Willis
• Major arteries: ACA, MCA, PCA
• Stroke syndromes:
1. ACA Stroke → Leg weakness, personality changes
2. MCA Stroke → Face/arm weakness, aphasia, neglect
3. PCA Stroke → Visual defects (homonymous hemianopia)
4. Basilar Artery Stroke → Brainstem dysfunction, locked-in syndrome
4. Common Brain Disorders
1. Traumatic Brain Injury (TBI) → Concussions, hemorrhages
2. Stroke (Ischemic/Hemorrhagic) → Sudden neurological deficits
3. Brain Tumors → Symptoms vary by location
4. Neurodegenerative Diseases → Alzheimer’s (hippocampus), Parkinson’s (midbrain)
5. Hydrocephalus → CSF accumulation, increased ICP