Brain Anatomy PDF

Brain:  Structure: The brain is the most important part of the nervous system, responsible for collecting, processing, and transmitting information. It consists of gray matter (neuronal cell bodies) and white matter (neuron projections). "The brain is the most important part of the n...

Brain:  Structure: The brain is the most important part of the nervous system, responsible for collecting, processing, and transmitting information. It consists of gray matter (neuronal cell bodies) and white matter (neuron projections). "The brain is the most important part of the nervous system because it collects and processes information from the external environment and the body's interior."  Weight and Energy Consumption: In humans, the brain weighs an average of 1.4 kg and consumes about 20% of the oxygen taken in by the body, indicating its crucial role in bodily function. "In humans, the brain weighs an average of 1.4 kg; however, despite its small mass, it consumes as much as 20% of the oxygen taken in by the body at rest, making it extremely sensitive to oxygen deprivation."  Division: The brain is divided into the cerebrum (the largest part), diencephalon, midbrain, hindbrain (cerebellum and pons), and medulla oblongata. Each of these parts performs specific functions.  Cerebral Cortex: It is the brain's outermost layer, consisting of two hemispheres connected by the corpus callosum. "The brain consists of gray matter, white matter, and the cerebral cortex." The cortex features numerous grooves and ridges.  Functions of the Cerebral Cortex: Di erent areas of the cortex are responsible for various functions, including sensory, motor, visual, auditory, muscle control, behavior, speech, planning, and thinking. "Functionally, the cerebral cortex is divided into the motor, sensory, visual, and auditory cortex (parietal lobe) – it contains centers controlling skeletal muscle activity. The sensory cortex (occipital lobe) receives sensations of vision, heat, and pain." Cerebellum:  Structure: Located behind the brainstem, the cerebellum consists of gray matter and white matter.  Functions: It is responsible for movement coordination, body posture, muscle tone, and balance. "The cerebellum is part of the hindbrain that maintains muscle tone and coordinates movements."  Disorders: Damage to the cerebellum results in di iculties maintaining balance, coordinating movements, and performing fluid movements. "Coordination disorders – movements become clumsy and imprecise, such  as missing the target with a fingertip (e.g., touching the tip of the nose with a finger) and inability to perform fast, precise movements like turning the hand over repeatedly." Spinal Cord:  Structure: The spinal cord is an elongated part of the central nervous system running through the spinal canal. It is made of gray matter centrally and white matter externally. "The spinal cord runs in the spinal canal, formed by the openings in the vertebrae of the spine."  Functions: It transmits nerve impulses between the brain and the body and controls reflexes. "The spinal cord transmits impulses from the brain to executive organs and back, and it participates in reflex actions." Cerebrospinal Fluid:  Protective Function: It fills the brain's ventricles and the spinal cord canal, protecting the nervous system structures from damage. "Cerebrospinal fluid performs the following functions: it protects the nervous system, ensures even pressure distribution in the cranial cavity, nourishes neurons, and removes unnecessary products of their metabolism."  Composition: It contains glucose, potassium and sodium ions, lymphocytes, and monocytes. "It contains small amounts of protein, high levels of sodium and chloride ions, and trace amounts of cells: lymphocytes and monocytes. The human body produces approximately 700 cm³ of it per day."  Blood-Brain Barrier: Protects the brain from substances that could disrupt its function. It prevents many substances, including drugs, from passing through. "The fluid is protected from the penetration of substances from the blood that could disrupt neuronal functions by the blood-brain barrier. This barrier is formed by the impermeable walls of the brain’s capillaries and the surrounding glial cells (astrocytes). It blocks many large-molecule substances, including drugs." Peripheral Nerves:  Division: Peripheral nerves are divided into cranial nerves and spinal nerves. "Nerves transmit information between the central nervous system and all other parts of the body."  Number of Nerves: There are 12 pairs of cranial nerves and 31 pairs of spinal nerves. "Among spinal nerves, there are 8 pairs of cervical nerves, 12 pairs of thoracic nerves, 5 pairs of lumbar nerves, 5 pairs of sacral nerves, and one pair of coccygeal nerves." Limbic System:  Functions: It is responsible for emotions, drives, instincts, motivation, and emotional memory. "The limbic system includes evolutionarily older areas of the cerebral cortex (archicortex) and subcortical structures. This system is responsible for emotions and drives, learning, and emotions. Emotions are feelings associated with moods (e.g., fear, sadness, anger) or positive states (e.g., joy, satisfaction)." Structure of the Limbic System The limbic system comprises several interconnected brain structures. Key components include: 1. Amygdala: o Function: Regulates emotions such as fear, anger, and pleasure. It is critical for emotional memory and processing threats. 2. Hippocampus: o Function: Essential for learning and forming new memories, particularly transferring short-term memory to long-term storage. 3. Hypothalamus: o Function: Maintains homeostasis by regulating autonomic processes like hunger, thirst, body temperature, and hormonal release through the pituitary gland. 4. Thalamus: o Function: Acts as a relay center, transmitting sensory information to the appropriate areas of the brain for further processing. 5. Cingulate Gyrus: o Function: Plays a role in emotional regulation, attention, and linking behavioral outcomes to motivation. 6. Mammillary Bodies:  o Function: Involved in memory processing and recollective memory. 7. Septal Nuclei: o Function: Associated with reward and reinforcement pathways, as well as emotional responses. Functions of the Limbic System The limbic system's primary functions are: 1. Emotion Regulation: o Responsible for producing and interpreting emotions like fear, anger, and happiness. 2. Memory Formation: o Particularly involved in the formation and retrieval of declarative memories (facts and events). 3. Motivation and Reward: o Plays a central role in motivating behaviors and processing rewards, often linked to survival instincts like eating and reproduction. 4. Autonomic and Endocrine Regulation: o Influences physiological functions through its interaction with the hypothalamus, including heart rate, respiration, and hormonal responses. 5. Olfaction: o The limbic system includes the olfactory bulb, which is responsible for processing smells, often tied to memory and emotions. 6. Stress Response: o Governs how the body responds to stress, linking emotional experiences to physical reactions. Key Role in Health and Behavior Disruptions or damage to the limbic system can lead to disorders such as anxiety, depression, PTSD, or memory-related conditions like Alzheimer’s disease. It is also implicated in addictive behaviors due to its connection with the brain's reward system. In summary, the limbic system is a central player in how humans experience and react to their environment emotionally, physically, and cognitively, highlighting its vital role in both survival and higher cognitive processes.