6.2

• Course Outline

  • The Brain and Cranial Nerves
  • The Spinal Cord and Spinal Nerves
  • Three Major Divisions of the Nervous System
• Central Nervous System (CNS)


  Brain and spinal cord, serves as the command center, processing information and coordinating responses
• Peripheral Nervous System (PNS)


  Nerves outside the CNS, extends throughout the body and can be further divided into the somatic and autonomic nervous systems
• Somatic Nervous System


  Controls voluntary movements and sensory perception
• Autonomic Nervous System


  Regulates involuntary processes such as heart rate, digestion, and breathing
• Major parts of the brain

  • Brain stem
  • Cerebellum
  • Diencephalon
  • Cerebrum
• Brain stem


  Part of the brain between the spinal cord and the diencephalon, consists of the medulla oblongata, pons, and midbrain
• Cerebellum


  Located at the back of the brain, below the cerebrum and behind the brain stem, plays a crucial role in the coordination of movement, balance, posture, and motor learning
• Diencephalon


  Extends from the brain stem to the cerebrum and surrounds the third ventricle, plays a critical role in relaying and integrating sensory information, regulating various physiological processes, and coordinating motor functions
• Cerebrum


  Largest and most highly developed part of the brain, responsible for many complex cognitive functions, including sensory perception, conscious thought, memory, language, and voluntary movement
• Protective Coverings of the Brain

  • Cranium (skull)
  • Cranial meninges: Dura Mater, Arachnoid Mater, Pia Mater
• Dura Mater


  Outermost layer, made of thick and tough membrane, lines the inside of the skull and forms a protective barrier around the brain, extends inward forming partitions that help stabilize and separate different regions of the brain
• Arachnoid Mater


  Situated beneath the dura mater, a delicate and web-like membrane that encloses the brain, subdural space between the dura mater and the arachnoid mater contains a small amount of fluid that helps reduce friction
• Pia Mater


  Innermost layer, thin and highly vascularized membrane, adheres closely to the surface of the brain, follows the contours of the brain, entering into every fold and groove, helps nourish the brain by supplying it with oxygen and nutrients through its extensive network of blood vessels
• Blood Flow in the Brain


  Flows to the brain via the internal carotid and vertebral arteries and away from the brain via the internal jugular veins, brain consumes about 20% of the oxygen and glucose used even at rest, an interruption in blood flow for 1 or 2 minutes impairs neuronal function, total deprivation of oxygen for about 4 minutes causes permanent injury, low level of glucose in blood entering the brain may cause mental confusion, dizziness, convulsions, and loss of consciousness
• Blood-Brain Barrier (BBB)


  Protects brain cells from harmful substances and pathogens by preventing passage of many substances from blood into brain tissue, formed by a combination of endothelial cells lining the blood vessels in the brain, tight junctions, and astrocytes
• Cerebrospinal Fluid (CSF)


  A clear, colorless liquid that protects the brain and spinal cord from chemical and physical injuries, carries oxygen, glucose, and other needed chemicals from the blood to neurons and neuroglia, mainly produced in the choroid plexuses located within the ventricles of the brain, continuously circulates through cavities in the brain and spinal cord and around the brain and spinal cord in the subarachnoid space, contributes to homeostasis by providing mechanical and chemical protection, and circulation
• Cavities where CSF circulates

  • Lateral Ventricles
  • Third Ventricle
  • Fourth Ventricle
• Medulla Oblongata


  Lowest part of the brain stem, merging with the spinal cord, controls vital functions such as breathing, heart rate, blood pressure, and reflex actions, regulates functions related to swallowing, coughing, sneezing, and vomiting, contains various centers responsible for controlling sleep, arousal, and certain cranial nerve functions
• Pons


  Situated above the medulla, serves as a bridge connecting different parts of the brain, helps relay signals between various regions of the brain, involved in regulating sleep and arousal, controlling certain aspects of breathing, and coordinating movements, contains nuclei that contribute to cranial nerve functions, including facial movement, hearing, and eye movement
• Midbrain / Mesencephalon


  Uppermost part of the brain stem, located between the pons and the cerebral hemispheres, plays a crucial role in visual and auditory processing, houses the substantia nigra which is involved in motor control and produces the neurotransmitter dopamine, contains the reticular formation which is a network of neurons responsible for regulating sleep, wakefulness, and arousal
• Cerebellum


  Highly organized structure consisting of layers of Purkinje cells, plays a crucial role in the coordination of movement, balance, posture, and motor learning, receives sensory information from various parts of the body and integrates this sensory input with motor commands from the cerebral cortex to fine-tune and coordinate movements, contributes to cognitive functions such as motor learning and procedural memory
• Thalamus


  Acts as a relay center for sensory information, receives and processes sensory signals from various sensory systems and then sends them to the appropriate areas of the cerebral cortex for further processing
• Hypothalamus


  Involved in maintaining homeostasis and regulating various physiological processes, controls body temperature, hunger and thirst, hormone production and release, circadian rhythm (sleep-wake cycles), emotions and behaviors, and the autonomic nervous system, plays a role in sexual behavior and the regulation of the pituitary gland
• Epithalamus


  Includes the pineal gland which produces the hormone melatonin that regulates sleep-wake cycles and circadian rhythms, contains the habenula which is involved in emotional and reward processing
• Circumventricular Organs


  Lie in the wall of the third ventricle, monitor chemical changes in the blood because they lack a blood-brain barrier, coordinate homeostatic activities of the endocrine and nervous systems, sites of entry into the brain of HIV causing dementia and other neurological disorders
• Cerebrum


  Largest and most highly developed part of the brain, responsible for many complex cognitive functions, including sensory perception, conscious thought, memory, language, and voluntary movement, divided into two hemispheres connected by the corpus callosum, cerebral cortex is the outer layer consisting of intricate folds and grooves known as gyri and sulci
• Frontal Lobes


  Located in the front of the cerebrum, involved in various higher-order functions, such as decision-making, problem-solving, reasoning, planning, personality, and voluntary muscle movement
• Parietal Lobes


  Situated behind the frontal lobes, responsible for processing sensory information, including touch, pressure, temperature, and spatial awareness
• Brain


  Located in the uppermost region, responsible for many complex cognitive functions, including sensory perception, conscious thought, memory, language, and voluntary movement
• Brain


  • Divided into two hemispheres, the right and left hemispheres, which are connected by a bundle of nerve fibers called the corpus callosum
• Cerebral cortex


  Outer layer of the cerebrum which consists of intricate folds and grooves known as gyri and sulci, respectively. These folds increase the surface area of the cortex, allowing for more extensive neural connections and higher cognitive capabilities
• Lobes of the Cerebrum

  • Frontal Lobes
  • Parietal Lobes
  • Temporal Lobes
  • Occipital Lobes
• Parietal Lobes


  • Situated behind the frontal lobes, responsible for processing sensory information, including touch, pressure, temperature, and spatial awareness, play a role in perception, attention, and spatial cognition
• Temporal Lobes


  • Located on the sides of the brain, near the temples, involved in auditory processing, language comprehension, memory formation, and aspects of emotion and social behavior
• Occipital Lobes


  • Positioned at the back of the cerebrum, primarily process visual information, responsible for visual perception, object recognition, and the interpretation of visual stimuli
• Deep structures found in the cerebrum

  • Basal Ganglia
  • Limbic System
• Basal Ganglia


  • A group of interconnected nuclei (caudate nucleus, putamen, and globus pallidus) located deep within the cerebral hemispheres, their functions include: Movement Regulation, Habit Formation, Reward and Reinforcement
• Limbic System


  • A collection of brain structures which include the hippocampus, amygdala, hypothalamus, and cingulate gyrus, their functions include: Emotional Processing (amygdala), Memory Formation (hippocampus), Motivation and Drives, Autonomic Functions
• Cranial Nerves

  • Olfactory Nerve (I)
  • Optic Nerve (II)
  • Oculomotor Nerve (III)
  • Trochlear Nerve (IV)
  • Trigeminal Nerve (V)
  • Abducens Nerve (VI)
  • Facial Nerve (VII)
  • Vestibulocochlear Nerve (VIII)
  • Glossopharyngeal Nerve (IX)
  • Vagus Nerve (X)
  • Accessory Nerve (XI)
  • Hypoglossal Nerve (XII)