Anatomy Theory 4 - Nervous System PDF

Duration: 2 Hours Anesthesia Technology Grade: 1st year Lecture # 4 Nervous system part I Lec. Dr. Ranj Talal Akreyi Doctorate in Diagnostic Radiology CABMS RAD M.B.Ch.B HMU - College of Medicine Agenda for this course Central Nervous System (CNS): Brain: Understanding the different...

Duration: 2 Hours Anesthesia Technology Grade: 1st year Lecture # 4 Nervous system part I Lec. Dr. Ranj Talal Akreyi Doctorate in Diagnostic Radiology CABMS RAD M.B.Ch.B HMU - College of Medicine Agenda for this course Central Nervous System (CNS): Brain: Understanding the different regions of the brain is important. For example, the cerebral cortex is involved in higher cognitive functions, while the brainstem regulates basic life functions. Spinal Cord: The spinal cord is responsible for relaying signals between the brain and the peripheral nervous system. Agenda for this course Peripheral Nervous System (PNS): Somatic Nervous System: Controls voluntary muscle movements and relays sensory information to the CNS. Autonomic Nervous System (ANS): Divided into sympathetic and parasympathetic divisions, which regulate involuntary functions like heart rate, digestion, and respiratory rate. Nervous system The nervous system is the highly complex part of human body that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. Nervous system The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine system to respond to such events. In Human it consists of two main parts, the central nervous system (CNS) and the peripheral nervous system (PNS). Nervous system The CNS consists of the brain and spinal cord. The PNS consists mainly of nerves, which are enclosed bundles of the long fibers or axons, that connect the CNS to every other part of the body. Nerves that transmit signals from the brain are called motor nerves or efferent nerves, while those nerves that transmit information from the body to the CNS are called sensory nerves or afferent. Nervous system Spinal nerves are mixed nerves that serve both functions. The PNS is divided into three separate subsystems, the somatic, autonomic, and enteric nervous systems. Somatic nerves mediate voluntary movement. The autonomic nervous system is further subdivided into the sympathetic and the parasympathetic nervous systems. Nervous system The enteric nervous system is the largest and most complex unit of the peripheral nervous system, with ~600 million neurons releasing a multitude of neurotransmitters to facilitate the motor, sensory, absorptive, and secretory functions of the gastrointestinal tract. Nervous system The brain is an organ of nervous tissue that is responsible for responses, sensation, movement, emotions, communication, thought processing, and memory. Protection for the human brain comes from the skull, meninges, and cerebrospinal fluids. The nervous tissue is extremely delicate and can suffer damage by the smallest amount of force. Nervous system In addition, it has a blood-brain barrier preventing the brain from any harmful substance that could be floating in the blood. Blood-Brain Barrier The blood vessels that vascularize the central nervous system (CNS) possess unique properties, termed the blood–brain barrier, which allow these vessels to tightly regulate the movement of ions, molecules, and cells between the blood and the brain. The blood-brain barrier Is a barrier between the brain’s blood vessels (capillaries) and the cells and other components that make up brain tissue. Whereas the skull, meninges and cerebrospinal fluid protect against physical damage, the blood– brain barrier provides a defense against disease- causing pathogens and toxins that may be present in blood. Nervous system The spinal cord is a vital aspect of the CNS found within the vertebral column. The purpose of the spinal cord is to send motor commands from the brain to the peripheral body as well as to relay sensory information from the sensory organs to the brain. Spinal cord protection is by bone, meninges, and cerebrospinal fluids. Divisions of the Nervous System Nervous system Peripheral Central Nervous Nervous system system (CNS) (PNS) Functionally Spinal cord (link Somatic Brain between brain Autonomic Nervous system Nervous system (control and peripheral (conscious and (controls functions center) nerves) voluntary control critical to life) of muscles) Sympathetic Nervous Parasympathetic Nervous system (rest system (fight and digest) or fly) Divisions of the Nervous System Sensory and Motor Neurons Brain Brain The human brain is the central organ of the human nervous system, and with the spinal cord makes up the central nervous system. Brain The brain consists of the cerebrum, Brain The brain consists of the cerebrum, the brainstem Brain The brain consists of the cerebrum, the brainstem and the cerebellum. Brain It controls most of the activities of the body, ▪ processing, ▪ integrating, ▪ and coordinating the information it receives from the sense organs, ▪ and making decisions as to the instructions sent to the rest of the body. Anatomy of the Cerebrum Cerebrum, the largest and uppermost portion of the brain. The cerebrum consists of the two cerebral hemispheres and accounts for two-thirds of the total weight of the brain. Anatomy of the Cerebrum A ridge is called a gyrus and a valley is called a sulcus. 1. The central sulcus is important because the gyrus anterior to it is the primary motor cortex, which initiates all motor functions. 1 2. The gyrus posterior to the central sulcus is the primary sensory cortex, which receives all sensory input. Gray and White Matter of Brain The nerve cell bodies constitute the gray matter. Gray The axons form the white matter. matter The gray matter (outer) appears roughly as an H-shaped area embedded in a white matter White matter (central). The horns; there are right and left posterior (dorsal) and anterior (ventral) gray horns. Cerebrum lobes Cerebrum lobes 1. Frontal lobe: responsible for thinking, planning and all motor control. 2. Parietal lobe: receives and integrates all sensory information. 3. Occipital lobe: serves as the visual processing center. 4. Temporal lobe: it creates and stores new memory and is involved in emotional regulation. Cerebellum The cerebellum (“little brain”) is a structure that is located at the back of the brain, underlying the occipital and temporal lobes of the cerebral cortex. Although the cerebellum accounts for approximately 10% of the brain’s volume, it contains over 50% of the total number of neurons in the brain. Anatomy of Cerebellum Cerebellar Cortex Cerebellar deep nuclei Function of Cerebellum 1. Maintenance of balance and posture. 2. Coordination of voluntary movements. 3. Motor learning: The cerebellum plays a major role in adapting and fine-tuning motor programs to make accurate movements through a trial-and-error process (e.g., learning to hit a baseball). 4. Cognitive functions: including learning, thinking, reasoning, remembering, problem solving, decision making, and attention. Function of Cerebellum Cerebellar dysfunction show, above all, problems with motor control, on the same side of the body as the damaged part of the cerebellum. They continue to be able to generate motor activity but lose precision, producing erratic, uncoordinated, or incorrectly timed movements. Brain stem Is the posterior part of the brain attached, and structurally continuous with, the spinal cord. The brainstem sits just inferior to the cerebrum Though small, the brainstem is an extremely important part of the brain, as the nerve connections from the motor and sensory systems of the cortex pass through it to communicate with the peripheral nervous system. Brain stem Plays an important role in the regulation of cardiac and respiratory function, consciousness, and the sleep cycle. The brainstem divided into: 1. the midbrain, 2. pons 3. and medulla. Brain stem nuclei 3 Ten of the twelve pairs 3 4 of cranial nerves 5 5 either target or are 6 sourced from the 6 brainstem nuclei 7 8 7 12 9 10 11 Brain stem nuclei 3 3. Oculomotor nerve (III), Midbrain 3 4 4. Trochlear nerve (IV) 5 5 5. Trigeminal nerve (V), 6. Abducens nerve (VI), 6 Pons 7. Facial nerve (VII) 6 8. Vestibulocochlear nerve (VIII) 7 7 8 9. Glossopharyngeal nerve (IX), 12 10. Vagus nerve (X), Medulla 9 11. Accessory nerve (XI) oblengata 10 11 12. Hypoglossal nerve (XII) Tracts of Brain stem All information relayed from the body to the cerebrum and cerebellum and vice versa must cross the brainstem. The ascending pathways coming from the body to the brain are the sensory pathways: This includes the posterior column-medial lemniscus pathway (fine touch, vibration sensation, and proprioception ) and the spinothalamic tract (pain, temperature, itch, and crude touch). Descending Pathway: the corticospinal tract (motor) from the brain to the body. Midbrain (mesencephalon) Is the anterior portion of the brainstem. Is associated with vision, hearing, motor control, sleep and wakefulness, arousal (alertness), and temperature regulation. Midbrain 1. Cerebrum 2. Thalamus 3. Mesencephalon - Midbrain 4. Pons 5. Medulla oblongata 6. Medulla spinalis - Spinal cord Pons The pons is a portion of the hindbrain that connects the cerebral cortex with the medulla oblongata. It also serves as a communications and coordination center between the two hemispheres of the brain. The pons is a relay station between the forebrain and cerebellum that passes sensory information from the periphery to the thalamus. Pons Along with nuclei that regulate sleep, respiration, swallowing, bladder control, hearing, equilibrium, taste, eye movement, facial expressions, facial sensation, and posture. Medulla oblongata The medulla oblongata is the lower half of the brainstem. Connects the higher levels of the brain to the spinal cord. The medulla oblongata is responsible for regulating basic functions of the autonomic nervous system, including respiration, cardiac function, vasodilation, and reflexes like vomiting, coughing, sneezing, and swallowing. Brain meninges Brain lobe's function ▪ The internal carotid arteries supply oxygenated blood to the front of the brain and the vertebral arteries supply blood to the back of the brain. ▪ These two circulations join in the circle of Willis, a ring of connected arteries that lies in the interpeduncular cistern between the midbrain and pons.