Nervous System For CN PDF

THE NERVOUS SYSTEM By: Dr. Khulood Al-Khater (MBBS, MSc., PhD, FHEA) [email protected] Department of Anatomy...

THE NERVOUS SYSTEM By: Dr. Khulood Al-Khater (MBBS, MSc., PhD, FHEA) [email protected] Department of Anatomy College of Medicine Wednesday, November 6, 2024  Lecture Objectives After this lecture you will be able to understand the following: 1) The structure and functions of the nervous tissue (neurons, neuroglia, and nerves). 2) Division of the Nervous system: CNS and PNS. 3) Brain and its main parts and function. 4) Spinal cord, structure and function. 5) Peripheral nerves: cranial and spinal. 6) Autonomic nervous system Wednesday, November 6, 2024 Presentation title  THE NERVOUS SYSTEM The nervous system controls all functions of our body: It receives information from the body sensory part It coordinates incoming information central part It acts according to the information Motor part Anatomically the nervous system is divided into two parts: Central nervous system (CNS) located inside the cranium and vertebral column. This includes: The brain & Spinal cord Peripheral nervous system (PNS) located outside the axial skeleton. This includes: Cranial nerves, Spinal nerves, & Ganglia. Wednesday, November 6, 2024 Presentation title  Divisions of the Nervous System Anatomical Functional division division Peripheral Central nervous Somatic nervous Autonomic nervous system system (CNS) system nervous system (PNS) Wednesday, November 6, 2024 Presentation title  Components of Nervous tissue The basic unit of the nervous tissue is the Neuron. In between the neurons are the neuroglial cells which perform different functions. So the cells of nervous tissue are: 1) Neurons & 2) Neuroglial cells Wednesday, November 6, 2024 Presentation title  NEURONS A Neuron is composed of: A) Cell body (soma) B) Cell processes: i) dendrites that receive impulses. ii) an Axon that carries or transmits the impulses away from the soma. Wednesday, November 6, 2024  HITOLOGICAL SLIDES OF NEURONS Dendrites Axon Cell body Dendrites Wednesday, November 6, 2024  Neuroglia The neuroglial cells are: 1) Oligodendrocytes. They cause myelination of fibers in the CNS 2) Astrocytes form support to neurons. 3) Microglial cells are phagocytic and protective. 4) Ependymal cells line ventricles. 5) Schwann cells produce myelin in the peripheral nervous system. Wednesday, November 6, 2024  Parts of the CNS This consists of the brain and spinal cord.  The brain lies within the cranial cavity and has the following parts: ❖ Cerebrum ❖ Brain stem ❖ Cerebellum Wednesday, November 6, 2024  Cerebrum This is the largest part of the brain. It consists of two hemispheres that are joined by a bridge of fibers called corpus callosum. Corpus Parts of the cerebrum: callosum Each cerebral hemisphere is divided into 4 lobes Wednesday, November 6, 2024  Cerebrum 4 lobes of the cerebrum The parts are named according to the bones near which they lie i.e. Frontal lobe P Parietal lobe F Temporal lobe Occipital lobe. O The functions of the cerebrum T are: To receive sensory information from all parts of the body To store this information, to think and coordinate To initiate and control motor function. Wednesday, November 6, 2024  Cortical areas The neurons controlling one function lie in the same area. The areas of cortex controlling specific functions are called cortical areas. The important cortical areas are: Sensory areas receive most of the sensations and are located in the parietal lobe behind the central sulcus. Motor area control the movements of the opposite side of the body and lie in the frontal lobe, in front of central sulcus. Wednesday, November 6, 2024  Cortical areas (cont.) ▪ Vision (sight) area located in the occipital lobe. ▪ Hearing area is present in the temporal lobe. ▪ Speech area located in the frontal lobe. ▪ Personality, intelligence and thinking are in the frontal lobe. ▪ The right hemisphere controls the left side of the body and vice versa Wednesday, November 6, 2024  Interior of the cerebrum Inside each cerebral hemisphere there is a cavity called lateral ventricle, which is filled with CSF Wednesday, November 6, 2024  Thalamus and hypothalamus The core of the cerebrum is formed by Thalamus and Hypothalamus. These are above the brain stem and control endocrine and visceral functions. A cavity lies between the two thalami called the third ventricle. Wednesday, November 6, 2024  THE BRAIN STEM This connects the cerebrum with the spinal cord. The brain stem consists of Midbrain Midbrain Pons Medulla Oblongata Medulla All 3 parts are connected to the oblongata Pons cerebellum Wednesday, November 6, 2024  THE BRAIN STEM (cont.) The Midbrain This is a region in the middle of the brain and consists of fibers Cerebral aqueduct from the two cerebral hemispheres in two bundles, which enter the pons. It contains a narrow canal called the cerebral aqueduct. The Pons It is a round globular part lying between the midbrain and medulla oblongata. Wednesday, November 6, 2024  THE BRAIN STEM (cont.) The Medulla oblongata This lies below the pons and is continuous with the spinal cord at the Foramen magnum. The medulla contains collections of grey matter called Vital centers. These control heart, blood vessels and respiration. Injury to medulla can cause death. Wednesday, November 6, 2024  Cerebellum THE CEREBELLUM This lies below the occipital lobe of the cerebrum and consists of two lobes or hemispheres joined with each other. It is also attached to all parts of the brain stem. Functions of cerebellum are: coordination of movements balance and posture control of muscle tone Wednesday, November 6, 2024  Cerebellum There are two cerebellar hemispheres joined by a A cavity is present between central vermis cerebellum and brain stem called the fourth ventricle. Vermis 4th Ventricle Vermis Wednesday, November 6, 2024  Meninges Three layers of fibrous tissue that cover and protect the brain and spinal cord ▪ Dura Mater ▪ Arachnoid Mater ▪ Pia Mater 21 Wednesday, November 6, 2024 Presentation title  Meninges Three protective membranes called meninges cover the brain & the spinal cord. These are: Dura mater: which is a tough membrane covering and supporting the brain. It sends folds inside to separate various parts of the brain. Arachnoid mater: a thin membrane covering the brain loosely. Pia mater: covers the brain closely and extends into the sulci. ▪ The space between Arachnoid and pia mater is called the subarachnoid space. Wednesday, November 6, 2024  Cerebrospinal fluid Cerebrospinal fluid (CSF) is a fluid present in the space between arachnoid mater and pia mater (subarachnoid space). Wednesday, November 6, 2024  clinical application ▪ Stroke: - means loss of function of a part of brain. This occurs because of the loss of blood supply due to: a blocked artery or hemorrhage If the damage is in the motor area the patient will have: Hemiplegia or paralysis of the opposite side of the body, he may also have difficulty in speech, If damage in both hemispheres the patient will have tetraplegia or paralysis of the whole body. Wednesday, November 6, 2024  Spinal cord The spinal cord is a part of CNS lying within the vertebral canal. It is continuous with the medulla oblongata at the foramen magnum and extends till the lower border of 1st lumbar vertebra (adult), or to upper border of L3 (young child) In the fetus it occupies the whole length of the vertebral canal. The meninges of the spinal cord extend till the S2 vertebra. Wednesday, November 6, 2024 Presentation title  SECTION OF THE SPINAL CORD The section of the spinal cord shows white matter (nerve fiber bundles) arranged on the outside. The grey matter is arranged in an H shaped manner inside. There is a central spinal canal located in the center of the grey matter which is filled with the CSF. Wednesday, November 6, 2024  MENINGES OF THE SPINAL CORD The spinal cord is covered like the brain with 3 layers of meninges: Dura mater. Arachnoid mater. Pia mater. The space between the arachnoid mater and pia mater is called the subarachnoid space. It is filled with the CSF. Wednesday, November 6, 2024  clinical CLINICAL NOTES ABOUT SPINAL CORD application Spinal cord injury also results in paralysis depending upon the site of lesion. If injury in thoracic region the patient ends up with paraplegia i.e., paralysis of both lower limbs. Meningitis is the disease or infection of meninges. Lumbar puncture is done between L3 and L4 vertebra to get a sample of CSF. Wednesday, November 6, 2024  PHERIPHERAL NERVOUS SYSTEM Wednesday, November 6, 2024  Spinal Cord It Consists of 31 segments grouped in 5 regions: ▪ 8 cervical segments ▪ 12 thoracic segments ▪ 5 lumbar segments ▪ 5 sacral segments ▪ 1 coccygeal segment Wednesday, November 6, 2024 Presentation title  Each spinal nerve is connected to the spinal cord by two roots: anterior root posterior root The two roots join to form a spinal nerve which comes out of the intervertebral foramen. Wednesday, November 6, 2024  PHERIPHERAL NERVE Each peripheral nerve consists of bundles of nerve fibers in a sheath of connective tissue. Wednesday, November 6, 2024  Spinal Nerves (cont.) The spinal nerves supply the body as follows: Cervical nerves: a) upper 4 supply head and neck b) lower 4 supply upper limb (with the first thoracic nerve forming the brachial plexus) Thoracic nerves: a) 1st thoracic nerve supplies upper limb in brachial plexus. b) All other thoracic nerves supply thorax and abdomen. Lumber and sacral nerves: Form lumbosacral plexus that supplies lower limb and pelvis. Wednesday, November 6, 2024  File:Brain human normal inferior view with labels en.svg CRANIAL NERVES These emerge from different parts of the brain stem and are 12 in number. Wednesday, November 6, 2024  THE AUTONOMIC NERVOUS SYSTEM The autonomic nervous system is a subdivision of the nervous system that controls the involuntary functions of our body. This system controls the smooth muscles such as of blood vessels, and viscera e.g. lungs, stomach, intestine, urinary bladder, uterus and rectum. It also controls glands like salivary, sweat glands etc. The autonomic system is divided into two parts: Sympathetic system Parasympathetic system The sympathetic and parasympathetic systems have opposite effects to each other e.g. Sympathetic increases heart rate and parasympathetic decreases it Sympathetic dilates the pupil and parasympathetic constricts it. Wednesday, November 6, 2024  06:52 Autonomic Nervous System (ANS) Divisions of the autonomic nervous system (ANS) Sympathetic division Increases heart rate and blood pressure Depresses digestive function Increases sweating Parasympathetic division Slows heart rate, fall in pressure Increases digestive functions Stops sweating Wednesday, November 6, 2024 Presentation title  Thank You Wednesday, November 6, 2024 Presentation title