L13 OVER VIEW OF CENTRAL NERVOUS SYSTEM II PDF

‫بسم الله الرحمن‬ ‫الرحيم‬ PHYSIOLOGY OF FOUNDATION BLOCK L13: OVER VIEW OF CENTRAL NERVOUS SYSTEM (CNS)-2  Learning Objectives By the end of this lecture you should be able to Identify the Central Nervous System parts description and func...

‫بسم الله الرحمن‬ ‫الرحيم‬ PHYSIOLOGY OF FOUNDATION BLOCK L13: OVER VIEW OF CENTRAL NERVOUS SYSTEM (CNS)-2  Learning Objectives By the end of this lecture you should be able to Identify the Central Nervous System parts description and functions Identify the Cerebrum description and functions Identify the Cerebral cortex description and functions Identify the Basal nuclei description and functions Identify the Diencephalon description and functions Identify the Thalamus description and functions Identify the Hypothalamus description and functions Identify the Cerebellum description and functions  Nervous system Nervous system Peripheral Central Brain & Somatic Autonomic spinal cord  Central Nervous System DESCRIPTION: CNS consists of brain and spinal cord – 100 billions neurons in brain FUNCTIONS – Subconsciously regulate your internal environment by neural means – Experience emotions – Voluntarily control your movements – Be consciously aware of your own body and your surroundings – Engage in other higher cognitive processes such as thought and memory  Brain Anatomy Brain components Forebrain a) Cerebrum i) Cerebral cortex ii) Basal nuclei b) Diencephalon i) Thalamus ii) Hypothalamus Brain stem - Mid brain - Pons - Medulla Cerebellum  CEREBRUM DESCRIPTION: Cerebrum constitutes 80% of total brain weight. Outer layer, i.e. cerebral cortex of cerebrum is highly convoluted. It has gyri [ridges] and sulci [depression]. 6  Basal Nuclei (Basal ganglia) Description Collection of nuclei in the brain Functions: Participate in control of voluntary movement Participate in planning and programming Act in subconscious action  Diencephalon DESCRIPTION: Diencephalon is present in the interior of cerebrum. It has 2 components: - Thalamus - Hypothalamus  Thalamus Function: All sensory information passes.  Hypothalamus Function: Regulates body temperature, has thirst and food intake center. 8  Brain Stem Description :Brain Stem [mid brain, Pons, Medulla]. Brain Stem is continuous below with spinal cord.  Functions: Majority of cranial nerves originate from brain stem. Control Center for cardiovascular, respiratory system. Role in sleep. 9  Cerebellum Description :Cerebellum is attached at the back portion of brain stem.  Functions: Balance of body. Co-ordination and planning of skilled movements e.g. dance. 10  CEREBRUM Description Cerebrum is the largest portion human brain. It is divided into TWO halves, Right and Left cerebral hemispheres. They are connected by CORPUS CALLOSUM which consists of about 300 million axons connecting two cerebral hemispheres. Cerebral cortex– It is the outer shell of Gray matter covering the inner white matter. 12  CEREBRUM  Q—What is the GRAY Matter ? A– It is the Cerebral cortex , which consists of cell bodies and their dendrites, as well as connective tissue glial cells.  Q– What is the WHITE Matter ? A– It is the myelinated nerve fibers (Axons). Its white appearance is due to Myelin sheath (lipid layer). 13  Cerebrum Consist right & left hemispheres Each hemispheres is divided into: Frontal lobe: 1. Has motor area 2. Area of smell Temporal lobe: 1. Has area of hearing 2. Area of memory  Cerebrum Parietal lobe 1. Has sensory area 2. Area for speech Occipital lobe: Has area of vision  Primary Motor Cortex Primary Motor Cortex is located in the pre- central gyrus in the frontal lobe. Motor Cortex controls the moments of opposite side of the body. Motor tracts originating from the right motor cortex cross to the opposite side at medulla and then go down to spinal cord to terminate on efferent motor neuron. 17  Primary Motor Cortex In motor cortex, presentation is not equal but some parts e.g. fingers, thumbs, muscles of speech [lips, tongue have more presentation due to fine degree of motor work]. Trunk, arms, lower limbs have less presentation than their size as they do not perform complex movements. 18  Primary Motor Cortex  Applied clinical aspect Damage to the right motor cortex will produce paralysis [loss of power] on the left side of the body. Damage to the left motor cortex will produce paralysis on the right side of the body. 19  Somato Sensory Cortex Somato Sensory Cortex is present in the post central gyrus in the parietal lobe. All body parts are not represented equally, but some areas have more representation due to their degree of fine work and have more receptors e.g. fingers [hand], face, tongue. 20  Somato Sensory Cortex Right side sensory cortex gets sensory input [information] from left side of the body. Left side sensory cortex gets sensory input from the right side of the body.  Why? Because sensory pathways carrying the information cross to the opposite side of the body before they terminate in the sensory cortex. 21  Somato Sensory Cortex  Applied clinical Aspect Damage to the sensory cortex in the left hemisphere [left side] produces sensory deficit on the right side of the body. Damage to the sensory cortex in right hemisphere produces sensory deficit on the left side of the body. 22  Functions of spinal cord 1. Contain ascending and descending tracts 2. Acts as integrating center for spinal cord reflexes  References Human physiology by Lauralee Sherwood, 9th edition Text Book Of Physiology by Guyton & Hall, 12th edition Review of Medical Physiology by Ganong, 24th edition