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Nervous anatomy sem2 [compatibility mode]
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Nervous anatomy sem2 [compatibility mode]

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    Nervous anatomy sem2 [compatibility mode] Nervous anatomy sem2 [compatibility mode] Document Transcript

    • 7/6/2012 Divisions of the Vertebrate Nervous SystemNeuroanatomy Central Nervous System-the brain and the spinal cord Peripheral Nervous System-the nerves outside the brain and spinal cord By Two Division of the PNS Somatic Nervous System-the nerves that convey messages Shahzad Bashir from the sense organs to the CNS and from the CNS to the muscles and glands RN, BScN Autonomic Nervous System-a set of neurons that control the NMC (ION) heart, the intestines, and other organs 7/6/2012 2 Figure 4.1 The human nervous system Both the central nervous system and the peripheral nervous system have major subdivisions. The closeup of the brain shows the right hemisphere as seen from the midline. 3 4 The Nervous SystemThe Spinal Cord-part of the CNS found within the spinal column The spinal cord communicates with the sense organs and muscles below the level of the head Bell-Magendie Law-the entering dorsal roots carry sensory information and the exiting ventral roots carry motor information to the muscles and glands Dorsal Root Ganglia-clusters of neurons outside the spinal cord Figure 4.3 Diagram of a cross section through the spinal cord The dorsal root on each side conveys sensory information to the spinal cord; the 5 ventral root conveys motor commands to the muscles. 6 1
    • 7/6/2012 Autonomic Nervous System The BrainSympathetic-prepares the Parasympathetic-facilitates vegetative, body for arousal nonemergency responses by the The Hindbrain/rhombencephalon Ex: increased body’s organs Posterior part of brain breathing, increased Ex: increase digestive activity, Medulla-controls vital reflexes like breathing, heart beat, etc heart rate, decreased activities opposing sympathetic system Pons-Area where many axons cross from one side of the brain to the digestive activity other Form chain of ganglia Consists of cranial nerves and nerves from sacral spinal cord Reticular formation-control motor areas of the spinal cord and sends just outside spinal output to cerebral cortex increasing arousal and attention cord Long preganglionic axons extend from the spinal cord to Raphe system-sends axons to much of the forebrain, increasing or Short preganglionic decreasing the brain’s readiness to respond to stimuli axons release parasympathetic ganglia norepinephrine close to each internal organ; Cerebellum-control movement, shifts of attention, balance and release norepinephrine coordination Long postganglionic axons release Shorter postganglionic fibers norepinephrine then extend from the parasympathetic ganglia in the organs; release acetylcholine 7 8 The Brain The Midbrain-middle of the brain Tegmentum-”roof or covering” Nuclei for third and fourth cranial nerves Parts of Reticular formation Extensions of the pathways between the forebrain and the spinal cord or hindbrain Tectum-”roof” Superior Colliculus & Inferior Colliculus-important in routes of sensory information Figure 4.8 The human brain stem This composite structure extends from the top of the spinal cord into the center of the forebrain. The pons, pineal gland, and colliculi 9 are ordinarily surrounded by the cerebral cortex. 10 The Brain The Forebrain-most anterior and most prominent part of the mammalian brain Thalamus Part of the Diencephalon Center of forebrain Relay Station for Sensory Information Hypothalamus Part of Diencephalon Regulates homeostasis, sexual behavior, fighting, feeding Pituitary Gland Endocrine gland attached to the base of the hypothalamus Figure 4.10 The limbic system is a set of subcortical structures that form a border (or limbus) around the brain stem 11 12 2
    • 7/6/2012 The Brain Forebrain Cont’d Basal Ganglia Responsible for motor behavior, some memory and emotional expression Basal Forebrain Located on the dorsal surface of the forebrain Received input from the hypothalamus and basal ganglia Send axons to cerebral cortex Important in arousal, wakefulness, and attention Hippocampus Located between thalamus and cerebral cortex Critical for the formation of new memory Figure 4.12 A sagittal section through the human brain 13 14 The Brain The Ventricles-Assists in cushioning the brain Central Canal-fluid-filled channel in the center of the spinal cord Ventricles-four fluid-filled cavities within the brain CSF-clear fluid similar to blood plasma Formed in choroid plexus Flows from lateral to third to fourth ventricle to central canal or between meninges Meninges-membranes that surround the brain and spinal cord Figure 4.14 The basal gangliaThe thalamus is in the center, the basal ganglia are lateral to it, and the cerebral cortex is on the outside. 15 16 The Cerebral Cortex Organization of the Cerebral Cortex Contains six distinct layers of cells Organized into columns-cells with similar properties; arranged perpendicular to the laminae Cells within a given column have similar or related properties Figure 4.16 The cerebral ventricles Diagram showing positions of the four ventricles. 17 18 3
    • 7/6/2012 The Parts of the Brain Left Hemisphere Cortex (Cerebrum) The Left hemisphere controls the right side of the body. It The cortex, or cerebrum, is made up of controls speech, comprehension, arithmetic, and writing. two hemispheres (or sides) connected by a band of tissue called the corpus Right Hemisphere callosum. These hemispheres control The right hemisphere controls the left side of the body. It is speech, intelligence, and memory. There responsible for more abstract skills, such as creativity, spatial are specific centres for specific functions; ability, and artistic and musical skills. for example, the speech centre governs the ability to form sounds into meaningful Each cerebral hemisphere is divided into lobes. (In this words, phrases, etc. illustration, the Frontal Lobe, the Temporal Lobe, the Parietal Lobe, Occipital Lobe, Motor Strip and Sensory Strip are all 19 the different parts that make up the Cortex). 20 Temporal LobeThe temporal lobe is located alongside the frontal and parietal lobes, just above the ear. It is the centre for the senses of hearing, taste, and Cerebellum The cerebellum is smell. It is also involved in receiving auditory located beneath the cerebral cortex in information and in memory. the back of the skull. It is smaller than Occipital Lobe The occipital lobe rests in back of the cortex the cortex. Its job is to transmit andbehind the parietal and temporal lobes. Damage coordinate the signals from the to this area may affect sight, such as perceiving cortex. It also controls the movement or understanding visual information. of voluntary muscles, balance, posture, 21 and in coordinating movements. 22 Brain Stem The brain stem is in front of the cerebellum and beneath the cerebral cortex. It connects the spinal cord to the cortex. Its role includes passing messages back and forth between various parts of the body and the cerebral cortex. 23 24 4
    • 7/6/2012 Brain Function How Do the Pieces Work Together? Does the Brain Operate as a Whole or a Collection of Parts? Each brain area has a function but it can’t do much by itself The Binding Problem The question of how the visual, auditory, and other areas of your brain influence on another to produce a combined perception of the single object Synchronized neural activity?Figure 4.20 Some major subdivisions of the human cerebral cortex The four lobes: occipital, parietal, temporal, and frontal. 25 26 5