structural organization of nervous system new
TRANSCRIPT
STRUCTURAL ORGANIZATION OF NERVOUS SYSTEM
INTRODUCTION
NERVOUS SYSTEM
• NERVOUS SYSTEM AND ENDOCRINE SYSTEM CONTROL THE FUNCTIONS OF THE BODY
• NERVOUS SYSTEM ENABLES THE BODY TO REACT TO CONTINUOUS CHANGES IN ITS INTERNAL AND EXTERNAL ENVIRONMENT
• CONTROLS AND INTEGRATES THE VARIOUS ACTIVITIES OF THE BODY LIKE CIRCULATION AND RESPIRATION
NERVOUS SYSTEM
• DIVISION OF NERVOUS SYSTEM• NERVOUS SYSTEM IS DIVIDED• STRUCTURALLY INTO---- CNS• ---- PNS• FUNCTIONALLY INTO---- SOMATIC• ---- AUTONOMIC
NERVOUS SYSTEM
• CELLS OF NERVOUS SYSTEM• CONSISTS OF TWO MAIN TYPES OF CELLS• 1 NEURONS• 2 NEUROGLIA• NEURONES• STRUCTURAL AND FUNCTIONAL UNITS OF
NERVOUS SYSTEM• COMPOSED OF A CELL BODY &PROCESSES
NERVOUS SYSTEM
• NEURONES [CONTD ]• PROCESSES ARE—DENDRITES &• ---AXONS• MYELIN CONSISTS OF LAYERS OF LIPIDS AND
PROTEINS• FORMS A SHEATH AROUND SOME AXONS
WHICH INCREASES THE VELOCITY OF IMPULSE CONDUCTION
NERVOUS SYSTEM
• NEUROGLIA• NONEXCITABLE• FORM A MAJOR COMPONENT OF NERVOUS
TISSUE• SUPPORT, INSULATE AND NOURISH THE
NEURONS
NERVOUS SYSTEM
• NEUROGLIA [ CONTD ]• IN THE CNS INCLUDE---• OLIGODENDROCYTES• ASTROCYTES• EPENDYMAL CELLS• MICROGLIA• IN THE PNS INCLUDE---• SATELLITE CELLS• SCHWANN CELLS
NERVOUS SYSTEM
• CNS• CONSISTS OF BRAIN AND SPINAL CORD• MAIN FUNCTIONS• 1 INTEGRATE AND COORDINATE INCOMING
AND OUTGOING NEURAL SIGNALS• 2 CARRY OUT HIGHER MENTAL FUNCTIONS
SUCH AS THINKING AND LEARNING
NERVOUS SYSTEM
• CNS [ CONTD ]• NUCLEUS---COLLECTION OF NERVE CELL
BODIES IN THE CNS• TRACT---ABUNDLE OF NERVE FIBRES[AXONS]
CONNECTING NEIGHBOURING AND DISTANT NUCLEI OF THE CNS
• BRAIN AND SPINAL CORD COMPOSED OF GREY MATER & WHITE MATER
NERVOUS SYSTEM
• CNS [ CONTD ]• GREY MATER FORMED BY NERVE CELL BODIES• WHITE MATER FORMED BY
INTERCONNECTING FIBRE TRACT SYSTEM• MENINGES• MEMBRANOUS LAYERS THAT COVER THE
BRAIN AND SPINAL CORD
NERVOUS SYSTEM
• MENINGES [CONTD ]• THREE LAYERS---• PIA MATER—INNERMOST• ARACHNOID MATER –MIDDLE• DURA MATER—OUTERMOST• CSF PRESENT B/W ARACHNOID AND PIA
MATER
NERVOUS SYSTEM
• PNS• CONSISTS OF NERVE FIBRES AND NERVE CELL
BODIES OUTSIDE THE CNS THAT CONDUCT IMPULSES TO OR AWAY FROM THE CNS
• PNS MADE UP OF NERVES THAT CONNECT THE CNS WITH PERIPHERAL STRUCTURES
• PERIPHERAL NERVE IS A BUNDLE OF NERVE FIBRES[AXONS] IN THE PNS
• GANGLION IS A COLLECTION OF NERVE CELL BODIES OUTSIDE THE CNS
NERVOUS SYSTEM
• PNS• CONSISTS OF NERVE FIBRES AND NERVE CELL
BODIES OUTSIDE THE CNS THAT CONDUCT IMPULSES TO OR AWAY FROM THE CNS
• PNS MADE UP OF NERVES THAT CONNECT THE CNS WITH PERIPHERAL STRUCTURES
• PERIPHERAL NERVE IS A BUNDLE OF NERVE FIBRES[AXONS] IN THE PNS
• GANGLION IS A COLLECTION OF NERVE CELL BODIES OUTSIDE THE CNS
NERVOUS SYSTEM
• PNS[CONTD]• PERIPHERAL NERVES• CRANIAL--- 12 PAIRS 12th PAIR ARISES MOSTLY FROM
THE SUPERIOR PART OF SPINAL CORD• SPINAL--- 31 PAIRS• C—8• T---12• L ---5• S ---5• CO-1
MAJOR DIVISIONS OF CNS
• SPINAL CORD• PRESENT WITHIN THE VERTEBRAL CANAL• SURROUNDED BY THREE LAYERS OF MENINGES• ROUGHLY CYLINDRICAL• BEGINS AT FORAMEN MAGNUM• INFERIORLY TAPERS OFF INTO CONUS
MEDULLARIS• TERMINATES AT THE LOWER BORDER OF L1 IN THE
ADULT
MAJOR DIVISIONS OF CNS
• SPINAL CORD [CONTD ]• FILUM TERMINALE IS A PROLONGATION OF PIA MATER –
EXTENDS FROM THE APEX OF CONUS MEDULLARIS AND IS ATTACHED TO THE BACK OF COCCYX
• 31 PAIRS OF SPINAL NERVES ATTACHED TO THE SP CORD• EACH SPINAL NERVE ATTACHED BY TWO ROOTS---• ANTERIOR OR MOTOR ROOT AND• POSTRIOR OR SENSORY ROOT• POSTERIOR ROOT GANGLION PRESENT ON POSTERIOR ROOT• CELLS IN THE GANGLION GIVE RISE TO CENTRAL AND
PERIPHERAL PROCESSES
MAJOR DIVISIONS OF CNS
• STRUCTURE OF SPINAL CORD• COMPOSED OF-- INNER CORE OF GREY MATER
SURROUNDED BY—OUTER CORE OF WHITE MATER
• GREY MATER IN CROSS SECTION IS H SHAPED WITH ANTERIOR AND POSTERIOR HORNS UNITED BY A THINLAYER OF GREY COMMISSURE CONTAINING THE CENTRAL CANAL
MAJOR DIVISIONS OF CNS
• STRUCTURE OF SP CORD [CONTD ]• IN THE THORACIC SEGMENT LATERAL HORNS
ARE ALSO PRESENT
• WHITE MATER DIVIDED INTO---• ANTERIOR WHITE COLUMN• LATERAL WHITE COLUMN• POSTERIOR WHITE COLUMN
MAJOR DIVISIONS OF CNS
• BRAIN• PRESENT IN THE CRANIAL CAVITY• SURROUNDED BY THREE LAYERS OF
MENINGES• DIVIDED INTO THREE MAJOR DIVISIONS---• HINDBRAIN• MIDBRAIN• FOREBRAIN
HIND BRAIN
• DIVIDED INTO---• MEDULLA OBLONGATA• PONS• CEREBELLUM
MEDULLA OBLONGATA
• CONICAL IN SHAPE• CONNECTS THE PONS TO THE SPINAL CORD• CONTAINS A NUMBER OF NUCLEI• SERVES AS A PASSAGE FOR ASCENDING AND
DESCENDING TRACTS
PONS
• PRESENT ON THE ANTERIOR SURFACE OF THE CEREBELLUM
• CONNECTS THE MIDBRAIN TO THE MEDULLA• HAS LARGE NUMBER OF TRANSVERSE FIBRES
CONNECTING THE TWO CEREBELLAR HEMISPHERES
• CONTAINS MANY NUCLEI AND ASCENDING AND DESCENDING NERVE FIBRES
CEREBELLUM
• PRESENT IN THE POSTERIOR CRANIAL FOSSA• THE TWO HEMISPHERES CONNECTED BY
VERMIS• CONNECTED TO THE MIDBRAIN BY—SUPERIOR
CEREBELLAR PEDUNCLES• CONNECTED TO THE PONS BY---MIDDLE
CEREBELLAR PEDUNCLE• CONNECTED TO THE MEDULLA BY---INFERIOR
CEREBELLAR PEDUNCLE
CEREBELLUM
• SURFACE LAYER CALLED THE CORTEX• CORTEX COMPOSED OF GREY MATER• CORTEX THROWN INTO FOLDS/FOLIA SEPARATED
BY TRANSVERSE FISSURES• INTRACEREBELLAR NUCLEI ARE FOUR ON EACH
SIDE ---DENTATE• ---EMBOLIFORM• ---GLOBOSE• ---FASTIGIAL
HINDBRAIN
• CAVITY OF HINDBRAIN IS 4th VENTRICLE• 4th VENTRICLE CONNECTED TO 3rd VENTRICLE
BY THE CEREBRAL AQUEDUCT• CONTINUOUS INFERIORLY WITH THE CENTRAL
CANAL OF SP CORD• COMMUNICATES WITH SUBARACHNOID
SPACE THROUGH THREE OPENINGS IN THE ROOF
MIDBRAIN
• NARROW PART THAT CONNECTS THE FOREBRAIN TO THE HINDBRAIN
• CAVITY IS THE CEREBRAL AQUEDUCT• CONTAINS MANY NUCLEI AND ASCENDING
AND DESENDING FIBRES
DIENCEPHALON
• HIDDEN FROM THE SURFACE OF THE BRAIN• CONSISTS OF ---• DORSAL THALAMUS• VENTRAL HYPOTHALAMUS• ITS CAVITY IS 3rd VENTRICLE• THALAMUS IS PRESENT ON EITHER SIDE OF
THE 3rd VENTRICLE
CEREBRUM
• LARGEST PART OF THE BRAIN• CONSISTS OF TWO HEMISPHERES CONNECTED
BY COROUS CALLOSUM• HEMISPHERES SEPARATED BY LONGITUDINAL
FISSURE• CORTEX IS THE SURFACE LAYER• CORTEX COMPOSED OF GREY MATER• CORTEX THROWN INTO FOLDS –THE SULCI
CEREBRUM
• GYRI SEPARATED BY FISSURES OR SULCI• LARGE SULCI ARE USED TO SUBDIVIDE EACH
HEMISPHERES INTO LOBES---• FRONTAL LOBE• PARIETAL LOBE• OCCIPITAL LOBE• TEMPORAL LOBE
CEREBRUM
• CENTRAL CORE OF WHITE MATER• CONTAINS LARGE MASSES O0F GREY MATER• CORONA RADIATA—FAN SHAPED COLLECTION OF
NERVE FIBRES• CORONA RADIATA CONVERGES ON THE BASAL NUCLEI
AND PASSES B/W THEM AS INTERNAL CAPSULE• CAUDATE NUCLEUS IS MEDIAL TO INTERNAL CAPSULE• LENTIFORM NUCLEUS IS LATERAL TO INTERNAL
CAPSULE
CEREBRUM
• CAVITY OF CEREBRAL HEMISPHERES IS LATERAL VENTRICLE
• LATERAL VENTRICLE COMMUNICATES WITH THE 3rd VENTRICLE THROUGH INTERVENTRICULAR FORAMEN
MAJOR DIVISIONS OF PNS
• 12 PAIRS OF CRANIAL NERVES---LEAVE THE BRAIN AND PASS THROUGH THE FORAMINA IN THE SKULL
• 31 PAIRS OF SPINAL NERVES---LEAVE THE SPINAL CORD AND PASS THROUGH INTERVERTEBRAL FORAMINA
SPINAL NERVES
• EACH SPINAL NERVE IS CONNECTED TO THE SPINAL CORD BY TWO ROOTS---
• ANTERIOR ROOT—CONSISTS OF EFFERENT/MOTOR NERVE FIBRES CARRYING IMPULSES AWAY FROM THE CNS—CELL BODIES IN THE ANTERIOR GREY HORN OF SP CORD
• POSTERIOR ROOT---CONSISTS OF AFFERENT/SENSORY NERVE FIBRES CARRYING IMPULSES TO THE CNS-- CELL BODIES IN THE POST ROOT GANGLION
SPINAL NERVES
• EACH SPINAL NERVE IS AMIXED NERVE CONTAINING BOTH MOTOR AND SENSORY FIBRES
• IN THE UPPER CERVICAL REGION THE ROOTS ARE SHORT AND ALMOST HORIZONTAL
• LENGTH OF THE ROOTS INCREASES FROM ABOVE DOWNWARDS
• THE ROOTS OF LUMBER AND SACRAL NERVES FORM A VERTICAL LEASH CALLED THE CAUDA EQUINA
SPINAL NERVE• EACH SPINAL NERVE IS A SHORT TRUNK • AFTER EMERGING FROM THE INTERVERTEBRAL FORAMEN IT
DIVIDES INTO –• ANTERIOR RAMUS AND SUPPLIES THE MUSCLES AND SKIN OVER
THE ANTEROLATERAL BODY WALL • ANTERIOR RAMI JOIN ONE ANOTHER AT THE ROOT OF THE LIMBS
TO FORM NERVE PLEXUSES• CERVICAL AND BRACHIAL PLEXUSES AT THE ROOT OF UPPER
LIMB• LUMBER AND SACRAL PLEXUSES AT THE ROOT OF LOWER LIMB • POSTERIOR RAMUS –PASSES TO THE BACK AND SUPPLIES
THEMUSCLES AND SKIN OF THE BACK
SPINAL GANGLIA
• THEY ARE SENSORY GANGLIA• SITUATED ON THE POSTERIOR ROOT OF EACH
SPINAL NERVE• FUSIFORM SWELLINGS