central nervous system the spinal cord. functions of the spinal cord conducts nerve impusles to and...
TRANSCRIPT
CENTRAL NERVOUS SYSTEM
THE SPINAL CORD
FUNCTIONS OF THE SPINAL CORD
• CONDUCTS NERVE IMPUSLES TO AND FROM THE BRAIN
• PROCESSES SENSORY INFORMATION (LIMITED)
DEVELOPMENT OF SPINAL CORD
• UNTIL THIRD FETAL MONTH, SPINAL CORD IS AS LONG AS THE VERTEBRAL COLUMN
• VETERBRAL COLUMN GROWS FASTER
FILIUM TERMINALE
CONUS MEDULLARIS
SPINAL NERVES
• 31 PAIRS
• CERVICAL
• THORACIC
• LUMBAR
• SACRAL
• COCCYGEAL
CAUDA EQUINA
CERVICAL ENLARGEMENT
• INFERIOR CERVICAL REGION
• GIVES RISE TO SPINAL NERVES THAT SERVE UPPER LIMBS
LUMBAR ENLARGEMENT
INFERIOR THORACIC
SUPERIOR LUMBAR REGIONS
GIVES RISE TO SPINAL NERVES THAT SUPPLY LOWER LIMBS
SPINAL CORD IN CROSS-SECTION
• ANTERIOR MEDIAN FISSURE
• POSTERIOR MEDIAN SULCUS
MENINGES OF THE SPINAL CORD
• DURA MATER
• ARACHNOID MATER
• PIA MATER
• DENTICULATE LIGAMENTS
SPINAL CORD COMPOSITION
• WHITE MATTER
• GRAY MATTER
GRAY MATTER OF THE SPINAL CORD
• GRAY COMMISSURE
• CENTRAL CANAL
• DORSAL/POSTERIOR HORNS
• VENTRAL/ANTERIOR HORNS
ROOTS OF SPINAL NERVES
• DORSAL
• VENTRAL
DORSAL ROOTS
• ENTER SPINAL CORD AT TIPS OF POSTERIOR HORN
DORSAL ROOT GANGLIA
• SPINAL GANGLIA
VENTRAL ROOTS
• LEAVE SPINAL CORD AT TIPS OF ANTERIOR HORN
• MOTOR
SPINAL NERVE
• FORMED BY FUSION OF DORSAL AND VENTRAL ROOTS
WHITE MATTER
• COMPLETELY SURROUNDS THE GRAY MATTER
DIRECTION OF TRAVEL
• UP THE SPINAL CORD TO HIGHER LEVELS OR THE BRAIN
• DOWN THE SPINAL CORD FROM BRAIN OR HIGHER LEVELS
• ACROSS THE CORD, FROM ONE SIDE TO THE OTHER
AREAS OF THE WHITE MATTER
• POSTERIOR FUNICULUS
• LATERAL FUNICULUS
• ANTERIOR FUNICULUS
TRACTS OR FASCICULI
• ASCENDING-SENSORY
• DESCENDING-MOTOR
ASCENDING TRACTS
• SENSORY
TYPES OF NEURONS
• FIRST ORDER
• SECOND ORDER
• THIRD ORDER
FIRST ORDER NEURON
• PERIPHERAL PORTION OF ITS NERVE FIBER IN SPINAL CORD
• CELL BODY IN DORSAL ROOT GANGLION
SECOND ORDER NEURON
• CELL BODY LOCATED IN SPINAL CORD OR MEDULLA
• CONNECTS FIRST ORDER WITH CELL BODY OF THIRD ORDER
THIRD ORDER NEURON
• CELL BODY LOCATED IN THE THALAMUS
• CONNECTS TO CEREBRAL CORTEX
DECUSSATION OF SENSORY INPUT
• CROSS AT LEVEL OF ENTRY
• CROSS A FEW SEGMENTS ABOVE
• CROSS IN THE MEDULLA
MAJOR ASCENDING TRACTS
• FASCICULUS GRACILIS
• FASCICULUS CUNEATUS
• SPINOTHALAMIC TRACTS
• SPINOCEREBELLAR TRACTS
FASCICULUS CUNEATUS
• LATERAL TO FASCICULUS GRACILIS
• UPPER LIMBS, TRUNK AND NECK
• PROPRIOCEPTION
• FINE TOUCH LOCATION
• TERMINATES IN NUCLEUS CUNEATUS
FASCICULUS GRACILUS
• MEDIAL TO FASCICULUS CUNEATUS
• LOWER LIMBS
• PROPRIOCEPTION
• FINE TOUCH LOCATION
• TERMINATES IN NUCLEUS GRACILIS
MEDIAL LEMNISCUS
SPINOTHALAMIC TRACTS
• SYNAPSE IN THALAMUS
• LATERAL SPINOTHALAMIC
• ANTERIOR SPINOTHALAMIC
LATERAL SPINOTHALAMIC TRACTS
• PAIN • TEMPERATURE
ANTERIOR SPINOTHALAMIC TRACTS
• TOUCH
• PRESSURE
SPINOCEREBELLAR TRACTS
• POSTERIOR CEREBELLAR TRACTS
• ANTERIOR SPINOCEREBELLAR TRACTS
• PROPRIOCEPTION• SYNAPSE IN
CEREBELLUM
DESCENDING TRACTS
• MOTOR
• PYRAMIDAL TRACTS
• EXTRAPYRAMIDAL TRACTS
PYRAMIDAL TRACTS
• CORTICOSPINAL TRACTS
• UPPER MOTOR NEURONS
• LOWER MOTOR NEURONS
• LATERAL CORTICOSPINAL TRACTS
• ANTERIOR CORTICOSPINAL TRACTS
EXTRAPYRAMIDAL TRACTS
• RUBROSPINAL TRACTS
• VESTIBULOSPINAL TRACTS
• TECTOSPINAL TRACTS
• OLIVOSPINAL TRACTS
• FUNCTIONS OVERLAP
• MODIFY CONTRACTIONS DEALING WITH POSTURE AND BALANCE
RUBROSPINAL TRACT
VESTIBULOSPINAL TRACT
TECTOSPINAL TRACT
OLIVOSPINAL TRACT
SPINAL REFLEX ARC
COMPONENTS OF A SPINAL REFLEX ARC
• RECEPTOR• SENSORY (AFFERENT) NEURON• INTEGRATING CENTER• MOTOR (EFFERENT) NEURON• EFFECTOR
MONOSYNAPTIC VS POLYSNAPTIC
STRETCH REFLEX
• PATELLAR REFLEX• RECIPROCAL
INHIBITION• RECIPROCAL
INNERVATION
PATELLAR REFLEX
TENDON REFLEX
NEURON POOLS
SPINAL DYSFUNCTIONS
• PARALYSIS
• LESIONS OF THE SPINAL CORD
• TABES DORSALIS
• POLIOMYELITIS
• SYRINGOMYELIA
• MULTIPLE SCLEROSIS
PARALYSIS
• MONPELEGIA
• DIPLEGIA
• PARAPLEGIA
• HEMIPLEGIA
• QUADREPLEGIA
COMPLETE TRANSECTION
• CORD IS SEVERED COMPLETELY
• ALL SENS
• ORY AND MOTOR FUNCTION BELOW IS LOST
• EXTENT OF PARALYSIS DEPENDS ON LEVEL WHERE TRANSECTION OCCURS
HEMISECTION
• PARTIAL TRANSECTION– ON ONE SIDE OR OTHER
FLACCID VS SPASTIC PARALYSIS
• FLACCID
• NO MOVEMENT
• SPASTIC
• EXAGGERATED, UNCONTROLLED MOVEMENTS
EFFECTS OF LESIONS IN THE SPINAL CORD
• DAMAGE IS LOCATED BY IDENTIFYING COMBINATIONS OF LOSS OF FUNCTION
POLIOMYELITIS
• VIRAL DISEASE• DESTROYS MOTOR NERVE CELL BODIES
IN ANTERIOR HORNS• ESPECIALLY IN CERVICAL AND LUMBAR
ENLARGMENTS• CAN LEAD TO RESPIRATORY OR HEART
FAILURE IF VIRUS INVADES NERVE CELLS IN MEDULLARY CENTERS
TABES DORSALIS
• SEQUELAE OF SYPHILIS
• POSTERIOR FUNICULI AND DORSAL ROOTS DEGENERATE
• ATAXIA
SYRINGOMYELIA
• SMALL FLUD FILLED CYSTS FORM IN GRAY MATTER OF SPINAL CORD, BRAIN STEM
• EPENDYMAL CELLS IN CENTRAL CANAL PROLIFERATE
• PRODUCES SENSORY DYSFUNCTIONS
• MOTOR WEAKNESS
• MUSCLE ATROPHY
MULLTIPLE SCLEROSIS
• CHRONIC DESTRUCTION OF MYELIN SHEATHS
• PLAQUES INTERFER WITH NORMAL NERVE TRANSMISSION
• AUTOIMMUNE DISORDER• VIRUS MAY TRIGGER• SYMPTOMS VARY DEPENDING ON
WHERE DAMAGE OCCURS
ENCEPHALITIS VS MYELITIS
MENINGITIS
• INFLAMMATION OF MENINGES
• CAUSES MAYBE FUNGAL, BACTERIAL AND VIRAL