nervous sytem 1 Flashcards
key functions
- communication
- regulation of internal events
- behavioural organisation
- storage of information
- sensations, perceptions and emotions
- makes us who we are, and how we feel and move in the world
organisational arrangement- structural
central nervous system
- brain and spinal cord
peripheral nervous system
- spinal nerves and cranial nerves
functions
peripheral NS (left)
- sensory: somatic afferent and visceral afferents
central NS (centre)
- brain and spinal cord
peripheral NS (right)
- motor: somatic efferents and visceral efferents (autonomic NS)
- pre synaptic -> ganglion-> visceral efferents ( involuntary, eg heart)
central nervous system
brain- 1.5kg
cerebrum- gyri and sulci
cerebellum- controls movement, coordination.
brainstem- responsible for breathing and heart rate
function of parts of brain
- telencephalon- cerebrum
diencephalon- thalamus, hypothalamus - telencephalon+diencephalon= forebrain
- mesencephalon- midbrain ( vision, hearing, motor function, arousal state)
- hindbrain- development organisation
frontal, parietal, occipital, temporal lobes
- frontal: long term memory, speech, movement, personality
- parietal: sensory integration, language interpretation, spatial/visual perception.
- occipital: visual processing
- temporal: primary auditory cortex, memory, understanding language
neuron
- main part is called cell body, nucleus found and cytoplasm
-information is coming into the neurone by dendrite cells - information is passed by electrical impulses through the axon, insulated by the myelin sheath (composed of schwan cells) fatty
- node of ranvier speed up impulses as they pass along the axon
- travel down to the axon terminals, fibres.
glia cells
astrocytes- provide nutrients to neurons in the CNS
microglia- defence role, phagocytic
ependymal cells- involved in the production eg. cerebrospinal fluid
oligodendrocytes- neuronal support and myelin formation in the CNS
schwann cells- neuronal support and myelin formation in the PNS
spinal cord
- ## 7 cervical, 12 pairs of thoracic, 5 lumbar, 5 sacral and coccygeal
conus medullaris
- lower end of the spinal cord at L12
cauda equina
- nerve rootlets compromised at L2-L5
- as the spinal cord ends at L1/L2, cerebrospinal fluid can be extracted at this point from the subarachnoid space.
-The caudal equine sits in a place called the lumbar cistern which is a space formed by the subarachnoid space - it extends from the conus medullar is to S2
structure of spinal cord
dorsal horn- towards the back (posterior)
ventral horn- towards the front (anterior)
- afferent information enters the dorsal root ganglion ( where cell bodies are located) then to dorsal horn
- information can pass upwards to the brain and then back down
- information will be relayed either directly or from the brain into the ventral horn
- ventral roots- efferent information, information from nerves that exit the spinal cord
- efferent signals to muscles and glands via ventral roots
somatic sensory nuclei and somatic motor nuclei
- afferent information arrives to
- ## somatic motor nuclei, information leave to gp to the skeletal muscles towards (example)
visceral sensory nuclei and autonomic efferent nuclei
- taken information from organ and internal organs
- information about to leave from the spinal cord
vertebral column
- body of vertebra (round)
- spinous process (central spike)
- transverse processes ( left and right spikes)
- all these structures surround the vertebral foramen
- spinal cord places in the centre
- information comes in from the periphery into the dorsal aspect (may go straight across spinal cord or up to brain and back for processing)
- informations goes out through the ventral area and back into spinal nerves
meninges
- 3 layers that wrap around the brain and spinal cord
dura- thick membrane and made of dense irregular tissue ( periosteal= outer, meningeal= inner) - arachnoid- does not pass into the suci and pressed against the dura
- pia- innermost layer of meninges and is delicate and allows blood vessels to pass through and nourish the brain
subarachnoid space- blood vessels and arachnoid villus/villi - dura membrane sits in between the left and right cerebral hemispheres
- subdural space- sits above arachnoid mater, tightly adhered together
spinal nerves
- 7 cervical verterbra but 9 spinal nerves
- plexus- collection of nerves
- brachial pexus- set of nerves from C5-T1, supplies motor and sensory information from/to upper limbs
- thoraces nerves alongside thoracic vertebra, 12 of them
lumbar plexus- from L1-L5
sacral plexus- S1-S5
coccyx, 5 nerves
intervertebral foramen- passage for spinal nerves to exit, information comes out
spinal nerves function
- each spinal nerve contains many sensory and motor axons
- the axons supply structure in a well defined part of the body
- for sensory neurone these regions are called dermatomes
- the motor axons supply blocks of muscle called myotomes
dermatomes
- C1 does not have may dorsal ( sensory) root, has no dermatome associated with it, only has motor root with supplies the neck muscles.
peripheral neuron system
- psuedonipolar neuron- has 1 extension from its cell body, and splits into 2 branches- one goes peripherally and the other centrally
multipolar neurons- single axon and many dendrites, typically motor neurone
automatic multi0polar neuron- synapses between 2 neuron’s
nerves of PNS
somatic multipolar motor- voluntary control of body
lateral grey horn- sympathetic nervous system will come off in the spinal cord, specifically from T1-L2
- presynaptic neuron: sends signals to postsynaptic nerve across synapse
-post synaptic neuron:
cranial nerves
- 12 pairs
- connected to the brain and brainstem
- provide sensory and motor supply to head and neck structures
names cranial nerves (PNS)
- olfactory- small
- optic- vision
- oculomotor-eye movement
- trochlear- eye movement
- trigeminal- motor to muscles of mastication and general sensory to the face
- abducens- eye movement
- facial- muscles of facial expression
- vestibulocochlear- hearing and balance
- glossopharyngeal- swallowing, taste
- vagus- wandering nerve around heart, lung, gut
- spinal accessory- neck muslces
- hypopglossal- muscle of tongue
somatic nervous system and autonomic nervous system
somatic nervous system- somatic sensory system, somatic motor system
autonomic nervous system- visceral afferent fibres and visceral efferent fibres: sympathetic (thoracolumbar T1-L2) parasympathetic (craniosacral S2-4)
