Nervous System Flashcards
What is the somatic nervous system
- somatic sensory- pain, temperature, touch, pressure, special sense
-somatic motor to skeletal muscle
What is the autonomic nervous system
-made up of sympathetic nervous system and parasympathetic nervous system
-no concious control
-visceral sensory- from organs and blood vessels
-motor to smooth and cardiac muscles and many glands
What is your central nervous system
-brain and spinal cord only
-co ordinates and integrates incoming and outgoing neural signals eg thinking and learning
What is your peripheral nervous system
-conduct neural impulses from the external environment to or form CNS to co ordinate a response
How many pairs of cranial nerves in the peripheral nervous system
12 pairs of cranial nerves
How many pairs of spinal nerves in the peripheral nervous system
31 pairs of spinal nerves
What are the pairs of 31 spinal nerves in the peripheral nervous system
-12 pairs of thoracic
-8 pairs of cervical
-5 pairs of sacral
-5 pairs of lumbar
-1 pair of coccygeal
How many lobes are there in each hemisphere of the brain
Frontal, parietal, temporal, occipital
Telencephalon
Cerebrum
Diencephalon
Thalamus and hypothalamus
Mesencephalon
Midbrain
Rhombencephalon
Cerebellum, pons, medulla oblong tea
Cerebral convolutions
-gyrus
-sulci
-grey matter
-white matter
What is gyri
The folds in the brain
What is sulci
The grooves in the brain
What is the grey matter of the brain
Outside of the brain
What is the white matter of the brain
Inside of the brain
Frontal lobe
-motor cortex (where all aspects of motor function originate)
-intellect
-planning
-mood
-socialo judgment
Parietal lobe
-processing sensory information
-general sensation but mainly taste
-somatosensory cortex
Temporal lobe
-auditory cortex
-memory
Occipital lobe
-visual cortex is situated in occipital lobe
Where’s is Broca’s area and winickes area located
Dominant hémisphère
What does the corpus callosum do
Links the two cerebral hemispheres together
What is the thalamus
The main sensory relay centre
What does the hypothalamus do in the sagittal section
Hormone secretion, interpretations centre for ANS, thermorégulation, hunger and satiety centres, thirst centres
Hindbrain cerebellum
-lies posterior to the brain stem
-involved in the maintenance of balance, posture, muscle tone
-co ordinated movement
Brain stem
- contains ascending and descending nerve fibre tracts
- contains vital centres such as cardiovascular and respiratory centres
- pons and medulla and mid brain all part of the brain stem
-pons is between these two
-medulla oblong is the most inferior structure of the brain stem
Spinal cord
-continuous with the brain stem
-lies within the verbral canal
-terminates the conus meduallaris at the venerable level L1-2
-spinal nerves passing through vertebral canal below this level from cauda equina
-cervical and lumbar enlargements- nerves arise to supply upper and lower limbs
What is the white part of the spinal cord segments
-outside part
-contains axons of ascending and descending neurones
-ascending neurones are the sensory neurones telling the spinal cord about the external environment
-descending are telling the muscle to contract
What is the grey matter of the spinal cord
-contrains nerve cell bodies
-inside part
-regions:
-dorsal horn(sensory neurones)
-ventral horn (motor neurones)
-lateral horn (autonomic neurones)
What does the dorsal root do
Carries sensory fibres to the spinal cord
What does the ventral root do
Carries motor fibres away from the spinal cord
What do the dorsal and ventral roots do together
Unite to form the spinal nerve which exits the veterbral column
Spinal nerves divide into the dorsal and ventral rami
What does the dorsal ramus do
Carries sensory and motor fibres to muscles and skin over the vertebral column
What does the ventral ramus do
Carries sensory and motor fibres which supply the upper and lower limbs and trunk
What does the dorsal root ganglion do
Contains nerve cell bodies of primary sensory neurones
Protection of the CNS
-brain and spinal cord perform essential functions but are fragile
-they are protected and supported by the connective tissues: the meninges
-and the bone, skull, and vertebral column
Protection of the spinal cord
-spinal cord lies in the vertebral canal protected by the vertebral column
-surrounded by the meninges three layers
-dura matter, arachnoid matter, pita matter
-the space between the arachnoid and pia matter contains cerebrospinal fluid
What are the 3 layers of meninges
Dura matter
Arachnoid matter
Pia matter
What is the meninges
Spaces
Actual space- inside of a balloon
Potential space- inside of a deflated balloon
Potential space can fill with fluid or blood
What is the dura matter
- outermost layer
-toughest membrane
-made of collagenous connective tissue
-the dural sheaths of cranial nerves fuse with the dura that surrounds the brain
-2 layers of cranial dura (inner meningeal layer- continuous with spinal dura. Outer periosteal layer- not found around spinal cord)
What are the four folds of dura matter
Four folds of dura matter:
Flax cerebi- between cerebral hemispheres
Flax cerebelli-between cerbrellas hemispheres
Tentorium cerebelli- between cerebellum and occipital lobe
Diaphragmatic sella- covers sella trucida
What are dural reflections
-four folds of dura matter
-stabilise Braine-prevents rotation
-dural sinuses are venous channels which lie between the dural folds, they drain cerebrospinal fluid and venous blood from the brain
Dural venous sinuses
-superior sagittal sinus
-inferior sagittal sinus
-between periosteal and meningeal layers of dura
-drains blood and cfs from brain
-contains no valves
-receives tributaries from the brain and ear etc
-drains to internal jugular vein
Arachnoid matter
-looks like a spiders web
-delicate
-transparent
-impermeable
Subarachnoid space and csf
-subarachnoid space traversed by cranial nerves and arteries of brain
-cfs in subarachnoid space
-cfs maintains balance of extra cellular fluid in the brain, provides nutrients for it, carries away metabolic wastes and cushions the brain
-arachnoid granulation allow csf to transfer to venous system
Pia matter
-delicate loose connective tissue membrane that follows contours of brain and spinal cord
-adheres closely to the surface of the brain and spinal cord
What are the ventricles
-choroid plexuses of ventricles produce csf
-paired lateral ventricles and single midline ventricles
-lateral ventricle inferior to corpus callosum
-interventricular foramen from lateral to third ventricle
How is the brain supplied with blood
Internal carotid and vertebral arteries
Anterior cerebral
Passes forward in a longitudinal fissure and back over corpus collosum to supply the medial surface of hemispheres form frontal to occipital lobe and a strip on upper lateral surface
Middle cerebral
Passes in lateral fissure to supply lateral surfaces of parietal, frontal and temporal lobes
Posterior cerebral
Passes around the midbrain to supply medial and inferior surfaces of the temporal lobes and occipital lobes
How does a cardiovascular accident (stroke) happen
-blood supply to brain cut off> cells in affected area do not receive oxygen> cells die> may cause permanent damage
What is an ischeamic stroke
Blood vessel blocked (thrombin or embolus)
What is an heamorrhagic stroke
Blood vessel ruptures which may be due to an aneurism. Bleeding into surrounding tissue compounds the problem
What are 4 causes of raised intercranial pressure
-inflammation
-trauma- inflammatory response leads to cerebral oedema
-meningitis- bacterial or viral infection of the meninges
-haemorrhage- blood from ruptured vessels will collect in the cranial cavity
What happens when there is raised intercranial pressure
-if pressure within the cranium rises there is no means of escape
-compression of the brain causes cell death
-clinical consequences will depend on the area affected
What is a intercranial haemorrhage (epidural)
Blood collects between dura matter and skull. May happen following blow to head leading to rupture of middle meningeal artery
What is an intercranial haemorrhage (sub dural)
Blood collects between dura matter and arachnoid matter
May happen following blow to head when brain is jerked inside the skull and a cerebral vein is ruptured as it enters the superior saggital sinus
What is an intercranial haemorrhage (subarachnoid)
Blood collects between arachnoid matter and pia matter
May happen following rupture on an aneurism
What is an intercranial haemorrhage (cerebral)
Bleeding into brain tissue. May happen following trauma or from ruptured cerebral vessel
What can happen when there is an occlusion in the anterior cerebral artery
Sensory and motor loss to contra lateral (opposite) lower limb
What can happen when there is Occlusion in the middle cerebral artery
Potential signifiant damage to speech, language, hearing loss, motor and sensory loss of control lateral upper limb
What can happen when’re there is occlusion in posterior cerebral artery
Loss of division on one side
What is a neurone
Nerve cell
What does a neurone do
-basic functional unit of the nervous system
-relays different information between different regions of the CNS
CNS and PNS
CNS and other body systems
what is a dendrite
Collects information and increases surface areas
Body of the neurone
Contains nucleus and organelles and synthesizes proteins eg neurotransmitters
Axon of a neurone
Propagates the action potential and may be myelinated (faster) or unmeylinated (slower)
Terminal bouton
Site of synapse (with another neurone or muscle cell)
Neuro transmitter is released here
What is the dermatome of the somatosensory system
Skin area which connects to the spinal cord through a single dorsal root of a spinal nerve
What do the 3 neurones do in the sensory (afférent) pathway
1)receptor in periphery, cell body in dorsal root ganglion or sensory ganglion in head
Remains ispilateral and terminates in a spinal cord or medulla
2)cell body in spinal cord or medulla axon decussates (change side) and terminates in the contralateral thalamus
3) cell body in thalamus, axon terminates in cerebral cortex . Each first order neurone responds to a stimulus which activates its own area
How do receptor fields differ
Spatially- some larger and smaller
Temporally-some only indicate stimulus onset/ offset, other continuously when stimulated
What does the motor pathway do
Causes skeletal muscles to contract
Motor pathway process
-nerve arises in the pre central gyrus
-passes down into brain stem
-decussates into brain stem or other side of spinal cord
-terminates by synapsing with the lower motor neurone in the brain stem (cranial nerves) or ventral horn of spinal cord (spinal nerves)
-lmn arises in brain stem (cranial nerves) or the ventral horn of the spinal cord (spinal nerves)
-axons projects to effector (skeletal muscle)
What are the two motor neurones in the pathway
-upper motor neurone (can either synapse directly onto or several)
-lower motor neurone
What cranial nerves are involved in the parasympathetic nervous system
3,5,7,11
Ocuolotmotor, vagus, facial, glossopharyngeal
I cranial nerve
Olfactory
Smell
Sensory
II cranial nerve
Optic nerve
Vision
Sensory
III cranial nerve
Oculomotor
Pupil constriction eye movement etc
Motor
V cranial nerve
Trigeminal
Sensation to face and muscles
Both sensory and motor
IV cranial nerve
Trochlear
Moves eye down and inwards
Motor
VI cranial nerve
Abducens
Moves eye laterally
Motor
VII cranial nerve
Facial
Facial expression, anterior 2 thirds of tongue and salivary glands
Both
VIII cranial nerve
Vestibulocochlear
Leaning and balance
Sensory
IX cranial nerve
Glossopharyngeal
Sensation to posterior 1/3 of tongue and swallowing
Both
X cranial nerve
Vagus
Parasympathetic supply to eye, heart, lungs, larynx
Both
XI cranial nerve
Accessory
Moves head lifts shoulders
Motor
XII cranial nerve
Hypoglossal
Supplies tongue muscles
Motor
