central nervous system Flashcards
what is the CNS composed of
the brain and spinal cord
what is the brain comprised of
forebrain
midbrain
hindbrain
what does the forebrain include
cerebral hemispheres and the diencephalon
what does the hindbrain include
pons
medulla
cerebellum
what are the different lobes of the brain
frontal
parietal
temporal
occipital
what does the frontal lobe do
regulating and initiating motor function, language, cognitive functions (executive function - eg planning)
attention and memory
what does the parietal lobe do
involved in sensation (touch, pain)
sensory aspects of language
spatial orientation
self perception
what does the temporal lobe do
processes auditory info
what does the occipital lobe do
processes visual info
what does the limbic lobe include
amygdala
hippocampus
mamillary body
cingulate gyrus
what does the limbic lobe do
concerned with learning, memory, emotion, motivation and reward
where does the insular cortex (lobe) lie
deep within lateral fissure
what does the insular cortex do
concerned with visceral sensations, autonomic control
interoception
auditory processing
visual vestibular integration
how many layers of meninges are there
3
dura mater
arachnoid mater
pia mater
what are the 2 layers the dura mater is composed of
2 thick layers
periosteal (layer of periosteum) and meningeal (durable, dense fibrous membrane)
what is the arachnoid mater
thin, transparent, fibrous membrane
what is the pia mater
thin, translucent and mesh like
where is CSF produced
in the choroid plexus of lateral 3rd and 4th ventricles
what does CSF occupy
ventricular system and subarachnoid space
how is CSF reabsorbed
via arachnoid villi (granulations) into superior sagittal sinus
features of CSF
lower pH
less glucose, protein and potassium than plasma
the spinal cord is composed of 5 segments which are
cervical thoracic lumbar sacral coccygeal
how many pairs of mixed spinal nerves in each
cervical - 8 thoracic - 12 lumbar - 5 sacral - 5 coccygeal - 1
where do nerves emerge through
intervertebral foramina
where do nerves C1-7 emerge
above vertebrae
where do nerves C8-C01 emerge
below vertebrae
what do cervical enlargements innervate
upper limbs
what do lumbar enlargements innervate
lower limbs
what is the major descending pathway for voluntary movement
corticospinal tract
what is the corticospinal tract composed of
upper motor neurones in primary motor cortex and lower motor neurones in brainstem and spinal cord
what is the major ascending pathway for sensation
dorsal column pathway and spinothalamic tract
what is the dorsal column pathway for
fine touch, vibration and proprioception (position) from the skin and joints
what is the spinothalamic pathway for
pain
temperature and crude touch from the skin
what are the two branches of the spinothalamic tract called
ventral and lateral
lateral (pain and temp)
ventral (crude touch)
what are the 4 brainstem motor tracts
vestibulospinal
tectospinal
reticulospinal
rubrospinal
what does the vestibulospinal tract do
provides information about head movement and position and mediates postural adjustments
what does the tectospinal tract do
orientation of the head and neck during eye movement
what dies the reticulospinal tract do
preparatory and movement related activities, postural control
what does the rubrospinal tract do
innervate lower motor neurons of the upper limb
what are the 2 principal ascending pathways
dorsal (posterior) column pathway
mechanical - fine discriminative touch, pressure, vibration, proprioception
spinothalamic pathway
mechanical, chemical and thermal - crude touch, pain and temp
explain the dorsal column pathway
fibres enter via the dorsal horn and enters the ascending dorsal column pathways
info is conveyed from lower limbs and body (below T6) travelling ipsilaterally along the gracile tract
info is conveyed from upper limbs and body (above T6) and travels ipsilaterally along the cuneate tract
where is the first synapse of the gracile tract
in the gracile nucleus
where is the first synapse of the cuneate tract
in the cuneate nucleus
where do 2nd order axons decussate and what do they form
in the caudal medulla
form the contralateral medial lemniscus tract (synapse in the thalamus)
where do 3rd order neurons from the thalamus project to
the somatosensory cortex
size of the somatotopic area is proportional to density of sensory receptors in that body region (somatosensory homunculus)
where do primary afferent axons terminate
upon entering the spinal cord
where do 2nd order neurons terminate
in the thalamus
where do 3rd order neurons from the thalamus project to
somatosensory cortex
