ascending pathways Flashcards
what cranial nerves carries taste
VII and IX (facial and glossopharyngeal)
what is interoception
pain, temperature, touch pressure of viscera
what is exteroception
pain, temperature, touch pressure of external world
what is proprioception
postition sense from joints/tendons/ligaments
what do nociceptors detect
monitor tissure damage
what do thermoreceptors detect
monitor temperature and hypothalamus
what do mechanoreceptors detect
contact and pressure
what do chemoreceptors detect
chemical composition of body fluids
what do baroreceptors detect
changes in pressure of tubular organs
where is the primary motor cortex
precentral sulcus (in frontal lobe)
where is the primary sensory cortex
postcentral gyrus (parietal lobe)
what is a dermatome
an area of skin supplied by a particular spinal nerve
how many dermatomes are in the body
31 dermatomes - 31 spinal segments
where is the first neuron between the peripheral receptor and the cerebral cortex.
enters the spinal cord through the dorsal root of a spinal nerve and its cell body lies in the dorsal root ganglion.
where does the first order neuron end
terminates in synaptic contact with the 2nd neuron either in the spinal gray matter or in the medulla oblongata
what is the function of the first order neuron
makes synaptic connections that mediate spinal reflexes
receive impulses from skin and proprioceptors and send them to the spinal cord
where is the second order neuron
has its cell body in the cord or medulla oblongata.
describe the path of the second order neuron
Its Axon crosses over to the opposite side of the CNS and ascends to the thalamus where it terminates upon the third neuron.
describe the path of the third neuron
has its cell body in the thalamus its Axon passes to the somatosensory cortex in the parietal lobe of the ipsilateral cerebral hemisphere.
what are the two paths of the sensory tract of the spinal cord
the dorsal posterior column and the medial lemniscus
where does the dorsal column run
from spinal cord to medulla
where does the medial lemniscus pathway run
from the medulla to the cortex (continuation of dorsal column)
what are the two tracts of the dorsal columns
the fasciculus gracilis situated medially and the fasciculus cuneatus situated laterally
where is the dorsal column located
between the dorsal median sulcus and the dorsal horn.
what do the tracts of the dorsal column carry
carry impulses concerned with proprioception and discriminative touch.
The dorsal columns contain primary afferent neurons they carry information relating to the ipsilateral side of the body
where does the fasciculus gracilis enter the spinal cord
that join the cord at sacral lumbar and lower thoracic levels and thus includes those from the lower limb.
where does the the fasciculus cuneatus enter the spinal cord
via the upper thoracic and cervical dorsal roots and thus involve those from the upper limb.
what information does the spinothalamic tract carry
to pain and thermal sensations and also non discriminative touch and pressure.
Interoception, exteroception and proprioception from trunk and limbs are delivered to the CNS by ________
first order neurons (PNS) to the spinal cord.
describe the path of Pain, temperature and crude touch pathways
decussate in the spinal cord and ascend contralaterally via the STT to the primary somatosensory cortex.
describe the path of Tactile and proprioceptive pathways
ascend ipsilaterally via the fasciculus gracilis and the fasciculus cuneatus before decussating in the brainstem to ascend contralaterally to the primary somatosensory cortex.
what does the Trigeminothalamic tract provides somatic sensation to
face and head
where is the trigeminal ganglion
convergence of the ophthalmic, maxillary and mandibular nerves.
where does the chief sensory nucleus lie
the pontine tegmentum close to the entry of the trigeminal nerve.
what is the function of the chief sensory nucleus
. It mediates fine touch stimuli, joint position and vibration.
what is the function of the spinal nucleus
It mediates pain and temperature.
where does the trigeminal sensory nucleus run
extends throughout the length of the brain stem and into the upper cervical spinal cord.
what is the spinal nucleus
the nucleus of the spinal tract of the trigeminal
Proprioceptive afferents from the muscles of mastication and the temporomandibular joint have their cell bodies in the ______
mesencephalic nucleus of the trigeminal
what are the only primary afferents to have their cell bodies located within the CNS
afferents from the muscles of mastication and the temporomandibular joint
Axons of 2nd order neurons in the trigeminal nucleus decussate to form the _______
contralateral trigeminothalamic tract to the ventroposteromedial (VPM) nucleus of the thalamus.
3rd order neurons in the thalamus project to the _______
postcentral gyrus i.e. primary sensory cortex.
what is syringomyelia
disrupts the decussating fibres of the spinothalamic system
