Ascending Tracts Flashcards
where are sensory receptors
many diff receptors are scattered throughout the body
how can sensory receptors be activated
exteroceptive input
interoceptive input
proprioceptive input
interoceptive input
relays info about the body’s internal state
exteroceptive input
relays sensory info about the body’s interaction with the external environment
proprioceptive input
conveys info about position sense from the body and its component parts
what are the 3 different receptors able to detect
mechanical, chemical, nociceptive and thermal stimuli
what are sensory reception detection converted into
nerve impulses
sent to CNS
where are next level or progression further processed
ascending sensory pathways
where does the info from the ascending sensory pathways go
cerebral cortex or cerebellum
3 distinct ascending pathways
anterolateral system (ALS)
dorsal column-medial lemniscal (DCML)
somatosensory pathways to the cerebellum
Anterolateral system
also known as spinothalamic tract
sensory pathway from the skin to the thalamus
where is info from the ALS relayed
upward to the somatosensory cortex
2 main parts of the spinothalamic tract (STT)
lateral STT
anterior STT
anterior STT
transits crude touch
lateral STT
transmits pain and temp
where does the anterolateral pathway decussates
level of the spinal cord
usually crosses 1-2 levels above the point on injury
anterolateral pathway provides
affective sensation
affective sensation
sensation accompanied by a compulsion to act
ex: a painful stimulus makes us want to withdraw from the pain
dorsal column medial lemniscus
sensory pathway of the CNS
what does DCML convey
localized sensation of fine touch, vibration, two point discrimination, proprioception (position sense)
where does the DCML transmit info
from the body tot he postcentral gyrus of the cerebral cortex
DCML receptors are found
skin
joints
golgi tendon organs via 1b axons
muscles
muscle spindles
DCML receptors in the skin
hair follicles
Merkel’s cells
Meissner
Pacinian or ruffini corpuscles via Ab axons
DCML is composed of
gracile fasciculus
cuneate fasciculus
gracile fasciculus
lower half of the body
carried fibers up to T7
arise from the fibers more medial
cuneate fasciculus
upper half of the body
carries fibers from C6 and above
DCML fibers
rapidly conducting
large
myelinated
where does DCML decussate
medulla
testing the DCML clinically
romberg’s test
romberg’s test below decussation
produce loss of sensation on the same side of the body as the lesion
romberg’s test above decussation
produce loss of sensation on the opposite side of the body
spinocerebellar tract
a set of axonal fibers originating in the spinal cord and terminating in the ipsilateral cerebellum
spinocerebellar tract conveys info to
the cerebellum about limb joint position
proprioception
spinocerebellar tract receptors
muscle spindles
golgi tendon organs
joint receptors via Aa axons
