Unit 5.2: spinal cord - internal structures Flashcards
sensory info _____ the cord
motor info _____ the cord
- goes up
- goes down
there are more ____, ____ pathways than ____, ____ pathways
more ascending, sensory than descending, motor
bundle of axons INSIDE the CNS
tract
bundle of axons OUTSIDE the CNS
nerves
motor/descending pathways AKA
efferent pathways
E-fferent; E-xiting the CNS
sensory/ascending pathways AKA:
afferent
A-fferent; A-scending to the CNS
what two main tracts make up the efferent/descending pathways?
- pyramidal
- extrapyramidal
what are the pyramidal tracts responsible for?
the vast majority of motor function
primarily voluntary movement
what are the extrapyramidal tracts responsible for?
lies outside the pyramidal tracts
accessory motor pathways that coordinate complex tasks
involuntary control; helps us “fine-tune” our motor commands
what 3 main tracts make up the afferent/ascending pathways?
- dorsal column tracts
- spinocerebellar tracts
- anterolateral system AKA spinothalamic tract
what is the dorsal column medial lemniscal system responsible for?
located in the dorsal spinal cord
touch/perception/pressure sensors
passes through the medial lemniscus
what is the anterolateral system responsible for?
has 2 parts: 1. anterior and 2. lateral; hence anterolateral
AKA spinothalamic tract because it transmits info from spinal cord to the thalamus; hence, spinothalamic
transmits pain information
what is Rexed’s laminae?
the spinal cord’s gray matter nomenclature system which are labeled from most dorsal to most ventral
Lamina I
aka lamina marginalis (on the margin)
sharp pain; “fast” pain
A-delta pain - myelinated neuron fibers
Lamina I, II, III, and V’s horizontal pathway to:
anterolateral spinothalamic pathway
Laminae II & III
AKA substantia gelatinosa
slow pain
C-fibers (nociceptors are unmyelinated) – this is why this is termed “slow pain” pathway
has a synaptic connection with Lamina V
Laminae I - VI
have mechanoreceptors (pressure sensors)
pain sensory
Lamina VII - IX
VII: intermediolateral nucleus
large motor neurons
lamina X
cross talk relay section of grey matter
categorize the 5 different spinal tracts
- spinocerebellar tracts
- dorsal-column medial lemniscal system
- spinothalamic tracts
- corticospinal tracts (AKA pyrdamidal tracts)
- extrapyramidal tracts
characterize the DCML pathway
- very fast signal propogation (all A fibers with all subunits)
- fine vibrations
- fine pressure
- cross over at medulla
what is meant by “cross over” in the DCML pathway?
typically the sensory information sent from the left hemisphere of the brain will cross over in the medulla to take care of the right side of the body’s motor function & vice versa
the further up the spinal cord you get, the _____ the DCML is
wider
where does the doral column gather lower extremity sensory information?
Fasiculus gracilis
the gracilis muscle is in the leg