Nervous System Tracts Flashcards
Ascending tracts send what kind of information
sensory
Ascending tracts
cuneocerebellar
fasciculus cuneatus (posterior or dorsal column)
fasciculus gracilis (posterior or dorsal column)
spinocerebellar tract (dorsal and ventral)
spino-olivary tract
spinoreticular tract
spinotectal tract
spinothalamic tract (anterior)
spinothalamic tract (lateral)
Cuneocerebellar tract
ipsilateral subconscious neck and UE
Fasciculus cuneatus (dorsal column)
trunk, neck and UE sensory, proprioception, vibration, 2-point discrimination and graphesthesia
Graphesthesia
ability recognize writing on skin
Fasciculus gracilis
sensory for trunk, LE proprioception, 2-point discrimination, vibration and graphesthesia
Spinocerebellar tract
sensory for cerebellum for ipsilateral subconscious proprioception, tension in muscles, joint sense, and posture of trunk and LE
Spino-olivary tract
ascends to cerebellum
relays info from cutaneous and proprioceptive organs
Spinoreticular tract
influences levels of consciousness
Spinotectal tract
spinovisual reflexes and assists with eye movement and head towards a stimulus
Spinothalamic tract (anterior)
crude touch and pressure
Spinothalamic tract (lateral)
pain and temperature
Descending tracts involved in
voluntary motor function, muscle tone, reflexes and equilibrium, visceral innervation and modulation of ascending sensory signals.
Largest descending tract….originates where?
corticospinal
cerebral cortex
Smaller descending tracts originate where?
midbrain
pons
medulla
Primary descending tracts
corticospinal anterior and lateral
reticulospinal
rubrospinal
tectospinal
vestibulospinal
Corticospinal (anterior)
ipsilateral voluntary, discrete and skilled movement
Discrete movement
recognizable beginning and end
reaching, grasping, throwing
Corticospinal (lateral)
contralateral voluntary fine movement
Damage to lateral corticospinal tract results in…
positive Babinski sign
absent superficial abdominal reflexes
cremasteric reflex and loss of fine motor skills or skilled voluntary movement
Cremasteric reflex
in males
stroking inner thigh causing cremasteric muscle to contract and pull up ipsilateral testicle
Reticulospinal tract
facilitation or inhibition of voluntary and reflex activity through influence on alpha and gamma motor neurons
Rubrospinal tract
gross postural tone
facilitating activity of flexor muscles and inhibiting activity of extensor muscles
Tectospinal tract
contralateral postural muscle tone associated with auditory/visual stimuli
Vestibulospinal tract
ipsilateral gross postural adjustments to head movements
facilitating activity of extensor muscles and inhibiting activity of flexor muscles
Damage to vestibulospinal tract
significant paralysis, exaggerated deep tendon reflexes, clasp-knife reaction
Brown-Sequard’s syndrome
paralysis and loss of vibratory sense and position sense on the same side as the lesion due to damage in corticospinal tracts and dorsal columns.
loss of pain and temp sense on opposite side due to the damage of lateral spinothalamic tract
Sympathetic nerves originate in which horn of spinal cord and where?
lateral of thoracic
Parasympathetic nerves originate from lateral…. of the ….level of the spinal cord and the brain itself.
gray matter
sacral
Dendrites …
receive signals from other neurons
Endoneurium
innermost covering the surrounds each individual axon
Epineurium
outermost covering surrounds entire nerve and provides buffer for the peripheral nerve
Perineurium
middle layer the covers groups of axons and maintains blood-nerve barrierS
Saltatory conduction
jumping from node to node; decreases the use of sodium-potassium pumps and increases speed of conductin
A fibers are
large
myelinated
high conduction rate
alpha, beta, gamma subsets
B fibers are
medium
myelinated
reasonably fast
preganglionic fiber of the autonomic system
