ASCENDING TRACTS
Receptors and
afferents
1st order
neuron
2nd order
neuron
Decussation
level
Fine touch,
pressure,
vibration,
movement,
position,
Pain,
temperature
Highly specialized
mechanoreceptors
Dorsal root
ganglia
Fasciculus gracilis
(T6 or lower)
Fasiculus
cuneatus (above
T6)
Lamina I and V
(nuc
posteromarginalis,
nuc proprius)
Cross midline at
medulla 
medial
leminiscus
VPL
(thalamus)
Somatosensory
cortex
VPL
Somatosensory
cortex
Paleospinothalamic tract
Dull, poorly
localized pain
Nerve endings in
skin
Intralaminar
nucleus
(thalamus)
Cingulate cortex
Anterior Spinothalamic
tract
Crude touch and
pressure, poorly
localized, nondiscriminative
Muscle sense
Nerve endings in
skin
DRG
Dorsal horn
Cross at each
spinal segment
 ascend in
anterolateral
fasciculus
Cross at each
spinal segment
 ascend in
anterolateral
fasciculus
ascend
bilaterally in
anterolateral
fasiculus
VPL
Somatosensory
cortex
Muscle spindles
Golgi tendon
organs
DRG
Clarke’s nucleus
(C8 and below)
External cuneatus
(above C8)
DC-ML
SYS
Tract
Dorsal column system
SPINOCEREBELLAR TRACTS
ANTEROLATERAL SYSTEM
Neospinalthalamic tract
Dorsal Spinocerebellar
tract (DSCT-C8 and
below)
Cuneocerebellar tract
(above C8)
Ventral Spinocerebellar
tract (VSCT)
Function
Whole limb
muscle sense,
mostly lower
limbs
Highly myelinated
SA fibers
Nerve endings in
skin
Golgi tendon
organs
DRG (via
Lissauer’s)
*signal
edited in
lamina II
DRG
*signal
edited in
lamina II
DRG
Lamina IV-VIII
Spinal border
cells
3rd order
neuron
Final
destination
Cerebellum (via
ICP)
DSCT
Do not cross
--
Cross  VSCT
 cross again
(end up on
same side)
Cerebellum (via
SCP)
--
CORTIOCSPINAL
DESCENDING TRACTS
Tract
Lateral corticospinal tract
(LCST)
Anterior corticospinal
tract (ACST)
SCS - LAT
GROUP
Rubrospinal
Raphespinal
SUBCORTICOSPINAL – MEDIAL GROUP
Tectospinal
Reticulospinal
Lateral vestibulospinal
(LVST)
Medial vestibulospinal
(MVST)
Function
Voluntary movement
Origin
Motor and premotor
cortex
Pathway/Decussation
Internal capsulecerebral peduncle pyramids
Destination
Some interneurons in
intermed gray
Cross midline in pyramids descend in LCST
Voluntary movement
*Only upper cervical
and upper thoracic
levels
Motor control,
coordination; muscle
tone – distal flexors
Modulating pain
(releases serotonin)
Motor: mediates
head, eye, postural
responses to visual
stimuli
Modulates spinal
reflexes
Axial muscle tone,
posture
Antigravity extensor
muscles in lower
limbs posture and
balance
Flexors  control
head position
according to
vestibular
information (in
cervical levels of SC)
Motor and premotor
cortex
Internal capsule cerebral peduncle  pyramids
alpha motor neurons
in distal muscles
Axial motor neurons
Stay ipsilateral, descend in ACST, cross midline at each
level
Red nucleus
Cross midline at Ventral Tegmental Decussation
(VTD) rubrospinal tract *always with LCST
Interneurons of
ventral horn
Dorsal raphe nucleus
Cross midline, descend next to RuST, LCST
Superior colliculus
Cross midline at Dorsal Tegmental Decussation (DTD)
Projects bilaterally onto grey matter
Reticular formation
Pontine reticulospinal tract: uncrossed
Medullary RTS: bilaterally
medial/lateral funiculus
Interneurons and SA
in laminae I, II, V
Interneurons (anterior
horn) and motor
neurons (neck, trunk
muscles) at cervical
levels
Interneurons at all
levels
Lateral vestibular
nucleus
Don’t cross midline  LVST
Motor and
interneurons of
extensors
Medial vestibular
nucleus
Don’t cross midline MVST
Interneurons and
motor neurons of
neck