NEUROLOGY PATHWAYS
NEUROLOGICAL
PATHWAYS
ASCENDING DESCENDING
(SENSORY) (MOTOR)
DORSAL
SPINOTHALAMIC SPINOCEREBELLAR
COLUMN-MEDIAL PYRAMIDAL EXTRAPYRAMIDAL
TRACT TRACT
LEMNISCAL
FASCICULUS CORTICOSPINAL CORTICOBULBAR RUBROSPINAL RETICULOSPINAL VESTIBULOSPINAL TECTOSPINAL
LATERAL TRACT TRACT TRACT TRACT
GRACILIS POSTERIOR TRACT TRACT
FASCICULUS MEDIAL
ANTERIOR LATERAL
CUNEATUS ANTERIOR
ANTERIOR LATERAL
DESCENDING TRACT
Corticospinal (pyramidal) Tract:
Definition: It is a descending motor pathway that conveys
voluntary motor commands from cerebral cortex to spinal cord
and is formed by axons of layer V pyramidal cells.
Types: lateral corticospinal tract and anterior corticospinal
tract (based on site of decussation)
,Function:
Voluntary motor control
Fine, skilled movements
Lateral CST: controls distal limb muscles and skilled
voluntary movements (hands, fingers, toes).
Anterior CST: controls axial and proximal muscles (trunk,
neck, shoulder girdle), mainly for posture and bilateral
proximal movement.
Origin:
Cerebral cortex (layer V pyramidal cells)
Primary motor cortex (area 4)
Premotor cortex (area 6)
Primary somatosensory cortex (area 3, 1 and 2)
Supplementary motor area.
Termination: spinal cord anterior horn, synapsing with
interneurons and alpha motor neurons
Point of decussation:
Lateral CST: (pyramidal decussation) decussate in caudal
medulla before descending in spinal cord
, Anterior CST: (segmental decussation) Fibers descend
ipsilaterally in anterior funiculus, fibers cross segmentally
at the level of termination via anterior white commissure.
Course:
Cerebral cortex
(layer V pyramidal cells)
Corona radiata
Internal capsule
~ Posterior limb
~ Somatotopy: face → arm → trunk → leg
Midbrain
~ Cerebral peduncle (crus cerebri)
~ Middle part of basis pedunculi
Pons
~ Ventral (basilar) pons
~ Fibers broken by pontine nuclei
NEUROLOGICAL
PATHWAYS
ASCENDING DESCENDING
(SENSORY) (MOTOR)
DORSAL
SPINOTHALAMIC SPINOCEREBELLAR
COLUMN-MEDIAL PYRAMIDAL EXTRAPYRAMIDAL
TRACT TRACT
LEMNISCAL
FASCICULUS CORTICOSPINAL CORTICOBULBAR RUBROSPINAL RETICULOSPINAL VESTIBULOSPINAL TECTOSPINAL
LATERAL TRACT TRACT TRACT TRACT
GRACILIS POSTERIOR TRACT TRACT
FASCICULUS MEDIAL
ANTERIOR LATERAL
CUNEATUS ANTERIOR
ANTERIOR LATERAL
DESCENDING TRACT
Corticospinal (pyramidal) Tract:
Definition: It is a descending motor pathway that conveys
voluntary motor commands from cerebral cortex to spinal cord
and is formed by axons of layer V pyramidal cells.
Types: lateral corticospinal tract and anterior corticospinal
tract (based on site of decussation)
,Function:
Voluntary motor control
Fine, skilled movements
Lateral CST: controls distal limb muscles and skilled
voluntary movements (hands, fingers, toes).
Anterior CST: controls axial and proximal muscles (trunk,
neck, shoulder girdle), mainly for posture and bilateral
proximal movement.
Origin:
Cerebral cortex (layer V pyramidal cells)
Primary motor cortex (area 4)
Premotor cortex (area 6)
Primary somatosensory cortex (area 3, 1 and 2)
Supplementary motor area.
Termination: spinal cord anterior horn, synapsing with
interneurons and alpha motor neurons
Point of decussation:
Lateral CST: (pyramidal decussation) decussate in caudal
medulla before descending in spinal cord
, Anterior CST: (segmental decussation) Fibers descend
ipsilaterally in anterior funiculus, fibers cross segmentally
at the level of termination via anterior white commissure.
Course:
Cerebral cortex
(layer V pyramidal cells)
Corona radiata
Internal capsule
~ Posterior limb
~ Somatotopy: face → arm → trunk → leg
Midbrain
~ Cerebral peduncle (crus cerebri)
~ Middle part of basis pedunculi
Pons
~ Ventral (basilar) pons
~ Fibers broken by pontine nuclei
