Exam 3: Descending Tracts Flashcards
Upper motor neurons =
corticospinal/corticobulbar
Lower motor neurons =
brainstem and spinal cord (and cranial nerve nuclei), start in CNS and end in PNS
Alpha motor
lower motor neurons to muscle
Gamma motor
to muscle spindle (stretch receptor) part of reflex
Renshaw cells are
interneurons, help control alpha motor neurons in a feedback loop
Corticospinal tract is 60-80% from
primary motor cortex
Corona radiata is __ brain
fore brain
Crus cerebri is __ brain
mid brain
Pontine corticospinal is part of which tract
corticospinal tract
Pyramidal tract is in the
medulla
80% cross as
lateral corticospinal
10% cross as
anterior corticospinal (at ant. white commissure)
10% remain
ipsilateral
Lateral corticospinal
- distal limb motor neurons
- renshaw cells
- excitatory interneurons
- presynaptic inhibitory neurons
Reticulospinal tract
- locomotion
- posture
Tectospinal tract
- crossed
- acts on axial motor neurons
Vestibulospinal tract
- uncrossed
- center of gravity -balance, posture
Raphespinal tract
- Raphe nucleus
- posterolateral tract of Lissaur
- modulates sensory information between 1st and 2nd order neurons
Aminergic pathways
- serotonin (5-HT)
- adrenergic
- noradrenergic
Central autonomic pathways: fibers descend in
intermediate gay matter
Intermediolateral cell column (preganglionic)
- Sympathetic (baroreflex)
- Parasympathetic (bladder function)
- —pons
