Motor Tracts Flashcards
What are the major motor tracts ?
Pyramidal tracts:
Corticospinal tract
Lateral
Anterior
Corticobulbar tract
Extrapyramidal tracts:
Tectospinal (colliulospinal) tract
Rubrospinal tract
Vestibulospinal tract
Reticulospinal tract
Explain the corticospinal tract
Main motor tract
Lateral tract:
Control of limbs
Decussation (crossing over) of in medullary pyramids
Anterior tract:
Control of axial muscles of trunk
Decussation of anterior tract (mostly) in spine near LMN synapses
Corticobulbar Tract
Control of voluntary face and neck movement
UMNs for cranial nerves, LMNs in brainstem nuclei
Travel to brainstem via ventral cerebral peduncles (crus cerebri)
LMNs exit via cranial nerves from brainstem
Rubrospinal Tract
Role in flexor muscle tone and co-ordination of reflexes;
Vestibulospinal Tract
Maintaining upright posture and reflexes (medial and lateral), head and head-eye co-ordination, vestibulo-ocular reflex.
Reticulospinal Tract
Maintaining upright posture and reflexes (medial and lateral), head and head-eye co-ordination, vestibulo-ocular reflex.
What is Amytrophic Lateral Sclerosis?
aka motor neurone disease, Lou Gehrig’s disease
Death of motor neurones (upper and lower)
Loss of co-ordination, weakness, slurred speech, eventually cognitive & behavioural deficits
90% sporadic (sALS), 10% familial (fALS). More common in athletes and highly active?
> 100 associated genes; most common familial form mutations in superoxide dismutase (SOD1)
What is the treatment and lifespan for people withAmytrophic Lateral Sclerosis?
Lifespan from diagnosis usually 2-5 years
Riluzole – mechanism of action unclear, reduces Glu release
Delays need for ventilation and extends lifespan ~2-3 months
Novel therapies in clinical trials to prevent progression – some early results very promising, but only target some genetic forms
Mostly biologics (reduce neuroinflammation)
Stem cell treatments also examined
What are the lower motor nuerons ?
+ MAKE SURE I KNOW ALPHA AND GAMMA NUERONS.
BETA NUERONS NOT VERY IMPORTANT.
What are muscle splindles
Extrafusal fibres (muscle) around outside
Intrafusal fibres (spindle) inside; these are small, non-contractile
Sensory neurones around the intrafusal fibres
Co-activation of α & γ:
Muscle contracts (α)
Spindle contracted (γ) to maintain tautness with muscle
Allows spindle to accurately report muscle contraction
Peripheral Motor Disorders
Some typical characteristics of peripheral motor disorders:
General weakness, hypotonia, hyporeflexia, fasciculations, stocking glove distribution
