Motor Systems 2 Flashcards
Golgi Muscle Tendon
IT’S A TRAP
Innervated by 1b afferents
In parallel with muscle
Muscle spindle
In series with muscle
Golgi Tendon Organ
Preferentially signals muscle stretch
Muscle spindle
Preferentially signals muscle tension
Golgi Tendon Organ
Important for stabilizing contractions
Golgi Tendon Organ
Composed of muscle fibers
Muscle spindle
Signals via Ia afferent fibers
Innervated by gamma motor neurons
Muscle spindle
Signals via Ib afferent fibers
Not contractile
Golgi Tendon Organ
Feedback system for maintaining muscle force
Golgi Tendon Organ
Feedback system for maintaining muscle length
Muscle spindle
Muscle spindle
In parallel with muscle Preferentially signals muscle stretch Important for maintaining muscle tone Composed of muscle fibers Signals via Ia afferent fibers Innervated by gamma motor neurons Feedback system for maintaining muscle length
In series with muscle Preferentially signals muscle tension Important for stabilizing contractions Composed of collagen fibers and capsule Signals via Ib afferent fibers Not contractile Feedback system for maintaining muscle force
Golgi Tendon Organ
Central pattern generation
Definition: neural networks that can produce patterned, rhythmic outputs in the absence of sensory or central input
Flexor activated….
NEEDS extensor relaxed
Enforced by inhibitory interneurons
central pattern generator. Describe a behavior that uses one and where it resides.
Spontaneous locomotor activity if transected rostral to mammillary bodies
No spontaneous locomotor activity if transected caudal to MB
Mesencephalic locomotor center stimulation necessary for locomotion
Lower motor neuron syndrome
Damage to lower motor neuron cell bodies or peripheral axons
Paralysis
Paresis (weakness)
Loss of reflexes
Loss of muscle tone (why?)
Later, muscle atrophy due to denervation of muscle
Spontaneous twitches: changes in excitability of denervated muscle/ abnormal activity of alpha motor neurons
Diseases that lead to lower motor neuron syndrome
Syphilis : DRG
Herniated disc: sens nerve root
Polio / ALS: motor neuron
Guillan-Barre: demyelination of peripheral motor nerve
Lambert-Eaton syndrome: peripheral Ca channel attack hits NMJ (mysteninc syndrome)
Myasthenia gravis
Muscular dystrophy: muscle directly.
Summary of lower motor neuron system
Motor units and motor unit types
Location of lower motor neurons in ventral horn of spinal cord
Anatomy and function of muscle spindles
Anatomy and function of Golgi tendon organs
Basic concept of the Central Pattern Generator
CPGs in locomotor behavior
Location of lower motor neurons in ________ of spinal cord
ventral horn
Spinal circuitry mediating simple spinal reflexes –
myotatic reflex, extensor-flexor coupling, crossed extensor-flexor coupling
