Stretch Relax- Soinal Cord Anatomy

Question 1

What is inside a muscle spindle

Answer 1

Nuclear bag fibres
Nuclear chain fibres
Gamma motor neurons relaying information
Alpha motor neurons

Question 2

What fibres does a muscle spindle consist of

Answer 2

Intrafusal & extrafusal fibres

Question 3

What do intrafusal fibres detect

Answer 3

Detective a change in length & velocity of the muscle & send sensory information to the soinal cord

Question 4

What neurons intervate the extrafusal & intrafusal fibres

Answer 4

Extrafusal = alpha motor neuron
Intrafusal = gamma motor neuron

Question 5

Explain a single stretch reflex

Answer 5

Intrafusal fibres (nuclear brags & nuclear chains) detect a change in length & velocity
Type 1a & type 2 sensory signal is the released
Enters into the dorsal horn via the dorsal route where it synapses with an alpha motor neuron Intrafusal
It also synapses with a gamma motor neuron
The alpha motor neuron sends a motor signal to the extrafusal fibres via the ventral route
Gamma motor neuron sends a motor signal to the intrafusal fibres telling them both to contract
An inhibitory neuron also synapses to send a motor signal to the antagonist Tao it doesn’t contract as well

Question 6

Name the 3 spinal tracts that are involved in modulation of the stretch reflex

Answer 6

Lateral reticular spinal tract
Medial reticular spinal tract
Vestibular spinal tract

Question 7

Which of the modulating spinal tracts are excitatory & inhibitory

Answer 7

Lateral retículo spinal tracts= inhibitory
Medial & vestibular spinal tract = excitatory