Genereal Flashcards
What is a reflex
Fast involuntary muscle contraction in response to a specific stimulus
Describe the reflex arch
Monosynaptic reflex arch ipsalateral information from 1 spinal level
Tap on the tendon stimulates sensory receptors and stretches muscle spindle which monitors change in length of muscle
In response to being stretched muscle spindle generates a nerve impulse which passes through the dorsal root ganglion and into the spinal cord
Within the integrating centre the sensory neurone EPSP activates the motor neurone in the anterior horn
If excitation reaches threshold one or more nerve impulses are generated and the motor neurone goes back to the atomistic muscle contracting it
At the same time the polysynaptic reflex arch there is reciprocal intervention which prevents the conflict of opposing muscles. There is efferent information travelling into the spinal cord and there is a inhibitory neurone which inhibits and relaxes the antagonist muscle which stops the agonist contracting too briskly.
- dampens down reciprocal inhibition
What are the responses to reflex tests
Normal
Absent
Diminished
Brisk
Which is the most serious reflex response and why?
Brisk
Due to more serious non-musculoskeletal pathology UMN lesion always I kid babinski and clonus
In the spinal cord the antagonist signal is not transmitted. If this occurs the agonist contraction is overly brisk
Therefore an UMN problem is preventing the reciprocal inhibition from occurring
