ses 4 Flashcards
what is the location of cell bodies of lower motor neurons
lamina IX
Where are the gamma neurons found and what is their function
in the spinal cord and they increase sensitivity of stretch reflexes
define motor unit
A lower motor neuron and all the muscle fibres it supplies
define reflex
Involuntary, unlearned, reputable, automatic reaction to specific stimuli that does not require involvement of the brain
How is the length of the muscle detected
muscle fibres (intrafusal) are located in the middle of the muscle and sense changes in length firing with stretch
what is the reflex arc
neural path\y involved in reflex; receptor=>afferent fibre=>integration centre=>efferent fibre=> effector
Define stretch reflex
hardwired connection between LMN and afferents of muscle-length senses organs
what does myosynaptic/ myotatic reflex refers to
single synapse involved with single jerk, descending inhibition of multi synaptic reflexes
where is the information sent with eliciting of a reflex
brain via dorsal column, cerebellum via spino-cerebellar tract, spinal motor neuron
what stimulates hyperreflexia
sleep, alcohol consumption
what stimulates hyporeflexia
inhibition from descending pathways
What reflexes can be elicited in upper limb and what nerve roots do they test
biceps and brachioradial =>C5/6; triceps => C6/7
What reflexes can be elicited in lower limb and what nerve roots do they test
Quadriceps reflex =>L3/4 and Achilles S1/2
What is the flexor reflex
It is a complex set of reflexes mediated in response to a noxious stimulus that allows coordinated response, polysynaptic
What is the muscle tone like in development
low in-utero, absent in new born
