Lecture 6: Motor Functions of Spinal Cord and Reflexes Flashcards
what are the 3 neurons part of Neuronal Organization of the Spinal Cord
sensory neurons
motor neurons
interneurons
Where do you find the sensort neurons in the spinal cord
dorsal root ganglion
where do you find the motor neurons in the spinal cord
anterior horn
What is the function of sensory neurons in the spinal cord
transmit signals to higher centers
what is the function of motor neurons in the spinal cord
directly innervate skeletal muscle fibers
Where do sensory neurons synapse and why
Synapse at the spinal cord level to elicit motor reflexes
what are the 2 types of motor neurons of the spinal crod
Alpha MNs
Gamma MNs
What is the fucntion of Alpha MN? Gamma MN?
excite extrafusal muscle fibers (motor units), muscle contraction
A-gamma axons) excite intrafusal (spindles) fibers (muscle sensory receptors)
Which motor neuron excites intrafusal msucle fibers
gamma MN
Which motor neurons excites extrafusual muscle fibers
alpha
What is the “typical muscle fiber”
alhpa
What are interneurons and what are the two types
Local neurons that have connections with sensory & motor neurons
They can be inhibitory or excitatory
true or false: Interneurons are only excitatory
false, theyre excitatory and inhibitor
What kind of receptors are sensory receptors of the muscle?
MECANORECEPTORS (i.e. stimulated by mechanical displacement of the muscle)
What are the two sensory receptors (mecanoreceptors) of the msucle>
MUSCLE SPINDLES
GOLGI TENDON ORGANS
Where are muscle spindles located
Are distributed throughout the muscle belly (midportion of intrafusal fibers)
What do muscle spindles sense
Sense muscle length (stretched, relaxed, contracted) and rate of change of length
Sensory signals in the muscle spendles are transmitte through what type of fibers?
1a (primary sensory ending) fibers
II (secondary sensory ending) fibers
Whree are golgi tendon organs lcocated?
in the muscle tendon
what do golgi tendons sense?
Sense tendon tension and rate of change of tension.
what are the Sensory signals of the golgi tendon transitted through
1b fibers
be able to locate the primary sensory endings, secondary sensory endings and 1b fibers
/
rank by 1a, 1b and II by conduction velocity
Ia, Ib, II
What is thje function of the msucle s[indles
Function: To provide info on the position of body parts (proprioception)
Where do the Primary sensory endings of the muscle spindle (type Ia fibers) terminate?
Terminate on nuclear bag and nuclear chain fibers
true or false: muscle spindles respond to both dynamic and static changes in the muscle length and stretch
true!! `
explain how muscle spindle fibers respond to dynamic and statoic
Respond to the rate of change in muscle length (dynamic) and to the degree of stretch of the muscle (static)
type 1a and type 2