Module 12 Flashcards
Do spinal nerves have motor or sensory neurons?
*TRICK QUESTION**
Both; sensory and motor
What do the spinal nerves do?
Innervate trunk and limbs
Which type of nerves do the spinal roots serve?
Dorsal roots: afferents
Cell body in dorsal root ganglia
Ventral roots: efferents
Cell body in ventral root ganglia
What type of neuron does the dorsal roots have?
Unipolar
What type of neuron does the ventral roots have?
Multipolar
Do the ipsilateral spinal roots form the spinal nerves?
Yes!!!
What do all spinal nerves supply?
Sensory innervation for skin segments
What do lesions to a single spinal nerve cause?
Nothing
Does a numerous amount of spinal damage nerves cause problems?
Helps to determine the level of the lesion
What comprises the peripheral parts of the SC?
White matter
How is the gray matter divided in the SC?
Horizontal plane:
I-VI- dorsal horn
VII- lateral horn
VIII- XI- ventral horn
How are the matter tracts oriented on the SC?
Vertically
What do the lateral, anterior and posterior funiculi contain?
Lateral- sensory and motor pathways
Anterior- motor
Posterior- sensory
Name the 2 types of motor neurons?
Alpha motor neurons (somatic)
GAMMA motor neurons (somatic)
What two fibers are in skeletal muscles?
Extrafusal (muscle fibers)- make up mass; innervated by ALPHA motor neurons
Infrafusal- part of muscle spindle; innervated by GAMMA motor neurons
Where are interneurons located?
In the gray matter of the SC
What is the function of the interneurons ?
Innervated anterior motor neurons
InterGRATIVE role in motor behavior
What terminates on the interneurons?
Incoming sensory neurons
Outgoing efferent neurons
What are the roles of the muscle receptors?
Excitation of the muscle by the alpha (anterior) motor neurons
Continuous feedback of info from the muscle (length, tension, rate of length/tension)
Name the two special sensory receptors?
Muscle spindle
The Golgi tendon organ
What does proprioceptors allow us to do?
Sense position
Sense movement of head, jaws, limbs, trunk
What kind of receptor is the muscle spindle?
What does it do?
Stretch receptor
Monitors the rate of change of the muscle length and the muscle length itself
Name the types of intradusal fiber of the muscle spinal?
Nuclear chain
Nuclear bag
What is the capsule of the spindle continuous with?
Tendon of the muscle
Where is the nuclei of the intrafusal fiber concentrated?
Middle of the fiber
Are type Ia sensory fibers slow or fast conduction?
Fast conducting
What are the sensory endings that wrap around the intrafusal fibers?
Primary -annulospinal
Secondary -flower spray ending
What does the annulospiral (primary ending) innervate?
Nuclear bag/ chain
What does the secondary (flower spray ending) innervate?
The nuclear chain intrafusal ONLY
What does the static response of the muscle spindle do?
Responds to:
Length/ stretch
Have primary/ secondary ending response
Response lasts for duration of stretch
Response from nuclear chain( Ia/II afferents)
What does the dynamic response of the muscle spindle do?
Monitors rate of change
Only primary ending responds
Response from nuclear bag
What’s the role of the gamma motor neuron?
Refine/ damping movements (BG/cerebellum/cortex)
Regulate spindle sensitivity
What’s the role of the alpha motor neurons?
Effect voluntary movements
Inputs from area 4/3-1-2
What does the Golgi tendon organ respond to?
Muscle tension and rate of change
What does the static response of the GTO ( Golgi) do?
Steady muscle tension
Steady firing
What does the dynamic response of the GTO (Golgi) do?
Suddenly increases tension
Increase in firing
Name the 2 types of intrafusal fibers?
Nuclear chain
Nuclear bag
