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Motor pathways include 2 principal Neurons:
- Lower Motor Neuron (LMN)
- Upper Motor Neuron (UMN)
The LMN's cell body resides in the _________ or ____________ and it's axon project to _________ or __________. It is also known as __________________
- spinal cord
- skeletal muscle
- smooth muscle
- alpha motor neurons
The UMN's cell body resides at _______________ (multiple words) and it's axon projects to the ______
- higher level in the CNS (cortex)
The skeletal muscles and parts of the nervous system that control them:
Somatic Motor System
Many Structures in the CNS are associated with movement, these are the:
All of these structures work in concert to allow for movement
- basal ganglion
- spinal cord
The _____ get input from the UMN but muscle contraction is only directly commanded by _____, so they are referred to as the _____________
The ventral horn contains ______, these exit via the ______ root and then join with the _______ root fibers and combines to form the spinal nerve. There are ____ spinal nerve pairs.
LMNs are _________ neurons
The _____ together with its target ___________ constitute a ___________. Small motor units control ________ movements and large motor units control __________ movements
- muscle fibers
- motor unit
- precise (fine)
Muscle fibers are surrounded by the __________ and the smaller units of muscle fibers, ________, are surrounded by the _____________________. This is linked to the sarcolemma via the ______________ and contains _________ ions.
- sarcoplasmic reticulum
- transverse tubule (t tubule)
The neuromuscular junction is the place in which the ___ synapses to the ______. The postsynaptic element in the muscle is called the ________, which is extensively ______.
- motor endplate
The action potential runs down the ____ axon, it reaches the terminal, ____ channels open, the vesicles dock, neurotransmitters are released (the only NT used in the neuromuscular junction is _________) The NT binds to receptors in the motor endplate.
Acetycholine is released into cleft, and allows ____ to flood the cell, causing the cell to depolarize, and changes the ________ potential, and causes an action potential to occur on the _________.
The action potential on the sarcolemma causes ____ to be released from the _______________, causing __________. when the ___________ reabsorbs the CA+ then _________ occurs.
- CA+sarcoplasmic reticulum
- sarcolplasmic reticulum
The LMN has 3 main sources of input:
- 1. UMN in the cortex (initiates/controls voluntary movement)
- 2. muscle spindles: a special sensory apparatus (feedback about muscle length)
- 3. Interneurons in the SC (part of circuitry that generates reflexes)
What is a reflex?
- Local motor response to local sensation
- all of these are mediated by the SC, independent of the brain
What are the two types of reflex synapses?
- Monosynaptic (straight onto LMN)
- Disynaptic (synapses first onto interneuron, then the interneuron synapses onto LMN)
What is affected in dysarthria?
Reflexes (either hypo or hyper)
reflexes represent basic __________ ________ mechanisms to sensory stimulation that is painful or potentially damaging. Most behaviors are a complex mix of __________ and _________ influences. Reflexes are important to _______
- involuntary defense