lower motor neurons and motor units Flashcards
1
Q
lower motor neuron (LMN)
A
the cell body (found in the brain stem or spinal cord) and axon that contributes to either the cranial or spinal nerves
2
Q
neuromuscular junction
A
where the lower motor neuron fiber terminates on a skeletal muscle fiber
3
Q
motor unit
A
includes the LMN, NMJ and skeletal muscle
4
Q
upper motor neuron
A
- originates in the cerebral cortex and brain stem with axons contributing to the corticospinal, rubrospinal, reticulospinal, and vestibulospinal tracts
- the UMR is confined to the CNS and terminates on the LMN
5
Q
monosynaptic spinal reflex
patellar reflex
A
- LMR cell body in ventral horn of spinal cord
- terminates on skeletal muscle
- sensory fibers coming in, cell bodies in spinal ganglia
- synapse on LMN in ventral horn
- UMN comes down from brain and terminares on LMN
6
Q
what are the two classifications of LMN
A
- alpha motor neuron
- gamma motor neuron
7
Q
alpha motor neuron
A
- skeletal muscle fibers
- reflexes
- voluntary motor function
lets reflex happen
8
Q
gamma motor neuron
A
- muscle spindles (composed of intrafusal fibers)
- regulate stretch reflex
- baseline activity in alpha MN
- proprioception and tone and position
9
Q
what are the spinal nerves of the front limbs
A
- radial
- ulnar
- musculocutaneous
10
Q
spinal nerves of the hind limbs
A
- femoral
- sciatic (tibial and peroneal)
11
Q
what are the thoracic limb reflexes
myotatic reflexes
A
- extensor carpi radialis reflex
- triceps reflex
- biceps reflex
12
Q
what are the pelvic limb reflexes
myotatic reflexes
A
- patellar reflexes
- cranial tibial reflex
- gastrocnemius reflex
13
Q
what are flexor or withdrawl reflexes
A
- pelvic limbs
- thoracic limbs
- noxious stimulus
- medial and lateral digits
14
Q
what nerve is a patellar reflex
A
femoral
15
Q
what are flexor reflexes
A
- perineal reflex
- other (crossed extensor reflex and babinski reflex)
