Neurophys II Flashcards
Where is the home for alpha motor neurons?
Alpha motor neurons are also known as LMN.
These are found in the ventral horn.
What is the concepts of the final common path?
Alpha motor neurons are only link between spinal cord and muscles.
Serve as pathway for other parts of CNS to jump onto.
Motorneuron pool?
All the motor units that serve single muscle.
Motor unit definition
One alpha motor neuron and all its skeletal muscle fibers it innervates.
Describe the effects caused by poliomyelitis
Large motor units damaged and forced to adapt, this leads to repeated denervation and reinnervation “remodeling”
Define: Fibrillation
Spontaneous activity within single muscle fibers.
Not visible by eye.
Define: Fasiculation
Visible twitch of muscle involving one or more motor units.
Describe how graded muscle contraction occurs.
Increase muscle force production via recruitment of many units and increasing rate of activated motor units (Temporal wave summation).
Describe the size of the motor units controlling the following structures: Extra-ocular eye muscles Muscles controlling fingers Large postural muscle Limb muscles affected by polio
Extra occular - many small motor units
Individual fingers - Many small motor units
Large postural - Large motor units
Polio infected muscles - Large motor units.
Are upper motor neurons truly motor neurons?
No as they do not actually synapse onto a muscle.
Muscle atrophy Decreased tone Flaccid paralysis Hyporeflexia Fibrillations Fasciculations are all signs of what sort of motor neuron lesion?
Are all part of what is considered a lower motor neuron lesion.
hypertonic muscles eliciting ... Spactisity Clasp-knife effect Clonus Hyerreflexia Babinskis sign are all signs of what sort of motor neuron lesion?
These are all indicitive of an upper motor neuron lesion.
Flaccid paralysis, areflexia, and loss of autonomic functions following a spinal lesion are indicitive of what?
Spinal shock.
Following spinal shock, which symptoms will remain permanent?
Loss of voluntary movement below level of transection.
Loss of true sensation “Anesthesia” below level of transection.
How does spinal shock change over time?
Following 1-6 weeks spinal shock progresses into
Hyperreflexia
Babinskis sign - “Release phenomena”
Flexor spasms
Alternate flexor and extensor spasms (mostly extensor)
Spastic paralysis below lesion - Cannot move limbs but have hyper reflex responses.
