Neurology 4 Flashcards
A reflex is
An involuntary movement produced in response to an excitatory stimulus
A reflex arc is
A series of anatomical parts through which the reflex impulses travels
Somatic stretch reflex arcs involve how many neurons
2 nerueons that are monosynpatic
A somatic reflex arc will produce
Contractions of skeletal muscle
A stretch reflex is caused by
Stimulus that stretches a skeletal muscle
The cell body of a stretch reflex is found in
Dorsal root ganglion
The efferent motor neuron of a stretch reflex is found in
The cell body in the anterior horn
Flexor or withdrawal reflex involves how many neurons
3 neurons (polysynaptic)
The stimulus in a flexor reflex is usually ____
Superficial
Why is a flexor reflex initiated
A protective withdrawal through the contraction of flexor muscles
What are the 3 neurons involved in a flexor response
Afferent sensory neuron -> inter neuron -> efferent motor neuron
A crossed extensor reflex involves how many neurons
3 neurons
The stimulus in a crossed extensor reflex is results in
Contraction of extensor muscles on the opposite side of body
What are the 3 neurons used in a crossed extensor reflex
Afferent sensory neuron in posterior horn
Interneuon in posterior horn
Efferent motor neuron to extensor muscle
An ipsilateral reflex is a
Reflex with a response on the same side of the body
A spinal cord reflex is a reflex in which
The central of the reflex arc is in the spinal cord
A deep reflex is produced by
Any stimulus to a deep structure (bone or tendon)
A tendon reflex is a
Deep reflex in which a tendon is stimulated
Ascending tracts are pathways by which
Sensory or motor information from the peripheral nerves is sent to cerebral cortex
The ascending spinothalmic tracts determine raw data such as
Pain, temperature, pressure, and touch
The ascending dorsal column medial leminsical pathway determine
Discriminating touch, vibration and proprioception
How does information for dorsal corlumn medial leminscal pathway travel
Sensory or motor neurons in peripheral -> spinal cord -. Up through dorsal columns -> brain stem -> up through medial lemniscus
A 3 neuron relay conducts impulses from
Peripheral to cerebral corder
A first order neuron is used to
Conduct impulses from peripheral to spinal cord
Second order neurons are used to
Conduct impulses form spinal cord to thalamus
Third order neurons are used to
Conduct impulses from the thalamus to primary sensory cortex
What is the pathway of a 3 neuron relay
First order detects stimulus -> synapse with second order _> synapse with 3rd order -> synapses with cerebral cortex
The crude first recognition of sensation occurs when
An impulse reaches the thalamus
Discriminating awareness occurs when impulses reach
Teh cerebral cortex
Most second order neuron axons decussate meaning
They cross over, letting the brain register sensation on the opposite side of hte body (i.e Left by right)
The principle of divergence describes
Each sensory neuron synapses with more than one neuron thus impulses diverge and may active many effectors q
descending pathways are functionally divided into 2 groups of
Pyramidal tracts and extrapyramidal tracts
Pyramidal tracts are
Voluntary
Pyramidal tracts run via the
Lateral and ventral corticospinal tracts
Describe how pyramidal tracts send information
From cerebral motor cortex - > lateral corticospinal pyramids of medulla oblongata -> anterior horn motor neurons
Pyramidal tract axons will
Decussate in the lateral corticospinal
Pyramidal tracts all skeletal muscles to be
Controlled by the opposite side of the brain
extrapyramidal tracts are
Involuntary
Extrapyramidal tracts originate in the ___ and carry
Origiante in the brain stem and carry motor fibers to spinal cord
Extrapyramidal tracts are used to the
Involuntary and autonomic control of musculature
Describe the process of extrapyramidal tract information
Brain stem -> spinal cord -> primary neuron -> secondary neuron -> anterior motor horn neurons
Does every extrapyramidal tract decussate
Not every tract will decussate
The principle of the common path describes how
Motor neurons in the antler horn of the spinal cord are the final common pathway for skeletal muscle impulses
The principle of convergence states
Axons from many neurons converge to synpase with anterior motor neurons
The principle of converge allows for a
Big widespread response to become a more specific movement
