Noception Flashcards
How many neuronal pathways are there for pain? What are they?
Pain is conducted along three neuron pathways (first, second and third order neurons) that transmit noxious stimuli from the periphery to the cerebral cortex.
Where are the primary afferent neurons located?
Primary afferent neurons are located in the dorsal root ganglion which lie in the vertebral foramina at each spinal cord level.
Each neuron has a single axon that bifurcates, where are the two locates that the axon bifurcates to?
Each neuron has a single axon that bifurcates, sending one end to the peripheral tissues it innervates and the other into the dorsal horn of the spinal cord.
Where are the majority of the First order neurons?
The majority, enter the dorsal spinal root at each cervical, thoracic, lumbar, and sacral level
The pain fibers of the first order neurons in the head originate by which cranial nerves?
Pain fibers originating in the head are carried by the trigeminal (V), facial (VII), glossopharyngeal (IX), and vagal (X)
What is the pathway for the first order neurons in the head?
Each have specific ganglion which hold cell bodies of these nerves. The first order neurons in the ganglia (head) reach the brainstem and synapse with the second order neuron
How many rexed lamina does the spinal cord gray matter have?
Spinal cord gray matter is divided by Rexed into 10 lamina
What are the second order neurons??
Second order neurons are either nociceptive-specific or wide dynamic range (WDR)
What are the first six lamina of the dorsal horn?
First six makeup the dorsal horn, receive all afferent neural activity, represent the principle site for modulation of pain
What does Lamina I respond to?
Lamina I responds to nociceptive stimuli from cutaneous and deep somatic tissues
What does Lamina II contain?
Lamina II (substantia gelatinosa), contains many interneurons responsible for processing and modulating nociceptive input from cutaneous tissue. Major site of action for opioids
which Lamina is the major site of action for opioids and what is the most abundant receptor?
Lamina II aka substantia gelatinosa is the major site of action for opioids. Mu2 is the most abundant.
What does Lamina VII contain?
Lamina VII contains preganglionic sympathetic neurons
Which Lamina contains visceral afferents?
Lamina V and I contains visceral afferents
Which Lamina responds to both noxious and non noxious stimuli? and receives both somatic and visceral inputs?
Lamina V responds to both noxious and non noxious stimuli and receives both somatic and visceral inputs
What is the pathway of the Spinothalamic tract?
The spinothalamic tract Cross the midline to the level of origin to the contralateral side of the spinal cord
How many divisions are the spinothalamic tract divided into? what are they?
The spinothalamic tract are Divided into lateral and medial
What does the lateral spinothalmic tract project to?
Lateral spinothalmic tract projects—location,density,duration of pain in the ventral posteriorlateral nucleus of the thalamus
What does the medial spinothalmaic tract project to?
Medial spinothalamic tract projects—unpleasant emotional perception of pain in the medial thalamus
What is the Spinalreticular pain pathway?
Spinalreticular pain pathway- arousal and autonomic responses to pain
What is the Spinalmesencephalic pathway?
Spinalmesencephalic–anti-nociceptive descending pathways because of its projections in the periductal gray area
Where are the third order neurons located? were are they synapsed?
Third order neurons are Located in the thalamus
Where does the third order neurons send fibers to?
Send fibers to the somatosensory areas I and II in the post central gyrus of the parietal cortex and superior wall of the sylvian fissure
Which afferent nerve fibers are mylinated?
A and B fibers
Which afferent nerve fibers are nonmylinated?
C fibers
Which afferent nerve fibers are slow poorly localized?
C fibers
Which afferent nerve fibers are fast, sharp well-localized sensation?
A delta fibers
Afferent “A” nerve fibers are defined into what?
Alpha, Beta, Gamma, and Delta
Each afferent nerve fibers innervation provides a specific function and the classification of these fibers are based on diameter and velocity of conduction. TRUE or FALSE?
TRUE.
Each afferent nerve fibers innervation provides a specific function and the classification of these fibers are based on diameter and velocity of conduction.
Which afferent nerve fibers are sympathetic preganglionic?
B fibers
Which afferent nerve fibers are sympathetic post ganglionic??
C fibers
Which afferent nerve fibers are muscle spindle motor to skeletal?
A alpha fibers
Which nerve fibers are touch and pressure afferents?
A Beta fibers
Which afferent nerve fibers are motor to muscle spindle?
A gamma fibers
Which afferent nerve fibers are mechanoreceptors and nociceptors?
A delta and C fibers
Which afferent nerve fiber has the fastest velocity?
A alpha with a mean velocity of 100m/sec
Which afferent nerve fiber has the slowest velocity?
C fibers with a mean velocity of 1m/sec