Nociception And Proprioception Flashcards
Receptors that receive information about the external environment (i.e. Touch, temp, pain)
Exterceptors
Receptors that receive information about the internal environment (i.e. Stretch receptors of organs/ visceral pain perception)
Interoreceptors
___________ provides information about the position and movement of the body
Proprioception
What are the 4 destinations of general sensory afferent (GSA) neurons?
Spinal cord segments
Cortex (via thalamus) conscious perception
Cerebellum -unconscious proprioception (muscle tone and balance)
ARAS (ascending reticular activating system)
What system maintain wakefulness?
Recticular formation (ARAS)
Neuronal network within the brainstem
What is parallel processing ?
Different aspects of the same sensory experience are perceived in different parts of the brain
Eg color, motion, form, and depth
What is the somatosensory pathway?
Receptor -> 1st order neuron (afferent) -> stimulation interneurons (2nd order) which may synapse other interneurons-> thalamus -> cortex
most will decussate to contralateral side
Excitatory or inhibitory
What is the relay and processing point for all conscious perception, except olfactory?
Thalamus
What are the three different pathways by which somatosensory pathways can reach the cortex?
- Afferent -> synapse to interneuron and ascend on ipsilateral side -> synapse to interneuron in lateral cervical nucleus-> decussate -> synapse in thalamus -> cortex
- Afferent -> ascend ipsilatterally in spinal cord before synapsing onto interneuron in the nucleus gracilis and cuneatus-> thalamus—-> cortex
- Afferent -> synapse and decussate to contralateral side -> ascend-> thalamus -> cortex
What are two important somatosensory pathways in the dorsal column of the spinal cord?
Fasciculus cuneatus
Fasciculus gracilis
___________ position is assessed via joint angle
Static
___________ position is assessed via movement of joints and muscles
Kinesthetic
General proprioception has two pathways. The ___________ pathway terminates in the cerebral cortex and the _____________ pathway goes to the cerebellum or the spinal cord
Conscious; unconscious
What is the somatosensory cortex?
Parietal lobe
What are the two primary conscious proprioceptive pathways?
Dorsal Column-Medial Lemniscal Pathway (DCML)
Trigeminal-Medial Lemniscal Pathway
The Dorsal Column- Medial Lemniscal Pathway carry conscious proprioception about
Limbs and body
The Trigeminal-Medial Lemniscal Pathway carry conscious proprioception about
Face
What are the Dorsal Column- Medial Lemniscal Pathway receptors??
Muscle spindles (change in muscle length)
Golgi tendon organs (tension in tendon and joint capsules)
Cutaneous mechanoreceptor
In the dorsal column what are the two tracts for conscious proprioception?
Fasciculus gracilis (medial) Fasciculus cuneatus (lateral)))))
The ______________ transmits sensory information from the lower body and is medially located in the dorsal column
Fasciculus gracilis
The ____________ transmits sensory information from the upper body and is laterally located in the dorsal column
Fasciculus cuneatus
Tracts of conscious proprioception traveling in the dorsal column will travel (ipsilateral or contralateral)?
Ipsilateral
The dorsal column CP pathways decussate in the ________
Medulla
The dorsal column CP pathways synapse onto second order neurons in the medulla at the _________ and ___________ nuclei
Cuneate and gracile
correspond to the tracts they run in… fasciculus cuneatus and fasciculus gracilis
2nd order neurons from the cuneate/gracile nuclei travel in the _________ to the thalamus
Medial lemniscus
Sensory information from the face travels in the trigeminal nerve to the ____________nucleus
Trigeminal nucleus
What is the conscious proprioceptive pathway of the face?
Trigeminal nerve (afferent) -> trigeminal nucleus -> 2nd order neuron -> medial leminiscus -> thalamus -> 3rd order neuron -> cortex
What can be observed in a proprioceptive deficit?
Gait abnormalities -long stride -hypermetria (excessive flexion) -wide swing phase Knuckling/dragging/scuffing toes
At what levels can a lesion occurs that would lead to proprioceptive ataxia
Peripheral nerve Dorsal root Spinal cord Brainstem Thalamus Cortex
What is the processing of noxious stimuli?
Transduction -> stimuli to electrical signal
Transmission -> AP to spinal cord
Modulation -> modified in the spinal cord
Perception -> awareness = nocciception
What kind of pain perception is discriminative and may be perceived as more “uncomfortable”
Superficial pain
What type of pain is non-discriminative but elicits strong behavioral responses or changes, referred to as “true pain”
Deep pain
Superficial pain perception is received by nociceptors in the _________ while deep pain perception is received by nociceptors in the ________________
Skin; muscle, joint, and bone
What are the fast conducting nociceptive fibers
Myelinated (A-delta)
What are the slow conducting nociceptive neuron fibers
Unmyeliniated (C) fibers
What are characteristics of myelinated (A-delta) fibers?
Fast conduction and accurate localization
Sharp pinprick pain
Pain does not outlast stimulus
Activated by mechanical and temperature stimuli of painful realm (and cold temperature)
Afferent component of reflex arcs
High levels of ___________________ fibers are found in the skin
Myelinated (A-delta) fibers
What are characteristics of Unmyelinated (C) neuron fibers
Slow conducting; not accurately localized
Dull, aching, throbbing pain
Can persist after stimulus is removed
High activation threshold
Activated by mechanical, thermal, and chemical stimuli
High levels of _______________ fibers are found in deep tissues (eg viscera or bone)
Unmyelinated (C) neuron fibers
What two ascending nociceptive pathways transmit superficial pain?
Spinocervicothalamic
Spinothalamic
Also transmit tactile sensation
The ___________ tract transmits deep and visceral pain
Spinorecticular
True/False: Somatotopy is well defined in the spinorecticulr tract
False
Not well defined due to multiple synapses and a larger receptive field
What is the pathway of the spinocervicothalamic tract?
Primary neuron -> synapse at dorsal horn -> 2nd order neuron ascends ipsilaterally in lateral funiculus ->synapse at lateral cervical nucleus(C1/C2) -> 3rd order neuron decussate in medulla -> synapse to 4th order neuron in thalamus -> cortex
What is the pathway of the spinothalamic tract?
Primary neuron -> synapse, decussate immediately and ascend in contralateral side -> lateral cervical nucleus (C1/C2)->3rd order neuron-> -> thalamus -> cortex
Describe the spinorectular tract
Multisynaptic
Synapse every 3-5 segments
Remain ipsilateral or contralateral
Ascend to reticular formation and thalamus -> cortex
The ___________ system is activated via the thalamus for emotional response to pain from the spinorecticular tract
Limbic
What role does the limbic system play in pain response. How could a lesion affect this response?
Limbic system -> negative emotional response to main
Lesion -> can feel and identify pain, but have no aversion to it
Nociception from the head is transmitted via the _________ nerve
Trigeminal
What type of pain arises from trauma or inflammation, is appropriate, and protective to the body
Acute pain
What type of pain persists beyond the time frame of the disease/injury, a maladaptive resposne.
Chronic pain
What type of neurons are responsible for referred pain?
Wide dynamic range (WDR)
nociceptive and non-noxious stimuli both synapse onto the same WDR neuron -> perceive pain coming from the non-noxious neuron
What is the purpose of inflammatory mediators?
Directly stimulates nociceptors
Lowers threshold of nociceptors
-in damaged/inflamed tissues the nociceptors are more easily activated and the perception of pain occurs more frequently with stimulation
_____________is released by sensory nerve terminals in response to a noxious stimuli. What is its purpose?
Substance P
Neurotransmitter and inflammatory mediator
-> increased sensitization of nociceptors and other sensory receptors
________ is when a minimal noxious stimuli produces greater than normal nociceptive activity
Hyperalgesia
__________ is when an innocuous stimuli provokes a pain response
Allodynia
What can contribute to hyperalgesia and allodynia?
Substance P-> sensitization of nociceptors and innocuous nerve fibers
What is wind-up?
Continuous firing of afferent nociceptors
Repeated stimulation of C type fibers -> sustained depolarization of spinal cord neurons
Prolonged stimuli leads to decreased threshold -> less stimulus is required to induce pain
What neurotransmitters have anti-nociceptive properties?
Endorphins, enkephalins, serotonin, and norepinephrine
Decrease pain perception
What is gate control theory
Inputs from non-nociceptive fibers activate inhibitory interneurons in the spinal cord -> inhibit projection neurons (pain) to the thalamus
Eg Compression Massage Water therapy Acupuncture
What is the decreased perception of pain
Hypoalgesia
What is the complete absence of pain perception?
Analgesia
What is the absence of all sensory perception
Anesthesia
What nerve fibers are involved in itch
Mainly C type, some A-delta types
travels in same pathway as nocicpetion
Where does differentiation between pain and itch occur
Spinal cord
Do you test for deep pain if superficial pain is intact?
No
Superficial pain would be lost before deep pain
Is it possible to have an absent withdrawal reflex and an normal deep pain reaction
Yes
Lesion could be relative to somatic efferent when afferent neurons, interneurons, and nociceptive pathways are intact
