Fund. PT Exam 2 Flashcards
Sensory input plays major roles in __ and protection from __. Sensory acuity [incr/decr] with age and is affected in certain disease/trauma states.
Sensory input plays major role in MOTOR CONTROL (postural control, balance, fine motor control, ability to learn new skills/motor learning) and PROTECTION FROM INJURY. Sensory acuity DECREASES with age. Affected in disease states e.g. diabetes, neuropathies, CNS problems, stroke, etc.
The sensory system is a __ (#) neuronal system for conscious sensation. Your goal is to get the signal from the __ to the __.
3 neuron system. Get signal from RECEPTOR to CORTEX.
The first order fiber in the sensory conduction system begins at a ___ related to the axon of a sensory neuron. Therefore, this fiber’s cell body lies [inside/outside] of CNS either in a __ or __. Its central process enters the ___ via the ___ and terminates in the ___. It relays information from ___.
The first order fiber in the sensory conduction system begins at a RECEPTOR related to the axon of a sensory neuron. Therefore, this fiber’s cell body lies OUTSIDE of CNS either in a DORSAL ROOT GANGLION or CRANIAL NERVE GANGLION. Its central process enters the SPINAL CORD via the DORSAL ROOT and terminates in the SPINAL CORD (or brainstem if it’s a CN). It relays information from ITS OWN RECEPTIVE FIELD IN THE PERIPHERY.
The second order fiber in the sensory conduction system begins at its cell body within the ___ of the [periphery/ spinal cord/ brain] or in analogous areas of the ___. So basically, it starts somewhere in the [PNS/CNS], and ascends [ipsilaterally / by crossing the midline]
The second order fiber in the sensory conduction system begins at its cell body within the DORSAL GRAY MATTER of the SPINAL CORD or in analogous areas of the BRAINSTEM. So basically, it starts somewhere in the CNS, and ascends BY CROSSING THE MIDLINE
The third order sensory fiber’s cell body lies within the ___ and projects onto ____ areas of the __ cortex.
The third order sensory fiber’s cell body lies within the THALAMUS and projects onto SOMATOSENSORY areas of the CEREBRAL cortex.
Different receptors respond to different stimuli. This is determined by the \_\_ of the receptor. Describe what the following receptors respond to... Mechanoreceptors Thermoreceptors Nociceptors Chemoreceptors Photoreceptors
The STRUCTURE of a receptor determines what stimulus will activate it.
Mechanoreceptors: mechanical deformation, pressure, touch
Thermoreceptors: Temperature
Nociceptors: painful stimuli, any stimulus of sufficient intensity may be noxious (responds to thresholds of tissue damage)
Chemoreceptors: chemical irritation, taste, smell, osmolarity of blood (chemical changes)
Photoreceptors: respond to light (rods and cones)
Name 7 types of cutaneous sensory receptors
Free nerve endings Ruffini Endings Merkel's Disks Meissner's Corpuscles Pacinian Corpuscles Hair Endings Temperature Receptors
Free nerve endings are usually attached to [myelinated/unmyelinated] axons. They [are/are not] encapsulated and are found [in the CNS/ PNS/ throughout the body]. They can provide perception of what stimuli? (6!) They are [fast/slow] adapting and in the presence of a stimulus, they send a [constant/singular] signal to the CNS>
Free nerve endings are usually attached to UNMYELINATED axons. They ARE NOT ENCAPSULATED and are found THROUGHOUT THE BODY. They can provide perception of PAIN, TEMPERATURE, TOUCH, PRESSURE, TICKLE, and ITCH. They are SLOW adapting and in the presence of a stimulus, they send a CONSTANT signal to the CNS>
Ruffini endings are [encapsulated/not encapsulated] with a special ending. They’re located in the deep layers of the __. They’re involved in the perception of ___ & ___ - this makes them important in signaling continuous states of skin ___. They’re [fast/slow] adapting.
Ruffini endings are NONENCAPSULATED with a special ending. They’re located in the deep layers of the DERMIS. They’re involved in the perception of TOUCH & PRESSURE - this makes them important in signaling continuous states of skin DEFORMATION. They’re SLOW adapting.
Merkel’s disks are [encapsulated/ not encapsulated] and are sensitive to ___ touch and the __ of touch. They play a role in ___ and ___ of touch. They’re [slow/fast] adapting and send a [continuous/burst of] response when sensation begins and then [goes quiet/continues sending signals]. The actual receptor is a separate cell that communicates with and surrounds the sensory axon (and looks like a disc! Fun fact.). It’s associated with a [myelinated/ unmyelinated] axon.
Merkel’s disks are ENCAPSULATED and are sensitive to FINE touch and the VELOCITY of touch. They play a role in 2-POINT DISCRIMINATION and LOCALIZATION of touch. They’re RAPIDLY adapting and send a BURST OF response when sensation begins and then GOES QUIET. The actual receptor is a separate cell that communicates with and surrounds the sensory axon (and looks like a disc! Fun fact.). It’s associated with a MYELINATED axon. Basically, they’re a bit fancier. Swag.
Meissner’s corpuscles are located in the ___. They are [encapsulated/ not encapsulated] and are [slow/fast] adapting. They’re [tonic/phasic], so they can detect __. Visually, they look like a spool of thread that contains __ fibers, and a nerve ending of the sensory axon wraps around it.
Meissner’s corpuscles are located in the DERMIS. They are ENCAPSULATED and are FAST adapting (and very sensitive). They’re PHASIC, so they can detect TAPS (fire at onset, detect a quick on/off). Visually, they look like a spool of thread that contains COLLAGEN fibers, and a nerve ending of the sensory axon wraps around it.
Pacinian corpuscles look like a sliced ___. They’re located in the __ layer of the skin and deep tissues of the body. They are [encapsulated/ not encapsulated] with ___. The nerve ending is located at the center core within this. These are stimulated by [slow/fast] movement. They’re the [fastest/slowest] adapting receptor - this is the only one that can detect ____. It plays a role in the perception of __ and ___. These
Pacinian corpuscles look like a sliced ONION!. They’re located in the SUBCUTANEOUS layer of the skin (JUNCTION BTWN DERMIS AND HYPODERMIS) and deep tissues of the body. They are ENCAPSULATED with A LAYERED CAPSULE. The nerve ending is located at the center core within this. These are stimulated by FAST movement. They’re the FASTEST adapting receptor - this is the only one that can detect VIBRATION (tuning fork oscillation at 250 cycles/second!). It plays a role in the perception of DEEP TOUCH and VIBRATION. This is the high end of the sensory system.
Hair endings are [encapsulated/non encapsulated] sensory axon endings that wrap around a ___. They are [slow/fast] adapting.
Hair endings are NON-ENCAPSULATED sensory axon endings that wrap around a BULB OF HAIR. They are RAPIDLY adapting.
Temperature receptors are ____ and are [slow/fast] adapting.
Temp receptors = FREE NERVE ENDINGS, RAPIDLY adapting
Muscle spindles involve both primary (___) endings that are associated with fiber type __ and secondary (___) endings associated with type __ endings. The muscle spindle lies in parallel to the __ fibers and play a vital role in ___ and movement sense, [phasic/tonic/both]
Muscle spindles involve both primary (ANNULOSPIRAL) endings that are associated with fiber type Ia and secondary (FLOWER SPRAY) endings associated with type II endings. The muscle spindle lies in parallel to the EXTRAFUSAL fibers and play a vital role in POSITION and movement sense, BOTH PHASIC & TONIC
What receptors contribute to joint and muscle perception? (6)
Muscle spindle Golgi Tendon Organs Joint and Muscle free nerve endings Golgi-type endings Ruffini Endings Paciniform endings
Golgi Tendon Organs lie in series at [proximal/ distal/ both] tendinous insertions of muscles and provide information about __.
GTO: lie in series at BOTH proximal and distal tendinous insertions of muscles. Provide info on TENSION
Joint and muscle free nerve endings are located in the ___ and ___. They provide [fine/crude] awareness to joint movement tissues. They’re associated with several types of sensation including …(4)
Joint and muscle free nerve endings are located in the JOINT CAPSULE and LIGAMENTS. They provide CRUDE awareness to joint movement tissues. They’re associated with several types of sensation including NOXIOUS STIMULATION, CRUDE TOUCH, PRESSURE, CHEMORECEPTION
Golgi-type endings are located in ___ and detect ___
Golgi-type endings are located in LIGAMENTS and detect TENSION
Ruffini endings are located in the __ and __. They respond at [mid-range/ extremes] of ROM and more to [passive/active] than [passive/active] ROM.
Ruffini endings are located in the JOINT CAPSULE and LIGAMENTS. They respond at EXTREMES of ROM and more to PASSIVE than ACTIVE ROM
Paciniform endings are located in the ___ and monitor [active/passive], [phasic/tonic] movement.
Paciniform endings are located in the JOINT CAPSULE and monitor ACTIVE, PHASIC movement.
Receptor types in the CNS encode different sensory information based on their structure through a process called ___. This is the conversion of one form of energy (light, mechanical, etc.) into __ that the nervous system can make sense of.
Receptor types in the CNS encode different sensory information based on their structure through a process called TRANSDUCTION. This is the conversion of one form of energy (light, mechanical, etc.) into ACTION POTENTIALS that the nervous system can make sense of.
The process of transduction requires an adequate ___. The receptors sensing the sensory input are [slow/fast/ either] adapting, determined by the ___ around the receptors. Those that are [fast/slow] adapting detect constant pressure. Those that are [fast/slow] adapting are more phasic and can detect, for example, a series of taps (___ - which receptor type?) or vibration (___ - which receptor type?).
The process of transduction requires an adequate STIMULUS. The receptors sensing the sensory input CAN BE RAPIDLY OR SLOWLY adapting, determined by the CAPSULE around the receptors. Those that are SLOW adapting detect constant pressure. Those that are FAST adapting are more phasic and can detect, for example, a series of taps (MEISSNER’S CORPUSCLES - which receptor type?) or vibration (PACINIAN CORPUSCLE - which receptor type?).
The intensity of stimulation to a receptor is determined by the frequency of ___ and the number of ___ activated.
Intensity related to FREQUENCY OF ACTION POTENTIALS (feel more pressure –> more APs) and the NUMBER OF RECEPTORS activated
___ is the area innervated by receptors and the SINGLE sensory axon associated with them.
RECEPTOR FIELD
The sensory system is ___ organized in the CNS at all levels and stays that way as you go up the neuronal axis. The ___ in the [premotor/ motor/ prefrontal/ somatosensory] cortex is a map of the body in which the body parts are adjacently arranged.
The sensory system is SOMATOTOPICALLY organized in the CNS at all levels and stays that way as you go up the neuronal axis. The HOMUNCULUS in the SOMATOSENSORY cortex is a map of the body in which the body parts are adjacently arranged.
What types of sensory input receptors are associated with unmyelinated and lightly myelinated axons?
Crude touch
Pain
Temperature
What types of sensory receptors are associated with large myelinated axons?
Discriminative touch
Vibration
Joint position
Which types of axons are lost first in peripheral neuropathies? As such, what sensations would you be likely to lose first and which would you likely preserve through initial losses in sensation?
In diabetes/peripheral neuropathies, BIGGEST axons are lost first.
You first lose FINE TOUCH
May preserve some PAIN, TEMPERATURE, and CRUDE TOUCH (from smaller, unmyelinated axons)
Pain, temperature, and crude touch are carried on the ___ tract (aka ____ system). This is a mostly unmyelinated and lightly myelinated system
SPINOTHALAMIC TRACT
aka ANTEROLATERAL system
Fine, discriminative touch, vibration, and proprioception are carried on the ___ system. This is a mostly heavily myelinated system.
DORSAL COLUMN MEDIAL LEMNISCAL system
Some sensations we experience are the result of the integration of individual sensations at the cortical level. These are called combined cortical sensations and they require intact ___ and ___ areas. Examples of combined cortical sensations include… (give 5!)
Combined cortical sensations require intact CORTICAL SENSORY ASSOCIATION AREAS and RECEPTORS
Examples…
Stereognosis (ability to feel an object and recognize what it is)
2-pt discrimination
Graphesthesia (when you write a letter on skin and they know what you’er writing)
Tactile localization (localize touch to a certain body part)
Recognition of texture
List the 4 primary reflex tests in a sensory exam
Deep tendon reflex
Withdrawal reflex (flex 1st toe, usual response is a slight withdrawal. Abnormal: exaggerated withdrawal = CNS damage)
Plantar Response (Babinski Reflex)
- Tests integrity of corticospinal tract
- Normal: Downward (flexor) plantar response = NEGATIVE Babinski
- Abnormal: Upward flare of toes, upward (extensor) plantar response = POSITIVE Babinski = UMN disorder
Hoffman’s Reflex (quick flick/squeeze of middle finger tip)
- Tests integrity of spinal cord reflex loop
- Normal = no response
- Abnormal/Positive = flexion of index finger and thumb after flicking middle finger from flexed position. Indicates UMN disorder
Norms exist for the 2-point discrimination test. Where are the smallest receptor fields? The biggest?
Smallest = finger tips (~2mm!) Biggest = Lower back part of neck, Back of calves, upper back
What potential confounders in performing sensory testing? (5)
- Cognitive status and/or attentional problems
- Scarring/skin integrity
- Language (e.g. aphasia)
- Visual, hearing acuity
- Pain
During sensory testing, you gather info on what structures? (6)
Receptors Axons in peripheral nerves Dorsal roots Spinal cord segment Sensory tracts through CNS Cortex
Find your dermatomes!
C1 - S3,4…go!
C1 — No Skin Innervation
C2 — Posterior Cranium
C3 — Posterior Neck
C4 — AC Joint, top of shoulder
C5 — Lateral Upper Arm
C6 — Lateral Forearm/Tip of Thumb
C7 — Palmar Distal Phalanx (3rd)
C8 — Palmar Distal Phalanx (5th), medial hand
T1 — Medial Forearm
T2 — Medial Upper Arm to axilla
L1 — Groin area
L2 — Ventral Thigh, 2 - 3” below ASIS
L3 — Middle 1/3 ventral/medial thigh to medial knee
L4 — Medial leg to Medial Malleolus
L5 — Dorsum of Foot, especially great toe
S1 — Lateral side & Plantar Surface of Foot, back of calf
S2 — Posterior Thigh
S3, 4 — Perianal Area (base of sacrum)
How do you evaluate myotomal loss? Give muscle/actions for the following myotome: C5 C6 C7 L2 L3 L4 L5 S1
DTR or Strength Testing (not all are amenable to DTR)
C5- Biceps, musculocutaneous C6 - Wrist Extension, DTR C6 - Brachioradialis, radial C7 - Triceps, radial L2 - Hip Flexion L3 - Quadriceps (patellar), femoral L4 - Anterior Tibialis, deep peroneal L5 - Extensor hallicus longus, deep peroneal S1 - Achilles, tibial
Describe DTR scoring
0 = Absent
1+ = Hyporeflexive
(0 & 1 generally indicate LMN lesion…could be nerve root or peripheral n)
2+ = Normal
3+ = Hyperreflexive
4+ = Clonus
(3+ and 4+ indicative of UMN CNS lesions)
In the trunk, the intercostal nerves innervate a single ___. In the limbs, peripheral nerves are formed by contributions of more than one ___ that combine in a ___.
Trunk = intercostal nn. innervate a single DERMATOME
Peripherally, peripheral nn formed by contributions of more than one VENTRAL PRIMARY RAMUS that combine in a PLEXUS
In metabolic disorders and aging, we see sensory loss in a ___ pattern. The longest/largest axons are affected first because ___. This means that ___ sensation is affected first, and you lose ___ later on. In aging, __ die off as well.
In metabolic disorders and aging, we see sensory loss in a STOCKING GLOVE pattern. The longest/largest axons are affected first because THEY ARE THE MOST METABOLICALLY DEMANDING. This means that VIBRATION, PROPRIOCEPTION, & JOINT POSITION sensation is affected first, and you lose PAIN, TEMP, CRUDE TOUCH later on. In aging, RECEPTORS die off as well.
If motor and sensory changes are present, they should [match/not match] if they stem from the same pathology. It’s most common to detect [motor/sensory] changes associated with aging and metabolic disorders first because this system is more sensitive to loss.
Motor and sensory changes should MATCH! Most common to lose sensory first because it’s mores sensitive to loss.
With lesions of the ___, we will see a pattern of sensory loss involving half of the body [on the same side as/opposite] the lesion. With ___ lesions, we may see loss of combined cortical modalities.
Lesion of CNS above spinal cord = sensory loss on half of body OPPOSITE lesion.
With CORTICAL LESIONS (of the parietal lobe), may see loss of combined cortical modalities.
Pain receptors are ___, and they [are/are not] encapsulated. Most are associated with ___, e.g. a stimulus that can cause tissue damage.
Pain receptors are FREE NERVE ENDINGS, and they ARE NOT encapsulated. Most are associated with NOCICEPTION, e.g. a stimulus that can cause tissue damage.
Pain receptors can be of what types? The key is that they’re reaching a threshold that causes tissue damage. You [can/cannot] distinguish between them.
Pain receptors can be THERMORECEPTORS, MECHANORECEPTORS, CHEMORECEPTORS, or POLYMODAL
You CANNOT distinguish between them morphologically
Chemoreceptors are stimulated by …(4!)
- External chemicals
- Inflammatory process by prostoglandins, arachindonic acid and leukotrienes, substance P, serotonin
- Local edema by bradykinin
- Mast cell degranulation by release of histamine and serotonin
___ is complete lack of sensation.
Anasthesia
___ is generalized decrease in sensation. ___ is generalized increase in sensitivity. ___ is pain to light touch.
HYPOESTHESIA = generalized DECREASE in sensation
HYPERESTHESIA = generalized increase in sensitvity *Allodynia = pain to light touch
___ is unpleasant pain. ___ is burning pain. ___ is tingling pain.
DYESESTHESIA = unpleasant pain CAUSALGIA = burning pain PARESTHESIA = tingling pain
The pain pathways (how many?) are both part of the ___ system, AKA the ___ pathway. These pain pathways include the __ and __ pathways.
There are 2 pain pathways:
The “Where?” Pathway
The “What are you going to do about it?” pathway
Both are part of the SPINOTHALMIC system aka ANTERIOLATERAL PATHWAY
The “Where?” pathway helps you to ____ pain. It conveys info regarding the ___ of the source of the pain. The signal is carried on ___ fibers which are [heavily/lightly/not] myelinated so they travel ~___m/s. It conveys information about what type of pain?
The “Where?” pathway helps you to LOCALIZE pain. It conveys info regarding the LOCATION of the source of the pain. The signal is carried on A DELTA fibers which are LIGHTLY/FINELY myelinated so they travel ~5-30/s.
Conveys info about localized, SHARP, FIRST, FAST, EPICRITIC pain (arrives sooner than 2nd part of system)
The “where?” pathway creates a more or less direct root from the periphery to the ___ (___ gyrus). It uses __ (#) neurons in the pathway. Describe where each originates and terminates.
Where pathway creates a route from the periphery to the SENSORY CORTEX (POST CENTRAL GYRUS). It uses 3 NEURONS.
1st order neuron:
- Associated with peripheral receptor
- Cell body in DORSAL ROOT GANGLION
- Comes in and synapses in DORSAL HORN
2nd order neuron:
- Crosses spinal cord
- Forms SPINOTHALAMIC TRACT in anterolateral white matter
- Ascends up to THALAMUS (VPL nucleus)
3rd order neuron:
- Thalamus to sensory cortex (postcentral gyrus)
The “Whatareyagonnadoaboutit?” pathway conveys [localized/poorly localized], [sharp/aching], [fast/slow], protopathic pain to widespread areas of the cortex. It affects ___, __, and ___ systems. Carried on ___ fibers, [myelinated/ unmyelinated/ finely myelinated] at ~___m/s. It is a __(#) system.
The “Whatareyagonnadoaboutit?” pathway conveys POORLY LOCALIZED, ACHING, SLOW, protopathic pain to widespread areas of the cortex. It affects AROUSAL, AUTONOMIC, and LIMBIC systems. Carried on C FIBERS, UNMYELINATED at ~0.5-2m/s. 3 neuron system
Describe the neuronal origins and synapses in the “whatareyagonnnadoaboutit?” pathway.
1st order neuron:
- Synapses in dorsal horn
2nd order neuron
- Transmission cell in dorsal horn
- Crosses and joins spinothalamic tract
- Branches into brainstem as it ascends to activate central pain mechanisms
- Fibers take an indirect course and form a polysynaptic pathway through a portion of the brainstem, aka RETICULAR FORMATION then goes to thalamus
3rd order neuron:
- From thalamus (intralaminar nuclei)
- To widespread areas of cortex (NOT just somatosensory cortex)
Effects of nociception include overall [increase/decrease] in CNS arousal, [increased/decreased] sympathetic tone, and [increased/decreased] alpha MN excitability.
Nociception —>
- INCREASED CNS arousal
- INCREASED SYMPATHETIC tone
- INCREASED alpha MN excitability
[Nociceptive/neuropathic] pain could be soft tissue damage, muscle, chemo irritant. [Nociceptive/neuropathic] pain arises when nervous tissue dysfunctions.
NOCICEPTIVE pain = soft tissue damage, muscle, chemo irritant
NEUROPATHIC pain = arises when nervous tissue dysfunctions
(can be peripheral nn or CNS)
Nociceptive chronic pain stems from ___. Chronic stimulation can [raise/lower] threshold of receptors contributing to chronic pain. Give an example.
Nociceptive chronic pain stems from CHRONICALLY-STIMULATED PERIPHERAL RECEPTORS.
This can LOWER threshold of receptors contributing to chronic pain. E.g. KNEE OA (innervated bone –> chronically stimulated pain)
Neuropathic chronic pain stems from ___ or ___. The symptoms are [the same as/different from] nociceptive chronic pain and include ___, ___, and ___.
Neuropathic chronic pain stems from a NERVE INJURY or SYNAPTIC REORGANIZATION. Symptoms are DIFFERENT from nociceptive chronic pain and include PARASTHESIA (tingling), DYSESTHESIA (unpleasant, often burning = causalgia), AND HYPERALGESIA (excessive pain in response to mildly painful stimulus, e.g. allodynia)
Neuropathic pain can have peripheral or central changes/mechanisms. Peripheral mechanisms include ___ and ___. Central changes include __, ___, and __.
Peripheral mechanisms
- Ectopic foci
- Ephatic transmission
Central changes
- Central sensitization
- Structural Reorganization
- Altered top-down modulation
Describe the difference between ectopic foci and ephatic transmission
ECTOPIC FOCI is one mechanism of peripheral neuropathic pain. It is generally the result of neuronal damage (direct injury to neuron) APs are generated from DEMYELINATED areas of axons:
- The recovering neuron makes mechanosensitive and chemosensitive sodium channels that are inserted in demyelinated portions of the membrane.
- Pressure on that portion of the nerve causes an AP (and pain!).
EPHATIC TRANSMISSION involves cross talk between neurons in areas of demyelinization. APs in touch neuron can cause APs in an adjacent pain neuron (because previously myelinated axons are now not myelinated). This may be a mechanism for allodynia in which touch causes pain.
Describe the differences between central sensitization, structural reorganization, and altered top down modulation in central changes associated with neuropathic chronic pain.
Central Sensitization
- Pain may be result of abnormally prolonged pain transmission in CNS cells
- Chronic stimulus –> stronger response centrally
- Intense signaling from periphery –> increased sensitivity due to upregulation of transmitters and receptors, making a mild stimulus very painful.
- This can happen at every level of pain transmission (SC, BS, Thalamus, Cortex)
Structural Reorganization
- Collateral growth from touch axons (which can be painful) that may start to communicate with pain transmission cells.
- Touch may be perceived as pain (aka allodynia)
Altered Top Down Modulation
- Reduced antinociceptive influence from higher centers to spinal cord, pronoception is increased
- Sometimes related to genetic susceptibility relative to neurotransmitter levels
- Doesn’t necessarily involve the periphery (no real source of incoming pain!).
Somatosensory representation changes with chronic pain. The cortical representation of the involved body part may [increase/decrease/either]. In Complex Regional Pain Syndrome (CRPS), the representation of the painful [enlarges/shrinks]…why?
Cortical representation of painful body part in the somatosensory cortex may change EITHER increasing or decreasing! In CRPS, representation of the painful hand SHRINKS because they aren’t using it! In LBP, you can’t not use your LBP, so those neurons continue to be active and maintain/enlarge somatosensory representation.
Phantom limb pain involves sensations felt in a body part that is ___. This involves complex plastic changes in the CNS, including the ___, following amputation. There is an [increase in/lack of] sensory info that causes neurons in CNS pathway to become overactive. Significant rewiring has to take place in brain. Phantom pain is [easy/difficult] to treat.
Phantom pain involves sensations felt after amputation in body part that is no longer there. Changes in CNS, including sensory cortex, following amputation leads to a LACK of sensory info that causes neurons in CNS pathway to become OVERACTIVE. DIFFICULT to treat.
What is referred pain? Why do we have referred pain? Example?
Referred pain is when you feel pain in a somatic body area (usually on the skin when you’re really having visceral pain). This occurs because cutaneous and visceral afferents both converge on the SAME PAIN TRANSMISSION NEURON in thes pinal cord! Spinal cord gets a little confused as per source of pain and “feels it” in an area that isn’t the source of the stimulus.
E.g. Angina (<3 ischemia) - heart is innervated by upper cervical segments so angina is felt over pecs and deltoid region
