Term
| what does the PNS consist of |
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Definition
| motor and sensory branches of the cranial and spinal nerves, the peripheral parts of the autonomic nervous system, and the peripheral ganglia |
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Term
| what do peripheral nerves contain |
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Definition
1. connective tissue sheaths that enclose their nerve fibers
2. outer fibrous sheath called the epineurium surrounds the medium-sized to large nerves; inside, a sheath called the perineurium invests each bundle of nerve fibers; and within each bundle, a delicate sheath of connective tissue known as the endoneurium surrounds each nerve fiber (axon)
3. - Inside the endoneurial sheath are the Schwann cells that produce the myelin sheath that surrounds the peripheral nerves |
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Term
| what do peripheral nerve disorders affect |
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Definition
| spinal nerve or nerve root, a nerve plexus, or peripheral nerve trunk (mononeuropathies), or multiple peripheral nerves (polyneuropathies) |
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Term
| what are the 2 types of of peripheral nerve damage |
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Definition
1. segmental demyelination: involving the Schwann cell
2. axonal degeneration: involving the neuronal cell body or its axon |
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Term
| segmental degeneration process |
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Definition
- Segmental demyelination occurs when there is a disorder of the Schwann cell (as in GuillainBarré syndrome) or damage to the myelin sheath (e.g., sensory neuropathies), without a primary abnormality of the axon.
-It typically affects some Schwann cells while sparing others.
-The denuded axon provides a stimulus for remyelination, and the population of cells in the endoneurium has the capacity to replace the injured Schwann cells. These cells proliferate and encircle the axon, and in time remyelinate the denuded portion. However, the new myelin sheath is thin in proportion to the axon, and over time, many chronic demyelinating neuropathies give way to axonal injury. |
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Term
| axonal degeneration process |
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Definition
1.Axonal degeneration is caused by primary injury to a neuronal cell body or its axon. Damage to the axon may be due either to a focal event occurring at some point along the length of the nerve (e.g., trauma or ischemia) or to a more generalized abnormality affecting the neuronal cell body (neuropathy).
2. When an injury occurs, the axon of the nerve will degenerate distal to the lesion site; the myelin surrounding the axon distal to the lesion will likely degenerate (Wallerian Degeneration).
3. In distal axonal degeneration, the proximal axon and neuronal cell body, which synthesizes the material required for nourishing and maintaining the axon, remain intact.
4. In neuropathies and crushing injuries in which the endoneurial tube remains intact, the outgrowing fiber will grow down this tube to the structure that was originally innervated by the neuron. However, it can take weeks or months for the regrowing fiber to reach its target organ and for communicative function to be reestablished. More time is required for the Schwann cells to form new myelin segments and for the axon to recover its original diameter and conduction velocity.
5. The successful regeneration of a nerve fiber in the peripheral nervous system depends on many factors.
-If a nerve fiber is destroyed relatively close to the neuronal cell body, the chances are that the nerve cell will die, and if it does, it will not be replaced.
6. If a crushing type of injury has occurred, partial or often full recovery of function occurs.
7. Cutting-type trauma to a nerve is an entirely different matter. Connective scar tissue forms rapidly at the wound site, and when it does, only the most rapidly regenerating axonal branches are able to get through to the intact distal endoneurial tubes. |
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Term
| nerve regeneration process |
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Definition
1. Axons may regenerate provided that the soma is intact
2. Occurs at a rate of 1-2 mm daily, with the more proximal nerve section regenerating faster
3. Even if regeneration occurs, there are factors affecting successful functional return
- Mixed nerve lesions have a lower rate of successful regeneration
- Reinnervated tissue is severely dystrophic |
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Term
|
Definition
- compression
- trauma
- systemic disorders
- systemic oedematous conditions ie. pregnancy |
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Term
| PNS lesion classifications |
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Definition
1. seddon (first degree)
- compression of nerve causing local demyelination resulting in local conduction block; no structural damage to the axon or tissue distal to lesion
- repair of demyelinated tissue occurs within weeks or months
- involves loss of motor function; sensory and autonomic fibres are unaffected
- prognosis is usually very good
2.axonotmesis (second degree)
- Prolonged severed nerve compression
- Causes lesion at site of compression followed by degeneration of the axons distal to the injury
- Endoneurial tube remains intact
- Sensory, motor and autonomic losses occur
- Prognosis is good since endoneurial tube provides an appropriate pathway through which the axons can regenerate to the correct end organs
3.neurotmesis (3rd - 5th degree)
- Severance of part or all of nerve trunk including endoneurial tube
- Results in degeneration of the nerve
- Sensory, motor and autonomic losses occur
- Prognosis is poor as axons have difficulty regenerating to distal end organs due to scar tissue at the lesion site; surgical repair is usually required to ensure some functional recovery
(complete= all fibres within nerve is affected)
(partiel= only some fibres are affected) |
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Term
|
Definition
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Clinical Features
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Complete Regenerating Lesions
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Partial Regenerating Lesions
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Permanent Lesions
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Edema
Motor function
Contractures
Pain
Scar tissue
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- Present initially
- More severe if autonomic nerves are involved
- Flaccid paralysis
- Fibrillation
- Diminished or lost DTR
- Develop in unopposed antagonistic muscles
- Area of anesthesia of the cutaneous division of the nerve
- Variable pain levels
- Decreased or altered sensation
- Present
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- Less severe than edema present in complete lesions
- Muscle weakness
- Fibrillation
- Often have diminished DTR
- May develop in unopposed antagonists
- Areas of hypesthesia and possibly dysesthesia which are perceived as painful
- Present
|
- Present and will remain
- Flaccid paralysis
- Other muscles compensate producing secondary s/s
- Develop and become more marked over time
- Areas of hypesthesia, anesthesia or paresthesia
- Present
- Neuroma may develop
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Term
| compression syndrome definition (NEUROPRAXIA) |
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Definition
| a local conduction block in a peripheral nerve, but no structural damage to the axon or to tissue distal to the lesion |
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Term
| external causes of compression syndromes |
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Definition
| pressure from casting, crutches, splints, a tourniquet or back back straps |
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Term
| internal causes of compression syndomes |
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Definition
- Numbness, tingling, pain and weakness in affected limb
--> due to ischemia of the nerve and mechanical compression of the nerve
- Entrapment of nerve trigger inflammatory response
-->increased vascular permeability, local edema--> impaired nerve transmission
-As there is no lymphatic capillaries within the nerve itself, the intraneural edema is difficult to resolve -->Recovery time varies after the compression is relieved; recovery of nerve function ranges from weeks to months
-Key to treatment is relief of the compression on the nerve |
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Term
| symptoms of compression syndromes |
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Definition
Numbness, tingling, pain and weakness in affected limb due to ischemia of the nerve and mechanical compression of the nerve
Entrapment of nerve trigger inflammatory response increased vascular permeability, local edema impaired nerve transmission
As there is no lymphatic capillaries within the nerve itself, the intraneural edema is difficult to resolve
- Recovery time varies after the compression is relieved; recovery of nerve function ranges from weeks to months
Key to treatment is relief of the compression on the nerve |
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Term
| the path of radial nerve lesions |
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Definition
Radial nerve is a continuation of the posterior cord (C5-T1 of the brachial plexus
From posterior axillary wall b/w the long and medial heads of triceps --> spiral groove of humerus, deep to lateral head of triceps -->winds around humerus to lateral side -->crosses elbow joint to the supinator, divides into 2 branches: posterior motor branch enters supinator, then travels down lateral aspect of radius ending at the wrist; other superficial sensory branch continues down posterior aspect of forearm, crosses extensor retinaculum, divides into more branches |
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Term
| muscles innervated (radial nerve lesions) |
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Definition
-Anconeus
-Brachioradialis
-Extensor carpi radialis brevis/longus
-Extensor carpi ulnaris
-Extensor digitorum
-Extensor indicis
-Extensor digiti minimi
-Extensor pollicis brevis/longus
-Abductor pollicis longus
-Supinator |
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Term
| causes of radial nerve lesions |
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Definition
- fractures: primarily at the spinal radial groove of the humerous
- dislocation: of the head of the radius
-post surgical complications: due to unrelieved pressure on the lateral arm from poor positioning during surgery
-compression
-supinator syndrome: may result in neuropraxia or axonotmesis |
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Term
| symptoms of radial nerve lesions |
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Definition
-Complete lesion produces WRIST DROP – hand hangs in flexion as wrist flexors are unopposed
-Injury is proximal to elbow before radial Nr branches – both sensory and motor functions are affected
-injury is distal to elbow – only 1 branch is affected
-Muscle wasting is possible depending on lesion site
-There may be swelling of the dorsum of the hand although etiology is unknown |
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Term
| sensory deficits of radial nerve lesions |
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Definition
| Paresthesia at the posterior arm/forearm/hand (radial 3 ½ digits, excluding the fingertips) |
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Term
| motor deficits of radial nerve lesions |
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Definition
1. Lesion in axilla
-affects triceps and anconeus --> loss of elbow extension
2.Lesion in arm to elbow
-Brachioradialis --> weakened forearm flexion in mid-pronated position
3. Lesion in elbow to forearm
-Loss of wrist extension, abduction; loss of thumb and finger extension at MCP
-Weakened wrist adduction, thumb extension at IP, thumb abduction at CMC |
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Term
| path of ulnar nerve lesions |
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Definition
-Ulnar nerve is a continuation of the medial cord (C8-T1) of the brachial plexus
-Travels along medial aspect of arm, follows a relatively superficial course --> at elbow, nerve goes posterior to medial epicondyle of the humerus --> continuing to the wrist, the nerve is joined midway by the ulnar artery and both structures travel over the flexor retinaculum, between the pisiform and hook of the hamate, and beneath the Palmaris brevis muscle (passage known as Guyon’s tunnel or Ulnar tunnel) --> divides into superficial (primarily sensory) and deep (primarily motor) branches |
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Term
| muscles innervated of ulnar nerve lesions |
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Definition
-Flexor carpi ulnaris
-Flexor digitorum profundus (ulnar half)
-Hypothenar muscles: abductor digiti minimi, flexor digiti minimi, opponens digiti minimi
-Palmar / dorsal interossei
-Adductor pollicis
-Flexor pollicis brevis
-3rd and 4th lumbricals |
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Term
| cause of ulnar nerve lesions |
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Definition
-Fractures: of medial condyle of humerus, mid-forearm or wrist
-dislocation: of the elbow
-Post surgical complications: such as unrelieved pressure from the arm hanging over the edge of a table or the arm positioned improperly while under anesthesia
-pathology: ei leprosy
- prolonged compression: From resting the elbow on a hard surface, wearing a too tight wrist band/handcuff or from bicycling
-repetitive action: ei pitching a ball, repeated flexion and extension with machine work --> Compression syndromes may develop due to fibrosis at specific sites such as the medial elbow or at Guyon’s canal
- direct trauma: contusion or laceration at the wrist or hand |
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Term
| symptoms of ulnar nerve lesions |
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Definition
1. Complete lesion produces CLAW HAND – little finger hyperextended and abducted at MCP and flexed at IP; ring finger is hyperextended at MCP with varying amounts of flexion at IP
2. Froment’s sign is positive
3. Muscle wasting – is most remarkable at the hypothenar eminence and in the interosseous spaces; may be present at the ulnar side of the forearm if flexor carpi ulnaris and flexor digitorum profundus are affected
4. Altered sensation, anhidrosis and vasomotor changes may occur |
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Term
| sensory deficits of ulnar nerve lesions |
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Definition
1. Paresthesia on the ulnar side of the hand (palmar and dorsal surface) in the little finger and medial half of the ring finger
2. Anesthesia occurs along the little finger to the wrist (d/t compromised blood supply) |
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Term
| motor deficits of ulnar nerve lesions |
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Definition
1. lesion in the arm and forearm
- weakened wrist flexion/adduction
-loss of flexion of 4th and 5th fingers at DIP
2. wrist
-loss of adduction of thumb at MCP, opposition of 5th digit, flexion of 4th and 5th digits at MCP
-weakened flexion of thumb at MCP, abduction of 2nd - 5th digits, adduction of 4th and 5th digits |
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Term
| path of median nerve lesions |
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Definition
1.Radial nerve is a continuation of the posterior cord (C5-T1 of the brachial plexus
2.From posterior axillary wall b/w the long and medial heads of triceps --> spiral groove of humerus, deep to lateral head of triceps --> winds around humerus to lateral side --> crosses elbow joint to the supinator, divides into 2 branches: posterior motor branch enters supinator, then travels down lateral aspect of radius ending at the wrist; other superficial sensory branch continues down posterior aspect of forearm, crosses extensor retinaculum, divides into more branches |
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Term
| muscles innervated in median nerve lesions |
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Definition
- Pronator teres
- Pronator quadratus
- Flexor carpi radialis
- Flexor digitorum superficialis
- Flexor digitorum profundus (radial half)
- Palmaris longus (absent in up to 20% of population)
- Thenar muscles: abductor pollicis brevis, flexor pollicis brevis, opponens pollicis
- 1st and 2nd lumbricals |
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Term
| causes of median nerve lesions |
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Definition
1.Fractures: primarily at the spinal radial groove of the humerus
2.Dislocation: of the head of the radius
3.Post surgical complications: due to unrelieved pressure on the lateral arm from poor positioning during the surgery
4. Compression
-Primarily at the axilla from crutch use
-Saturday night palsy: when arm is draped over back of a chair or table edge, or when arm is fully abducted and supporting the head against a hard surface (as with undisturbed sleep resulting from drug use, alcohol intoxication or extreme fatigue
5.Supinator syndrome
-Compression in the forearm where the nerve penetrates the supinator muscle
-May result in neuropraxia or axonotmesis |
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Term
| symptoms of median lesions |
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Definition
-Complete lesion produces WRIST DROP – hand hangs in flexion as wrist flexors are unopposed
-Injury is proximal to elbow before radial Nr branches – both sensory and motor functions are affected
-Injury is distal to elbow – only 1 branch is affected
-Muscle wasting is possible depending on lesion site
-There may be swelling of the dorsum of the hand although etiology is unknown |
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Term
| sensory deficits of median nerve lesions |
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Definition
| parenthesis at the posterior arm/forearm/hand (radial 31/2 digits, excluding the fingertips) |
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Term
| motor deficits of median nerve lesions |
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Definition
1. lesion in axilla
-affects triceps and anconeus --> loss of elbow extension
2. lesion in arm to elbow
-brachioradialis --> weakened forearm flexion in mid pronated position
3. lesion in elbow to forearm
- loss of wrist extension, abduction; loss of thumb and finger extension at MCP
-weakened wrist adduction, thumb extension at IP, thumb abduction at CMC |
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Term
| classifying nerve injuries (NEUROPRAXIA) (first degree) |
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Definition
• 1st degree injury
• Compression
• Local conduction blocked
• No structural damage to axon or tissue distally
• Local demyelination
• Repaired over weeks or months
• Affects motor function only (not sensory or
autonomic)
• Prognosis is good |
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Term
| classifying nerve injuries (AXONOTMESIS) (second degree) |
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Definition
• 2nd degree injury
• Compression
• Degeneration of axon distal to injury
• Endoneurial tube stays intact
• Motor, sensory, and ANS all affected
• Regeneration good due to preservation of
tube |
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Term
| classifying nerve injuries (NEUROTMESIS) (3RD/4TH/5TH DEGREE) |
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Definition
• 3rd, 4th, & 5th degree injury
• Severance (partial or complete)
• Degeneration of nerve
• Scar tissue at site develops and makes regeneration difficult
• Motor, sensory, and ANS all affected
• Prognosis is poor
• Surgical repair to restore some function |
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Term
| peripheral nerve pain (NEURITIS) |
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Definition
• Inflammation of a nerve (term can still be used for non-inflammatory conditions)
• Originates from the myelin sheath and connective tissue wrappings, not the axon
• Constant, dull pain
• May experience paresthesia
• May be motor and sensory deficits if long duration
• Caused by:
• Pathology (diabetes, leprosy, TB)
• Trauma
• Chronic exposure to toxin (lead, drugs, alcohol)
• Massage may be CI’s |
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Term
| peripheral nerve pain (NEURALGIA) |
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Definition
• Nerve pain
• Recurrent attacks of extreme pain along a nerve pathway
• Described as “electric” or “lightening”, and occasionally “throbbing”
• No perceivable nerve damage
• Paroxysmal attacks of pain are triggered, often by stimulating the cutaneous region supplied by the nerve, or by movement
• Common conditions are trigeminal neuralgia and intercostal neuralgia
• Other types are phrenic, lumbar, brachial, and sciatic neuralgia
• Caused by:
• Local compression (trauma causing inflammation and scar tissue, subluxation, or osteophyte • Prolonged exposure to cold
• Massage may alleviate discomfort or relieve pressure and local swelling, but is CI’d in acute |
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Term
| peripheral nerve pain (INTERCOSTAL NEURALGIA) |
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Definition
• affects intercostal nerves, travelling between the intercostal muscle layers, along with blood vessels
• caused by: DIABETES (metabolic changes may cause neuralgia that lasts 1-2 years) or POST-HERPES ZOSTER or shingles (some cases lead to chronic neuralgia with intermittent attacks of pain along the affected intercostal nerve (may resolve within 2 years)
• “triggered” by light touch or movement over the affected area
• Treated by doctor or neurologist with drugs
• May benefit from stress reduction strategies, including massage (may have to avoid the trigger zones) |
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Term
| peripheral nerve pain (CAUSALGIA) |
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Definition
• severe pain syndrome
• sudden onset of intense,
persistent, burning pain
• associated with traumatic injury
• typically, incomplete injury accompanied by vascular damage
• common causes: • gunshot wounds
• iatrogenic nerve injures (ie. surgery or injections)
• electrocution
• amputation
• high velocity sharp objects (ie. industrial machinery)
• may be accompanied by autonomic or trophic disturbances, such as:
• poor vasomotor control (blood vessel constriction/dilation) • swelling
• dystrophic skin changes
• commonly affects the median nerve and the tibial nerve division of the sciatic nerve (lots of sympathetic fibres) |
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Term
| reflex sympathetic dystrophy (RSD) aka (complex regional pain syndrome) Is characterized by what symptoms |
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Definition
• abnormal sympathetic reflexes and vascular spasm
• edema and possible ischemia
• pain, that can be extreme, and is out of proportion to the injury • warmth or coolness
• increased or decreased sweating
• trophic changes (hair, skin, nails)
• tissue atrophy (muscle and bone) |
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Term
| NEUROMAS (definition / how there formed / treatment / where they grow) |
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Definition
• tumor of nerve cells
• formed by nerve fibres at the edge of a
partial or complete severance
• these fibres are attempting to grow toward the distal edge of the severed fibres and may be blocked by scar tissue, or wander randomly into surrounding tissue
• neuromas may be a clump of tangled fibres, or a “softer” neuroma of unprotected nerve endings – which tends to be more painful, and/or, result in paresthesia
• may be treated with surgery & relaxation techniques (massage could be a local CI) |
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Term
|
Definition
– traction injury to the lower brachial plexus – C8-T1
• Horner’s Syndrome
• Often caused by separation of the shoulder from the thorax (i.e. grabbing something to break a fall, dragging a child
by the arm)
• Main losses/damage is to the Ulnar nerve and therefore causes...
• Weak wrist flexion (FDP and FCU)
• Weak wrist adduction (FCU)
• Ulnar Claw hand (Lumbricals and Interossei) |
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Term
| erbs paralysis & signs/symptoms |
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Definition
Signs and Symptoms:
• Inability to abduct the GH joint→lack of innervation in the deltoid + supraspinatus
• Difficulty externally rotating the GH joint→lack of innervation for teres minor + infraspinatus
• Decreased elbow flexion→damage to the musculocutaneous nerve (and therefore the elbow flexors)
• Loss of supination (biceps + supinator)
• Sensory losses on the lateral arm and forearm
traction injury to the upper brachial plexus – C5-C6 |
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Term
| what is waiters tip deformity |
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Definition
in result of eras palsy/paralysis
• Arm adducted and internally rotated • Elbow extended
• Forearm pronated
• Wrist flexed |
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Term
|
Definition
If the T1 spinal nerve is affected Horner’s syndrome may occur
Horner’s syndrome is a condition in which the sympathetic innervation to the head is disrupted resulting in:
1. Miosis (constricted pupils)
2. Anhydrosis (no sweating on the face) 3. Ptosis (drooping eyelid) |
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Term
| radial nerve lesion symptoms (c5-t1) |
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Definition
1. Decreased/altered sensation on the dorsal aspect of the hand including the thumb, except the distal interphalangeal joints
2. Weak arm extension and inability to extend the elbow, wrist, and fingers
3. Weak supination
4. Weak radial deviation of the wrist
5. Wrist drop |
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Term
| ulnar nerve lesion symptoms (c8-t1) |
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Definition
1. Loss of sensation to the medial half of 4th finger and all of 5th finger
2. Atrophy of interosseous muscles
3. Atrophy of the hypothenar eminence
4. Claw hand deformity |
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Term
| median nerve lesions symptoms |
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Definition
Symptoms if injury is at the WRIST
1. Numbness or tingling in the thumb and adjacent two or three fingers and palm of the hand
2. Impaired fine finger movements
3. Weak grip and difficulty in carrying bags (a common complaint)
4. In advanced or long-term cases there may even be wasting of the
muscle of the thumb (Thenar eminence)
• Symptoms if injury is at/or above the elbow:
1. Loss of Pronation
2. Extremely weak grip
3. Weakness in Radial Deviation
4. Accompanied by all symptoms associated below the wrist |
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Term
| jedi hand (hand of benediction) |
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Definition
• Median nerve damage is more proximal than CTS affecting the wrist and finger flexors
• 4th and 5th digits can still curl down when asked to make a fist because
their FDP is innervated
by the Ulnar nerve |
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Term
| sciatic nerve lesions (pelvis/butt/thigh) |
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Definition
• Fractures to pelvis or femur
• Contusions to the gluteals
• Hip Dislocations
• Surgeries, lacerations to gluteals or hamstrings
• Injections in gluteal region
• Injuries to mother during childbirth |
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Term
| sciatic nerve lesions (knee/leg/ankle) |
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Definition
• Knee dislocations
• Fracture of the tibia
• Contusions/lacerations of the popliteal fossa
• Excessive knee flexion, (kneeling)
• Severe sprains, (eg. eversion)
• Long term tarsal tunnel syndrome |
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Term
|
Definition
• It is a neurologic condition affecting the Facial nerve that causes paralysis or weakness of the muscles of the face
• The exact etiology is not known and viral infections are often implicated
• The symptoms may be transient (very short term) or permanent and the symptoms are often noticed in the morning having usually developed overnight |
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Term
| what are common compression symptoms of peripheral nerve |
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Definition
1. Thoracic Outlet Syndrome
2. Carpal Tunnel Syndrome
3. Piriformis Syndrome |
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Term
| thoracic outlet syndrome (where its compressed/causes/symptoms) |
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Definition
where its compressed
• Ant and middle scalenes • 1st rib and the Clavicle
• Pec Minor and the ribs
causes
• Physical trauma from an injury • Repetitive strain
• Certain anatomical deficits
• Pregnancy
symptoms
• Numbness or tingling in your arm or fingers
• Pain or aches in your neck, shoulder or hand
• Weakening grip |
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Term
| carpel tunnel syndrome (symptoms) |
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Definition
1. Numbness or tingling in the thumb and adjacent two or three fingers and palm of the hand
2. Impaired fine finger movements
3. Weak grip and difficulty in carrying bags (a common complaint)
4. In advanced or long-term cases there may even be wasting of the
muscle of the thumb (Thenar eminence) |
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Term
| piriformis syndrome ( what it compresses/ symptoms) |
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Definition
• Compression of the sciatic nerve by a hypertonic piriformis muscle
• Symptoms: Pain and numbness down the leg |
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Term
| nociceptive vs neuropathic pain |
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Definition
-nociceptive: when receptors are activated in response to actual or impending tissue injury (nociceptive pain is the consequence)
-neuropathic pain: arises from direct injury or disfunction of the sensory axons of peripheral or central nerves |
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Term
| two pain theories and definitions |
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Definition
specificity theory: regards pain as a separate sensory modality evoked by the activity of specific receptors that transmit information to pain centres
pattern theory: it proposes that pain receptors share endings or pathways with other sensory modalities, but that different patterns of activity of the same neurone can be used to signal painful and non painful stimuli |
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Term
| gate control pain theory definition |
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Definition
| that perception of physical pain is not a direct result of activation of nociceptors, but is modulated by interaction between different neurons |
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Term
| what are nociceptors & pain receptors |
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Definition
| are sensory receptors that are activated by noxious insults to peripheral tissues |
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Term
| what fibres are nociceptor action potentials through |
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Definition
afferent fibres:
myelinated a fibres: fast pain.. transmitting impulses at 10 to 30m/sec that are elicited by mechanical or thermal stimuli
unmyelinated c fibres: slow wave pain... transmitting impulses at 0.5-2.5m/sec that are incited by chemical stimuli or persistent mechanical or thermal stimuli (responsible for central sensitization to chronic pain) |
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Term
| two pathways for pain transmission |
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Definition
1. The pathway for fast, sharply discriminated pain that moves directly from the receptor to the spinal cord using myelinated Aδ fibers and from the spinal cord to the thalamus using the neospinothalamic tract
2. The pathway for slow, continuously conducted pain that is transmitted to the spinal cord using unmyelinated C fibers and from the spinal cord to the thalamus using the more circuitous and slower-conducting paleospinothalamic tract |
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Term
| mediators in the spinal cord |
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Definition
in the spinal cord, the transmission of impulses between the nociceptors neurone and the dorsal horn neurone in mediated by chemical neurotransmitters (amino acids ei glutamate) others are (amino acids derivatives norepinephrine)
glutamate is a major excititory neurotransmitter released from the central nerve endings of the nociceptive neurone |
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Term
| substance P (mediators in the spinal cord) |
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Definition
| a neuropeptide is released in the dorsal horn by C fibres in response to nociceptive stimulation. it elicits slow excitatory potentials in dorsal horn neurons. some neuropeptides released in the dorsal horn can diffuse some distance because they aren't inactivated by reuptake mechanisms. |
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