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Nerve conduction
Sompol Tapechum M.D., Ph.D.Department of PhysiologyFaculty of Medicine Siriraj
Hospital
Objectives
• นั�กศึ�กษาสามารถบอกประโยชนั�ของการวั�ด nerve conduction velocity ได�
• นั�กศึ�กษาสามารถบอกวั�ธี�การวั�ด nerve conduction velocity ได�
• นั�กศึ�กษาสามารถบอกป�จจ�ยที่�!ม�ผลต่%อ nerve conduction velocity ของ axon ได�
Nervous system
Structure of Nervous system
• Central nervous system (CNS)– Brain
• Cerebrum• Cerebellum• Brainstem
– Spinal cord
• Peripheral nervous system (PNS)– Nerves
• Cranial nerve 12 pairs• Spinal nerve 31 pairs
Spinal nerve and Cranial nerve
Nerve structure
• Nerve = Bundle of axon
• Component of nerve– Motor
• Somatic• Autonomic
– Sensory• Somatic• Visceral
AxonS
enso
ry n
euro
nsM
otor
neu
rons
Orthodromic
Antidromic
Orthodromic
Antidromic
Types of axon
Type of axon
Table ISomatosensory Receptors and their Peripheral Axons
Receptor Type Axon3 Group CAP Peak Conduction Velocity Axon Diameter Information Processed
Muscle Spindle: Annulospiral endings Ia A 70 - 120 m/sec 12 - 20 M Muscle length and velocity
Muscle Spindle: Flower Spray endings II A 30 - 70 m/sec 6 - 12 M Muscle length
Golgi Tendon Organ Ib A 70 - 120 m/sec 12 - 20 M Muscle tension
Joint: Pacinian II A 30 - 70 m/sec 6 - 12 M Joint movement
Joint: Ruffini II A 30 - 70 m/sec 6 - 12 M Joint angle
Joint: Golgi Tendon Organ II A 30 - 70 m/sec 6 - 12 M Joint torque
Meissner corpuscle II A 30 - 70 m/sec 6 - 12 M Touch, flutter or movement
Pacinian corpuscle II A 30 - 70 m/sec 6 - 12 M Vibration
Ruffini corpuscle II A 30 - 70 m/sec 6 - 12 M Skin stretch
Hair follicle II & III A & A 10 - 70 m/sec 2 -12 M Touch movement
Merkel complex II A 30 - 70 m/sec 6 - 12 M Fine touch
Free Nerve Endings III A 5 - 30 m/sec 1 - 6 M Sharp pain or cool/cold
Free Nerve Endings IV C 0.5 - 2 m/sec < 1.5 M Dull or aching pain, or touch or warm
Nerve conduction
Sensory conduction study
• Antidromic
Sensory conduction study
• Orthodromic
Motor conduction study
• Orthodromic
Median nerve
Motor conduction study:Median nerve
Motor neuron
Neuromuscularjunction
Neuromuscular junction
Nerve conduction velocity
D1
D2
Latency (s) L1
L2
NCV = D1-D2L1-L2
Sensory conduction study:Median nerve
Purposes of Nerve conduction study
• To diagnose nerve damage or destruction
• To follow up nerve regeneration after damage
• To evaluate diseases of nerve or muscle
Normal nerve conduction velocity
• normal conduction velocity– approximately 50 to 60 meters per second .– may vary from one individual to another and
from one nerve to another .
Carpal tunnel syndrome
Nerve injury
Axon regeneration
2-4 mm/day
Myasthenia gravis
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