See Also: disc sequestration(medicine)
Herbal medicine (botanical medicine, herbology, phytomedicine)(health)
sequestration(dictionary)
sequestration(encyclopedia)
Sequestration(medicine)
SEQUESTRATION, contracts(law)
bronchopulmonary sequestration(medicine)
sequestration dermoid(medicine)
intralobar sequestration(medicine)
extralobar sequestration(medicine)

all-or-nothing phenomenon (medicine) and disc sequestration (medicine)


all-or-nothing phenomenon (medicine)


all-or-nothing phenomenon
<physiology> Refers to the phenomenon where the strength of a nerve impulse is not dependent on the strength of the stimulus. Instead, there is a threshold level of stimulus strength that must be reached before the nerve will fire an impulse (at full capacity). Below the threshold, the nerve will not fire at all.

<cardiology> It also refers to the same phenomenon observed in the heart muscle, which will either contract fully or not at all.

<psychology> In studies of behaviour, it refers to the same phenomenon where a behavioural stimulus will either produce a complete response or no response at all. Also called all-or-nothing principle, all-or-none law, all-or-none responsiveness, etc.


disc sequestration (medicine)


disc sequestration
<radiology> Complete separation of disc material with rupture through posterior longitudinal ligament into the epidural space; free fragment herniation findings: migration superiorly/inferiorly with compression of nerve roots above/below the level of herniation, disc material noted more than 9mm from disc space Differential diagnosis: postoperative scarring (retraction of thecal sac to the site of surgery), epidural abscess/tumour, conjoined nerve root: 2 nerve roots arising simultaneously from the thecal sac; normal variant in 1-3% see: degenerative disc disease