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Type II sensory fiber
Encyclopedia
Type II sensory fiber (group Aβ) is a type of sensory fiber, the second of the two main groups of stretch receptor
s. They are non-adapting, meaning that they keep responding even when the muscle has stopped changing its length. They are the second most highly myelinated fibers in the body.
Their firing rate is directly related to the muscle's instantaneous length, or position. This information would indicate the position of one's leg once it has stopped moving. They do not respond to rate of length changes as do the Ia fibers.
Type II fibers connect to nuclear chain fiber
s, but not to nuclear bag fiber
s. These connections, referred to as "flower spray endings" due to their appearance, embed into the poles
(ends) of the fibre. It is thought that the relative position of the equatorial regions of the spray when stretched determines the action potential
output.
Stretch receptor
Stretch receptors are mechanoreceptors responsive to distention of various organs and muscles, and are neurologically linked to the medulla in the brain stem via afferent nerve fibers...
s. They are non-adapting, meaning that they keep responding even when the muscle has stopped changing its length. They are the second most highly myelinated fibers in the body.
Their firing rate is directly related to the muscle's instantaneous length, or position. This information would indicate the position of one's leg once it has stopped moving. They do not respond to rate of length changes as do the Ia fibers.
Type II fibers connect to nuclear chain fiber
Nuclear chain fiber
A nuclear chain fiber is a specialized sensory organ contained within a muscle. Nuclear chain fibers are intrafusal fibers which, along with nuclear bag fibers, make up the muscle spindle responsible for the detection of changes in muscle length....
s, but not to nuclear bag fiber
Nuclear bag fiber
A nuclear bag fiber is a type of intrafusal muscle fiber that lies in the center of a muscle spindle. Each has a large number of nuclei concentrated in bags and they cause excitation of both the primary and secondary nerve fibers....
s. These connections, referred to as "flower spray endings" due to their appearance, embed into the poles
Poles
thumb|right|180px|The state flag of [[Poland]] as used by Polish government and diplomatic authoritiesThe Polish people, or Poles , are a nation indigenous to Poland. They are united by the Polish language, which belongs to the historical Lechitic subgroup of West Slavic languages of Central Europe...
(ends) of the fibre. It is thought that the relative position of the equatorial regions of the spray when stretched determines the action potential
Action potential
In physiology, an action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory. Action potentials occur in several types of animal cells, called excitable cells, which include neurons, muscle cells, and...
output.