A muscle fascicle is a bundle of
skeletal muscle fibers surrounded by
perimysium, a type of
connective tissue.
Structure
Muscle cells are grouped into muscle fascicles by enveloping
perimysium connective tissue.
Fascicles are bundled together by
epimysium connective tissue.
Muscle fascicles typically only contain one type of muscle cell (either
type I fibres or
type II fibres), but can contain a mixture of both types.
Function
In the
heart
The heart is a muscular Organ (biology), organ found in humans and other animals. This organ pumps blood through the blood vessels. The heart and blood vessels together make the circulatory system. The pumped blood carries oxygen and nutrie ...
, specialized
cardiac muscle cells transmit
electrical impulses from the
atrioventricular node
The atrioventricular node (AV node, or Aschoff-Tawara node) electrically connects the heart's atria and ventricles to coordinate beating in the top of the heart; it is part of the electrical conduction system of the heart. The AV node lies at the ...
(AV node) to the
Purkinje fibers – fascicles, also referred to as bundle branches. These start as a single fascicle of fibers at the AV node called the
bundle of His that then splits into three bundle branches: the right fascicular branch, left anterior fascicular branch, and left posterior fascicular branch.
Clinical significance
Myositis may cause
thickening of the muscle fascicles.
This may be detected with
ultrasound scans.
Muscle fascicle structure is a useful diagnostic tool for
dermatomyositis. Myocytes towards the edges of the muscle fascicle are typically narrower, while those at the centre of the muscle fascicle are a normal thickness.
Muscle fascicles may be involved in
myokymia, although commonly only individual myocytes are involved.
See also
*
Deep fascia
*
Endomysium
*
Epimysium
References
External links
* – "Slide 77
skeletal muscle
Skeletal muscle (commonly referred to as muscle) is one of the three types of vertebrate muscle tissue, the others being cardiac muscle and smooth muscle. They are part of the somatic nervous system, voluntary muscular system and typically are a ...
"
* – "Smooth Muscle"
Diagram at kctcs.edu
Muscular system
{{muscle-stub