| Muscle fascicle | |
|---|---|
 Structure of a skeletal muscle. (Fascicle labeled at bottom right.) | |
| Details | |
| Part of | Skeletal muscle |
| Identifiers | |
| Latin | fasiculus muscularis |
| TA2 | 2006 |
| TH | H3.03.00.0.00003 |
| FMA | 76740 |
| Anatomical terminology | |
A muscle fascicle is a bundle of skeletal muscle fibers surrounded by perimysium, a type of connective tissue. [1]
Muscle cells are grouped into muscle fascicles by enveloping perimysium connective tissue. [1] Fascicles are bundled together by epimysium connective tissue. [1] 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. [2]
In the heart, specialized cardiac muscle cells transmit electrical impulses from the atrioventricular node (AV node) to the Purkinje fibers – fascicles, also referred to as bundle branches.[ citation needed ] 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.
Myositis may cause thickening of the muscle fascicles. [3] This may be detected with ultrasound scans. [3]
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. [4]
Muscle fascicles may be involved in myokymia, although commonly only individual myocytes are involved. [5]
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