Muscle fascicle

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Muscle fascicle
Structure of a skeletal muscle. (Fascicle labeled at bottom right.)
Part ofSkeletal muscle
Latinfasiculus muscularis
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.

Clinical significance[edit]

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]

See also[edit]


  1. ^ a b c Damjanov, Ivan (2009-01-01), Damjanov, Ivan (ed.), "Chapter 21 - Skeletal Muscles", Pathology Secrets (Third Edition), Philadelphia: Mosby, pp. 434–447, doi:10.1016/b978-0-323-05594-9.00021-0, ISBN 978-0-323-05594-9, retrieved 2020-11-04
  2. ^ Gandevia, SIMON C.; Burke, DAVID (2004-01-01), Paxinos, GEORGE; Mai, JÜRGEN K. (eds.), "CHAPTER 5 - Peripheral Motor System", The Human Nervous System (Second Edition), San Diego: Academic Press, pp. 113–133, doi:10.1016/b978-012547626-3/50006-5, ISBN 978-0-12-547626-3, retrieved 2020-11-04
  3. ^ a b Möller, Ingrid; Bong, David; Mendieta, Eugenio de Miguel (2010-01-01), Wakefield, Richard J.; D'Agostino, Maria Antonietta (eds.), "Chapter 19 - Soft Tissue Rheumatism", Essential Applications of Musculoskeletal Ultrasound in Rheumatology, Philadelphia: W.B. Saunders, pp. 219–235, doi:10.1016/b978-1-4377-0127-2.10019-x, ISBN 978-1-4377-0127-2, retrieved 2020-11-04
  4. ^ Harati, Yadollah; Biliciler, Suur (2010-01-01), Rolak, Loren A. (ed.), "CHAPTER 4 - Myopathies", Neurology Secrets (Fifth Edition), Philadelphia: Mosby, pp. 63–82, doi:10.1016/b978-0-323-05712-7.00004-0, ISBN 978-0-323-05712-7, retrieved 2020-11-13
  5. ^ Ha, Ainhi D.; Jankovic, Joseph (2011-01-01), Brotchie, Jonathan; Bezard, Erwan; Jenner, Peter (eds.), "An Introduction to Dyskinesia—The Clinical Spectrum", International Review of Neurobiology, Pathophysiology, Pharmacology, and Biochemistry of Dyskinesia, 98, Academic Press: 1–29, doi:10.1016/b978-0-12-381328-2.00001-8, ISBN 9780123813282, PMID 21907081, retrieved 2020-11-13

External links[edit]