Muscle fascicle

A muscle fascicle is a bundle of skeletal muscle fibers surrounded by perimysium, a type of connective tissue.[1]

Muscle fascicle
Structure of a skeletal muscle. (Fascicle labeled at bottom right.)
Details
Part ofSkeletal muscle
Identifiers
Latinfasiculus muscularis
TA22006
THH3.03.00.0.00003
Anatomical terminology

Structure

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]

Function

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. 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.[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

References

  1. 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. 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, Academic Press, 98: 1–29, doi:10.1016/b978-0-12-381328-2.00001-8, ISBN 9780123813282, PMID 21907081, retrieved 2020-11-13
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