Global InformationSkeletal muscle information
| Skeletal muscle | |
|---|---|
 A top-down view of skeletal muscle | |
| Details | |
| Synonyms | Skeletal striated muscle / Striated voluntary muscle |
| System | Muscular system |
| Identifiers | |
| Latin | muscularis skeletalis |
| MeSH | D018482 |
| TH | H2.00.05.2.00002 |
| Anatomical terminology [edit on Wikidata] | |
Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton.[1][2] The muscle cells of skeletal muscles are much longer than in the other types of muscle tissue, and are often known as muscle fibers.[3] The muscle tissue of a skeletal muscle is striated – having a striped appearance due to the arrangement of the sarcomeres.
Skeletal muscles are voluntary muscles under the control of the somatic nervous system. The other types of muscle are cardiac muscle, which is also striated, and smooth muscle, which is non-striated; both of these types of muscle tissue are classified as involuntary, or, under the control of the autonomic nervous system.[4]
A skeletal muscle contains multiple fascicles – bundles of muscle fibers. Each individual fiber, and each muscle is surrounded by a type of connective tissue layer of fascia. Muscle fibers are formed from the fusion of developmental myoblasts in a process known as myogenesis resulting in long multinucleated cells. In these cells the nuclei, termed myonuclei, are located along the inside of the cell membrane. Muscle fibers also have multiple mitochondria to meet energy needs.
Muscle fibers are in turn composed of myofibrils. The myofibrils are composed of actin and myosin filaments called myofilaments, repeated in units called sarcomeres, which are the basic functional, contractile units of the muscle fiber necessary for muscle contraction.[5] Muscles are predominantly powered by the oxidation of fats and carbohydrates, but anaerobic chemical reactions are also used, particularly by fast twitch fibers. These chemical reactions produce adenosine triphosphate (ATP) molecules that are used to power the movement of the myosin heads.[6]
Skeletal muscle comprises about 35% of the body of humans by weight.[7] The functions of skeletal muscle include producing movement, maintaining body posture, controlling body temperature, and stabilizing joints.[8] Skeletal muscle is also an endocrine organ.[9][10][11] Under different physiological conditions, subsets of 654 different proteins as well as lipids, amino acids, metabolites and small RNAs are found in the secretome of skeletal muscles.[12]
Skeletal muscles are substantially composed of multinucleated contractile muscle fibers (myocytes). However, considerable numbers of resident and infiltrating mononuclear cells are also present in skeletal muscles.[13] In terms of volume, myocytes make up the great majority of skeletal muscle. Skeletal muscle myocytes are usually very large, being about 2–3 cm long and 100 μm in diameter.[14] By comparison, the mononuclear cells in muscles are much smaller. Some of the mononuclear cells in muscles[15] are endothelial cells (which are about 50–70 μm long, 10–30 μm wide and 0.1–10 μm thick),[16] macrophages (21 μm in diameter) and neutrophils (12-15 μm in diameter).[17] However, in terms of nuclei present in skeletal muscle, myocyte nuclei may be only half of the nuclei present, while nuclei from resident and infiltrating mononuclear cells make up the other half.[13]
Considerable research on skeletal muscle is focused on the muscle fiber cells, the myocytes, as discussed in detail in the first sections, below. However, recently, interest has also focused on the different types of mononuclear cells of skeletal muscle, as well as on the endocrine functions of muscle, described subsequently, below.
- ^ Betts, J. Gordon; Young, Kelly A.; Wise, James A.; Johnson, Eddie; Poe, Brandon; Kruse, Dean H.; Korol, Oksana; Johnson, Jody E.; Womble, Mark; Desaix, Peter (6 March 2013). "Interactions of Skeletal Muscles, Their Fascicle Arrangement, and Their Lever Systems". Interactions of skeletal muscles. OpenStax. Archived from the original on 23 March 2022. Retrieved 24 May 2021.
- ^ Cite error: The named reference
SEERwas invoked but never defined (see the help page). - ^ Moore, Keith L. (2018). Clinically oriented anatomy (Eighth ed.). Philadelphia: Wolters Kluwer. pp. 30–33. ISBN 9781496347213.
- ^ Birbrair, Alexander; Zhang, Tan; Wang, Zhong-Min; Messi, Maria Laura; Enikolopov, Grigori N.; Mintz, Akiva; Delbono, Osvaldo (21 March 2013). "Role of Pericytes in Skeletal Muscle Regeneration and Fat Accumulation". Stem Cells and Development. 22 (16): 2298–2314. doi:10.1089/scd.2012.0647. ISSN 1547-3287. PMC 3730538. PMID 23517218.
- ^ Cite error: The named reference
Hendersonwas invoked but never defined (see the help page). - ^ Brainard, Jean; Gray-Wilson, Niamh; Harwood, Jessica; Karasov, Corliss; Kraus, Dors; Willan, Jane (2011). CK-12 Life Science Honors for Middle School. CK-12 Foundation. p. 451. Retrieved 18 April 2015.
- ^ Janssen I, Heymsfield SB, Wang ZM, Ross R (July 2000). "Skeletal muscle mass and distribution in 468 men and women aged 18-88 yr". J Appl Physiol. 89 (1): 81–8. doi:10.1152/jappl.2000.89.1.81. PMID 10904038. S2CID 9232367.
- ^ McCuller C, Jessu R, Callahan AL (January 2022) [Updated 25 Mar 2022]. Physiology, Skeletal Muscle. Treasure Island, FL: StatPearls Publishing. PMID 30725824. NBK537139 – via StatPearls [Internet].
- ^ Iizuka K, Machida T, Hirafuji M (2014). "Skeletal muscle is an endocrine organ". J Pharmacol Sci. 125 (2): 125–31. doi:10.1254/jphs.14r02cp. PMID 24859778.
- ^ Hoffmann C, Weigert C (November 2017). "Skeletal Muscle as an Endocrine Organ: The Role of Myokines in Exercise Adaptations". Cold Spring Harb Perspect Med. 7 (11): a029793. doi:10.1101/cshperspect.a029793. PMC 5666622. PMID 28389517.
- ^ Severinsen MC, Pedersen BK (August 2020). "Muscle-Organ Crosstalk: The Emerging Roles of Myokines". Endocr Rev. 41 (4): 594–609. doi:10.1210/endrev/bnaa016. PMC 7288608. PMID 32393961.
- ^ Florin A, Lambert C, Sanchez C, Zappia J, Durieux N, Tieppo AM, Mobasheri A, Henrotin Y (March 2020). "The secretome of skeletal muscle cells: A systematic review". Osteoarthr Cartil Open. 2 (1): 100019. doi:10.1016/j.ocarto.2019.100019. PMC 9718214. PMID 36474563.
- ^ a b Von Walden F, Rea M, Mobley CB, Fondufe-Mittendorf Y, McCarthy JJ, Peterson CA, Murach KA (November 2020). "The myonuclear DNA methylome in response to an acute hypertrophic stimulus". Epigenetics. 15 (11): 1151–1162. doi:10.1080/15592294.2020.1755581. PMC 7595631. PMID 32281477.
- ^ Alberts, Bruce; Johnson, Alexander; Lewis, Julian; Raff, Martin; Roberts, Keith; Walter, Peter (2002). Genesis, Modulation, and Regeneration of Skeletal Muscle. Garland Science.
- ^ Giordani L, He GJ, Negroni E, Sakai H, Law JY, Siu MM, Wan R, Corneau A, Tajbakhsh S, Cheung TH, Le Grand F (May 2019). "High-Dimensional Single-Cell Cartography Reveals Novel Skeletal Muscle-Resident Cell Populations". Mol Cell. 74 (3): 609–621.e6. doi:10.1016/j.molcel.2019.02.026. PMID 30922843.
- ^ Introduction. Morgan & Claypool Life Sciences. 2011.
- ^ Tigner, A.; Ibrahim, S. A.; Murray, I. (2022). "Histology, White Blood Cell". StatPearls. PMID 33085295.