Determination of muscle architecture and fiber characteristics of the superfacial and deep digital flexor muscles in the forelimbs of adult horses

Laura Zarucco, Ken T. Taylor, Susan M Stover

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Objective - To provide a quantitative description of the architecture of superficial digital flexor (SDF) and deep digital flexor (DDF) muscles in adult horses to predict muscle-tendon behavior and estimate muscle forces. Sample Population - 7 forelimb specimens from 7 adult Thoroughbreds. Procedure - Muscle and tendon lengths and volumes were measured from 6 fixed forelimbs, After processing, fiber bundle and sarcomere lengths were measured. Optimal fascicle lengths and muscle length-to-fascicle length, muscle length-to-free tendon length, and fascicle length-to-tendon length ratios were calculated, as were tendon and muscle physiologic cross-sectional areas (PCSAs). Pennation angles were measured in 1 embalmed specimen. Results - The SDF optimal fascicle lengths were uniformly short (mean ± SD, 0.8 ± 0.1 cm), whereas DDF lengths ranged from 0.9 ± 0.2 cm to 10.8 ± 1.6 cm. The DDF humeral head had 3 architectural subunits, each receiving a separate median nerve branch, suggestive of neuromuscular compartmentalization. Pennation angles were small (10° to 25°). The PCSAs of the SDF and DDF muscle were 234 ± 51 cm2 and 259 ± 30 cm2, with estimated forces of 4,982 ± 1148 N and 5,520 ± 544 N, respectively. Conclusions and Clinical Relevance - The SDF muscle appears to provide strong tendinous support with little muscle fascicular shortening and fatigue-resistance properties. The DDF muscle combines passive and dynamic functions with larger tension development and higher shortening velocities during digital motion. Architectural parameters are useful for estimation of forces and have implications for analysis of muscle-tendon function, surgical procedures involving muscle-tendon lengthening, and biomechanical modeling.

Original languageEnglish (US)
Pages (from-to)819-828
Number of pages10
JournalAmerican Journal of Veterinary Research
Volume65
Issue number6
DOIs
StatePublished - Jun 2004

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Forelimb
forelimbs
Horses
dietary fiber
horses
Muscles
muscles
tendons
Tendons
shortenings
Tenotomy
Humeral Head
Sarcomeres
sarcomeres
Median Nerve
Fatigue
nerve tissue
surgery

ASJC Scopus subject areas

  • veterinary(all)

Cite this

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title = "Determination of muscle architecture and fiber characteristics of the superfacial and deep digital flexor muscles in the forelimbs of adult horses",
abstract = "Objective - To provide a quantitative description of the architecture of superficial digital flexor (SDF) and deep digital flexor (DDF) muscles in adult horses to predict muscle-tendon behavior and estimate muscle forces. Sample Population - 7 forelimb specimens from 7 adult Thoroughbreds. Procedure - Muscle and tendon lengths and volumes were measured from 6 fixed forelimbs, After processing, fiber bundle and sarcomere lengths were measured. Optimal fascicle lengths and muscle length-to-fascicle length, muscle length-to-free tendon length, and fascicle length-to-tendon length ratios were calculated, as were tendon and muscle physiologic cross-sectional areas (PCSAs). Pennation angles were measured in 1 embalmed specimen. Results - The SDF optimal fascicle lengths were uniformly short (mean ± SD, 0.8 ± 0.1 cm), whereas DDF lengths ranged from 0.9 ± 0.2 cm to 10.8 ± 1.6 cm. The DDF humeral head had 3 architectural subunits, each receiving a separate median nerve branch, suggestive of neuromuscular compartmentalization. Pennation angles were small (10° to 25°). The PCSAs of the SDF and DDF muscle were 234 ± 51 cm2 and 259 ± 30 cm2, with estimated forces of 4,982 ± 1148 N and 5,520 ± 544 N, respectively. Conclusions and Clinical Relevance - The SDF muscle appears to provide strong tendinous support with little muscle fascicular shortening and fatigue-resistance properties. The DDF muscle combines passive and dynamic functions with larger tension development and higher shortening velocities during digital motion. Architectural parameters are useful for estimation of forces and have implications for analysis of muscle-tendon function, surgical procedures involving muscle-tendon lengthening, and biomechanical modeling.",
author = "Laura Zarucco and Taylor, {Ken T.} and Stover, {Susan M}",
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T1 - Determination of muscle architecture and fiber characteristics of the superfacial and deep digital flexor muscles in the forelimbs of adult horses

AU - Zarucco, Laura

AU - Taylor, Ken T.

AU - Stover, Susan M

PY - 2004/6

Y1 - 2004/6

N2 - Objective - To provide a quantitative description of the architecture of superficial digital flexor (SDF) and deep digital flexor (DDF) muscles in adult horses to predict muscle-tendon behavior and estimate muscle forces. Sample Population - 7 forelimb specimens from 7 adult Thoroughbreds. Procedure - Muscle and tendon lengths and volumes were measured from 6 fixed forelimbs, After processing, fiber bundle and sarcomere lengths were measured. Optimal fascicle lengths and muscle length-to-fascicle length, muscle length-to-free tendon length, and fascicle length-to-tendon length ratios were calculated, as were tendon and muscle physiologic cross-sectional areas (PCSAs). Pennation angles were measured in 1 embalmed specimen. Results - The SDF optimal fascicle lengths were uniformly short (mean ± SD, 0.8 ± 0.1 cm), whereas DDF lengths ranged from 0.9 ± 0.2 cm to 10.8 ± 1.6 cm. The DDF humeral head had 3 architectural subunits, each receiving a separate median nerve branch, suggestive of neuromuscular compartmentalization. Pennation angles were small (10° to 25°). The PCSAs of the SDF and DDF muscle were 234 ± 51 cm2 and 259 ± 30 cm2, with estimated forces of 4,982 ± 1148 N and 5,520 ± 544 N, respectively. Conclusions and Clinical Relevance - The SDF muscle appears to provide strong tendinous support with little muscle fascicular shortening and fatigue-resistance properties. The DDF muscle combines passive and dynamic functions with larger tension development and higher shortening velocities during digital motion. Architectural parameters are useful for estimation of forces and have implications for analysis of muscle-tendon function, surgical procedures involving muscle-tendon lengthening, and biomechanical modeling.

AB - Objective - To provide a quantitative description of the architecture of superficial digital flexor (SDF) and deep digital flexor (DDF) muscles in adult horses to predict muscle-tendon behavior and estimate muscle forces. Sample Population - 7 forelimb specimens from 7 adult Thoroughbreds. Procedure - Muscle and tendon lengths and volumes were measured from 6 fixed forelimbs, After processing, fiber bundle and sarcomere lengths were measured. Optimal fascicle lengths and muscle length-to-fascicle length, muscle length-to-free tendon length, and fascicle length-to-tendon length ratios were calculated, as were tendon and muscle physiologic cross-sectional areas (PCSAs). Pennation angles were measured in 1 embalmed specimen. Results - The SDF optimal fascicle lengths were uniformly short (mean ± SD, 0.8 ± 0.1 cm), whereas DDF lengths ranged from 0.9 ± 0.2 cm to 10.8 ± 1.6 cm. The DDF humeral head had 3 architectural subunits, each receiving a separate median nerve branch, suggestive of neuromuscular compartmentalization. Pennation angles were small (10° to 25°). The PCSAs of the SDF and DDF muscle were 234 ± 51 cm2 and 259 ± 30 cm2, with estimated forces of 4,982 ± 1148 N and 5,520 ± 544 N, respectively. Conclusions and Clinical Relevance - The SDF muscle appears to provide strong tendinous support with little muscle fascicular shortening and fatigue-resistance properties. The DDF muscle combines passive and dynamic functions with larger tension development and higher shortening velocities during digital motion. Architectural parameters are useful for estimation of forces and have implications for analysis of muscle-tendon function, surgical procedures involving muscle-tendon lengthening, and biomechanical modeling.

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