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European Journal of Sport Science Sep 2018There is an abundance of evidence that suggests elastic tendons can enhance both animal and human muscle performance. However, in many terrestrial animals, including... (Review)
Review
There is an abundance of evidence that suggests elastic tendons can enhance both animal and human muscle performance. However, in many terrestrial animals, including humans, a large proportion of the elastic tissue within the muscle-tendon unit is located within the muscle. This continuous elastic sheet, which provides muscle fibre attachment, is known as the aponeurosis. The aponeurosis has a much more complicated shape than the free tendon and it undergoes a more complicated loading regime during contraction, due to its relationship with the bulging muscle fibres, which remain isovolumetric during force production. Muscle contraction may dynamically modulate the stiffness of the aponeurosis at the same active versus passive force, by increasing the intramuscular pressure and transverse forces within the muscle, which may stretch the aponeurosis in width and subsequently reduce its longitudinal strain. Some evidence also suggests that the aponeurosis mechanical properties may be affected by muscle length, which appears to reduce the fascicle strains for a given muscle force at longer muscle lengths. This narrative review outlines the animal and human studies that have investigated aponeurosis behaviour during contraction and discusses how an elastic sheet with a variable stiffness under activation might be beneficial for muscle performance. While it is clear that our understanding of the role of aponeurosis is lacking, it is hoped that further work will attempt to determine how this tissue contributes to power amplification and elastic energy savings during locomotion and potentially uncover how aponeurosis behaviour contributes to injury risk.
Topics: Animals; Aponeurosis; Humans; Locomotion; Muscle Contraction; Muscle, Skeletal; Tendons
PubMed: 29806988
DOI: 10.1080/17461391.2018.1472299 -
European Journal of Applied Physiology Jul 2020The aponeurosis, a sheet of fibrous tissue, is the deep and superficial fascia where muscle fibers attach in pennate muscles. It is quite possible that the aponeurosis... (Review)
Review
PURPOSE
The aponeurosis, a sheet of fibrous tissue, is the deep and superficial fascia where muscle fibers attach in pennate muscles. It is quite possible that the aponeurosis size increases in response to resistance training-induced fiber hypertrophy due to an increase in connection area. As a result, it leads to an increase in anatomical muscle cross-sectional area. However, attention has not been paid to aponeurosis area changes. This review sought to determine whether muscle hypertrophy changes aponeurosis width following short-term resistance training using an equation we modified [post/pre changes in aponeurosis width (AW) = post/pre changes in anatomical cross-sectional area (CSA) ÷ post/pre changes in pennation angle (PA) ÷ post/pre changes in fascicle length (FL)].
METHODS
A search using two electronic databases (PubMed and Google Scholar) was conducted. Nine studies measured CSA, PA, and FL of the vastus lateralis muscle by ultrasound and magnetic resonance imaging.
RESULTS
There was a statistically significant 2.73 [95% CI 1.11, 4.36; p = 0.009] cm increase in CSA along with a statistically significant 1.21° [95% CI 0.44, 1.97; p = 0.002] increase in PA and a statistically significant 0.36 cm [95% CI 0.19, 0.54; p = 0.0002] increase in FL. These results yield an estimated 1% reduction in aponeurosis width.
CONCLUSION
Our results suggest that while muscle CSA, pennation angle, and fascicle length all increase following short-term resistance training, the aponeurosis width is not altered.
Topics: Aponeurosis; Humans; Hypertrophy; Muscle Contraction; Muscle, Skeletal; Quadriceps Muscle; Resistance Training
PubMed: 32468284
DOI: 10.1007/s00421-020-04400-x -
Dermatologic Surgery : Official... Oct 2020The etiology of cellulite is unclear. Treatment of cellulite has targeted adipose tissue, dermis, and fibrous septae with varying degrees of success and durability of... (Review)
Review
BACKGROUND
The etiology of cellulite is unclear. Treatment of cellulite has targeted adipose tissue, dermis, and fibrous septae with varying degrees of success and durability of response.
OBJECTIVE
Results from clinical trials that target different anatomical aspects of cellulite can provide insights into the underlying pathophysiology of cellulite.
MATERIALS AND METHODS
A search of the PubMed database and ClinicalTrials.gov website was conducted to identify clinical trials that have investigated treatments for cellulite.
RESULTS
A lack of trial protocol standardization, objective means for quantification of improvement and reported cellulite severity, and short-term follow-up, as well as variation in assessment methods have made comparisons among efficacy studies challenging. However, the lack of durable efficacy and inconsistency seen in clinical results suggest that dermal or adipose tissue changes are not the primary etiologies of cellulite. Clinical studies targeting the collagen-rich fibrous septae in cellulite dimples through mechanical, surgical, or enzymatic approaches suggest that targeting fibrous septae is the strategy most likely to provide durable improvement of skin topography and the appearance of cellulite.
CONCLUSION
The etiology of cellulite has not been completely elucidated. However, there is compelling clinical evidence that fibrous septae play a central role in the pathophysiology of cellulite.
Topics: Aponeurosis; Buttocks; Cellulite; Clinical Trials as Topic; Extracorporeal Shockwave Therapy; Humans; Lipectomy; Massage; Microbial Collagenase; Muscle, Skeletal; Phototherapy; Radiofrequency Therapy; Skin; Skin Cream; Subcutaneous Fat; Thigh; Treatment Outcome
PubMed: 32976174
DOI: 10.1097/DSS.0000000000002388 -
Journal of Anatomy Dec 2012In this overview, new and existent material on the organization and composition of the thoracolumbar fascia (TLF) will be evaluated in respect to its anatomy,... (Review)
Review
In this overview, new and existent material on the organization and composition of the thoracolumbar fascia (TLF) will be evaluated in respect to its anatomy, innervation biomechanics and clinical relevance. The integration of the passive connective tissues of the TLF and active muscular structures surrounding this structure are discussed, and the relevance of their mutual interactions in relation to low back and pelvic pain reviewed. The TLF is a girdling structure consisting of several aponeurotic and fascial layers that separates the paraspinal muscles from the muscles of the posterior abdominal wall. The superficial lamina of the posterior layer of the TLF (PLF) is dominated by the aponeuroses of the latissimus dorsi and the serratus posterior inferior. The deeper lamina of the PLF forms an encapsulating retinacular sheath around the paraspinal muscles. The middle layer of the TLF (MLF) appears to derive from an intermuscular septum that developmentally separates the epaxial from the hypaxial musculature. This septum forms during the fifth and sixth weeks of gestation. The paraspinal retinacular sheath (PRS) is in a key position to act as a 'hydraulic amplifier', assisting the paraspinal muscles in supporting the lumbosacral spine. This sheath forms a lumbar interfascial triangle (LIFT) with the MLF and PLF. Along the lateral border of the PRS, a raphe forms where the sheath meets the aponeurosis of the transversus abdominis. This lateral raphe is a thickened complex of dense connective tissue marked by the presence of the LIFT, and represents the junction of the hypaxial myofascial compartment (the abdominal muscles) with the paraspinal sheath of the epaxial muscles. The lateral raphe is in a position to distribute tension from the surrounding hypaxial and extremity muscles into the layers of the TLF. At the base of the lumbar spine all of the layers of the TLF fuse together into a thick composite that attaches firmly to the posterior superior iliac spine and the sacrotuberous ligament. This thoracolumbar composite (TLC) is in a position to assist in maintaining the integrity of the lower lumbar spine and the sacroiliac joint. The three-dimensional structure of the TLF and its caudally positioned composite will be analyzed in light of recent studies concerning the cellular organization of fascia, as well as its innervation. Finally, the concept of a TLC will be used to reassess biomechanical models of lumbopelvic stability, static posture and movement.
Topics: Biomechanical Phenomena; Dissection; Fascia; Histological Techniques; Humans; Low Back Pain; Lumbar Vertebrae; Models, Biological; Muscle, Skeletal; Thoracic Vertebrae
PubMed: 22630613
DOI: 10.1111/j.1469-7580.2012.01511.x -
Acta Biomaterialia Sep 2023Aponeurosis is a sheath-like connective tissue that aids in force transmission from muscle to tendon and can be found throughout the musculoskeletal system. The key role...
Aponeurosis is a sheath-like connective tissue that aids in force transmission from muscle to tendon and can be found throughout the musculoskeletal system. The key role of aponeurosis in muscle-tendon unit mechanics is clouded by a lack of understanding of aponeurosis structure-function properties. This work aimed to determine the heterogeneous material properties of porcine triceps brachii aponeurosis tissue with materials testing and evaluate heterogeneous aponeurosis microstructure with scanning electron microscopy. We found that aponeurosis may exhibit more microstructural collagen waviness in the insertion region (near the tendon) compared to the transition region (near the muscle midbelly) (1.20 versus 1.12, p = 0.055), which and a less stiff stress-strain response in the insertion versus transition regions (p < 0.05). We also showed that different assumptions of aponeurosis heterogeneity, specifically variations in elastic modulus with location can alter the stiffness (by more than 10x) and strain (by approximately 10% muscle fiber strain) of a finite element model of muscle and aponeurosis. Collectively, these results suggest that aponeurosis heterogeneity could be due to variations in tissue microstructure and that different approaches to modeling tissue heterogeneity alters the behavior of computational models of muscle-tendon units. STATEMENT OF SIGNIFICANCE: Aponeurosis is a connective tissue found in many muscle tendon units that aids in force transmission, yet little is known about the specific material properties of aponeurosis. This work aimed to determine how the properties of aponeurosis tissue varied with location. We found that aponeurosis exhibits more microstructural waviness near the tendon compared to near the muscle midbelly, which was associated with differences in tissue stiffness. We also showed that different variations in aponeurosis modulus (stiffness) can alter the stiffness and stretch of a computer model of muscle tissue. These results show that assuming uniform aponeurosis structure and modulus, which is common, may lead to inaccurate models of the musculoskeletal system.
Topics: Animals; Swine; Aponeurosis; Muscle, Skeletal; Tendons; Muscle Fibers, Skeletal; Muscle Contraction
PubMed: 37392931
DOI: 10.1016/j.actbio.2023.06.035 -
Journal of Materials Science. Materials... May 2022Detergent treatment is the most commonly used method for the decellularization of ligaments and tendon grafts. However, it is well recognized that detergent treatment...
Detergent treatment is the most commonly used method for the decellularization of ligaments and tendon grafts. However, it is well recognized that detergent treatment can also adversely affect the extracellular matrix. This study found that discission into the aponeurosis layer of the patellar tendon (PT) before decellularization is conducive to extracting cells from the PT using a low quantity of detergent in a short time period. The acellular aponeurosis discission ligament (AADL) retains its native collagen fibril structure and mechanical properties. Moreover, the PT retained cell and tissue compatibility in vitro and in vivo. After implantation into a defective allogeneic PT, we found that the AADL healed well in the host, and its collagen structure exhibited gradual improvement 12 months after implantation with satisfactory reconstruction. IMPACT: The aponeurosis of tendons/ligaments is the main barrier to achieving complete decellularization, and it thus prevents complete recellularization for applications in tissue engineering. Aponeurosis can obstruct the removal of cell components. We found that excising the aponeurosis before decellularization allows for the removal of cellular components with a reduced amount of detergent, thus improving the biological properties of the acellular ligament. To the best of our knowledge, no similar studies have been performed. Graphical abstract.
Topics: Aponeurosis; Collagen; Detergents; Extracellular Matrix; Ligaments; Tissue Engineering; Tissue Scaffolds
PubMed: 35507049
DOI: 10.1007/s10856-022-06661-8 -
The Journal of Hand Surgery Jun 2018To evaluate the thumb dorsal aponeurosis anatomy. Consideration of structural differences between the fingers and thumb will provide an improved clinical understanding...
PURPOSE
To evaluate the thumb dorsal aponeurosis anatomy. Consideration of structural differences between the fingers and thumb will provide an improved clinical understanding of the thumb dorsal aponeurosis anatomy.
METHODS
Ten fresh cadaver hands from 5 patients with an average age of 31.6 (range, 22-41) years were dissected. The thenar muscles were identified and insertion sites were documented. The fibers of the dorsal aponeurosis and contributions were identified.
RESULTS
The flexor pollicis brevis superficial head contributed to the radial fibers of the dorsal aponeurosis in 8 specimens and contributed to the deep head in 1 specimen. The abductor pollicis brevis provided fibers to the radial dorsal aponeurosis in all 10 specimens. The oblique and transverse heads of the adductor pollicis contributed to the ulnar dorsal aponeurosis in 8 and 9 hands, respectively. The fibers of the intrinsic apparatus were composed of 3 major types: transverse, oblique, and long.
CONCLUSIONS
This investigation provides a detailed anatomic study of the dorsal aponeurosis of the thumb with observation of both intrinsic and extrinsic contributions.
CLINICAL RELEVANCE
Understanding the anatomy of the dorsal aponeurosis of the thumb remains important not only for evaluation of the classic Stener lesion, but also for the appropriate treatment of deformity, contracture, and neuromuscular disorders involving the thumb.
Topics: Adult; Aponeurosis; Cadaver; Humans; Male; Muscle, Skeletal; Tendons; Thumb; Young Adult
PubMed: 29361325
DOI: 10.1016/j.jhsa.2017.11.009 -
Journal of Biomechanics 2006Fibres, aponeuroses, and tendons are often considered mechanically "in series" in skeletal muscles. This notion has led to oversimplified calculations of fibre forces... (Review)
Review
Fibres, aponeuroses, and tendons are often considered mechanically "in series" in skeletal muscles. This notion has led to oversimplified calculations of fibre forces from tendon forces, to incorrect derivations of constitutive laws for aponeuroses, and to misinterpretations of the recovery of elastic energy in stretch-shortening cycles of muscles. Here, we demonstrate theoretically, using examples of increasing complexity, that tendon and aponeurosis are not in series in a muscle fibre-aponeurosis-tendon complex. We then demonstrate that assuming the tendon and aponeurosis to be in series can lead to the appearance of mechanical work creation in these passive viscoelastic structures, a result that is mechanically impossible. Finally, we explain the mechanical role of the incompressible muscle matrix in force transmission from fibres to aponeuroses and tendon, and emphasize that incompressibility necessitates the introduction of extra forces necessary to maintain this constraint. Unfortunately, this requirement eliminates, for all but the simplest cases, a theoretical approach of muscle modeling based on intuitive free-body diagrams.
Topics: Animals; Biomechanical Phenomena; Humans; Models, Biological; Muscles; Tendons
PubMed: 16085074
DOI: 10.1016/j.jbiomech.2005.06.011 -
The Japanese Dental Science Review May 2016Limited mouth opening is a common health problem that interferes with eating, makes examination of the oral cavity difficult, and may increase the mortality rate during... (Review)
Review
Limited mouth opening is a common health problem that interferes with eating, makes examination of the oral cavity difficult, and may increase the mortality rate during emergency intubation. Here we introduce a disease designated as masticatory muscle tendon-aponeurosis hyperplasia, which is a new clinical condition of limited mouth opening. Most oral surgeons and dentists are still unaware of this disease condition, thus increasing the risk of incorrect diagnosis as some other disease, such as temporomandibular joint disorder. We will review the clinical features, epidemiology, pathophysiology, etiology, diagnosis, treatment, and prognosis of this disease and also appraise the literature available on the subject.
PubMed: 28408955
DOI: 10.1016/j.jdsr.2015.11.001