Histological Description of the Interaction Between Muscle Fibers and Connective Tissue of the Fascia of the Human Trapezius Muscle Descripción Histológica de la Interacción entre las Fibras Musculares y Tejido Conectivo de la Fascia del Músculo Trapecio Humano

SUMMARY: The skeletal muscle fascia corresponds to a condensation of connective tissue. Fascias are highly innervated andsensitive, and can cover n on-expandable structures as well as musculature. It is suggested that fascias have a pivotal role in functions suchas postural regulation, peripheral motor coordination and proprioception. Also, the presence of inflammation and microcalcification infascia of patients with localized muscle pain has been described, suggesting a pathogenic role in pain. The aim was to describe the histologicalstructure of the external deep fascia of the trapezius muscle, with emphasis on the content and arrangement of muscle fibers, type I collagen,and adipose tissue. Sample material was obtained from a male cadaver (60-70 years old), by dissection of the posterior cervical region of thesuperficial fascia of the trapezius muscle and fixed in buffered formalin. Samples were processed by routine histological techniques andembedded in paraffin, obtaining 5 µ m-thick sections that were stained according to the van Gieson technique. The trapezius fascia iscomposed of type I collagen, organized into high-density collagen bundles and oriented in different directions, and by adipocytes disposedin longitudinal groups on the main axis of the fascia. Muscle fibers are organized into bundles that are inserted laterally on the thickness ofthe fascia. It is possible that lateral transmission of tensional forces between the fibers might be present.