Читать книгу Musculoskeletal Disorders - Sean Gallagher - Страница 66

Fascia is the term applied to the sheets or broad bands of fibrous connective tissue that (a) lies beneath the skin; (b) attaches, stabilizes, encloses, and separates muscle and tendons from each other; and (c) separates internal organs from each other. It is classified by layer (superficial, deep, visceral, or peritoneal fascia), function, or anatomical location. Superficial fascia is the subcutaneous layer of connective tissue that lies immediately deep to the skin. It serves as a storehouse of water and fat (which acts as insulation) and provides a pathway for nerves, vessels, and immune cells to travel between other tissues (Figure 3.1b). Deep fascia is a denser connective tissue that holds muscles and tendons together, fills spaces between tissues, and lines the body wall and extremities (e.g., the lower leg’s crural fascia). Functionally, deep fascia allows free movement of muscles and tendons, carries blood vessels and nerves, and sometimes provides an attachment for muscle (e.g., the palmaris brevis muscle of the hand).

There are several extensions of deep fascia around and into individual muscles and tendons (Figure 3.3). The epimysium is the deep fascial dense connective tissue wrapping around the entire muscles. Invaginations of the epimysium into a muscle are termed perimysium (a type of irregular connective tissue) and endomysium (a type of reticular connective tissue). The epimysium, perimysium, and endomysium are all continuous with similar structures in tendons (epitenon, peritenon, and endotenon). Since tendons and aponeuroses (broad flat tendons) attach skeletal muscles to bones and other muscles, respectively, the continuity of these coverings allows skeletal muscles to produce movement.

Figure 3.3 Extensions of deep fascia around and into individual muscle fibers. The epimysium (deep fascial fibrous connective tissue wrapping around entire muscle), perimysium (around individual fascicles), and endomysium (Endo; around individual muscle fibers/cells) are indicated.

Interstitial fascia or interstitium has been recently highlighted as a new term in the literature (Stecco & Caro, 2019; Stecco, Macchi, Porzionato, Duparc, & De Caro, 2011). By definition of its name, interstitial fascia is the located “between the cells.” Anatomically, interstitial fascia is the highly vascularized and highly innervated superficial and deep fascial components mentioned earlier.