The area of a transverse section of muscle. When a muscle is tested physiologically in situ and then removed; PCSA = (muscle mass)(cosine theta)/(fibre length)(muscle density), where muscle mass is the wet weight of the muscle; theta is the angle of fibre pinnation; fibre length is the mean fibre length within the muscle; and muscle density is assumed to be a constant (1.067 g cm−3. The PCSA of a muscle or muscle group can be estimated from the following equation: PCSA = muscle volume/fibre length, where muscle volume is determined, for example, non-invasively by nuclear magnetic resonance imaging; and fibre length is estimated from the relatively consistent fibre length to muscle length ratios reported for dissected muscles. PCSA is an important anatomical parameter because the maximum force that a muscle can generate is directly related to its physiological cross-sectional area, with maximum force being approximately 80 N cm−2.
Subjects: Sports and Exercise Medicine.