The document discusses the main components and functions of the muscular system in humans. It mentions that muscles are made of bundles of fibres that work together as tissue to allow movement. Muscles connect to bones via tendons and work in pairs like the biceps and triceps to flex and extend the arms. Key muscle groups mentioned include the abdominals, quadriceps, trapezius, deltoids, dorsals, calves, gluteus, and muscles that cause goosebumps.