Puzzle It Out: Muscle Terms Test your knowledge of some of the terms associated with muscles by completing the following crosword puzzle. 11 12 10 ACROSS 1. Muscle that assists another muscle 3. A strong, fibrous cord that attaches muscle to bone 4. In attachment, muscle fibers merge with the periosteum of the bone 6. The continuous state of partial muscle contraction is called muscle 8. A flat sheet of connective tissue that attaches at muscle to another muscle 10. A lack of ATP, such as occurs following death, causes muscles to become 11. Contraction in which the muscle changes length while the tension remains the same 98 Chapter 9 Muscular System 12. The condition of rapid contraction with only partial relaxation is called incomplete Ter don 13. Contraction in which the tension within a muscle increases while its length remains the same DOWN 1. The cytoplasm of a muscle cell 2. The connection between a motor neuron and a muscle fiber is called a junction 5. Muscle that opposes the action of a prime mover 7. The process by which an increasing number of motor units are called into action, increasing the force of contraction 9. A single, brief contraction resulting when a muscle fiber receives a stimulus at or above threshold