Final answer:
Musculotendinous units undergo eccentric contractions to control movement, with the nervous system regulating this through motor units and muscle fiber recruitment. The lever system of muscles and bones determines force and range of motion, facilitated by different fascicles within multipennate muscles like the deltoid.
Step-by-step explanation:
Musculotendinous units are essential components in muscle contraction and movement control, particularly during eccentric contractions where muscles lengthen under tension. This process allows for controlled movement, such as lowering a weight slowly in a bicep curl.
In human anatomy, one way the nervous system controls muscle movement is by motor units, each consisting of a motor neuron and the muscle fibers it innervates. In more fine-tuned movements, more motor units are activated for greater precision and muscle control.
The lever system of muscle and bone interactions also plays a crucial role in determining muscle function. Muscles work in pairs, and the connection to the skeleton influences the resulting force and range of motion. Muscle fibers are organized into fascicles, and within muscles like the deltoid, different fascicles can be stimulated to alter the direction of force, enabling complex movements.
This intricacy of muscle control is critical for performing everyday tasks, requiring a delicate balance between different types of muscle contractions, muscle fiber recruitment, and overall muscle tone, all tightly regulated by neural control.