In what ways does yoga change the muscular structure to improve health.

One of the greatest benefits of yoga poses is injury prevention. 

Yoga restores strength and flexibility of the muscles, and because no muscle works in isolation, all muscles in the muscular system engage with each other through the connective tissue.

For example in side stretching poses, the muscles between the ribs and pelvis are being lengthened. In addition the muscles of the front leg are gaining strength, and stamina.

Also because of the eccentric movements in the arm, the arm's muscles are strengthening by the relationship of the weight of the arm to gravity.

How do the postures in yoga work to enhance the connective tissue.

Connective tissue sheath encapsulates and separates individual muscles. A thin layer of body fluid coats these sheaths, and helps the muscle to to glide smoothly over the neighboring structures.

Sensory nerves are residing through our various facial planes and are stimulated by stretching the facia during yoga poses.

How does yoga go so deep it affects the skeletal structure and how so.

The most important benefit of practicing yoga poses is balance. Bones of the skeletal system play important roles in other systems in the body. Yoga poses poses strengthen the bones and maintain the bone mass. The bones and the skeleton link together at the joints and act as levers for the muscles that cross the joints. 

Going even deeper, how does yoga penetrate the cellular level and the benefits that result.

Cells are the fundamental building blocks of life, they metabolize nutrients, which are turned into energy. Prana breathing helps the cells to eliminate toxic waist - which is Apana.