The cleido-mastoid generally arises from the basi-occipital, and the pectoralis major is connected with the latissimus dorsi.
The posterior patagium, the fold between trunk and inner surface of the upper arm, is stretched by the metapatagialis muscle, which is composed of slips from the serratus, superficialis, latissimus dorsi and the expansor secundariorum muscles.
Muscles developed arm depressors, pectoralis major, latissimus dorsi and teres major.
As a consequence, the ' non mirror muscles ', lower trapezius, rhomboids, latissimus dorsi and rear deltoid are underdeveloped.
The latissimus dorsi muscle was reflected laterally to reveal the thoracolumbar fascia lying beneath.