1. Passing from a more complex to a simpler biological form
   - degeneration 
2. Returning to a former state
   - regression, regress, reversion, retroversion

Derived forms: retrogressions

See also: retrogress

Type of: reversal, shift, transformation, transmutation

• musculus pectoralis
• musculus pectoralis major
• musculus pectoralis minor
• musculus quadriceps femoris
• musculus rhomboideus major
• musculus rhomboideus minor
• musculus sartorius
• musculus scalenus
• musculus serratus anterior
• musculus serratus posterior
• musculus sphincter ani
• musculus sphincter ani externus
• musculus sphincter ani internus
• musculus sphincter ductus choledochi
• musculus sphincter ductus pancreatici
• musculus sphincter pupillae
• musculus sphincter pylori
• musculus sphincter urethrae
• musculus sphincter vesicae
• musculus sternocleidomastoideus
• musculus temporalis
• musculus teres major
• musculus teres minor
• musculus tibialis
• musculus transversalis abdominis