The muscular systems of humans and frogs share a number of anatomic and biochemical similarities, including the same basic muscle groups, a similar muscle fiber structure and the presence of acetylcholine-based neuromuscular junctions. The myosin and actin protein family present in muscles is also well-conserved between human and frogs.
Almost all major human muscle groups, including the pectorals, deltoids, quadriceps and abdominal muscles are present in frogs and recognizably similar in structure to those of humans. While the form of the muscles is different due to the anatomical differences between the species, common features such as the division of the quadriceps muscles into the rectus femoris, vastus lateralis and vastus medialis are apparent. These similarities are less apparent in the smaller muscles of the feet of the frog, where the anatomy of humans and frogs is highly dissimilar.
Frogs and humans also both have neuromuscular junctions that transmit impulses from the nervous system to muscles via release of the neurotransmitter acetylcholine. Frogs and humans also have skeletal muscles that are organized into striated fibers organized into subunits known as sarcomeres. Sarcomeres are composed of filaments of actin and myosin proteins that are well-conserved not only between frogs and humans, but among nearly all species on the Earth.