Final answer:
Circular and longitudinal muscles are the types that exist in the walls of the stomach, and are responsible for peristalsis which moves food through the digestive system.
Step-by-step explanation:
The types of muscles that exist in the walls of the stomach are circular muscles and longitudinal muscles. These layers of smooth muscle are components of the muscularis externa layer, and they play a crucial role in the mechanical digestion of food through a process known as peristalsis. The circular muscles encircle the organs of the GI tract, while the longitudinal muscles run the length of the GI tract organs. Together, they coordinate to contract and relax in a wave-like fashion to move food through the digestive system. The options 'gastric muscles' and 'latissimus muscles' do not specifically refer to the layers of smooth muscle found in the stomach wall; gastric generally refers to the stomach itself, and latissimus muscles refer to a large, flat muscle on the back that is part of the skeletal muscle system, not related to the digestive system.