Which muscle is not considered part of the core body?

The soleus muscle is not considered part of the core body because it is located in the lower leg and primarily functions to assist with ankle flexion and stability during walking and running. The core body typically refers to the muscles of the abdomen, lower back, and pelvis, which play a crucial role in stabilizing the trunk and supporting movements of the limbs.

In contrast, the rectus abdominis, transverse abdominis, and obliques are all integral components of the core. The rectus abdominis is responsible for flexing the spine and is commonly known as the 'six-pack' muscle. The transverse abdominis acts like a corset, stabilizing the pelvis and lower back, while the obliques, located on the sides of the abdomen, help facilitate rotation and lateral movement of the torso. Thus, the correct identification of the soleus as a muscle outside the core structure highlights the distinct roles that various muscle groups play in human movement and stability.