The rectus abdominal muscle is an example of a _____ muscle.a. pennateb. convergentc. fusiformd. parallel

Break Down the Problem

1. Identify the type of muscle represented by the rectus abdominal muscle.
2. Evaluate the options given: pennate, convergent, fusiform, parallel.

Relevant Concepts

1. Muscle Types:
   • Pennate: Muscle fibers are arranged at an angle to the tendon.
   • Convergent: Muscle fibers converge toward a single tendon.
   • Fusiform: Muscle fibers are arranged parallel to the long axis but taper toward the ends.
   • Parallel: Muscle fibers run parallel to the long axis of the muscle.

Analysis and Detail

• The rectus abdominis muscle is characterized by long, strap-like fibers that run in parallel with one another. This arrangement allows for effective contraction and strength in flexing the lumbar spine.

Verify and Summarize

• Upon reviewing the definitions of each muscle type and considering the structure of the rectus abdominis, it is clear that it fits the definition of a parallel muscle.

Final Answer

The rectus abdominal muscle is an example of a parallel muscle (option d).