The triceps brachii muscle is the large muscle on the back of the upper limb of many vertebrates. It is the muscle principally responsible for extension of the elbow joint.
Both chickens and pigs are omnivores so they eat scrap, grain, and most importantly for this subject vegetables and fruits. Vegetables and fruits both came from photosynthesis, so when we eat bacon and eggs we are eating pigs and chickens that ate plants and vegetables that gained energy due to photosynthesis. At least that’s what I think