Chicken Dissection Lab Analysis

In this lab we dissected a whole chicken. The goal of our dissection was to identify the different muscles on the chicken and to observe how the tendons and bones interact with the muscles. Through this lab, we were able to better learn the function and location of the primary muscles on the body. While chickens and humans, are very different organisms, they share key muscles, while still varying in proportions. Because the chicken we dissected were meat chicken, the muscles on their bodies were disproportional in comparison to an egg laying chicken. In our chicken, the breasts and thighs were much larger. 

We began the dissection by opening up the chicken's chest and identifying the pectoralis major, pectoralis minor, and the sternum. The pectoralis major is in charge of pulling the wing ventrally to power the flapping of wings for flight. This muscle works with the pectoralis minor, which lifts the wing dorsally. The sternum is in the middle of the bird, connecting the muscles on both sides of the body can work together in unison to enable the act of flight. The sternum is very long and curved, which gives support to the large pectoral muscles and allows them to be the size that they are. The tendons connect the muscles to the sternum, acting as the glue to make everything work. 

Anterior view of chicken
Blue: Sternum- connects to pectorals
Red: Pectoralis Minor-triangularly shaped, pulls wing dorsally
White: Pectoralis Major- triangularly shaped, pulls wing ventrally

Green: Deltoid- triangular, raises upper arm or wing
Black: Bicep brachii- has two origins, flexes wing or arm
Yellow: Tricep humeralis- has three origins, flexes wing or arm

We also dissected the chicken wing, where we were able to observe the different roles that the tendon's origin and insertion play. The origin of a tendon is the immovable end of the muscle. The point of insertion is the movable end of the muscle. In the wing, the triceps humeralis, biceps brachii, and deltoids came into play. The biceps contract the muscle, which brings the point of insertion closer to the origin. The tendons connect the muscles together at the joints, allowing them to flex and straighten. The action of these muscles allows for the flapping of wings. 

Yellow: Flexor carpi ulnaris- The largest muscle on the
posterior side of the lower wing away from the ulna.
It flexes the hand.

Blue: Brachioradialis- largest muscle on the superior side of the lower wing closest to the alua. It pulls the hand back

Humans and chicken have similar, yet different muscles. Just like a chicken, humans have pectorals; however, the pectorals of humans are not as large as they are on a chicken. Birds, unlike humans, require strong pectoral muscles so that they can flap their wings at a constant rate. On the other hand, humans do not raise their arms that much in their day-to-day activities. Both humans and chicken have a trapezius, which is located on the upper back. In the chicken, the muscle runs from the backbone to the shoulder, and the shoulder to the back. On the other hand, in humans, the trapezius is split into two separate parts. In humans, the trapezius shrugs the shoulders and pulls the shoulders back. On the other hand, because the muscle is one main part in the chicken, I believe that the trapezius primarily helps pull up the arms. 

Posterior View of Chicken
Green: Trapezius- trapezoidal, pull shoulders back
Yellow: Latissimus dorsi- help extend or pull the wing or arm

Another similar muscle between humans and chicken is the peroneus longus. The main difference between these muscles in humans and chickens is the relative size of the muscle in comparison to chicken. Chicken calves are completely round, unlike a human's. While I am unsure why chicken calves are so large, it may have to do with the fact that they walk in a squatted-like position and need the muscle, or they are bred that way so that consumers get more meat per bone. 

Calf
Blue: Peroneus longus- longest muscle in calf,
extends the foot
Yellow: Gastrocnemius- extends foot and
flexes the lower leg
Green: Tibialis anterior- flexes the foot

Anterior view of thigh
Yellow: Quadriceps femoris- four origins, flexes thigh and extends the lower leg
Blue: Sartorius- flexes thigh and allows crossing of the legs
Green: Semitendinosus- extends the thigh 

Posterior view of thigh
White: Biceps femoris- has two origins, flexes the leg
Black: Iliotibialsi- extends the thigh and flexes the leg
Red: Semimembranosus- extends the thigh