Chicken Dissection Analysis

In this lab, we dissected a whole chicken from the grocery store in order to understand how muscles are positioned. Chickens have many muscle structure similarities to humans and we were able to see not only the muscles but the tendons and ligaments that connected them. We started with the front of the bird and cut through the pectoralis major (Green pin) and the pectoralis minor (white pin)  which runs directly superior and parallel in both humans and birds. The P. minor lifts the wing dorsally and in humans, pulls the shoulder forward and down. We observed the tendons at the ends of the muscles that helped move the muscles. (Red Pin) Meat chickens are grown for food, and overtime have been genetically modified to have larger thighs and breasts for more efficient production.

Green Pin- Pectoralis Major

White pin- Pectoralis Minor

Red Pin- Tendon insertion

We then dissected the upper back to reveal the Trapezius (blue pin) muscles that run perpendicular from the backbone to the shoulder which pulls the shoulder back. In humans, this muscle is split into two, one that runs up the neck and shrugs the shoulders and the one running across the back pulls the shoulders back. Distal to the trapezius sits the latissimus dorsi (black pin) on both the human and chicken, extending the appendage. 

Blue pin- Trapezius

Black pin- Latissimus Dorsi

The upper arm, or wing is composed of several muscles to help movement. The shoulder muscle at the top is called a Deltoid (red pin), helping to raise the arm/wing. The biceps brachii (blue pin) have two origin points and is the upper wing or arm and flexes the appendage.  On the opposite side of the arm is the triceps humeralis, which relaxes as the biceps brachii contracts. 

Blue Pin- Biceps brachii

Red Pin- Deltoid

Yellow pin- Triceps humeralis

 

The flexor carpi ulnaris (red pin) is the largest muscle on the posterior side of the lower wing and flexes the hand/ alula or birds thumb, and the brachioradialis (green pin) runs from the elbow to the thumb side of the hand, pulling it back.

Overall, the muscles of a chicken help to understand how they relate in a human. I now understand how the bicep brachii in the arm or wing flexes while triceps humeris relaxes.