Chicken Dissection Lab Analysis 3/15 (the real pi day)

We took a cleaned, sanitized, chicken cadaver and began to pick it apart using a variety of dissection instruments while labeling any muscles we came across. For example, the contraction of the pectoralis major (pictured below)

pulls on the humerus of the chicken (as it is connected with a tendon) to lift the wing up. This is nearly identical to the human use of the same muscle, which moves the (much larger scale) humerus of a human. When looking at the tendons on both ends of the muscle, the origin always seemed to have more tendons stretching out from the muscle to anchor itself to the bone. Chicken muscles, and more specifically, the artificially selected variety that we humans have bred, seem extremely unbalanced. Looking at the pectoralis major and minor, they are easily five or six times the size and mass of any other muscle, while in humans, many of our muscles are similar in size to at least a few others. Also, the fact that the pectoralis major and minor are antagonists of each other and are located close enough to touch each other is confusing, as antagonist muscles in the human body are usually separated by a bone so that one can contract while the other relaxes. Lastly, while the arm limbs of a chicken are wings, the upper limbs of a human are arms. Even with this distinct difference, the muscle groups are essentially the same, with a lookalike elbow and wrist joint.

MUSCLE PHOTOS

Sternum (bone)
Pectoralis major - pulls humerus up
Pectoralis minor - antagonist of P. major (pulls down)

Trapezius - pulls shoulder back
Latissimus dorsi - group of muscles, extends and pulls arm

Deltoid - raise upper arm (aids P. major)

Biceps Brachii - flexes arm

Triceps humeralis - antagonist to biceps brachii, extends arm

Flexor carpi ulnaris - flexes hand/wing (at wrist)

Brachioradialis - hyperextends wrist (bend backwards)

Sartorius - flexes thigh to cross legs

Iliotibialis in birds or Tensor fasciae latae, Gluteus maximus and Iliotibial tract for humans - antagonist to sartorius, extends thigh and also flexes leg (knee)

Biceps femoris - flexes leg (high power)

Semimembranosus - extends thigh

Semitendinosus - extends thigh

Quadriceps femoris in birds or Vastus lateralis, intermedius and medialis; and Rectus femoris for humans - flexes thigh and extends leg

Gastrocnemius - extends foot and flexes lower portion of leg

Peroneus longus - extends foot

Tibalis anterior - flexes foot