Chicken Dissection Lab

In this lab, our lab group identified the major muscles on a whole chicken by using pins and labels. First, we cut through the chicken's breast area and identified the chest muscles: pectoralis major and pectoralis minor.

Pectoralis major: flexes, adducts, and rotates the arm medially

Pectoralis minor: elevates ribs and protracts scapula

After locating the chest muscles, our lab group located a few tendons at the bottom of the chest:

The tendons are the white, shiny tissue.

At the origin of the muscle, the muscle is immovable, and the insertion of the muscle is the movable end of the muscle. When a muscle contracts, the insertion is moved toward the origin. 

Next, flipped the chicken over and cut open its upper back to identify the muscles there: trapezius and latissimus dorsi. 

Trapezius: extends head and adducts, elevates, or depresses scapula

Latissimus Dorsi: extends and adducts scapula; broadest muscle of the back

There is a difference between the trapezius of a chicken and the trapezius of a human. In humans, the trapezius is split into two parts, each part having its own action. The part going up the neck shrugs elevates and depresses the scapula, and the part running across the back retracts the scapula. 

After dissecting the back of the chicken, we moved onto its wing, or upper arm to locate the deltoid, biceps brachii, and triceps humeralis. 

Deltoid: abducts, flexes, and extends arm

Biceps Brachii: flexes elbow joint

Triceps Humeralis: extends the arm 

The triceps humeralis does not exist in humans; this muscle would be the triceps brachii in humans instead, and is the muscle used in doing reverse curls. In order to see how the muscles in the arm worked together to create movement, we used our hands to flex and extend the elbow joint. Once we did this, we could see the muscles, specifically the deltoid, lengthening and we could also feel the tendon moving along with the muscle lengthening. 

Next, we dissected the forearm of the chicken to find the flexor carpi ulnaris and brachioradialis. 

Brachioradialis: largest muscle on the superior side of the wing; pulls the hand back

Flexor Carpi Ulnaris: largest muscle on the posterior side of the wing; flexes the hand

Our lab group also tried flexing the wrist joint to see if the hand of the arm would move because we were lengthening and contracting the muscles of the forearm. Sure enough, the when we lengthened the flexor carpi ulnaris, the hand flicked upward. 

Next, we dissected the thigh of the chicken to find the sartorius, iliotibialis, biceps femoris, semimembranosus, semitendinosus, and quadriceps femoris.

Sartorius: flexes the thigh; runs down the front edge of the thigh

Iliotibialis: covers the whole lateral side of the thigh; extends the thigh and flexes the leg

The iliotibialis does not exist in humans; instead, there is the gluteus maximus and iliotibial tract in humans. Also, in birds, this muscle group covers the whole lateral side of the thigh, but in humans, it has three parts and runs from the dorsal and alteral sides of the pelvis to the lateral side of the knee. 

Biceps Femoris: flexes the leg; part of hamstring group

Semimembranosus: inferior and medial to biceps femoris; extends the thigh

Quadriceps Femoris: group of four muscles; flexes the thigh and extends the lower leg

Semitendinosus: anterior and medial to semimembranosus; extends the thigh

Lastly, we dissected the chicken's drumstick/calf to identity the gastrocnemius, peroneus longus, and tibialis anterior muscles.

Gastrocnemius: primary muscle of dorsal and medial sides of drumstick; extends the foot and flexes lower leg

Peroneus Longus: extends the foot

Tibialis Anterior: directly under peroneus longus; flexes the foot