Chicken Muscle Dissection

tendon is where the tool is pointing

In this lab, we dissected a chicken to see the different muscles, tendons, ligaments, and how they work with each other to create movement and structure in the body.

yellow=pectoralis major
blue=pectoralis minor

Starting with the chicken's breast, there is the pectoralis major which stretches from the shoulder to the humerus. Also on the chest is the pectoralis minor which is underneath the pectoralis major and stretches from the shoulder to the dorsal side of the humerus. This muscle is used for pulling the shoulder forward and down. The tendons of both these muscles attach to the shoulder or the humerus and they are shiny and white.

Yellow= Latissimus dorsi
Blue= Trapezius

For the chickens upper back, to begin, there is the trapezius which is perpendicular to the scapula, is a shiny faded color, and is used for shrugging shoulders. Next is the latissimus dorsi, which runs from the spine to the armpit and attaches to the posterior side of the humerus. This is used for extending the arm and the tendon is attached to the spine and the humorous posterior.

Blue= Deltoid
Yellow= Triceps Humeralis
Green= Biceps Brachii

The chicken's upper arm contains the deltoid, which is the muscle that is on the center top of the shoulder and helps raise the arm. The biceps brachii is on the cranial side of the upper arm and is used to flex the arm (bicep curls). There are 2 tendons, bi means two because the brachial attaches to the bone are 2 places. Triceps humeralis is on the inferior side and straightens the arm. The origin includes the shoulder and then the insertion includes where the muscles move which in turn will either flex or straighten the arm.

Green= Brachioradialis
Yellow= Flexor Carpi Ulnaris

In the chicken's forearm, there is the flexor carpi ulnaris which is on the posterior side and runs from the elbow to the pinky which is really the ulna to the farthest phalanges is where the tendons are placed. This muscle flexes the hand. There also is the brachioradialis which is on the superior side and closest to the elbow. This pulls the hand back.

Yellow= Sartorius
Blue= Quadriceps
Black= Iliotibialis
Red= Biceps Femoris
Green= Semitendinosus
White= Semimembranosus

For the chicken's thigh, there is the sartorius which has a tendon at the ilium and one at the patella and is in the front of the leg that lets the thigh flex the leg. Then there is the Iliotibial (for chickens) that runs from the side of the leg from the pelvis to the lateral side of the patella. This helps the leg flex and is a common injury. The biceps femoris which is inferior and medial to the iliotibial and makes up the hamstring that flexes the leg. The semimembranosus is inferior and medial to the biceps femoris and extends the leg. The semitendinosus is anterior and medial to the semimembranosus and extends the thigh. Bothe those attach with a tendon on the pelvis and attach at the patella.  Lastly, the Quadriceps femoris is on the inside of the thigh and is made up of 4 muscles. This is used in leg extensions.

Red= Gastrocnemius
Yellow= Tibialis anterior
Blue= Peroneus Longus

The chicken's calf has the gastrocnemius which has 2 heads and they attach to the Achilles tendon that runs along the bird's heel. This enables people to stand on toes. The peroneus longus is actually smaller and runs on the lateral side of the lower leg and extends the foot. The tibialis anterior runs along the tibia bone with a tendon connecting the two and this muscle flexes the foot. This muscle is also known for causing pain such as in "shin splints".

Most of the muscles in the chicken are homologous to those fo humans but there are a few exceptions. The trapezius in humans is split into two parts whereas in the chicken there is only one part. In humans, the gastrocnemius attaches both its heads to the Achilles heal whereas the bird's muscle wraps around the hock.  Lastly, the flexor carpi ulnaris in birds runs from the ulna to the "thumb" but in humans, it runs from the ulna to the "pinky" finger.