Chicken Dissection Lab

Unfortunately I was absent for this assignment/dissection, however, I am still educated on the material. I asked class members who did do the lab, how it went and how the process of determining muscles went. They all, for the most part, referred to their in-class notes handouts of the human body. In general, the size of the muscles differed from chickens to humans, however the locations stayed the same. For example, the pectoralis major was far larger in the chicken than in the human. This difference is likely caused by the fact that to lift itself off the ground, the muscle would have to be larger. This causation ultimately results to form fits function. As the chicken needs to lift itself off the ground, the muscles need to be stronger, and therefore larger. In contrast, humans are far less reliant on the pectoralis major as we don't fly (if only). Some characteristic similarities are are in the trapezius and the deltoid. An important reminder is that muscles grow and atrophy depending on usage and resistance the muscle receives. This can help determine the physical activity and nature of the animal, for instance our largest muscle is the gluteus maximus which is due to our nature as a 2 legged animal.  

Not only are muscles used for movement, but so are bones and tendons. Muscles connect to the bone through tendons and help to show increase the range of motion and release tension. The bones allow for stability. As muscles contract, certain muscles contract as others relax. The muscle that contracts is called the agonist whereas the muscle that relaxes is the antagonist. For example in elbow extension, the triceps contracts, whereas the biceps relaxes. The lever system in this interaction allow the bicep to contract with less stress. These levers vary in class; each class identifies a different type of lever system.

Just as levers vary in class, so do tendons. There are two types, named, the origin, and the insertion. The origin is the end that does not move when the muscle moves while the insertion is the tendon that does move when the muscle contracts. The origin also tends to be more proximal while insertion tends to be more distal. The origin of a muscle attaches to a less movable bone whereas the insertion of a muscle attaches to a more moveable bone. The insertion also has less mass than the site of origin.

• The pectorals are predominantly used to control the movement of the arm, with the contractions of the pectoralis major pulling on the humerus to create lateral, vertical, or rotational motion
• large muscle in the upper chest, fanning across the chest from the shoulder to the breastbone

• thin, flat muscle found immediately underneath the pectoralis major

• The primary actions of this muscle include the stabilization, depression, abduction or protraction, upward tilt, and downward rotation of the scapula

1. The muscle also covers the lower tip of the scapula, or shoulder blade. When flexed, the muscle works at extending, adducting and rotating the arm.
2. One of the widest back muscles. Broad muscle bands cross the back, providing upright posture support. The trapezius muscle is a postural and active movement muscle, used to tilt and turn the head and neck, shrug, steady the shoulders, and twist the arms

• The deltoid muscle is responsible for the brunt of all arm rotation and allows a person to keep carried objects at a safer distance from the body.

2.  The triceps run along the humerus (the main bone of the upper arm) between the shoulder and the elbow. When the triceps are contracted, the forearm extends and the elbow straightens; if the triceps are relaxed and the biceps flexed, the forearm retracts and the elbow bends.

3.  The biceps brachii is a bi-articular muscle, which means that it helps control the motion of two different joints, the shoulder and the elbow. The function of the biceps at the elbow is essential to the function of the forearm in lifting.

1. Also called the brachialis anticus, its primary action is to flex the forearm muscles at the elbow
2. flexes the wrist and adducts it

1. Is a muscle located on the back portion of the lower leg, being one of the two major muscles that make up the calf. The flexing of this muscle during walking and bending of the knee creates traction on the femur, pulling it toward the tibia in the lower leg and causing the knee to bend.
2. It serves to steady the leg upon the foot.
3. the largest muscle located in the anterior compartment of the leg. Helps with dorsiflexion, which is the action of pulling the foot toward the shin.

- a group of muscles located in the front of the thigh

- The quadriceps assist in extending the knee

1. The muscle helps flex, adduct, and rotate the hip.
2. a tiny muscle, inferior to the iliotibial band.  It also provides lateral stability to the knee.

1. It is found on the back of the thigh and runs from the base of the pelvis to the back of the tibia, one of the bones that make up the lower leg. The muscle has several functions, including enabling the leg to flex and rotate, and serving as a thigh extensor
2. One of three hamstring muscles that are located at the back of the thigh. These three muscles work collectively to flex the knee and extend the hip.

1. The biceps femoris muscle is a double-headed muscle located on the back of thigh. It is important for knee flexion, internal and external rotation, and hip extension.
2. A large muscle group that includes the four prevailing muscles on the front of the thigh.They are crucial in walking, running, jumping and squatting. Because rectus femoris attaches to the ilium, it is also a flexor of the hip.