Upper Body Muscles Assignment #1

Triceps Brachii

A muscle, larger than the biceps on the back of the upper limb, that gets its name from the three heads of muscles. This muscle works with the biceps and the brachialis to flex the arm at the elbow joint. The triceps are the most commonly known extensor in the upper body. It is used for simple tasks such as writing.

Teres Major and Minor

A thick and flat back muscle that is found in the upper limbs beside the traps. These act as a rotator cuff muscle and facilitates the movement of the arm also called the humerus. This muscle works with the lats to provide full medial coverage of the arms including twisting and turning.

Pectoralis Major

Commonly called the pecs, major muscle in the chest cavity that is fan shaped on the right/left side. The muscle is primarily used for movement of the shoulders including carrying something, flapping the arm, and twisting the arm.

Latissimus Dorsi

Large, flat muscle on the back of the body that are commonly referred to as the lats by bodybuilders. These muscles are below the traps and work with the pecs to facilitate shoulder movements such as the ability to do push-ups and extending arms.

Rectus Abdominis

Located in the lower chest and is referred to as the abs., there are usually two sets of four to six "packs." These muscles are important in flexing the lumbar spine, which is used to perform tasks like sit-ups. The abs also help people perform respirations and manage breathing.

Biceps Brachii

One of the most common muscles and located in the arms, this muscle has two heads thus its name has the prefix bi meaning two. This muscle is primarily used in carrying heavy objects and also stabilizes the arm during exercises or activities. The biceps have three joints that are supposed to flex the elbow and supinate the arm.

External Oblique

The largest and outermost muscle in the abdominal cavity in the lower back, the external oblique is broad and thin. This muscle does not perform many functions other than rotating the vertebral column, but it does compress the abdominal cavity to build pressure on it.

Deltoid

The muscle in both the front and back of the body, forming the shoulder muscles. This muscle is split into many different parts including the medial and lateral deltoid, but the muscle mainly functions to move the arm and perform arm abductions. The deltoid works with most back muscles to perform these actions, so tears in the deltoid are relatively common.

Trapezius

The trapezius is a major muscle in the upper back that got its name for being shaped like a trapezoid. The muscle is important in performing actions like moving your arm and shoulder backwards, shrugging your shoulders, tilting your head back.

Brachialis

This muscle is deeper than the biceps, but is up to 50% stronger the biceps and use more energy. However, this muscle does not supinate the arm like the biceps; it does help the biceps flex the arm at the elbow joint. Since the brachialis lies under the biceps, it is not visible from the outside of the hand like the biceps are.