The Rectus Abdominis is the most superficial of the abdominal muscles. It is this muscle which forms the six-pack shape! It is a paired muscle running vertically on each side of the anterior wall of the abdomen. There are two parallel muscles, separated by a midline band of connective tissue called the linea alba.

The latissimus dorsi is the larger, flat, dorsolateral muscle on the trunk, posterior to the arm, and partly covered by the trapezius on its median dorsal region.

The Deltoid muscle is the muscle forming the rounded contour of the shoulder. It is divided into three portions, anterior, lateral and posterior, with the fibers having different roles due to their orientation.

The Infraspinatus muscle is one of the four rotator cuff muscles crossing the shoulder joint and is commonly injured. It is the main external rotator of the shoulder joint.

The Biceps brachii is  actually two separate bundles of muscles (heads). The two heads of the Biceps vary in length and as a result, are called the Short and the Long Biceps heads.

The Triceps Brachii muscles  have three muscle heads: Lateral, Medial and Long head. Primarily responsible for the extension of the elbow joint. The lateral head is used for movements requiring occasional high-intensity force, while the medial fascicle enables more precise, low-force movements.

The Pronator teres pronates the forearm, turning the hand posteriorly. If the elbow is flexed to a right angle, then pronator teres will turn the hand so that the palm faces inferiorly. It is assisted in this action by pronator quadratus.

The Extensor Digitorum muscle helps in the movements of the wrists and the elbows. It extends the phalanges, then the wrist, and finally the elbow. It acts principally on the proximal phalanges. It tends to separate the fingers as it extends them.

The pectoralis major makes up the bulk of the chest muscles in the male and lies under the breast in the female.

The pectoralis minor is a thin, triangular muscle, situated at the upper part of the chest, beneath the pectoralis major. 

The External Oblique is situated on the lateral and anterior parts of the abdomen. It is broad, thin, and irregularly quadrilateral. It is the largest and the most superficial (outermost) of the three flat muscles of the lateral anterior abdomen. 

The Erector Spinae is not just one muscle, but a bundle of muscles and tendons. Paired, they run more or less vertically. It extends throughout the lumbar, thoracic and cervical regions, and lies in the groove to the side of the vertebral column.

The gluteal muscles are a group of three muscles which make up the buttocks: the gluteus maximus, gluteus medius and gluteus minimus. The three muscles originate from the ilium and sacrum and insert on the femur. The functions of the muscles include extension, abduction, external rotation, and internal rotation of the hip joint.

A hamstring is any one of the three posterior thigh muscles in between the hip and the knee (from medial to lateral: semimembranosus, semitendinosus and biceps femoris). The hamstrings are quite susceptible to injury.

The gastrocnemius and the soleus form what we know as calf. They are involved in activities such as walking, running, jumping… 

The trapezius is a broad, flat and triangular muscle. The muscles on each side form a trapezoid shape. It is the most superficial of all the back muscles.