Shoulder Anatomy

Shoulder Anatomy

Anatomy Lesson 9 – Part 1

In this video lesson, you will discover the shoulder anatomy.

Shoulder Anatomy for Figurative Artists

The collarbones start from the manubrium of the sternum and go outward, first following the oval of the first pair of ribs and then following the axis of the shoulders. The curvature of the collarbones, or as they are called in Latin, the clavicles, resemble the handlebars of a bicycle.

In the middle of each collarbone, there is a triangular gap between the deltoid and the chest muscle. This gap is detectable on the body.

The length of the collarbone is equal to the height of the breastbone.

The shape of the breastbone resembles a sword with its blade end facing downward. The sternum, or the breastbone, consists of two parts.

At the top, there is the manubrium of the sternum and in the middle is the sternum body. Between these two parts there is the sternal angle.

At the bottom part of the breastbone there is the axis of the chest, or the breast line.

At the intersection between the two vertical lines and this horizontal axis is the location of the nipples on the male breast.

Talking about the shoulder anatomy, we need to mention some major muscles every figurative artist must know.

The deltoid muscle goes downward from the outer half of the collarbone. This muscle takes its name from the fourth letter of the Greek alphabet, delta, and resembles the letter’s triangular shape. The deltoid is responsible for many movements of the arm. It helps in abduction, flexion, extension, and medial and lateral rotation, which means it raises the arm sideways, raises the arm forward in front of the torso, moves the arm backward, and also rotates the arm both inward and outward.

The upper arm bone is called humerus. On the front side of the humerus, beneath the deltoid, there is the place where the breast muscle inserts into it.

The breast muscle has three portions. The top portion, or the collarbone portion, starts from the inner half of the collarbone and goes to the bottom of the insertion point on the humerus. The middle portion of the breast muscle starts from the breastbone, which is also known as the sternum. Therefore, this portion of the breast muscle is called the sternal portion. This sternal portion of the breast muscle inserts into the middle of the insertion point on the humerus. There is also the third, lower portion of the breast muscle. It starts from the sixth and seventh ribs and inserts into the upper point of the insertion place on the humerus. The fibers of the breast muscle cross over each other near the armpit.

The chest muscle has three main functions- adduction, flexion, and medial rotation. This muscle brings the arms towards to the body. It also moves the arms in front of the torso and rotates the arms inward.

When the upper arm is raised upward, humerus it actually locks with the acromion, which is the top part of the shoulder blade.

When arm is raised even higher, it comes together with the collarbone and the shoulder blades. These two bones also rotate upward.

Next to the point where the chest muscle inserts into the humerus, there is another big muscle that inserts there as well. It is the widest muscle of the back, or the latissimus dorsii.

There are also other muscles in the region of the armpit, which are connected to the shoulder blade and insert to the humerus close to its head…

[ The full lesson is avaibale to Anatomy Master Class members ]