Shoulder Muscles

Shoulder Muscles

Anatomy Lesson 9 – Part 2

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

Shoulder Muscles Anatomy for Figurative Artists

Examining the shoulder muscles, we need to say few words about some major shoulder bones. The scapula, or the shoulder blade, has a triangular shape.

The upper arm bone, or humerus, is connected to the scapula at the ball-and-socket joint.

The head of the humerus is round and is approximately the size of a golf ball.

The socket of this joint is connected to the scapula at the glenoid fossa.

At the top of the scapula there is a bony ledge, which is known as the spine of scapula.

At the outer edge of this spine is the acromion. The acromion is hanging above the ball of the humerus. This is the part of the shoulder blade that connects to the collarbone.

Now let’s examine the shoulder muscles, including some muscles of the scapula. At the top of the shoulder blade, there is the muscle called supraspinatus, which goes from the scapula to the humerus.

This muscle assists in lifting the arm sideways.

There is another bigger muscle that goes from the middle part of the scapula to the upper part of the humerus. This muscle is called the infraspinatus. It assists in rotating the arm outward.

There is another smaller muscle that also helps in this rotation. It is called the teres minor.

And the last muscle of the scapula is the teres major.

When contracted, this muscle abducts the arm, or brings it closer to the torso, and also assists in medial rotation and extension, or the rotation of the arm inward and pulling it backward.

Close to the point where this muscle inserts into the humerus there is another muscle that attaches to the bone.

It is called the latissimus dorsi – the widest muscle of the back.

This muscle partly covers the scapula at its lower end and prevents the scapula sticking out from the back.

The main action of this muscle is to pull the extended arm back to the side of the torso. It also assists in the extension of the arm from a flexed position in front of the torso back to the side of the torso. It also plays a role in the medial rotation of the arm, which is the rotation of the arm inward…

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