Shoulder Anatomy

Knowing shoulder anatomy is important for creating accurate medical illustrations because it allows the illustrator to depict the structures and their relationships to each other in a precise and accurate manner. This is important for a variety of purposes, such as patient education, surgical planning, and scientific research. Inaccurate illustrations can lead to confusion and miscommunication, which can have serious consequences in a medical setting. Additionally, detailed knowledge of shoulder anatomy allows the illustrator to create images that are aesthetically pleasing and easy to understand for the intended audience.

Shoulder Anatomy

The shoulder is a complex joint made up of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone). The head of the humerus fits into a shallow socket on the scapula called the glenoid. The glenoid is surrounded by a ring of cartilage called the labrum, which helps to deepen the socket and provide stability to the joint.

The shoulder joint is surrounded and supported by a group of muscles, tendons, and ligaments, the most important of them are the rotator cuff muscles (supraspinatus, infraspinatus, teres minor, and subscapularis) which attach to the scapula and the head of the humerus and they are responsible for the stability of the joint and the ability to lift and rotate the arm.

What muscles attach to the shoulder?

There are several muscles that attach to the shoulder. These include:

1. Deltoid muscle – This muscle covers the shoulder joint and is responsible for shoulder abduction, flexion, and extension.
2. Rotator cuff muscles (Supraspinatus, Infraspinatus, Teres minor, Subscapularis) – These muscles are responsible for stabilizing the shoulder joint and allowing for rotation and elevation of the arm.
3. Biceps brachii muscle – This muscle is located in the front of the upper arm and attaches to the shoulder via the bicipital groove. It is responsible for arm flexion and supination.
4. Triceps brachii muscle – This muscle is located in the back of the upper arm and attaches to the shoulder via the scapula. It is responsible for arm extension.
5. Pectoralis major muscle – This muscle is located in the chest and attaches to the shoulder via the clavicle. It is responsible for arm flexion and adduction.
6. Latissimus dorsi muscle – This muscle is located in the back and attaches to the shoulder via the scapula. It is responsible for arm extension and adduction.
7. Teres major muscle- This muscle is located in the back, right behind latissimus dorsi and attach to the shoulder via the scapula. It also responsible for arm extension and adduction.

Types of Shoulder Injuries

There are several types of shoulder injuries, some of the most common include:

1. Rotator cuff injuries – These injuries can include strains, tears, and impingements of the muscles and tendons that make up the rotator cuff.
2. Labral tears – The labrum is a ring of cartilage that surrounds the socket of the shoulder joint. Tears to this tissue can occur as a result of trauma or overuse.
3. Dislocated shoulder – This occurs when the upper arm bone (humerus) is forced out of the socket of the shoulder blade (scapula).
4. Fractures – The collarbone (clavicle) or upper arm bone (humerus) can be fractured as a result of trauma.
5. Bursitis – This occurs when the fluid-filled sacs (bursae) that cushion the shoulder become inflamed.
6. Tendinitis – This is inflammation of the tendons that attach the muscles to the bones in the shoulder.
7. Frozen shoulder – This condition is characterized by pain and stiffness in the shoulder, and a limited range of motion.
8. Arthritis – This is a degenerative condition that can affect the shoulder joint, causing pain and stiffness.

Some of these injuries are common in athletes like shoulder injuries in tennis players or injuries in swimmers.