Your shoulder is made up of three bones: your upper arm bone (humerus), your shoulder blade (scapula), and your collarbone (clavicle). Shoulder problems usually involve the muscles, ligaments, and tendons, rather than the bones. Athletes are especially vulnerable to shoulder problems, which can develop slowly through repetitive, intensive training routines.

Bursitis
Excessive use of the shoulder can lead to inflammation and swelling. The result is a condition known as subacromial bursitis. Bursitis often occurs in association with rotator cuff tendinitis. Many daily activities, such as combing your hair or getting dressed, may become difficult.

Tendinitis
Tendinitis is a result of a wearing down of the tendon that occurs slowly over time from overuse. Generally, tendinitis is one of two types:

Acute - Excessive ball throwing or other overhead activities during work or sport can lead to acute tendinitis.

Chronic - Degenerative diseases like arthritis or repetitive wear and tear due to age, can lead to chronic tendinitis.

Tendon Tears
Tearing of tendons may result from an injury or degenerative changes in the tendons due to advancing age, long-term overuse and wear and tear, or a sudden injury. Rotator cuff and biceps tendon injuries are among the most common of these injuries.

Tears can be located either above (superior) or below (inferior) the middle of the glenoid socket.

A SLAP lesion (superior labrum, anterior [front] to posterior [back]) is a tear of the rim above the middle of the socket that may also involve the biceps tendon.

A tear of the rim below the middle of the glenoid socket that also involves the inferior glenohumeral ligament is called a Bankart lesion.

Tears of the glenoid rim often occur with other shoulder injuries, such as a dislocated shoulder (full or partial dislocation).

Impingement
Impingement is caused by excessive rubbing of the shoulder muscles against the top part of the shoulder blade This problem can occur during activities that require excessive overhead arm motion. You should seek medical advice immediately for inflammation in the shoulder because it could eventually lead to a more serious injury. Over time, severe impingement can even lead to a rotator cuff tear.

Instability
When one of the shoulder joints moves or is forced out of its normal position, the condition is called instability. This can happen as a result of a sudden injury or from overuse. Instability will cause pain when raising the arm and it may also feel as if it is slipping out of place.

Arthritis
There are many types of arthritis. The most common type of arthritis in the shoulder is osteoarthritis, Symptoms, such as swelling, pain, and stiffness, typically begin during middle age. Osteoarthritis develops slowly and the pain it causes worsens over time. Osteoarthritis, may be related to sports or work injuries and chronic wear and tear.