The shoulder, or pectoral girdle, is a structure that plays an essential role in many functions and movements. The three shoulder bones include the scapula, the clavicle, and the humerus.

The shoulder bones attach to a collection of tendons, joints, and muscles that work together to ensure mobility. Issues with any part of the shoulder can cause shoulder pain.

Functions and movements of the shoulder include lifting, rotating, and moving the arm.

Shoulder bone injuries include joint dislocations and bone fractures. Any of these injuries can result in arthritis, which is inflammation of the joint.

This article looks at the shoulder bones and other structures and discusses some common conditions that affect them.

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The shoulder joint consists of the following:

  • Scapula: The scapula, or shoulder blade, is a large bone in the upper back. It is triangle-shaped, with a ridge at the top called the scapular spine. There are 17 muscles that attach to the scapula, helping stabilize and move it.
  • Acromion: The acromion forms the top portion of the scapula.
  • Coracoid process: Also part of the scapula, this small bone attaches to the underside of the scapula and points toward the chest.
  • Clavicle: The clavicle, or collarbone, rests at the top of the chest, under the neck, running vertically on either side. It connects to the breastbone via a joint called the sternoclavicular joint.
  • Glenoid cavity: This is the shoulder joint socket that meets the humerus.
  • Humerus: This is the long bone of the upper arm. It connects the shoulder to the elbow.

Numerous types of soft tissue connect to the shoulder bones, such as tendons, ligaments, cartilage, and muscle.

Some important and commonly injured structures include:

  • Rotator cuff: This group of muscles and tendons surrounds the shoulder joint. It includes the infraspinatus, supraspinatus, subscapularis, and teres minor muscles, which work together to rotate and move the shoulder.
  • Tendons: The rotator cuff and bicipital tendons help lift the arm and rotate the shoulder. They are a common site of shoulder injuries.
  • Ligaments: These thick bands of tissue help connect bones. Some of the most crucial ligaments connect the scapula, clavicle, and humerus.
  • Bursae: These fluid-filled sacs help bones move more smoothly by reducing friction, especially along joints. They allow tendons and muscles to glide over bones when they move. The largest bursa of the shoulder is under the acromion.

Click on the BodyMap above to interact with a 3D model of the shoulder.

A person may experience various injuries involving the shoulder joint.

Shoulder dislocation

A shoulder dislocation happens when the humerus slips fully or partially out of the shoulder joint socket, or the glenoid.

Dislocations can move the humerus forward, backward, or down. A forward dislocation, or anterior instability, is one of the most common injuries.

Sports injuries can dislocate the shoulder, especially when the arm enters a throwing position. A person may also sustain other injuries, such as sprains and strains, resulting from the dislocation.

Shoulder dislocation requires immediate treatment. The pain due to dislocation can be severe, and a person may have trouble moving the shoulder. If they do not receive treatment, permanent nerve damage to the arm and hand may occur.

In most cases, a doctor treats a dislocated shoulder by putting the shoulder back in the joint. Sometimes, they can do this safely in the office, but it may also require surgery.

Typically, a person will need to rest and immobilize their shoulder following a dislocation. They may also need physical therapy.

Strains and sprains

A sprain is an injury or tear in a ligament, while a strain injures a muscle or tendon. Rotator cuff sprains and strains are among the most common shoulder injuries.

People may develop rotator cuff sprains or strains due to sudden trauma, such as an awkward fall or blow. These injuries may also appear over time due to overuse or improper use.

While minor injuries usually heal on their own, a complete tear of the soft tissue of the rotator cuff may require surgery.

Another common sprain is that of the acromioclavicular joint, where the acromion connects to the clavicle.


Tendinitis is swelling and inflammation in a tendon. It commonly affects the rotator cuff and usually appears steadily over time. It can result from overuse, awkward movements or positions, or sports such as tennis.

Depending on the severity of an individual’s tendinitis, doctors may suggest the following treatment approaches:


A shoulder fracture occurs when a bone in the shoulder breaks. Trauma due to a car accident, being hit by an object, or fall can cause a fracture or a break of one or more shoulder bones.

This type of injury can be very painful. However, a doctor may need to order an X-ray to distinguish a fracture from other injuries. Therefore, people should seek immediate medical attention for an accurate diagnosis.

Depending on the type of fracture, a person may need to wear a sling and immobilize the shoulder or undergo surgery. In addition, they may need pain relief medication and physical therapy.

Fractures may also occur in the following shoulder parts:

  • Clavicle (collar bone): Children commonly break the clavicle during a collision or fall.
  • Humerus: Breaks in this areas are more common in adults, particularly elderly individuals who experience low-energy falls.
  • Scapula: Fractures are rare but can happen following a car accident or significant fall.


Bursitis is inflammation of the fluid-filled sacs surrounding the shoulder joint. In most cases, it results from repetitive suboptimal use, such as in certain sports.

Medication, rest, and exercise may help heal bursitis, although some people may need physical therapy as well. Doctors may also prescribe corticosteroid injections.

If bursitis does not respond to any of these treatments, a person may need surgery.

Bone spurs

A bone spur is a bony growth that can affect any bone or joint, including the shoulder. Sometimes, bone spurs cause no symptoms, but they can also be painful or make moving the shoulder difficult.

Arthritis can sometimes cause bone spurs. This can happen when damage to the cartilage affects the production of bone cells, causing them to overgrow and form bone spurs, usually along the joint.

Pain relief medication may help, and bone spurs may not require treatment if they do not cause symptoms. However, individuals with symptoms may need surgery to remove the bone spurs.


Shoulder arthritis is not an injury in itself, but it can result from an injury.

Arthritis is joint inflammation. It can develop due to chronic conditions, such as rheumatoid arthritis, or wear and tear of the joint cartilage.

Arthritis can cause pain, swelling, and difficulty moving the shoulder or arm. Treatment options depend on the type of arthritis but may include:

If none of these can bring relief and alleviate pain, a person may need surgical treatment, such as joint replacement surgery.

The shoulder plays a critical role in many daily activities, from lifting and reaching to writing and driving. Consequently, shoulder pain can make regular functioning difficult, and repetitive suboptimal use may cause or worsen shoulder injuries.

Individuals who have shoulder pain may try home treatment initially, especially if the pain is not severe or sudden. Many minor injuries heal on their own. However, serious injuries are unlikely to improve on their own and may worsen without treatment.

A person should contact a doctor for sudden, intense shoulder pain, a suspected dislocated or broken shoulder, and any shoulder injuries that do not improve with home treatment.