BONES
The shoulder complex is made up of the humerus, scapula and clavicle. The humerus is the long bone in our upper arm which runs from the elbow to our shoulder where it articulates with the scapula at the glenohumeral joint. The scapula is the flat bone that lies on our back, it serves as an attachment point for several important muscles of the shoulder complex and articulates both with the humerus and with the clavicle. The clavicle, also known as the collarbone, connects the shoulder complex to the sternum.
JOINT CAPSULE
A joint capsule is an envelope made out of fibrous tissue that surrounds most joints of the body. It provides stability to the joint by preventing movement beyond normal ranges and also contains receptors which inform the brain about joint position. In the shoulder complex, each of the joints, except the Scapulothoracic joint, has a capsule. The Glenohumeral joint capsule is the most well known; it surrounds the joint and serves as an important passive stabilizer, but is also surprisingly lax. The front of the capsule is thicker to prevent the humeral head from dislocating anteriorly.
BURSA
A bursa is a synovial fluid-filled sac which helps protect certain structures by dissipating forces and acting as a cushion. The bursae are innervated and can therefore be a source of pain, but also give our brain valuable information on joint position. In the shoulder complex there are a total of 8 bursae; the subacromial bursa is worth a mention as it is frequently affected in the subacromial pain syndrome.
LIGAMENTS & LABRUM
A ligament is a fibrous band of tissue that connects two or more bones with the aim to limit or prevent movement, passively stabilizing the joint, think of it as a string attached between two bones. The labrum is a ridge-like structure made of cartilage, that attaches around the margin of the glenoid cavity, providing stability to the glenohumeral joint by deepening said cavity.
MUSCLES I
The muscles in the shoulder aren’t only in charge of producing movement but are also extremely important in the dynamic stabilisation of the shoulder. There are a huge number of muscles that attach and act on the shoulder complex, necessary for allowing and controlling the greatest range of motion of any joint in the body. Intrinsic muscles are those that originate and attach within the shoulder itself, whilst extrinsic muscles originate elsewhere, such as the thorax, but attach to any of the bones of the shoulder complex.
MUSCLES II
The rotator cuff deserves a special mention for it’s importance in the correct biomechanics of the shoulder complex. The rotator cuff is the term given to several relatively small muscles that originate from the scapula and attach to the humerus, they are: Supraspinatus, Infraspinatus, Teres minor and Subscapularis. Their tendons blend with the joint capsule reinforcing it before attaching to the humeral head at different points. Rotator cuff dysfunctions are one of the main causes for shoulder pain and/or impaired function.
LET’S TALK ABOUT OUR SHOULDER
The shoulder complex is made up of the humerus, scapula and clavicle. The humerus is the long bone in our upper arm which runs from the elbow to our shoulder where it articulates with the scapula at the glenohumeral joint. The scapula is the flat bone that lies on our back, it serves as an attachment point for several important muscles of the shoulder complex and articulates both with the humerus and with the clavicle. The clavicle, also known as the collarbone, connects the shoulder complex to the sternum.
A joint capsule is an envelope made out of fibrous tissue that surrounds most joints of the body. It provides stability to the joint by preventing movement beyond normal ranges and also contains receptors which inform the brain about joint position. In the shoulder complex, each of the joints, except the Scapulothoracic joint, has a capsule. The Glenohumeral joint capsule is the most well known; it surrounds the joint and serves as an important passive stabilizer, but is also surprisingly lax. The front of the capsule is thicker to prevent the humeral head from dislocating anteriorly.
A bursa is a synovial fluid-filled sac which helps protect certain structures by dissipating forces and acting as a cushion. The bursae are innervated and can therefore be a source of pain, but also give our brain valuable information on joint position. In the shoulder complex there are a total of 8 bursae; the subacromial bursa is worth a mention as it is frequently affected in the subacromial pain syndrome.
A ligament is a fibrous band of tissue that connects two or more bones with the aim to limit or prevent movement and to stabilize joints. In the shoulder complex, there are many ligaments passively stabilizing the different joints. The labrum is is a ridge like structure attached around the margin of the glenoid cavity which provides stability to the glenohumeral joint by deepening said cavity.
The muscles in the shoulder aren’t only in charge of producing movement but are also extremely important in the dynamic stabilisation of the shoulder. There are a huge number of muscles that attach and act on the shoulder complex, necessary for allowing and controlling the greatest range of motion of any joint in the body. Intrinsic muscles are those that originate and attach within the shoulder itself, whilst extrinsic muscles originate elsewhere, such as the thorax, but attach to any of the bones of the shoulder complex.
The rotator cuff deserves a special mention for it’s importance in the correct biomechanics of the shoulder complex. The rotator cuff is the term given to several relatively small muscles that originate from the scapula and attach to the humerus, they are: Supraspinatus, Infraspinatus, Teres minor and Subscapularis. Their tendons blend with the joint capsule reinforcing it before attaching to the humeral head at different points. Rotator cuff dysfunctions are one of the main causes for shoulder pain and/or impaired function.
DOES YOUR SHOULDER HURT?
Rotator cuff injuries include tendinopathy and tears and can affect people of any age. In young people, it is most commonly found in athletes that carry out repetitive overhead motions such as pitchers or volleyball players, due to overuse or secondary to trauma. In older individuals, degenerative changes due to aging, poor biomechanics, and overuse, frequently cause rotator cuff injuries. Most times it is a combination of several factors that are to blame. Rotator cuff tendinopathy refers to pathology in, and pain arising from, any of the tendons making up the rotator cuff. Rotator cuff tears occur when any of the tendons are torn, either partially or completely. As mentioned earlier, many factors are involved so it is usually not possible to pinpoint a single cause. Symptoms of either can include pain, muscle weakness, and impaired function, although they may not always be present.
Tendinopathy that affects the shoulder is not limited only to the rotator cuff tendons. The tendon of the long head of the biceps is also a common source of pain. The biceps is one of the muscles that flex your elbow although it also aids in flexion of the shoulder. As the name suggests it has two heads, a short one and a long one. The long head is called that way because it attaches all the way inside the glenohumeral joint, specifically at the supraglenoid tubercle and superior glenoid labrum. As with the rotator cuff, the tendon of the biceps long head can become injured through overuse and repetitive overhead motions. In most cases, there is an associated rotator cuff or labrum tear. Symptoms include deep throbbing pain that usually worsens during a throwing motion, and during the night, especially if sleeping on the affected shoulder.
Bursitis refers to the inflammation of a bursa and can be caused by a traumatic injury, inflammation of nearby joints, or through overuse where a repetitive motion causes excessive friction between the bursa and nearby structures. The subacromial bursa is the most commonly affected of the shoulder bursas, and when inflamed provokes persistent anterior or lateral shoulder pain that usually worsens at night, interrupting sleep.
A dislocation occurs when the humeral head moves out of the glenoid cavity. If it comes out partially it is referred to as subluxation and if it comes out completely as a complete dislocation. Depending on whether the humeral head falls out towards the front or back it is called anterior or posterior dislocation. An anterior dislocation is a lot more common and can occur as a result of a traumatic event or as a result of deficient supporting structures. A posterior dislocation happens as a result of an external blow to the front of the shoulder and is almost always due to a fall onto an outstretched, internally rotated arm. After a first dislocation, the supporting structures are damaged or overly stretched, making it common for recurring dislocations, either partial or complete, to occur and increasing the chances of developing other pathologies such as arthritis.
Shoulder arthritis is a condition that causes pain and inflammation in the shoulder joints. There are several types of arthritis that can affect your shoulders. Osteoarthritis is the most common and is caused by wear and tear, affecting people more as they age. The articular cartilage, that lines the joints, begins to deteriorate which makes it more difficult for the bones to slide against each other. With time, the cartilage loss results in bone rubbing against bone. Rheumatoid arthritis is an autoimmune disease that can affect several joints in your body. The body’s immune system targets the body’s joints causing pain and inflammation and like in Osteoarthritis the cartilage lining eventually deteriorates. Post-traumatic arthritis may follow a traumatic injury to the shoulder, such as a dislocation or fracture, where damage occurs to the cartilage lining, causing it to wear out more quickly.
Shoulder fractures can involve any of the three bones making up the shoulder complex and usually result from trauma. In older individuals, they’re often caused by a fall from standing height whereas in younger people they’re often the result of a high energy impact, such as a traffic accident or a sports injury. Symptoms include pain, swelling, functional impairment, and a bump or deformation may sometimes be present.
Frozen shoulder is sometimes referred to as adhesive capsulitis. It is a condition characterised by a progressive reduction in both the active and passive range of motion of the glenohumeral joint caused by the inflammation and hardening of the joint capsule. Why this happens is generally unknown although there are several risk factors, such as prolonged immobility due to injury or trauma, that can predispose someone to this condition. It can take several months or years for the condition to resolve, having a significant effect on function and quality of life.
