Anatomy of the shoulder – puzzle or inigma ?

The shoulder joint is extremely flexible. A look at the anatomy shows that the large range of motion also has disadvantages.

Before we can discuss shoulder pain we need to understand the basic framework of the shoulder, how it operates and its limitations. Once we understand the basics we can move on to “why “ we get shoulder pain.

The shoulder joint is guided primarily by muscles, the joint capsule is rather loose. The associated large range of motion is advantageous, and the shoulder generally has to bear significantly less weight than other joints, such as the hips. The disadvantage is the risk of instability and increased vulnerability. We tend to have light shoulders by nature, and this sometimes leads to unpleasant surprises.

Structure of the shoulder joint: 3-4-3: three bones, four articular surfaces, three strong muscles (group) 

The shoulder is constructed very unusually – with three to four joints (in other words: four joint surfaces), three bones, three muscle groups and many tendons and ligaments for the joint capsules. Since they all “stick together” closely, minor problems can often be compensated for for a long time.

The three bones that make up the shoulder skeleton are the humerus, shoulder blade, and collarbone. When the shoulder joint is mentioned, most people think of the connection between the upper arm and the shoulder, in fact the main joint of the shoulder. What is less common is the fact that the shoulder actually consists of more than one joint.

• Shoulder joint number 1 is called the humeroscapular joint, the humerus stands for the humerus and the scapula for the shoulder. Strictly speaking, it consists of the head of the humerus (joint head) and the hollow (joint socket) in the shoulder blade, into which the joint head is immersed, and the surrounding capsule.

A marginal detail is the so-called joint lip (labrum). It actually lies on the edge of the socket and enlarges it. This is where the long biceps tendon originates. If this is exposed to a sudden tension or pressure in a tense state, for example when falling on the outstretched arm, so-called SLAP injuries (the abbreviation stands for “Superior Labrum from anterior to posterior”) with pain in the shoulder can occur.

• The second shoulder joint: The shoulder, acromioclavicular or outer clavicle joint has gained a certain degree of awareness through another injury called the shoulder joint splinter. It lies at the end of the collarbone towards the roof of the shoulder. The roof consists of a bone process (acromion) at the top of the shoulder blade and a firm ligament that leads to a second, upstream bone process on the shoulder blade (raven beak). The shoulder joint occasionally shows wear and tear, usually as a result of injuries or rheumatism.
• The third shoulder joint: At the front, the shoulder is positioned like a lever with the collarbone on the sternum (inner collarbone joint). Only here is the shoulder attached to the torso!
• The fourth joint is incomplete. It lies at the back of the back, between the inside of the shoulder blade and the ribs. Two important bursa form so-called “secondary joints” as sliding surfaces.

Muscles and tendons

The movements in the shoulder joint result from the interaction of three muscle groups:

• Four rotating muscles (rotators) for external and internal rotation as well as lifting the arm: They pull on the front and back of the shoulder blade with their tendons to the head of the humerus, which they span. Hence the name rotator cuff. The rotators hold the humerus head centrally in the joint socket of the shoulder blade and strengthen the naturally loose joint capsule.

The supraspinatus or upper bone muscle in particular takes on an important function as the strongest external turner, since it lifts the arm when pulled and turns the humerus head outwards in the further lifting phase. Then the joint head can slide under the canopy. Bursa between the tendons and the roof of the shoulder facilitate the sliding process in the narrow space, which is also called the subacromial space. Many wear problems of the shoulder joint occur here, called subacromial syndromes or subacromial impingement syndromes.

• Second, the chest muscles: you and a little bit of the well-known biceps muscle also help with shoulder work.
• Third in the bundle is the bulging deltoid muscle, the more or less prominent contour-giving muscle on the shoulder, depending on the volume. He covers the rotators, splays the arms, but also pulls the upper arm up. This is important to know because shoulder exercises often require the rotators to be strengthened without the deltoid muscle, because rotator weakness is more common in everyday life.

The shoulder: a lot of leeway, but also vulnerable

As the joint with the greatest range of motion, the shoulder is quite stable, but a little more prone to injury than our other joints. In addition to acute tendon tears or chipped off due to injuries, for example during sports, the smallest, initially barely noticeable tears can develop on the tendon structure at an early stage. Over time this can increase and lead to shoulder discomfort.

And: with a worn shoulder tendon, sudden, but by no means excessive, strain (minor trauma) is sometimes sufficient to cause the tissue to tear more severely.

But this scenario is far from everything.

Acute or Chronic?

Shoulder pain that lasts for up to two weeks is considered acute. After that, they are classified as chronic.

Often shoulder pain can be felt on the front and side of the shoulder. Important causes: Damage to the rotator cuff, tendon tear, calcified shoulder, frozen shoulder, bursitis, SLAP tear, damage to the long biceps tendon, shoulder joint damage.

Important accompanying symptoms: Increased pain when moving overhead, when lifting an object from the floor, when lying on the shoulder, shoulder movements less or more restricted, phenomena such as joint noises or “snapping” of the shoulder.

Causes: How does (chronic) shoulder pain occur?

If a patient with shoulder pain has nothing to report about an obvious shoulder injury, there are essentially two options:

Either the problem lies directly in the shoulder. Then the point where the pain is mainly felt and the movements that trigger it can provide further clues. By far the most common causes of (chronic) shoulder pain are problems with the so-called rotator cuff. Pain in the front and side of the shoulder, which increases when the arm is raised upwards and when lying on the affected shoulder (night pain), are possible indicators.  Or: A pain that can be localized at the outer end of the collarbone is an indication of damage to the shoulder joint.

That means: If it comes to a problem on the shoulder, it is important to find out which part is affected.

From overload to wear

Shoulder pain plagues many people. The basic pattern: chronic overload and muscle imbalances. “Overhead workers”, for example painters, or “overhead athletes”, such as handball, volleyball and tennis players, are particularly affected. But even well-established movements using the shoulder, arm and hand in production or in the operating theater can lead to shoulder problems over time.

Overloading the movement system creates roughness, fibrillation and sometimes spurs at critical points. A bottleneck syndrome (impingement) can develop. That means: A shoulder, in which the inner sliding no longer works smoothly, is exposed to a constant state of irritation. Then it will not be long before, in addition to pain, there may also be greater damage (or vice versa).

This mainly affects the so-called soft tissue such as tendons and bursa around the main joint of the shoulder and under the shoulder roof. Specifically, it is about tears and adhesions, shrinkage of the joint capsule, possibly a stiff shoulder.

Wear and tear on the joints resulting in osteoarthritis occurs less frequently on the shoulder than, for example, on the knee or hip joint. Sometimes it affects the joint on the sternum, or the corner joint at the outer end of the collarbone: Arthrosis can develop here as a result of injuries such as a split shoulder or rheumatism.

If the head of the humerus is damaged, for example by a defective rotator cuff, then osteoarthritis is also possible in the main shoulder joint over time.

The other possibility: There is a disease outside of the shoulder in which the pain “only” radiates towards the shoulder. Most of the time, other symptoms come to the fore, for example shortness of breath or abdominal pain. The doctor will immediately rule out potentially dangerous diseases in the chest or abdomen in order to then investigate the causes of the shoulder pain further.

First painful, then stiff shoulder: the mysterious Frozen shoulder

“Frozen shoulder”  is a clinical picture in which the shoulder starts to hurt for an unclear cause and then stiffens. Active and passive movements are clearly restricted. This also makes a restful sleep more difficult, which everyday life often suffers from. Months can pass before the whole thing begins to resolve itself again.

Sometimes a certain lack of movement remains, but consistent exercise makes the shoulder much more flexible again. Certain diseases sometimes coexist with a frozen shoulder. These include diabetes, lipid metabolism disorders, thyroid diseases and diseases that can lead to movement disorders or paralysis such as Parkinson’s disease or a stroke.

Starting point cervical spine?

Tension in the neck muscles due to drafts, poor posture and misalignments of the spine are often painful. Initially, the symptoms usually focus on the starting point, i.e. the neck. If things don’t go well, they can expand and radiate over the shoulder and into the arm. Many people believe they have a shoulder problem. The actual causes, however, are usually dysfunction of the neck and back muscles. Doctors speak of pseudoradicular pain when the nerve roots (lat. Radix, derived from radicular) on the spinal canal are not affected.

If the symptoms do not improve or worsen within a few weeks, the doctor will review the findings. Depending on the evidence, different diagnoses should be considered, starting with wear and tear on the cervical spine. For example, although a herniated disc is rare, it cannot always be ruled out. Warning signs in this direction can include sensory disturbances such as tingling or numbness and a loss of strength in the arm, hand or individual fingers. Then quick action is called for.

Inflammation, nerve damage & Co.

One of the more rare triggers of shoulder pain is bacterial inflammation of the shoulder joint. Gout and rheumatic diseases, for example in the form of polymyalgia rheumatica, can also affect the shoulder (s). This leads to muscle pain and stiffness due to inflamed vessels. In addition, bursitis occurs on the shoulder. It is not uncommon for muscles in the pelvic girdle to also hurt. Sometimes those affected still suffer from general complaints such as fever, fatigue, weight loss and night sweats. Some of those affected also have vascular inflammation in the head area, which can lead to headache in the temples, pain when chewing and visual disturbances.

Sometimes nerve damage to the shoulder occurs. The over-shoulder blade or suprascapular nerve, for example, supplies the shoulder bone muscles. Constant pulling or pressure on the nerves can lead to muscle atrophy in the shoulder, which limits its range of action. For example, volleyball and basketball players are more often affected.

Occasionally, a bulge (cyst) in the joint capsule or tendon sheath constricts the nerve. The symptoms are similar to the aforementioned bottleneck or impingement syndrome.

The fact that shoulder pain is caused by a malignant lump in the bone or soft tissue of the shoulder or at the tip of the lung is also an exception. Likewise, the possibility that a tumor presses a nerve, for example in the so-called arm plexus. This is the plexus of nerves for the shoulder, arm and chest; the nerve fibers run from the cervical spine under the collarbone to the armpit and further into the arm.

These nerve tracts can also be damaged in so-called thoracic outlet syndrome. This involves obstacles in the triangle between the cervical spine, muscles, first rib and back of the collarbone. The arm nerve plexus running along here can be cornered, for example, by bone or ligament parts. The main complaints are sensory disorders such as numbness and muscle weakness in the arm or hand, especially when moving the arm overhead or doing computer work. The arm vessels take the same route.

If a venous vessel is mainly squeezed in, symptoms such as pain, swelling and changes in the color of the skin (purple color) occur. If an arterial vessel becomes narrowed and closes (thrombosis), it can lead to a circulatory disorder in the hand. In the event of signs such as feeling cold, pain, paleness, numbness in the hand, see a doctor as soon as possible!

Circulatory disorders with damage to the bones (osteonecrosis) rarely lead to shoulder pain.

Disorders of the shape of the shoulder due to the shape of the body can be associated with visible malpositions and a tendency to dislocations (dislocations).

Acute pain events radiating to the shoulder

Acute chest pain caused by internal illnesses, such as a heart attack, often radiates into the left shoulder and left arm. It can, but does not have to be preceded by repeated chest pain, which those affected often, but not necessarily, feel on the left side of the shoulder or arm. Alert the emergency doctor or the emergency services in the event of warning signs such as acute chest pain, tightness, shortness of breath, weakness, cold sweat, nausea.

Acute gallbladder diseases, such as colic, occur primarily in the right upper abdomen, but the associated abdominal pain can radiate into the right shoulder.

A very rare occurrence is a rupture of the spleen, i.e. a tear in the capsule and tissue. This can happen spontaneously or as a result of a push or pressure on the abdomen if the spleen is abnormally swollen, otherwise, for example, as a result of an accident injury. The pain associated with a tear is concentrated on the left upper abdomen and the left flank of the body. If necessary, they also radiate into the left shoulder. Because of the risk of heavy bleeding into the abdominal cavity, there is a high risk of shock.

In Summery, we really need to take care with our shoulders and strengthen mobility. Just for fun try to imagine the below-described positions. This is a great understanding of where you should be as far as having healthy shoulder function.

A few numerical examples:

• In the horizontal position, we can move the arm away to about 180 degrees,
• In front we can also get quite far, up to about 40 degrees to the opposite side.
• We have around 90 degrees of leeway when turning the shoulder inward when the arm is against the body.
• We extend the arm up to about 180 degrees, backwards to about 40 degrees.

As a veteran naturopath specializing in gut health, this is usually the place in my articles where I associate the health topic with colon hydrotherapy and suggest that getting regular colonics will be of help. But in this case, I just have to go back to the general lifestyle advice of doing regular excercise, as it is a clear matter of use it or lose it. Of course as with everything moderation is the key. Don’t overdo it and start slowly to strengthen your muscles and increase the range of motion.

Colon hydrotherapy can not help with your shoulder pain, but it can strengthen your immune system to fight any inflammation.