The Shoulder

How the shoulder works!

The shoulder is made up of three bones: the scapula (shoulder blade), the humerus (upper arm bone), and the clavicle (collarbone).

The rotator cuff connects the humerus to the scapula. The rotator cuff is formed by the tendons of four muscles: the supraspinatus, infraspinatus, teres minor, and subscapularis.

Tendons attach muscles to bones. Muscles move the bones by pulling on the tendons. The rotator cuff helps raise and rotate the arm.

As the arm is raised, the rotator cuff also keeps the humerus tightly in the socket of the scapula. The upper part of the scapula that makes up the roof of the shoulder is called the acromion.

A bursa is located between the acromion and the rotator cuff tendons. A bursa is a lubricated sac of tissue that cuts down on the friction between two moving parts. Bursae are located all over the body where tissues must rub against each other. In this case, the bursa protects the acromion and the rotator cuff from grinding against each other.

In order to know if you have injured your rotator cuff you should have it examined by a Doctor of Chiropractic. They will ask questions about your medical history, your injury, and your pain. Then they will perform a physical examination of the shoulder. The physical exam is most helpful in diagnosing a rotator cuff tear. A complete tear is usually very obvious. 

X-rays won't show tears in the rotator cuff. However, the Doctor of Chiropractic may want you to have a shoulder X-ray to see if there are bone spurs, a loss of joint space in the shoulder, or a down-sloping (hooked) acromion. These findings are associated with tears in the rotator cuff. An X-ray can also show if there are calcium deposits in the tendon that are causing your symptoms, a condition called calcific tendonitis. Further studies may include: an ultrasound and/or an MRI.

The shoulder is a joint than can be treated with a combination of many different treatments.  The treatment types are dependent on the injury.  These can include – the Interferential current machine, acupuncture, massage therapy, active release, and chiropractic to restore the joint motion, stretching, strengthening, and modifications to activities.

The shoulder joint is very complex and works with the shoulder blade, neck and upper back to co-ordinate movements.

The rotator cuff is made up of four muscles that ‘cuff’ the shoulder.  These muscles can be injured due to different factors.

 The shoulder
• A complex structure:  3 Bones, 3 Joints which attach it to the mid back and arm, 5 Ligaments, over 30 Muscles, 4 Bursa, 3 capsules.
• 75% of North Americans will experience shoulder problems requiring care at some point.
• The shoulder joint comprises the part of the body where the humerus attaches to the scapula.  The shoulder refers to the group of structures in the region of the joint.

The shoulder joint is made up of 3 bones: Collarbone (clavicle), Shoulder blade (scapula), Upper arm bone (humerus) 

• The bones of the shoulder are held in place by: muscles, ligaments, and tendons.
• Ligaments attach shoulder bones to each other, providing the main stability for the shoulder. The front of the joint capsule is anchored by three glenohumeral ligaments. 
• Tendons are tough cords of tissue that attach the shoulder muscles to bone and assist the muscles in moving the shoulder.
• There are 30 muscles providing movement and support for the shoulder complex. 
• The muscles that are responsible for movement in the shoulder attach to the scapula, humerus, and clavicle. The muscles that surround the shoulder form the shoulder cap and the underarm. 
• The capsule is a watertight sac (soft tissue envelope) that encircles the glenohumeral joint. It is lined by a thin, smooth synovial membrane. 
• Three main nerves begin together at the shoulder: the median nerve, the ulnar nerve, and the radial nerve. These nerves run under the collarbone and are known as the Brachial Plexus before they divide.
• The shoulder movement occurs as a result of all these structures and from the use of the ribs, thoracic spine, neck and even the elbow.  Often unresolved shoulder problems are a result of the other areas involved not being treated.   

Scapular-thoracic motion

• Scapular activity during shoulder motion is critical for normal shoulder function – shoulder moves 2/3 of the movement and the scapula the other 1/3 motion. 
• The scapulo-thoracic motion is the movement between the scapula (shoulder blade) and the thoracic spine. 
• The scapula moves with the shoulder in many daily and athletic activities. Anytime you raise your arm up this motion occurs!
• It is often over-looked in shoulder problems and that is one reason they do not resolve properly.