Structure of the Shoulder

The shoulder structures comprise three bones, the scapula (shoulder blade), the humerus (upper arm) and the clavicle (collarbone). The shoulder is a ball and socket joint. The top of the humerus (ball) slides into the socket of the scapula (the glenoid). The scapula extends up and around the shoulder joint at the rear to form a roof, called the acromion, and the scapula at the front of the shoulder joint has a bony area that sticks out, called the coracoid process.
The true shoulder joint, the glenohumeral joint, comprises the humeral head and the glenoid of the scapular bone; whereas, the shoulder contains a second joint, called the acromioclavicular joint (ACJ) that links the clavicle with the acromion area of the scapula. The ACJ passes on forces through the upper limb and shoulder to the main part of our skeleton, but it possesses negligible mobility due to being limited by the ligaments. .
A cuff (bracelet-like) of cartilage, called the labrum, exists between the head of the humerus and the glenoid of the scapula. The cartilage provides a spongy cushion filled with gel-like fluid between the humerus and scapula. . The rotator cuff consists of a collection of muscles and tendons that encircle the shoulder, with the tendons conferring stability to the shoulder and the muscles permitting a broad range of motion like rotating. The rotator cuff provides stability to the shoulder joint that normally the ligaments supply. The muscles of the rotator cuff include the teres minor, infraspinatus, supraspinatus and the subscapularis. Each muscle of the rotator cuff inserts at the scapula and possesses a tendon (teres minor, infraspinatus, supraspinatus and the subscapularis) that attaches to the humerus. .
Three main ligament groups protect and surround the shoulder joint. The superior, middle and inferior
glenohumeral ligaments hold the shoulder in place and prevent it from dislocating. The coraco-acromial ligament links the coracoid to the acromion. The coraco-clavicular ligaments use two ligaments (trapezoid and conoid) to connect the clavicle coracoid process to the scapula. . The bursa, a small sac of liquid, takes care of protecting the tendons of the rotator cuff. Bursa functions as a gliding surface to reduce friction between the tissues in the joint. . Nerves travel down the arm under the shoulder joint through the axilla (armpit) in an area of nerves, called the Brachial Plexus, before splitting into individual nerves. These nerves signal the muscles to move or return messages to the brain about senses such as feeling cold or pain. .

Acute Conditions of the Shoulder

Shoulder bursitis means inflammation of the bursa in the shoulder joint. Injury (like lifting a grocery bag) or inflammation of the bursa causes the shoulder bursitis. Inflammation can occur from underlying rheumatic conditions. Common symptoms include shoulder pain, swelling, tenderness and pain. Your doctor will usually advise ice packs, rest and anti-inflammatory medication (like ibuprofen or celebrex).
Physical therapy aids in returning the shoulder joint to full function. Less frequently, your doctor will suggest aspiration of the bursa fluid, where the doctor uses a needle and syringe to remove fluid. Dislocation of the shoulder occurs easily from sudden jerks of the arm, especially in young children before muscle strength develops.
The shoulder joint dislocates more frequently than any other joint in the body.
The dislocation produces severe pain.
Closed reduction (a manipulation to return the joint to its socket) initially treat most dislocations using sedation medication without the need for surgery.
If closed reduction fails, surgical repair may be required. Frozen shoulder (adhesive capsulitis) develops from increasing inflammation, stiffness and pain of the shoulder that progresses to severely limiting the movement in the shoulder.
Two percent of the general population gets frozen shoulder; as a rule, people between the ages of 40 and 60 develop the condition.
No direct causes known, but a few factors associated with developing a frozen shoulder include diabetes, Parkinson’s disease, hypothyroidism, or protracted periods of immobilization.
Your doctor orders x-rays, ultrasound or MRIs to determine the problem. Non-surgical treatments consist of non-steroidal anti-inflammatory drugs (like ibuprofen or Celebrix), steroid injections, and physical therapy with specific stretching and range of motion.
If medication and physical therapy fails after a protracted time, your physician may discuss surgery. Tears of the rotator cuff tendons transpire from repetitive or sudden injury.
The supraspinatus tendon suffers the most from overuse and trauma out of the four tendons.
The injury occurs not infrequently in sports like baseball, football or tennis. Symptoms of a rotator cuff tear include pain, weakness in the shoulder and pain when trying to raise the arm overhead. Your physician will recommend rest, ice, over-the-counter pain medication and physical therapy for less severe injuries. Severe injuries may require surgery.

Chronic condition of the Shoulder

Severe shoulder arthritis occurs when the cartilage wears away in the shoulder joint. The chronic pain makes daily-life activities, like pulling clothes over your head, brushing your hair or reaching for a book off a top shelf, exceedingly tough to perform. When physical therapy and anti-inflammatory medications provide little relief for you, your surgeon may suggest shoulder replacement surgery.