The shoulder is the most flexible joint in the body enabling a wide range of movements including, forward flexion, abduction, adduction, external rotation, internal rotation, and 360-degree circumduction.
Thus, the shoulder joint is considered the most insecure joint of the body but the support of ligaments, muscles and tendons function to provide the required stability.
Bones of the Shoulder
The shoulder is a ball and socket joint made up of three bones, namely the humerus, scapula and clavicle.
The end of the humerus or upper arm bone forms the ball of the shoulder joint. An irregular shallow cavity in the scapula called the glenoid cavity forms the socket for the head of the humerus to fit in. The two bones together form the glenohumeral joint, which is the main joint of the shoulder.
The scapula is a flat triangular-shaped bone that forms the shoulder blade. It serves as the site of attachment for most of the muscles that provide movement and stability to the joint. The scapula has four bony processes - acromion, spine, coracoid and glenoid cavity. The acromion and coracoid process serve as places for attachment of the ligaments and tendons.
The clavicle bone or collarbone is an S-shaped bone that connects the scapula to the sternum or breastbone. It forms two joints: the acromioclavicular joint, where it articulates with the acromion process of the scapula, and the sternoclavicular joint where it articulates with the sternum or breast bone. The clavicle also forms a protective covering for important nerves and blood vessels that pass under it from the spine to the arms.
Soft Tissues of the Shoulder
The ends of all articulating bones are covered by smooth tissue called articular cartilage which allows the bones to slide over each other without friction enabling smooth movement. Articular cartilage reduces pressure and acts as a shock absorber during movement of the shoulder bones.
Extra stability to the glenohumeral joint is provided by the glenoid labrum, a ring of fibrous cartilage that surrounds the glenoid cavity. The glenoid labrum increases the depth and surface area of the glenoid cavity to provide a more secure fit for the half-spherical head of the humerus.
Ligaments of the Shoulder
Ligaments are the thick strands of fibers that connect one bone to another. The ligaments of the shoulder joint include:
- Coraco-clavicular ligaments: These ligaments connect the collarbone to the shoulder blade at the coracoid process.
- Acromio-clavicular ligament: This connects the collarbone to the shoulder blade at the acromion process.
- Coraco-acromial ligament: It connects the acromion process to the coracoid process.
- Glenohumeral ligaments: A group of 3 ligaments that form a capsule around the shoulder joint, and connect the head of the arm bone to the glenoid cavity of the shoulder blade. The capsule forms a water-tight sac around the joint. Glenohumeral ligaments play a very important role in providing stability to the otherwise unstable shoulder joint by preventing dislocation.
Muscles of the Shoulder
The rotator cuff is the main group of muscles in the shoulder joint and is comprised of 4 muscles. The rotator cuff forms a sleeve around the humeral head and glenoid cavity, providing additional stability to the shoulder joint while enabling a wide range of mobility.
The deltoid muscle forms the outer layer of the rotator cuff and is the largest and strongest muscle of the shoulder joint.
Tendons of the Shoulder
Tendons are strong tissues that join muscle to bone allowing the muscle to control the movement of the bone or joint. Two important groups of tendons in the shoulder joint are the biceps tendons and rotator cuff tendons.
Bicep tendons are the two tendons that join the bicep muscle of the upper arm to the shoulder. They are referred to as the long head and short head of the bicep.
Rotator cuff tendons are a group of four tendons that join the head of the humerus to the deeper muscles of the rotator cuff. These tendons provide more stability and mobility to the shoulder joint.
Nerves of the Shoulder
Nerves carry messages from the brain to muscles to direct movement (motor nerves) and send information about different sensations such as touch, temperature and pain from the muscles back to the brain (sensory nerves). The nerves of the arm pass through the shoulder joint from the neck.
These nerves form a bundle at the region of the shoulder called the brachial plexus. The main nerves of the brachial plexus are the musculocutaneous, axillary, radial, ulnar and median nerves.
Blood vessels of the Shoulder
Blood vessels travel along with the nerves to supply blood to the arms. Oxygenated blood is supplied to the shoulder region by the subclavian artery that runs below the collarbone. As it enters the region of the armpit, it is called the axillary artery and further down the arm, it is called the brachial artery. The main veins carrying de-oxygenated blood back to the heart for purification include:
- Axillary vein: this vein drains into the subclavian vein
- Cephalic vein: this vein is found in the upper arm and branches at the elbow into the forearm region. It drains into the axillary vein.
- Basilic vein: this vein runs opposite the cephalic vein, near the triceps muscle. It drains into the axillary vein.
- Shoulder Pain
Pain in the shoulder suggests a shoulder injury which is more common in athletes participating in sports such as swimming, tennis, pitching and weightlifting. The injuries are caused due to the over usage or repetitive motion of the arms.Know More
- Shoulder Arthritis
The term arthritis literally means inflammation of a joint but is generally used to describe any condition in which there is damage to the cartilage. Damage of the cartilage in the shoulder joint causes shoulder arthritis.Know More
- SLAP Tears
- Shoulder Fracture
A break in a bone that makes up the shoulder joint is called a shoulder fracture.Know More
- Shoulder Dislocation
Playing more overhead sports and repeated use of the shoulder at the workplace may lead to sliding of the upper arm bone, the ball portion, from the glenoid–the socket portion of the shoulder. The dislocation might be a partial dislocation (subluxation) or a complete dislocation causing pain and shoulder joint instability.Know More
- Rotator Cuff Tear
- Massive Irreparable Rotator Cuff Tear
Massive rotator cuff tears involve tears in two complete tendons of the rotator cuff. A tear of more than 5 cm is described as massive. A massive tear may be associated with degeneration and retraction of the tendon and can be difficult to repair if treatment is delayed.Know More
- Shoulder Labrum Tear
Traumatic injury to the shoulder or overuse of shoulder (throwing, weightlifting) may cause labral tear. In addition, ageing may weaken the labrum leading to injury.Know More
- Biceps Tendon Rupture
- Shoulder Impingement
Shoulder impingement is the condition of inflammation of the tendons of the shoulder joint. It is one of the most common causes of pain in the adult shoulder.Know More
- Shoulder Trauma
Shoulder injuries most commonly occur in athletes participating in sports such as swimming, tennis, pitching and weightlifting. The injuries are caused due to the over usage or repetitive motion of the arms.Know More
- Thrower's Shoulder
Throwing injuries of the shoulder are injuries sustained as a result of trauma by athletes during sports activities that involve repetitive overhand motions of the arm as in baseball, American football, volleyball, rugby, tennis, track and field events, etc.Know More
- Shoulder Arthroscopy
- SLAP Repair
- Total Shoulder Replacement
- Shoulder Labrum Reconstruction
The labrum is a ring of fibrous cartilage surrounding the glenoid, which helps in stabilizing the shoulder joint. The biceps tendon is attached inside the shoulder joint at the superior labrum of the joint.Know More
- Rotator Cuff Repair
Surgery to repair the rotator cuff has traditionally been done through a large shoulder incision, about 6-10cm long, and the muscle over the rotator cuff was separated. Newer, advanced surgical techniques have been developed to minimize pain and recovery time.Know More
- Shoulder Instability Repair: Shoulder Stabilization
Shoulder instability is a chronic condition that causes frequent dislocations of the shoulder joint. A dislocation occurs when the end of the humerus (the ball portion) partially or completely dislocates from the glenoid (the socket portion) of the shoulder.Know More
- Shoulder Reconstruction Surgery
During surgery, your surgeon examines the labrum and the biceps tendon. If the damage is confined to the labrum without involving the tendon, then the torn flap of the labrum will be removed. In cases where the tendon is also involved or if there is detachment of the tendon, absorbable wires or sutures will be used to repair and reattach the tendon.Know More
- Reverse Shoulder Replacement
- Bankart Repair
Arthroscopic Bankart repair is a minimally invasive surgical procedure performed to reattach and tighten the detached labrum within the shoulder joint.Know More
- Latarjet Procedure
The Latarjet procedure is a surgical procedure performed to treat shoulder instability by relocating a piece of bone with an attached tendon to the shoulder joint.Know More
- Superior Capsular Reconstruction
Superior capsular reconstruction is a surgical procedure performed to restore shoulder stability in irreparable rotator cuff tears. A fall on an outstretched arm, repetitive stress, abnormal bone growth or a sudden jerk while lifting a heavy object can cause the rotator cuff to tear.Know More
- Latissimus Dorsi Tendon Transfer
Coming SoonKnow More
- Lower Trapezius Tendon Transfer
Coming SoonKnow More