Ortho 400: Shoulder

The joint where the humerus (upper arm bone) meets the scapula (shoulder blade) and clavicle (collarbone). It's responsible for positioning the arm in space for hand function.

The rotational movement of the shoulder inward, toward the body.

The outward movement of the arm away from the body.

The inward movement of the arm towards the body.

The muscles surrounding the shoulder joint, responsible for its movement and stability.

A strong band of tissue that connects bones, providing stability and limiting excessive movement.

Ligament that helps stabilize the shoulder joint, positioned between the coracoid process and the humerus.

Ligament connecting the scapula and clavicle, important for shoulder stability.

A fluid-filled sac that reduces friction between tendons and bones, located beneath the acromion process.

A specialized mechanism that allows for coordinated movement of the scapula (shoulder blade) and thorax (rib cage).

A series of joints that work together to produce a movement. For example, the scapulothoracic, sternoclavicular, and acromioclavicular joints work together to allow for arm elevation.

Movement of a bone around a fixed axis.

Movement of one joint surface on another.

A type of arthrokinematic movement where one joint surface rolls over another.

A type of arthrokinematic movement where one joint surface slides across another.

A type of arthrokinematic movement where one joint surface spins on another.

A rule that states that the direction of slide/glide is opposite to the direction of osteokinematic movement when a concave surface moves on a convex surface.

A rule that states that the direction of slide/glide is the same as the direction of osteokinematic movement when a convex surface moves on a concave surface.

A movement of the arm in a plane that is 20 degrees anterior to the frontal plane.

A movement of the arm in the frontal plane, similar to shoulder abduction but with a more controlled scapular movement.

The glenoid fossa (shallow socket on the scapula) is shallow, meaning that the humeral head (top of the arm bone) can easily move out of the glenoid fossa. The rotator cuff muscles provide active stability to counteract this. This means they actively control the joint to prevent instability.

The rotator cuff muscles help rotate the shoulder both internally and externally. They control movement and prevent the greater tubercle (part of the humerus) from colliding with the acromion (part of the scapula).

A condition where the scapula rotates forwards, due to weak scapular muscles, leading to poor shoulder stability and potential for impingement of the tendons. The scapula may move into a position similar to thoracic kyphosis (a forward curvature of the upper back).

A condition where the humerus is positioned outside of the glenoid fossa, due to weak or imbalanced muscles. This causes a loss of shoulder stability and potential for impingement.

A condition where either the superior capsule or the coracoacromial ligaments become loose due to muscle imbalance. This leads to a decrease in passive stability, meaning the shoulder is more prone to instability.

A condition where the scapula rotates forward due to muscle weakness or imbalance. This causes a loss of shoulder stability and potential for inferior dislocation or subluxation of the humerus.

A condition where the tendons of the rotator cuff muscles become compressed under the acromion, causing pain and inflammation. This can happen due to repetitive motion, poor posture, or injury.

The coordinated movement of the scapula and humerus during arm raising. It occurs in stages with different ratios of movement between the scapula and the humerus.

This is the initial stage of arm elevation, where the scapula is relatively stable. The humerus moves independently for the first 30 degrees of abduction.

This is the middle stage of arm elevation, where the scapula starts rotating. The humerus moves twice as much as the scapula (2:1 ratio). This controlled movement occurs between 30 and 90 degrees of abduction.

This is the final stage of arm elevation, where the scapula continues its movement with the humerus. The 2:1 ratio of movement between the scapula and humerus continues. The clavicle also elevates and rotates posteriorly.

The force couples of the shoulder are groups of muscles that work together to produce specific movements during arm elevation and rotation.

The trapezius and serratus anterior muscles create a force couple to help with the rotation of the scapula during arm elevation.

The long head of the biceps muscle helps to depress the head of the humerus during arm abduction and external rotation.

The movement of the clavicle (collarbone) occurs at the sternoclavicular (SC) and acromioclavicular (AC) joints, contributing to shoulder movement.

The movement of the axial skeleton, especially the thoracic spine, influences scapular movement and therefore shoulder function.

A disruption to the normal coordinated movement between the scapula and humerus during arm elevation, where the scapula moves more than the humerus.

A loss of normal scapulohumeral rhythm where the scapula moves too early and excessively to aid in arm elevation, resulting in poor movement efficiency. The scapula 'elevate's before the arm.

The clavicle's movement on the sternum (manubrium) at the sternoclavicular (SC) joint. The clavicle moving in this joint is similar to an apple core rotating.

The movement of the clavicle at the SC joint is a spin movement.

The scapula, clavicle, and humerus each contribute to total arm abduction.

The axial skeleton (spine, ribs, etc.) also plays a crucial role in achieving full arm elevation. This includes extension, side bending, and rotation of the upper T/S, and movement of the ribs and manubrium.

The humerus moving upward in relation to the scapula during abduction.

A 'sagging' or 'flattening' below the acromion process where a rounded deltoid muscle would be; indicates a shoulder dislocation or deltoid paralysis.

A condition where the medial border of the scapula moves away from the thorax, indicating serratus anterior injury, long thoracic nerve compromise, muscle imbalance, or strain to rhomboids or upper trapezius.

A condition where the medial border of the scapula is permanently away from the thorax, indicating structural issues like scapular, clavicle, spine, or rib deformities.

A condition where the superior or inferior angles of the scapula tilt away from the chest wall, indicating weakness and instability of the shoulder girdle.

A painful arc of motion during shoulder abduction, occurring between 60-120 degrees, due to impingement of inflamed structures under the acromial arch.

Passive stability refers to the structural support of the shoulder joint provided by ligaments, tendons, and the bony anatomy. It's like a sturdy frame that helps hold things together.

Active stability is achieved through the coordinated contraction of muscles surrounding the shoulder joint. These muscles act like stabilizers to control movement and prevent injury.

Compromised stability occurs when either the passive or active mechanisms are compromised. This can be due to faulty mechanics, muscle fatigue, or injury.

Pain in the front of the arm, may indicate bicipital tendonitis, an irritation of the biceps tendon.

Pain in the side of the arm, may indicate supraspinatus tendonitis, bursitis, or adhesive capsulitis.

Pain in the top and back of the shoulder may indicate an AC sprain, an injury to the acromioclavicular joint.

A strain is an injury to a muscle or tendon, the tissue that connects muscles to bones. They are graded according to severity of muscle tissue damage.

Inflammation of tendons due to overuse, primarily affecting the SITS muscles and biceps brachii.

The Supraspinatus tendon, vital for shoulder stability, experiences constant strain due to repetitive movements and poor blood supply, leading to degenerative changes and pain.

Inflammation of the biceps tendon in the bicipital groove, often caused by compression and repetitive movements.

A later stage of rotator cuff tendonitis, characterized by calcium deposits forming in the tendon, leading to pain and potential impingement.

The condition occurs when there is degeneration, inflammation, and pain in the tendons of the rotator cuff muscles, often caused by repetitive overhead movements.

The biceps tendon is compressed in the bicipital groove, causing inflammation and potentially leading to a rupture with continued overuse.

A condition where the joint capsule surrounding the shoulder becomes inflamed and stiff, causing pain and restricted movement.

The stage of adhesive capsulitis characterized by gradual onset of pain, especially at night, with difficulty sleeping on the affected side.

A contributing factor to adhesive capsulitis where pain causes the arm to be unused, leading to muscle weakness and joint stiffness.

The initial area of adhesion in adhesive capsulitis, located between the subscapularis and biceps tendons.

A type of adhesive capsulitis caused by factors like underlying medical conditions or previous injuries, rather than an unknown cause.

Tendinitis or tenosynovitis describes inflammation or irritation of a tendon. It can be caused by overuse, injury, or repetitive motions.

A test that involves manually resisting a muscle's contraction to assess its strength, indicating potential tendinopathy.

A test that involves actively moving a joint through its range of motion to test for pain or limitations, suggesting potential tendon injury.

Pain referred to the front of the upper arm, usually caused by inflammation of the biceps tendon.

Pain referred to the side of the upper arm, often associated with inflammation of the supraspinatus tendon or subacromial bursitis.

Pain or tenderness felt when applying pressure to a tendon, a sign of potential inflammation or injury.

An inflammation of a bursa, a fluid-filled sac that cushions tendons and bones, often caused by overuse or injury.

The subacromial bursa, located under the acromion bone and over the supraspinatus tendon, is prone to inflammation due to its location.

The subscapular bursa, situated over the anterior joint capsule and under the subscapularis tendon, can also be affected by inflammation.

Painful arc, Empty Can, Neer Impingement, Hawkins-Kennedy tests are used to assess shoulder impingement.

The space formed by the coracoid process, coracoacromial ligament, and acromion, which can compress the rotator cuff tendons, including the supraspinatus, and the biceps tendon.

The theory that poor scapular coordination and movement contribute to impingement syndrome by altering the position of the humeral head.

The first stage of impingement syndrome characterized by reversible inflammation and pain, mostly affecting the supraspinatus tendon.

The second stage of impingement syndrome marked by persistent tendonitis and bursitis, fibrosis, and recurrent inflammation.

The third stage of impingement syndrome, usually requiring surgery, characterized by bone spur formation, tendon tears, and significant pain.

The weakening or dysfunction of the muscles that control the shoulder blade, leading to poor shoulder movement and stability, contributing to impingement syndrome.

The decreased ability of ligaments and tissues to support and stabilize the shoulder joint, making it more susceptible to impingement.

The inability of the humerus to rotate outwards properly, leading to increased pressure on the rotator cuff tendons and potential for impingement.