The scapula (from the Greek ômoplatê, from ômos, “shoulder”) is a triangular bone located in the upper part of the thorax and which is involved in the shoulder joint.

The scapula, or scapula in the new nomenclature, is a bone in the upper and posterior part of the thorax. It is a flat triangular shaped bone present on either side of the body. It has three edges (superior, medial and lateral) and forms three angles (superior, inferior and lateral). Associated with the clavicle, it forms the shoulder girdle (or pectoral).

The scapula is marked in its upper part by four anatomical elements:

• The coracoid process, which emerges on the upper edge of the shoulder, participates in the fixation of certain muscles of the arm (eg: the biceps brachii muscle).
• The acromion which articulates on the side with the collarbone.
• The scapular spine, the point of attachment of certain muscles.
• The glenoid cavity, located in the lateral angle, articulates with the head of the humerus; they form the scapulo-humeral joint of the shoulder which allows movements whose amplitudes are extremely important.

Several muscles are inserted at the level of the scapula. Four muscles in particular, the subscapularis, the infraspinatus, the teres minor and the supraspinatus, which form the rotator cuff (set of muscles of the shoulder joint).

The scapula is also held in place by trunk muscles such as the serratus anterior muscle. The trapezoid also attaches itself to the level of its spine and participates in its movements and stabilization. The deltoid muscle and the biceps brachii muscle also find their insertion on the scapula.

The shoulder girdle, formed by the joint between the clavicle and the scapula, attaches the arms to the trunk and participates in the shoulder joint. Poorly maintained, the scapula is very free in the thorax which contributes to the flexibility of the shoulder girdle.

It is also an attachment point for many muscles and tendons of the arm, neck and thorax.

Fracture : scapular fractures are rare, they happen in the event of violent shocks. The fracture can affect several parts of the scapula or one in particular. Treatment is usually done by immobilization for several weeks. However, a glenoid cavity fracture requires surgery to restore the articular surface in contact with the humerus.

Scapulo-humeral dislocation : dislocation of the anterior shoulder joint, the head of the humerus comes out of the glenoid cavity. This dislocation is the most common of the shoulder dislocations (95%) 4. It occurs especially in athletes and the elderly following a fall on the hand or elbow or on the shoulder.

Acromioclavicular dislocation : dislocation of the joint which joins the clavicle to the acromion. Frequent pathology that usually occurs in sports accidents and traffic accidents.

Bursite scapulo-thoracique : inflammation of a bursa located between the scapula and the rib cage. This bursa is a pocket of synovial fluid that promotes bone movement and reduces bone friction. It rarely occurs on its own, it usually follows a trauma or is associated with a joint problem in the shoulder.

Wigging scapula (or “wigging scapula”) : corresponds to a detachment of the scapula. A deformity in the back is visible, especially when the patient pushes on the wall with his hands. This detachment occurs during the paralysis of the serratus anterior muscle which is generally related to an injury to the long thoracic nerve which innervates this muscle in its thoracic portion. The serratus anterior muscle can then no longer fulfill its initial role, which is to press the scapula against the thorax. Paralysis can occur in the event of compression or stretching of the nerve following repeated movement of the shoulder (sport or carrying heavy loads, for example).

Scapula to bounce (or “snapping scapula”) : rare and poorly understood cause of shoulder pain linked to a mechanical impingement responsible for bursitis between the scapula and the rib cage. The pathology results in audible and painful friction during arm movements. A scapula alata can be associated with the syndrome.

Supra-scapular nerve compression (or suprascapularis): the suprascapular nerve innervates two muscles of the rotator cuff, the supraspinatus (supraspinatus) and the infraspinatus (infraspinatus). The most frequent point of compression is at the level of the coracoid notch. The causes of compressions are multiple: fractures of the scapula or humerus, anterior dislocation, stretching or tumor of the nerve … More rarely, the compression can also be due to a cyst in the spino-glenoid notch (area where the nerve passes between the spine of the scapula and the superior glenoid).

Adhesive capsulitis : possible complication of rotator cuff tendinopathy if the latter is not well treated. It is the inflammation of the joint capsule, the fibrous and elastic envelope that surrounds the joint. Adhesive capsulitis occurs mostly when you avoid moving your arm too much.

Pathologies of the scapula mainly have traumatic causes which are difficult to prevent.

However, avoiding violent sports, repetitive shoulder movements or carrying heavy loads will help keep lesions away.

Clinical examination: carried out by the doctor, it initially includes the questioning (general, on the causes of the accident for example). It is followed by the physical examination of the scapula: visual assessment, verification of the positioning of the scapula, mobility assessment (movements in the different planes of space and the scapulo-humeral joint), instrumental measurement (measurement of distance between the tip of the scapula and the thoracic spine), tests (elevation of the arm, tilting, etc.).

Radiography: a medical imaging technique that uses X-rays. Standard reference examination, the frontal and lateral radiography of the scapula confirms the diagnosis of fracture or dislocation. It also makes it possible to check the condition of adjacent bone and joint structures.

MRI (magnetic resonance imaging): medical examination for diagnostic purposes carried out using a large cylindrical device in which a magnetic field and radio waves are produced. It can show a projection of the scapula (“snapping”) or a cyst responsible for the compression of the supascapular nerve for example.

Electromyogram: examination which allows to evaluate the functioning of the suprascapular and thoracic nerves long in the cases of compression.