I- GENERAL :
The shoulder is a union segment that connects the upper limb to the trunk through the shoulder girdle. It includes a joint complex formed by five joints :
- Articulation scapulo-humérale.
- acromioclavicular joint.
- sternoclavicular joint costoclavicular.
- Inter-scapulothoracic joint (false joint).
- Articulation under deltoid (false joint)
II- ARTICULATION SCAPULO-HUMÉRALE :
1- Definition :
It is a diarthrosis variety of enarthrosis (spheroid). She unite the scapula to the humerus. This is a very mobile aiticulation but fragile.
2- The articular surfaces :
a- The glenoid cavity of the scapula :
Of oval form. It is located at the upper-lateral angle of the scapula. It presents the central glenoid tubercle and the anterior edge T glenoid notch (glenoid notch). It is surrounded on its peripheral edge by the glenoid rim.
b- The humeral head :
It occupies the proximal humeral epiphysis. Rounded, representing the 1/3 a sphere of 30 mm. Its surface is covered with a coating of cartilage. Its axis forms with that of the shaft at an angle of 130 °.
c- The labrum glenoid (glenoid labrum :
It is a fibrocartilaginous ring applied around the periphery of the glenoid cavity and for increasing the depth of the cavity. Seen in section, it is triangular, so we can recognize him three faces : peripheral, external or articular, and adherent internal.
*The peripheral face extends outside the surface of the neck of the scapula.
*The outer face or articular, free, smooth and concave, is part of the glenoid articulating surface. *The inner face or adherent is in close connection with the periphery of the glenoid cavity.
3- The means of union :
a- The joint capsule :
It is a thin fibrous sleeve of great looseness allowing a spacing of the articular surfaces of 2 at 3 cm Extended. 11 fits a graze, on the peripheral face of the glenoid labrum (glenoid labrum) and other =, the anatomical neck of the humerus.
b- Passive ligaments :
1- Le ligament coraco-huméral :
This is the strongest ligament. 11 born on the side edge of the coracoid process. 11 ends with two beams: one on the greater tuberosity (trochiter), and the other on the lesser tubercle (Trochin) humeral.
2- Glenohumeral ligaments :
Three in number: the glenohumeral ligaments higher, middle and lower.
*The superior glenohumeral ligament
Is born on the glenoid rim and the upper part of the neck of the sacpula and ends on the top of the lesser tuberosity (Trochin) humeral.
*The glenohumeral ligament means
It comes ahead of the previous and ends on the bottom of the lesser tubercle (Trochin) humeral.
*The ligament inferior glenohumeral
He was born on the glenoid rim and the neck of the sacpula and ends under the surgical neck of the humerus.
NB / These three ligaments between them delimit two spaces :
*Le foramen ovale the Weitbrecht : ente the glenohumeral ligaments upper and middle.
*The foramen Rouviere : ente glenohumeral ligaments middle and lower.
3- Le ligament coraco-glénoidien :
It is the deep beam ligament coracohumeral. It is located in the posterior region of the joint. It is stretched from the posterior part of the lateral edge of the coracoid process glenoid rim.
4- Assets ligaments :
These are the periarticular muscles and tendons mobilizers Y joint glenohumeral, these are the muscles :
Supraspinatus (supraspinatus), infraspinatus (infraspinatus), the subscapularis (subscapularis), the small round, teres, the pectoralis, latissimus dorsi, the deltoid and coracobrachialis.
5- the synoviale :
It lines the deep surface of the capsule to its insertions, where it is reflected to extend to the coating cartilaginous articular surfaces.
Synovial fluid produced by the synovial membrane allows the lubrication and nutrition, articular cartilage. The synovium is raised at the level of the neck of the humerus by the capsular brakes (frenules capsules).
6- Scholarships serous periarticular :
There are a number of bursa between the capsule and the periarticular muscles whose role is to facilitate the sliding, the most important are :
- The subscapularis bursa.
- The bicipital bursa.
- The bursa subdeltoid.
- The sub-coracoid bursa.
- The bursa of infraspinatus muscle.
III- JOINT PHYSIOLOGY :
The glenohumeral joint is fragile but very mobile, having three degrees of freedom according to the 3 plans and movements 3 axes :
In the frontal plane. Around the anteroposterior axis
* The supply : It bears the member inside, l’pure adduction is not possible, associated with a reverse drive or ante-drive can wait 40 °.
*L’abduction : It bears the member outside, the amplitude 90 without the participation of the scapulothoracic ailicuiation, it can reach 180 ° with the participation of the latter.
In the sagittal plane. Around transverse tax :
*Fante-bending drive) : It projects the member forward, the magnitude 50-80 ° without the participation of scapulothoracic articulation can reach 180 ° with the participation of the latter. *Extension (retro-pulsion): It projects the member rearwardly never exceeds 30 ° up to 40 ° as a result of abduction and the posterior sliding of the scapula.
In the horizontal plane. About a vertical axis
The forearm is flexed to 90 ° to eliminate pronosupination:
Lateral rotation (external): is limited to 30 ° amplitude,
The medial rotation (internal): is limited to 80 ° anterior flexion of the shoulder blade the full 90 °. La circumduction
It encompasses all types of movements and describes a summit cone through the center of the humeral head.
Course of Pr Hayette BELHOULA-DJEROUA – Faculty of Constantine