Question

ball and socket joints disorder and its prevention

Answer 1

The shoulder joint is an enarthrosis (ball and socket joint) though its chief movement is as a ginglymus (flexion and extension). It is also a synsarcosis: its stability relies on the integrity of the surrounding musculature rather than intrinsic supporting ligaments.

The scapula has four centres of ossification:
1.
Body.
2.
Scapular cartilage.
3.
Tuber scapulae (supraglenoid tubercle) – fuses to body by 12–24 months.
4.
Cranial part of glenoid cavity – fuses to body by 5 months.

The proximal humerus has three centres of ossification:
1.
The diaphysis.
2.
The humeral head.
3.
The greater (lateral) tubercle.