What is a Ball and Socket Joint?
The ball and socket joint is composed of two parts of bone structure. It is a synovial joint, which is the most flexible joint. The end of the movable bone is spherical, and it can be inserted into the groove of the fixed bone. The bone can rotate and face in all directions. Turn.
- Chinese name
- Ball and socket joint
- Foreign name
- Ball-and-socket joint
- The ball and socket joint is composed of two parts of bone structure. It is a synovial joint, which is the most flexible joint. The end of the movable bone is spherical, and it can be inserted into the groove of the fixed bone. The bone can rotate and face in all directions. Turn.
Physiological significance of ball and socket joints
- The joint head is a part of the ball, and the shallow joint socket covers only a part of the joint head (less than 1/3 of the spherical surface). The joint head and the socket are loosely connected, and it is the most active multi-axis joint in the joint. The joint head can move around countless motion axes, can perform a variety of motions, and can perform flexion and extension, adduction and abduction, rotation and circular movement , Such as the shoulder joint.
Ball and socket joint ligament anatomy
- Consists of the glenoid and humeral head of the scapula. The size of the articular surfaces of the two connected bones differs greatly (the joint socket can only accommodate 1/4 to 1/3 of the joint head. There is a joint lip on the periphery of the joint socket to deepen the glenoid. The joint capsule is weak and loose, attached to the periphery of the glenoid and the humerus There is also a long biceps brachii tendon wrapped by the synovium between the neck and the joint capsule wall. This tendon strengthens the shoulder joint. The main ligaments of the shoulder joint are:
- 1. Coracohumerallig. From the coracoid to the nodule of the humerus, some fibers are fused with the articular capsule at the posterior upper part to strengthen the upper part of the joint capsule and prevent the humeral head from dislocating upward.
- 2. The glenohumeral lig. Is located in the anterior wall of the articular capsule, and can be divided into upper, middle and lower parts, from the anterior part of the glenoid to the small tuberosity of the humerus. Strengthen the anterior wall of the joint capsule.
- 3. Transverse humeral lig. Is the inherent ligament of the humerus. It crosses the nodular sulcus and fixes the biceps long head tendon to the nodular sulcus.
- The shoulder joint is a typical ball-and-socket joint that can move around three basic axes: flexion and extension about the frontal axis; adduction and abduction about the sagittal axis; internal rotation and external rotation about the vertical axis, and also a ring. turn. Because the shoulder joint is a multi-axis joint, the size of the articular surfaces of the connected bones varies greatly, the joint capsule is thin and loose, and the joint itself has fewer and weaker ligaments. Therefore, it is the most flexible joint in the human body, but it is also a joint with poor stability. . Regular physical exercise helps to strengthen the auxiliary structure of the joints and the surrounding muscles, making the joints flexible and strong.
Anatomy of the ball and socket joint shoulder
- The joint head consists of the humeral head of the humerus, and the joint socket consists of the glenoid of the scapula. Its labrum-lip device enlarges and deepens the joint socket, which belongs to the ball and socket joint. The limbs flexion and extension around the frontal (crown) axis of the joint, adduction and abduction around the sagittal axis of the joint, internal rotation and external rotation around the vertical axis of the joint, and circular movement around their intermediate axis. Devices for strengthening joints: glenohumeral ligament (located deep in the anterior wall of the joint capsule, from the anterior upper part of the glenoid to the small humerus nodule and its lower part), coracohumeral lig. Part of the fibers are woven into the upper part of the joint capsule), the transverse humerus ligament (horizontal in the nodular sulcus), the coracoacromial lig. Head tendon (located in the wall of the joint capsule, through the nodules through the nodular sulcus, and migrates into the long head of the biceps brachii and the coracoclavicular lig.).