SHOULDER JOINT INTRODUCTION (SHOULDER JOINT COMPLEX BIOMECHANICS)Physiotherapy Tutorials

Summary

In this video, Adeb from Movement Science introduces the anatomy and biomechanics of the shoulder joint complex. He covers the four main bones involved—the sternum, clavicle, scapula, and humerus—and their articulations at the sternoclavicular, acromioclavicular, and glenohumeral joints. Adeb also discusses false joints like the scapulothoracic and suprahumeral joints. The video explains key shoulder movements such as flexion, extension, abduction, and rotation. The importance of scapulohumeral rhythm and muscle stability to prevent injuries is highlighted. The video concludes with a promise of more detailed discussions on each joint and injury prevention strategies.

Takeaways

• 😀 The shoulder joint complex consists of four bones: the sternum, clavicle, scapula, and humerus.
• 😀 The first joint in the shoulder complex is the sternoclavicular (SC) joint, connecting the sternum and clavicle.
• 😀 The second joint is the acromioclavicular (AC) joint, where the acromion process of the scapula articulates with the clavicle.
• 😀 The third joint is the glenohumeral (GH) joint, a ball-and-socket joint where the humerus articulates with the glenoid fossa of the scapula.
• 😀 Apart from the true joints, there are two false joints: the scapulothoracic joint and the suprahumeral joint.
• 😀 The scapulothoracic joint is formed by the movement of the scapula on the ribcage, and the suprahumeral joint exists above the humerus, but it’s not a true articulation.
• 😀 Common pathology tests for the AC joint include the cross-adduction test, where pain occurs at the AC joint during the movement.
• 😀 The shoulder joint complex allows various movements such as 180° flexion, 60° extension, 180° abduction, adduction, and 90° internal and external rotation.
• 😀 The glenohumeral joint contributes two-thirds of the shoulder's total mobility, with the scapulothoracic joint assisting in the other third.
• 😀 The scapulohumeral rhythm describes the coordinated movement between the scapula and the humerus during shoulder motion, which is essential for stability and smooth function.

Q & A

What are the four bones present in the shoulder joint complex?

The four bones present in the shoulder joint complex are the sternum, clavicle, scapula, and humerus.

What joint does the sternum and clavicle form?

The sternum and clavicle form the sternoclavicular joint (SC joint), which connects the upper limb to the axial skeleton.

What are the parts of the sternum?

The parts of the sternum are the manubrium, body (sternite), and the xiphoid process.

What is the acromioclavicular joint, and where is it located?

The acromioclavicular (AC) joint is formed where the acromion process of the scapula articulates with the lateral end of the clavicle.

What is the glenohumeral joint?

The glenohumeral joint is a ball-and-socket joint formed between the humerus and the glenoid fossa of the scapula, allowing a wide range of shoulder movements.

What are the two false joints in the shoulder joint complex?

The two false joints in the shoulder joint complex are the scapulothoracic joint and the suprahumeral joint.

How is the scapulothoracic joint different from true joints?

The scapulothoracic joint is not a true anatomical joint, as the scapula moves on the thorax (ribcage), not forming a typical joint with bone-to-bone articulation.

What are the primary movements that occur at the shoulder joint?

The primary movements at the shoulder joint include flexion, extension, abduction, adduction, internal rotation, and external rotation.

What is scapulohumeral rhythm?

Scapulohumeral rhythm refers to the coordinated movement between the scapula and humerus, where the scapula moves along with the humerus to ensure smooth shoulder joint motion.

What contributes to the stability of the shoulder joint?

The stability of the shoulder joint is provided by both active (muscles) and passive (ligaments) structures. Weakness in these structures can lead to shoulder injuries such as labrum tears, rotator cuff tears, and biceps tendon injuries.