Final answer:
The 'upper 2/3 of the lateral border of the scapula' refers to an area on the edge of the scapula (shoulder blade) that harbors important anatomical features such as the glenoid cavity, which forms part of the shoulder joint, and the supraglenoid and infraglenoid tubercle, which are attachment sites for arm muscles.
Step-by-step explanation:
The scapula, also known as the shoulder blade, is a flat, triangular-shaped bone that lies on the posterior aspect of the shoulder. It has three borders: the superior border, medial border, and the lateral border. The reference to the 'upper 2/3 of the lateral border of the scapula' in your question pertains to the upper two-thirds section of the lateral edge of this bone.
Several important anatomical landmarks are found here. For example, the glenoid cavity (or glenoid fossa) is located at the corner between the superior and lateral borders. This shallow depression articulates with the humerus bone of the arm to form the glenohumeral joint (shoulder joint).
Also, the small bony bumps located immediately above and below the glenoid cavity are the supraglenoid tubercle and the infraglenoid tubercle, respectively. These functions as attachment points for muscles of the arm. Therefore, the upper 2/3rd of the lateral border of the scapula is essential for shoulder and arm movements due to its function in muscle organization and joint formation.
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