Corpus: Shoulder

The shoulder is the dome-shaped area of the body that connects the arm to the trunk, forming part of the upper limb. It consists of the shoulder joint and the bony shoulder girdle.

The shoulder can be divided into four regions:

• Infraclavicular region (anterior shoulder region)
• Deltoid region (lateral shoulder region)
• Scapular region (posterior shoulder region)
• Axillary region (armpit region)

The shoulder is supported by a bony framework that includes the scapular spine, the acromion, and the clavicle. Its dome-like shape is primarily created by the muscles that pass over the joint, particularly the deltoid muscle. The contour extending toward the neck is defined by the trapezius muscle.

3.1. Joints

Shoulder movement involves a total of five joints, which are categorized into true joints and auxiliary (secondary) joints.

3.1.1. True joints

• Sternoclavicular joint
• Acromioclavicular joint
• Glenohumeral joint (the actual shoulder joint)

3.1.2. Auxiliary joints

• Subacromial joint
• Scapulothoracic joint

4.1. Pathways

The shoulder region contains several important structures that supply the arm, including:

• Brachial plexus
• Axillary artery
• Axillary vein