hen it comes to the shoulder there are some misconceptions. Did you know that the shoulder is designed primarily for mobility, and because of its design, the shoulder joint is one of the most unstable joints in the body? Did you know that the shoulder is actually made up of two joints, once being one of the must unique joints in the body? Let’s dive into the shoulder so that you understand how complex and important this piece of anatomy is.
There is more than one place that the shoulder connects to the body; the actual shoulder joint, which is the first one you think of called your glenohumeral joint. This joint is a ball in socket type joint where the humerus (arm bone) connects to the glenoid fossa of the scapula (shoulder blade). The socket of his joint is the most shallow socket of all of the ball-in-socket joints in the body, which contributes to the extreme limits of range of motion in the shoulder. However, that extreme range of motion and minimal stability around the joint also makes the shoulder joint very susceptible to dislocations.
The other joint related to the should is not actually a true joint but it is where the scapula ‘articulates’ with the underlying rib cage, also referred to as a pseudojoint. This is called the scapulothoracic joint. The shoulder blade is held flush along the back of the rib cage through muscular attachments with the levator scapula, rhomboid minor and major, and trapezius muscles. In conjunction with the muscles of the chest and shoulder joint, the shoulder blade glides upwards, downwards, forward (protraction), and backwards (retracted). This unique movement pattern of the scapula has direct impacts on the position of the shoulder joint and is ultimately closely correlated with biomechanical effects to and from upper body posture.
Now that we know about those two joints in the shoulder, how about the muscles that function in the shoulder.