An Intro to The Shoulder Girdle
The shoulder girdle, also referred to as the pectoral girdle, comprises the clavicle (collar bone) and the scapula (shoulder blade). Part of the scapula is the glenoid cavity, into which the humeral head sits forming the shoulder joint. There are several muscles associated with the shoulder girdle including the Rhomboids (major and minor), the Levator Scapulae, the Pectoralis Minor, the Trapezius, The Sternocleidomastoid, Subclavius, and Serratus Anterior. All of these muscles have actions and function relevant to the shoulder girdle.
The clavicle is found anteriorly and is more commonly referred to as the collar bone. it is the most commonly broken bone in the body given it's location and superficial nature. This bone can be easily palpated along it's entire length. The clavicle connects from the acromial joint (see below) laterally to the sternum medially. The joint that connects the sternum and the clavicle is called the sternoclavicular joint, and it is possible for restriction to occur here causing dysfunction in the shoulder region. The clavicle connects to the spine of the scapula via a joint known as the acromioclavicular joint. The acromion itself is found at the lateral end of the spine of the scapula, and can be felt as a small bump or sometimes a groove between the spine of scapula and the clavicle. When therapists sometimes refer to 'sub-acromial space' they are talking about the space found directly below this structure.
The scapula is found on the posterior side of the body and is the attachment point for many muscles including the rotator cuff muscles (discussed in the previous article). At it's medial border it serves as an attachment for the rhomboids and for the levator scapulae at it's superior angle. The scapula can elevate or depress, and rotate (adduction or abduction of the arm). The scapula should sit nicely on the ribcage, but dysfunction through things like upper crossed syndrome can cause it to lift off the ribcage leading to a condition known as 'winged scapula'. Therapists will sometimes refer to the 'scapulocostal joint' where the scapula sits on the ribcage. This is a misleading term as there is no actual joint here at all. Upper crossed syndrome would cause the scapula to also pull apart causing stretch and inhibition in the rhomboids which is quite common. At the superior portion of the scapula is the supraspinous fossa which houses the supraspinatus muscle, and below that is the infraspinous fossa, where you will of course find infraspinatus. The spine of the scapula runs from the upper lateral border laterally to finish at the acromion.
The coracoid process of the scapula serves as an attachment point for pectoralis major and also the coracobrachialis muscle of the arm. It is a finger like projection which is easily accesible from the anterior side of the body, as the image below shows.
The coracoid process resides underneath the clavicle and is the insertion point for pectoralis minor. It connects to the clavicle via the coracoclavicular ligament, and to the acromion via the coracoacromial ligament.