Shoulder Girdle

It is a circular bony structure around the trunk at the upper end. IT consists of 2 major horizontal bones- 2 Clavicles at the front side and 2 Scapulae at the backside and also Sternum at the front center and Vertebral column at the back Center.

It is also called as Pectoral Girdle and responsible for providing structural support to your shoulder region. It allows a large range of motion, connecting muscles necessary for shoulder and arm movement.

Figure 1: Shoulder Girdle

Major Bones:

1. Clavicle: The clavicle or collarbone is an S-shaped bone situated at the front of your body in a horizontal position. Clavicle has three parts:
• Medial end: This portion of the clavicle attaches to the sternum. It also called a sternal end and it is triangular and forms the sternoclavicular joint.
•  Lateral end: This portion of the clavicle attaches to the scapula. This flat piece is often referred to as the acromial end and forms the acromioclavicular joint. 
• Shaft: This is the body of the clavicle. The clavicle is one of the most commonly fractured bones in the body. 
2. Scapula: The scapula bone or shoulder blade is located at the back on the outer surface of the upper ribs. This is a flat triangular bone with 2 surfaces, 3 borders, and 3 angles and this connects your humerus with your clavicle.

Scapula has projection on its outer surface like a handle, called as spine of Scapula. This spine of scapula is extended at lateral side and it is called as acromion or acromial process. This acromial process forms a join with lateral end/ acromial end of clavicle and it is called as acromioclavicular joint.

Scapula Borders:

1. Medial border (vertebral border), which runs parallel to the thoracic vertebrae
2. Lateral border (axillary border)
3. Superior border, the thinnest and shortest of the three borders

Scapula Movements:

1. Elevation - Movement in upward direction
2. Depression - Movement in downward direction
3. Retraction - Movement towards mid-line
4. Protraction - Movements away from mid-line.

Joints:

• Sternoclavicular joint: joint between the manubrium of the sternum and the first costal cartilage with the medial end of the clavicle.
• Acromioclavicular joint: Joint between acromial process and lateral end of clavicle.
• Glenohumeral joint: Also known as the shoulder joint or ball-and-socket Joint and it is between the head of the humerus and the glenoid fossa of the scapula.