The shoulder girdle, also known as the pectoral girdle, connects your arms to the bones and muscles along the axis of your body. You have two shoulder girdles that are responsible for supporting the shoulder regions on both sides of your body and enabling movement.
Your shoulder girdle is made up of two bones: your collarbone (clavicle) and your shoulder blade (scapula).
Clavicle bone
Your clavicle an S-shaped bone. It is situated at the front of your body in a horizontal position. It helps to protect the nerves and blood vessels that pass between your trunk and arms. It is the only direct connection between your shoulder girdle and axial skeleton.
The clavicle bone consists of three sections:
- Medial end
The medial end is triangular. It attaches to the sternum, forming the sternoclavicular joint.
- Lateral end
The lateral end is a flat piece that connects to the scapula. It forms the acromioclavicular joint.
- Shaft
The shaft is the body of the clavicle, which connects the lateral and medial end.
Scapula bone
The scapula is a triangular bone situated at the back of your shoulder. It connects your humerus (upper arm) with your clavicle. It is also an attachment point for various muscles in your shoulder, upper arm, neck and back.
Your scapula consists of three borders:
- Medial border
The medial border, also known as the vertebral border, runs parallel to the thoracic vertebrae (12 bones that make up the upper part of your spine).
- Lateral border
The lateral border is also known as the axillary border.
- Superior border
The superior border is the thinnest as well as the shortest of the three borders. The scapula also has two angles: the lateral angle and the inferior angle.
Shoulder joints
Your shoulder joint consists of four main joints:
- Sternoclavicular joint
The sternoclavicular joint is where your clavicle and sternum meet. It allows your clavicle to move in three different planes.
- Scapulothoracic joint
The scapulothoracic joint, or scapulocostal joint, is where the scapula bone meets the ribs at the back of your chest. It relies on the muscles, which surround it, for control.
- Acromioclavicular joint
Your clavicle and acromion of the scapula come together at the acromioclavicular joint. It also enables movement in three planes.
- Glenohumeral joint
The glenohumeral joint, or shoulder joint, is the ball-and-socket connection between the humerus and scapula.
When we think about how the arm and shoulder are connected, this is usually the joint we picture.
Your shoulder girdle is the most agile and also the most vulnerable joint in the body. You have two of these joints. It is made up of the clavicle and scapula bones and four joints: sternoclavicular joint, scapulothoracic joint, acromioclavicular joint and glenohumeral joint. This series of bones and joints is responsible for connecting your arm and shoulder. It enables you to move your arm.
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