The pectoral girdle, which connects the upper limbs to the axial skeleton, is comprised of four main bones. These bones include two clavicles (collarbones) and two scapulae (shoulder blades).
The clavicles are slender, S-shaped bones that sit horizontally at the top of the chest, acting as a strut to stabilize the shoulder. Each end of the clavicle connects to the sternum at the manubrium and to the acromion of the scapula. This arrangement allows for a certain degree of flexibility while supporting the arm’s range of motion.
The scapulae are flat, triangular bones located on the posterior side of the rib cage. They provide a surface for muscle attachment and play a crucial role in the movement of the shoulder joint. Each scapula features several important landmarks, such as the glenoid cavity, which articulates with the humerus to form the shoulder joint.
In summary, the pectoral girdle consists of a total of four bones: two clavicles and two scapulae. Together, they allow for a wide range of arm movements while providing stability to the upper body.