Final answer:
The scapula, also known as the shoulder blade, is a flat, triangular bone situated at the back of the pectoral girdle and is an essential part of the shoulder joint.
Step-by-step explanation:
The bone known as the shoulder blade is referred to as the scapula. The scapula is a large, flat, triangular bone located at the back of the pectoral girdle. It forms part of the shoulder joint by articulating with the humerus, and is supported by the clavicle. The scapula features a ridge called the spine, which can be felt through the skin and provides a large area of attachment for muscles.
The spine of the scapula extends laterally to become the acromion, which is the bony tip of the shoulder. The acromion articulates with the clavicle, allowing the clavicle and scapula to move as a unit, facilitating shoulder and arm movement. The scapula serves as a crucial attachment site for muscles that enable these movements.