Final answer:
The bone known as the collar bone is the clavicle, which is an S-shaped bone crucial for support, movement, and protection of the upper limb and shoulder region.
Step-by-step explanation:
The bone commonly known as the collar bone is the clavicle. The clavicle is an S-shaped long bone that positions the arms on the body and serves several vital roles.
This bone acts as a strut to support the scapula, thereby holding the shoulder joint superiorly and laterally from the torso, which is essential for the upper limb's range of motion. It also transmits forces from the upper limb to the sternum and axial skeleton, and plays a protective function for the nerves and blood vessels passing between the trunk and the upper limb.
Notably, the clavicle is prone to fractures, often due to falls on outstretched arms or direct impacts to the shoulder.
The clavicle articulates with the sternum medially and with the acromion of the scapula laterally, forming part of the pectoral girdle (shoulder girdle) along with the scapula. These structures are critical for the mobility and stability of the shoulder region.