Upper Body: Shoulder Girdle and Arms
Your shoulder girdle connects your arms to your trunk and consists of two main bones: the clavicle (collar bone) and scapula (shoulder blade). These lightweight bones prioritize mobility over strength.
The clavicle braces your shoulders, keeping your arms positioned away from your chest. It provides attachment sites for muscles and helps distribute force when you fall on your outstretched hands. Unfortunately, this makes it prone to fractures!
Your upper limbs contain 30 separate bones working together. The humerus (upper arm) connects to your forearm bones (ulna and radius), followed by your carpals (wrist bones), metacarpals (palm), and phalanges (fingers). Your thumb, or pollex, has special mobility that sets humans apart.
Fun fact: The scapula has a distinctive triangular shape with a ridge called the "spine" on its back surface. The point where your shoulder meets your clavicle is called the acromion process—feel this bony bump on top of your shoulder!
