Overview

Your clavicle (collarbone) is the long, gently S-shaped bone that runs across the front of your chest, connecting your breastbone to your shoulder blade. You can feel it easily by running a finger from the base of your neck out toward your shoulder. It acts like a strut — a rigid brace that holds your shoulder out to the side of your body so your arm has room to move freely. It's also one of the most commonly broken bones in the body, especially after a fall onto the shoulder or an outstretched hand.

Location

Sits horizontally at the top of the chest, just under the skin
Runs from the sternum (breastbone), at its inner end, to the acromion (the bony tip of the shoulder blade), at its outer end
Lies directly above the first rib and major nerves and blood vessels heading into the arm

The clavicle is one of the few bones in the body you can trace with your finger along its entire length, because it sits so close to the skin's surface. It forms the front "roof" over the top of the lungs and the bundle of nerves and vessels that supply your arm (StatPearls: Clavicle).

Function

Acts as a rigid strut that holds the shoulder blade and arm away from the ribcage
Allows the arm to swing freely without the shoulder blade sliding forward against the chest wall
Transmits force from the arm back to the central skeleton (for example, when you catch yourself in a fall)
Protects the major nerves and blood vessels running from the neck into the arm, which pass just underneath it
Provides an attachment point for several muscles that move the shoulder and neck

Think of the clavicle as a spacer bar. Without it, your shoulder blade would collapse in toward your ribcage every time your arm muscles pulled on it, and your arm's range of motion would shrink dramatically.

Structures It Connects To

Sternum (breastbone) — at the sternoclavicular joint, the inner end
Scapula (shoulder blade), specifically the acromion — at the acromioclavicular joint, the outer end
Coracoid process of the scapula — via the coracoclavicular ligaments (conoid and trapezoid), which anchor it from below
First rib — sits just above and in front of it
Muscle attachments: trapezius and deltoid (top surface), pectoralis major and subclavius (front/underside), sternocleidomastoid (inner end)

The clavicle links to the rest of the skeleton at only two joints — one at each end — but it also acts as an anchor point for several muscles that connect the arm, shoulder blade, chest, and neck together.

Movements It Assists

Shoulder elevation (shrugging the shoulders up)
Shoulder retraction and protraction (pulling shoulder blades back and forth)
Arm overhead reaching, by allowing the shoulder blade to rotate upward as the clavicle rotates along its own axis
Weight-bearing through the arms, such as pushing up from a chair

Common Injuries

Clavicle fracture — usually from a fall onto the shoulder or outstretched arm, or a direct blow (Clavicle fracture)
Acromioclavicular (AC) joint injury — sprain or separation at the outer end of the clavicle (AC joint injury)
Sternoclavicular joint sprain — less common, usually from high-impact trauma at the inner end
Distal clavicle osteolysis — gradual bone breakdown at the outer end, often from repetitive heavy lifting (e.g., weightlifting)

Because the clavicle sits so close to the skin and bridges two joints, it's vulnerable both to direct trauma and to the wear-and-tear forces that pass through the shoulder during heavy or repetitive use.

Pain Referral Patterns

Pain from a clavicle problem is usually felt directly over the bone itself, along the top of the chest
Fractures often cause pain that spreads to the whole shoulder region and can make it painful to move the arm at all
Problems at the outer end (AC joint) tend to cause pain that's sharply localized to the top of the shoulder
Problems at the inner end (sternoclavicular joint) cause pain near the base of the neck, close to the breastbone

Clinical Relevance

The clavicle's superficial position makes it easy to feel and assess during a physical exam — a clinician can often see or feel a fracture through the skin. It's also one of the few bones that can often be treated with a sling rather than surgery in many fracture cases, since the surrounding muscles hold the broken ends in reasonably good position (StatPearls: Clavicle). However, because major nerves and blood vessels to the arm pass directly beneath it, clinicians always check hand and arm sensation, pulse, and movement after a clavicle injury to rule out deeper damage.

Interesting Facts

The clavicle is the last bone in the body to finish growing — it doesn't fully harden (ossify) until the mid-to-late twenties, which is unusual since most other bones finish growing in the teens (StatPearls: Clavicle).
It's the most frequently fractured bone in the body, accounting for roughly 2.6–4% of all fractures (StatPearls: Clavicle).
Its gentle double-curve (S-shape) is thought to help it act like a spring, absorbing shock when force is transmitted through the arm.

Scapula (shoulder blade) — the clavicle's outer end attaches to the scapula's acromion, forming the AC joint
Sternoclavicular joint — where the clavicle's inner end meets the breastbone
Acromioclavicular joint — where the clavicle's outer end meets the shoulder blade
Trapezius — attaches along the top of the clavicle and helps elevate it
Brachial plexus (shoulder overview) — the major nerve network that runs just beneath the clavicle

Clavicle fracture — a break in the bone itself, one of the most common fractures in the body
Acromioclavicular joint injury (AC sprain/separation) — involves the clavicle's outer attachment
Shoulder dislocation — can occur alongside clavicle-region trauma in high-force injuries

References

StatPearls (NCBI Bookshelf). "Anatomy, Shoulder and Upper Limb, Clavicle." https://www.ncbi.nlm.nih.gov/books/NBK534836/
Cleveland Clinic. "Clavicle (Collarbone)." https://my.clevelandclinic.org/health/body/22894-clavicle
Physiopedia. "Clavicle." https://www.physio-pedia.com/Clavicle
OrthoInfo (AAOS). "Shoulder Anatomy." https://orthoinfo.aaos.org/en/diseases--conditions/shoulder-anatomy/

Clavicle (Collarbone)