The human skeleton supports the body, facilitates movement, and protects vital organs. While bones are strong, they can fracture under sufficient force. Some bones are more susceptible to injury than others, leading to questions about which bones are least likely to break.
The Rarest Bone to Fracture
The hyoid bone, a small, U-shaped bone located in the front of the neck, is widely cited as the rarest bone to fracture. It sits below the lower jaw and above the thyroid cartilage, playing a role in speech and swallowing. This unique bone is distinct because it is the only bone in the human body that does not directly connect with any other bone. Instead, it is suspended by a complex network of muscles, ligaments, and cartilage. Fractures of the hyoid bone are exceptionally uncommon, accounting for a mere 0.002% of all bone fractures.
Why This Bone Seldom Breaks
The hyoid bone’s protected position and unique anatomy contribute to its rare fracture rate. It is located deep within the neck, shielded by the mandible (lower jaw) and the cervical spine. This bony framework provides a barrier against external forces. The hyoid’s mobility also enhances its resilience, allowing it to move in multiple directions and absorb impacts.
Numerous muscles, ligaments, and cartilage attach to the hyoid bone, supporting its position. This suspension creates a cushioning environment that acts as a shock absorber, protecting the hyoid from direct trauma. Due to these protective factors, a hyoid fracture typically requires a specific and extreme mechanism of injury, such as strangulation, hanging, or severe blunt force trauma to the neck. These forces compress the neck in a way that overcomes the bone’s inherent protection and mobility.
Other Bones That Are Rarely Fractured
Beyond the hyoid, several other bones are also infrequently fractured due to their deep protection, small size, or the extreme forces required to break them.
Middle Ear Bones
The bones of the middle ear—the malleus, incus, and stapes—are among the smallest bones in the body and are rarely fractured. Their location deep within the temporal bone of the skull, surrounded by protective structures, makes them resistant to injury from external forces. Fractures to these tiny bones usually only occur with severe head trauma that directly compromises the inner ear.
First Rib
The first rib is rarely fractured. While ribs are susceptible to breaks, the first rib is protected by the clavicle (collarbone), scapula (shoulder blade), and muscles in the upper chest and shoulder. Fracturing the first rib often indicates a high-energy impact, such as those sustained in severe motor vehicle accidents, as the force needed to break it is considerable.
Scapula
The scapula, or shoulder blade, is also a rare site for fractures. Its broad, flat shape and position, cushioned by thick muscles, allow it to absorb and distribute force. A fractured scapula typically results from high-impact trauma, such as a direct blow or a fall from a height.