Final answer:
It is true that a difficult birth can result in a fractured clavicle in newborns, evidenced by a lump, limited arm movement, and a unilateral Moro reflex. The clavicle is the most commonly fractured bone and can also be injured during falls or blows to the shoulder in older individuals. Despite the potential for injury, the vital blood vessels and nerves under the clavicle are typically protected.
Step-by-step explanation:
It is true that a difficult birth because of broad fetal shoulders can result in a fractured clavicle. Newborns may show signs of a fracture with a knot or lump at the break site, limited movement of their arm, and a unilateral Moro reflex, which is an asymmetric response when the baby is startled. This condition is a result of the challenges faced during childbirth wherein the baby's shoulders may have difficulty navigating through the birth canal, leading to excessive pressure on the clavicular area.
The clavicle or collarbone is known to be the most frequently fractured bone in the body. A strong blow to the shoulder or a hard fall onto an outstretched hand can lead to fractures or other injuries in the pectoral girdle. These incidents are particularly significant as the clavicle plays a crucial role in supporting the head, attaching the upper limbs to the axial skeleton, and aiding in locomotion.
When a fracture occurs, it tends to happen between the middle and lateral portions of the clavicle, causing the shoulder and lateral clavicle fragment to sag. This may lead to a natural compensatory action where individuals support the affected limb with their other hand. Although blood vessels and nerves lie beneath the clavicle, they are generally shielded from injury due to the anterior displacement of the fractured clavicle fragments.