Comprehensive Osteopathic Medical Licensing Examination (COMLEX USA) Practice

Which ribs demonstrate bucket handle motion during respiration?

1. Ribs 1-5

2. Ribs 6-10

3. Ribs 11-12

4. Ribs 8-9

The correct answer is: Ribs 6-10

Bucket handle motion during respiration primarily occurs in the lower ribs, specifically ribs 6-10. This type of movement is characterized by the lateral (outward) motion of the ribs during inhalation, which resembles the action of a bucket handle being lifted. As the ribs move in this manner, they increase the transverse diameter of the thoracic cavity, facilitating expansion of the lungs and enhancing airflow. The anatomy of the ribs plays a crucial role in this motion. The lower ribs have a more significant horizontal orientation and are connected to the sternum via the costal cartilages, allowing for more pronounced lateral movement. Ribs 6 through 10 exhibit this bucket handle motion effectively because they are located in the lower thorax, where this mechanism optimally accommodates the lung volume during the breathing cycle. In contrast, the upper ribs (including ribs 1-5) primarily exhibit pump handle motion, which mainly increases the anteroposterior dimension of the thoracic cavity. The last two ribs (11-12), being floating ribs, have limited movement and are not involved in bucket handle motion due to their lack of attachment to the sternum and their more fixed position within the thoracic framework.Thus, ribs 6-10 are the