Geometry and kinematics of dog ribs.
Five anesthetized supine beagle dogs were scanned using a fast, multislice computed tomographic X-ray technique to determine the orientation of the ribs at total lung capacity (TLC) and functional residual capacity (FRC). A plane was fit to each rib using a coordinate system in which the z-axis was aligned approximately cephalocaudally and the x-z-plane coincided with the sagittal midplane. The orientation of each plane was described by "pump-handle" and "bucket-handle" angles. The ribs rotated downward and inward during a passive deflation of the lungs from TLC to FRC. Rib displacement was not uniform: bucket-handle motion was predominant in the upper ribs, and pump- and bucket-handle motions were equal in the lower ribs. The change in the pump-handle angles between TLC and FRC was approximately 6 degrees for ribs 3-8, and the change in the bucket-handle angles decreased with rib number from 16 degrees for rib 3 to 6 degrees for rib 8. Rib shape was described by fitting an ellipse to the data for each rib; the ribs became larger and more circular with increasing rib number.
Margulies
S S
SS
Division of Thoracic Diseases Research, Mayo Clinic, Rochester, Minnesota 55905.
Rodarte
J R
JR
Hoffman
E A
EA
D000818:Animals; D004285:Dogs / Q000502:physiology*; D008433:Mathematics; D012115:Residual Volume; D012143:Respiratory Physiological Phenomena; D012272:Ribs / Q000033:anatomy & histology*; D013909:Thorax / Q000033:anatomy & histology; D014057:Tomography, X-Ray Computed; D014109:Total Lung Capacity