Marked lateral deviation of the phrenic nerve due to variant origin and course of the thyrocervical trunk: a cadaveric study.

Phrenic nerve impairment can often lead to serious respiratory disorders under various pathological conditions. During routine dissection of an 88-year-old Japanese male cadaver, a victim of heart failure, we recognized an extremely rare variation of the right thyrocervical trunk arising from the subclavian artery laterally to the anterior scalene muscle. In addition to that, the ipsilateral phrenic nerve was drawn and displaced remarkably laterad by this vessel. We examined all of the branches arising from subclavian arteries, phrenic nerves and diaphragm muscles. The embryological background of this arterial variation is considered. The marked displacement with prolonged strain had a potential to cause phrenic nerve impairment with an atrophic change of the diaphragm muscle. Recently many image diagnostic technologies have been developed and are often used. However, it is still possible that rare variations like this case may be overlooked and can only be recognized by intimate regional examination while keeping these rare variations in mind.

[Cranial nonmetric variation of Yayoi people in the Kyushu District].

The Yayoi people in Kyushu and Yamaguchi area are generally classified by metrical analyses mainly into the Yayoi people in the northern Kyushu and Yamaguchi area who are regarded as migrants from the Asian Continent and their posterity and the Yayoi people in the northwestern Kyushu who are regarded as having inherited the characteristics of the Jomon people. Such classification is verified by the analysis with the 22 traits in the cranial nonmetric variation. Of the 22 traits, supraorbital foramen, transverse zygomatic suture vestige, biasterionic suture vestige, jugular foramen bridging, hypoglossal foramen bridging, pterygospinous foramen, mylohyoid bridging and tympanic dehiscence are particularly important as the traits to classify two types of Yayoi peoples. The analysis by the C. A. B. Smith's Mean Measure of Divergence (MMD) suggests that out of the migrant Yayoi peoples, the very Yayoi people who are closely related to the formation of the modern Japanese are the ones in the northern Kyushu area, not the ones in the Doigahama site. Also, it is assumed that the appearance and disappearance of cranial nonmetric variations is affected by genetic elements, because the incidencies of cranial nonmetric variations is largely different between two types of Yayoi peoples in infants like in adults. Lastly the cranial nonmetric variation in the people of the period equivalent to Jomon and Yayoi in the Okinawa district, and in the Kofun people in southern Kyushu area, was briefly introduced.

Diffusion-weighted echo planar imaging of the normal human cervical spinal cord.

We obtained diffusion-weighted echo planar images of the human cervical cord in vivo and correlated them with histopathologic findings. Images were obtained in 17 healthy volunteers using a 1.5 T clinical MR unit. When motion-probing gradients were added perpendicular to the long axis of the cord, the white matter was hyperintense because of anisotropic diffusion. However, the gracile fasciculus was hypointense probably due to the small diameter of neural fibers and the large extracellular space.