Anatomical science international
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The aim of the present study was to examine the vertebral arteries. The origins of the right and left vertebral arteries and their entrance points into the cervical transverse foramen were examined in dissections of 515 Japanese cadavers (303 males, 212 females) at Kurume University School of Medicine from 1990 to 2003. There were 515 right vertebral arteries and 514 left vertebral arteries. ⋯ Seventy-eight percent of our cases had right and left vertebral arteries that originated in the subclavian arteries and entered the cervical transverse foramen at C6. Among the 30 left vertebral arteries that originated from the aortic arch, 20 arteries (66.7%) entered a cervical transverse foramen at a level higher than C6. This frequency was higher than that for the left vertebral artery that originated from the subclavian artery.
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An aberrant axillary artery running deep to the brachial plexus during its course was observed. The brachial plexus in this case was formed by the fourth cervical nerve to the first thoracic nerve and the radial nerve received a small nerve bundle (accessory radial nerve root) from the posterior aspect of the lower trunk. ⋯ This axillary artery was recognized as the deep axillary artery, the same as the axillary artery we have reported previously. It was thought that the branches to the subscapularis and serratus anterior muscles, nutrient branch to the radial nerve root and the subscapular artery played important roles in its formation.
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The structure of the ligamentum flavum has yet to be fully elucidated and no studies have investigated fine structural differences at different spinal levels in any animals. The aim of the present study was to clarify structural differences in the ligamentum flavum at different spinal levels (cervical: C3/4 and C5/6; upper thoracic: T2/3; lower thoracic: T9/10; lumbar: L3/4) using light and electron microscopy of rabbit specimens. Light microscopy using resorcin-fuchsin staining revealed that the distribution of elastic fibers was diffuse in the cervical and upper thoracic regions, but was generally dense in the lower thoracic and lumbar regions. ⋯ Quantitative image analyses displayed thick elastic fibers in the lower thoracic and lumbar regions, with high area ratios. Radiographic examinations revealed that ranges of motion were large at the cervical region, but small at the lower thoracic and lumbar regions. These findings suggest that structure of the ligamentum flavum varies at different spinal levels with respect to differences in motion.
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An aberrant axillary artery that descended deep beneath the brachial plexus during its course was observed. The artery passed between the lateral and medial cords, as would an ordinary axillary artery, but further passed between the posterior divisions forming the posterior cord. ⋯ The aberrant axillary artery is judged to reach deeper to the brachial plexus, because it penetrated the posterior division of the brachial plexus from superficial to deep. It is possible to account for the formation of this artery as one of the combinations of the ordinary axillary artery and its branches, with the positional relationships between the brachial plexus.