Despite the recent progress in physiological studies of acupuncture, few morphological studies from the viewpoint that acupuncture stimulation produces with a small tissue injury have been reported. In this study, we evaluated the mechanism of acupuncture stimulation by a histopathological approach. First, we confirmed the tissue structure from the skin to the muscle layer in a corpse. In the human body, free terminals (endings) of unmyelinated nerve fibers (1.5μmin diameter, Group III or Group IV) were present subcutaneously or in the endomysium of muscle tissues. Next, the extent of tissue injury caused by insertion of needles 0.20-0.95mm in diameter evaluated in human and animal tissues. The extent of the injury was in proportional to the diameter of the needle. These confirmed that acupuncture stimulation is clearly a small tissue injury. Also, the free terminals (endings) of unmyelinated nerves similar to those observe in the human tissue were obsurved in the endmysium near the injury site. These morphological findings suggest that acupuncture stimulation is related to Group III or Group IV fibers.

Recently, magnetic resonance imaging (MRI) has brought significant advancements in the diagnosis of spinal disorders. But there is much debate about the abnormalities detected by MRI clinically. In this study, we try to clarify the correlation between spinal abnormalities detected by MRI and physical signs in 45 patients with neck, shoulder, and low back pain. Physical signs were segmental sensory disturbance, amyotrophy, and radicular pain, and the abnormalities of MRI were bulging, protrution, extrution, and osteophytes. MRI showed a symptomatic change, that is a false positive (abnormality of MRI^* (+), physical sign^** (-)), in 26 of the 45 patients (57.7%), a true positive (+, ^**+) in 15 of 45 patients (31.1%), a true negative (^*+, ^**-) in the remaining 5 patients (11.1%).
These results suggested that the physical signs are more important than the abnormalities of MRI in patients with neck, shoulder and low back pain. We think that the acupuncture therapist should carry out a more detailed physical examination of the patients clinically.

The anatomical structures penetrated by a needle which was inserted in an acupuncture point into the stellate gaglion, 1.5cm lateral to and 2.5cm above the point Tentotsu, were studied bilaterally with dissection of 19 cadavers. Furthermore, the size of the dissected stellate ganglion, its anatomical position, and its positional relation to structures located near it were measured or observed.
Though 8 out of 38 inserted needles pricked the medial margin of the ganglion, the remaining 30 needles all missed medially from the ganglion. In the cases pricking the ganglion, all of 8 needles penetrated either the vertebral or the subclavian artery before reaching the ganglion, and 7 of these did also the dome of the pleura in addition to the artery. In the cases missing from the ganglion, however, a frequency of penetrating the above structures were considerably lower.
The dissected stellate ganglion almost lay on beteen the mid-level of the vertebral body of the 7th cervical vertebra and the upper level of body of the second thoracic vertebra, with their mean size 27.1, 7.7 and 2.8mm in length, width and thickness, respectively. All of the ganglions were located dorsal to the vertebral and subclavian arteries and the dom of the pleura the distances from the median line to their upper and lower extremity being 21.9 and 22.7mm in average, respectively.
The pricked point for directly aiming at the stellate ganglion from the body surface is within a range 20 to 30mm lateral to and 10 to 40mm above the point tentotsu on the right, and on the left it is within a range 15 to 25mm lateral and 10 to 35mm above; the depth from the point is about 4.0 and 3.8cm on the right and left, respectively. But when directly aiming at the ganglion, the possibility of injuring the vertebral or subclavian artery and the dome of the pleura was suggested to increase considerably owing to their location ventral to the ganglion.

The incidences of the middle cervical and the vertebral ganglia and their sizes were investigated bilaterally during dissection of 18 cadavers. Furthermore, the positional relations of each ganglion to the vertebral column, the point Tentotsu, the anterior tubercle of the sixth cervical (C₆) vertebra, and the cricoid cartilage were investigated along with the relations of the anterior tubercle of the C₆ vertebra to the point Tentotsu and the cricoid cartilage. The middle cervical ganglion was 14, 4 and 2mm in average length, width and thickness, respectively, on the right, and on the left these values were 14, 5 and 2mm. The ganglion was found in about half the cases, and it was located at about the level of the cricoid cartilage and close laterally and above to the anterior tubercle of the C₆ vertebra. In the cases lacking the middle cervical ganglion, the sympathetic trunk passed immediately medial to the tubercle. The vertebral ganglion was found in almost all cases, with its mean size 8, 5 and 3mm on the right and 9, 5 and 2mm on the left in lenght, width and thickness, respectively. The ganglion was included in many cases within a range 15 to 30mm lateral and 20 (the left) or 25 (the right) to 45mm above the point Tentotsu, and it lay at the level of the C₇ vertebra. The anterior tubercle of the C₆ vertebra was within a range 20 to 30mm lateral to that point, and in the upper to lower direction, it lay at the level slightly upper than the cricoid cartilage in the male and at about the level of the cartilage in the female.

The projection region of the dome of the pleura to the surface of the anterior neck was investigated in 31 domes of 17 cadavers. The point “Tentotsu”, and a line connecting that point and the most lateral edge of the acromion were adopted for a basis of measurement of the projection region. The mean length of the Tentotsu-Acromion line was 185mm on either side of the body. Its upward angle to the horizontal plane was 22° and 23° in average on the right and left sides, respectively, while its backward angle to the frontal plane was 23° on the right and 25° on the left. The right pleural domes (17 cases) were included within a range 0-58mm lateral to the Tentotsu and lower than 44mm above, and on the left side (14 cases), these values were 5-58mm and 49mm, respectively. On the other hand, when adopting the Tentotsu-Acromion line as the basis, the pleural domes were located within the medial one-third of the line. Their summits lay on the point of its medial one-fourth in medio-lateral direction, and were situated at levels lower than about 35 (on the right) or 32mm (on the left) above the line.

Twenty-six domes of the pleura of thirteen cadavers were investigated. The summits of all domes protruded above the clavicle. Mediolateral positions of the summits were located between the lateral edge of the origin of the sternal head of the sternocleidomastoid muscle (CL3) and the lateral edge of the origin of its clavicular head (CL5), and their craniocaudal positions were located between the Point “Suitotsu” (S₁₀) and the medial edge of the origin of the clavicular head (CL4). The lateral edges of the domes did not reach the level of the clavicle. Their mediolateral positions were located between CL4 and the Point “Ketsubon” (S₁₂), and their craniocaudal positions were located between CL5 and the sternal extremity of the clavicle (CL2). The medial edges of the domes were both mediolaterally and craniocaudally located between CL2 and the suprasternal point. Projection regions of the domes of the pleura to the surface of the anterior neck were included, in all cases, within the quadrate region connecting the following four points: the Point “Suitotsu” (S₁₀), a point of intersection between the median line and a line drawn vertically from the Point “Suitotsu” (S₁₀) toward the median line, the suprasternal point, and a point on the clavicle corresponding to the medial one-third of the half shoulder width.