Anatomical characteristics of two cases of aberrant right subclavian artery.

An aberrant right subclavian artery is a branching variation of the aortic arch. We encountered two female cadavers with an aberrant right subclavian artery during routine student dissection at our school. In both cases, the right subclavian artery was not a branch of the brachiocephalic trunk but originated directly from the distal part of the aortic arch as the last branch and ran between the esophagus and vertebral column, traveling to the upper limb. The right recurrent laryngeal nerve was absent, but a non-recurrent inferior laryngeal nerve branching from the vagus and traveling directly toward the larynx was observed. In the first case, the right and left common carotid arteries originated solely from the aortic arch as the first and second branches, respectively, whereas the right and left common carotid arteries formed a bicarotid trunk at their origin in the second case. A Kommerell diverticulum was present at the base of the aberrant right subclavian artery in the second case, but not in the first case. We analyzed the anatomical differences between the two cases and discussed the developmental aspects and potential clinical risks.

A case of double inferior vena cava with renal, ovarian and iliac vein variation.

We encountered a rare case of an anatomic variant of inferior vena cava (IVC) duplication with renal, ovarian and iliac vein variation in an 81-year-old Japanese female cadaver during a student dissection course of anatomy at Aichi Gakuin University School of Dentistry. The two IVCs ran upwards bilaterally to the abdominal aorta. The left IVC joined with the left renal vein (RV) to form a common trunk that crossed anterior to the aorta and ended at the right IVC. We detected a vein [interiliac vein (IiV)] connecting the two IVCs at the level of the aortic bifurcation. The IiV was formed by the union of two tributaries from the left IVC and a tributary from the left internal iliac vein (IIV) and ran obliquely upwards from left to right. Two right ovarian veins, arising separately from the ipsilateral pampiniform plexus, ran vertically in parallel to each other, and each one independently terminated at the right IVC and the right RV. Two right IIVs, connecting each other with small branches, ascended and separately joined the right external iliac vein. The right and left IIVs were connected to each other. These variations cause abnormal drainage, which could lead to clinical symptoms associated with the dysfunction of the vascular and urogenital systems. Here we describe the detailed anatomical features of the area and discuss the related anatomical and developmental aspects.

Control of Precision Grip Force in Lifting and Holding of Low-Mass Objects.

Few studies have investigated the control of grip force when manipulating an object with an extremely small mass using a precision grip, although some related information has been provided by studies conducted in an unusual microgravity environment. Grip-load force coordination was examined while healthy adults (N = 17) held a moveable instrumented apparatus with its mass changed between 6 g and 200 g in 14 steps, with its grip surface set as either sandpaper or rayon. Additional measurements of grip-force-dependent finger-surface contact area and finger skin indentation, as well as a test of weight discrimination, were also performed. For each surface condition, the static grip force was modulated in parallel with load force while holding the object of a mass above 30 g. For objects with mass smaller than 30 g, on the other hand, the parallel relationship was changed, resulting in a progressive increase in grip-to-load force (GF/LF) ratio. The rayon had a higher GF/LF force ratio across all mass levels. The proportion of safety margin in the static grip force and normalized moment-to-moment variability of the static grip force were also elevated towards the lower end of the object mass for both surfaces. These findings indicate that the strategy of grip force control for holding objects with an extremely small mass differs from that with a mass above 30 g. The data for the contact area, skin indentation, and weight discrimination suggest that a decreased level of cutaneous feedback signals from the finger pads could have played some role in a cost function in efficient grip force control with low-mass objects. The elevated grip force variability associated with signal-dependent and internal noises, and anticipated inertial force on the held object due to acceleration of the arm and hand, could also have contributed to the cost function.

Malignant phyllodes tumor composed almost exclusively of a fibrosarcomatous component: a case report and review of malignant phyllodes tumors with metastases.

Here we present a case of malignant phyllodes tumor which was composed almost exclusively of a fibrosarcomatous component. A 52-year-old Japanese female noted a rapid increase of her right breast tumor. On admission, multiple lung metastases were detected by imaging. Right simple mastectomy was performed. The tumor, 10 x 10 cm in the largest dimension, had somewhat of a pushing margin, and showed a flesh-like appearance with marked necrosis. Microscopically, the tumor showed proliferation of atypical ovoid- or spindle-shaped cells in a myxoid matrix. Multiple sectioning revealed that the tumor had only focal occurrence of elongated tubular structures, and the occurrence of a small component of benign phyllodes tumor, leading to the aforementioned final diagnosis. Spindle cell carcinoma was excluded on the basis of the HE findings and the lack of immunoreactivity for cytokeratin when using a broad spectrum antibody mixture. Although the patient received adjuvant chemotherapy, no responsiveness was obtained. The patient died 4 months following surgery. We reviewed 15 malignant phyllodes tumors with metastases reported in Japan. The estimated 2.2-year survival rate following detection of metastasis was 11%, thus confirming the aggressiveness of the disease.

Effects of changing the initial horizontal location of the center of mass on the anticipatory postural adjustments and task performance associated with step initiation.

The aim of this study was to elucidate whether and how the duration and/or amplitude parameters of anticipatory postural adjustments (APAs) affected the task performance in a single step forward from differences in the initial horizontal location of CoM. Ten male subjects performed initiation of a single step forward with the right swing leg with strict regulation of the step length at three initial body positions (Sw, step initiation from a 50% position of the center of pressure (CoP) shift in the maximum lateral right side; N, step initiation from the upright position at rest; St, step initiation from a 50% position of the CoP shift in the maximum lateral left side). The duration required for stepping from the heel-off to foot-contact of the swing leg (step time) in the Sw condition was significantly shorter than of the other two conditions. The APAs durations in the Sw condition was significantly longer than in the other two conditions. In the Sw condition, the durations of the anticipatory electromyographic (EMG) activities of the tibialis anteriors (TA) of the swing leg correlated significantly with mechanical parameters (the displacement of the CoM, velocity of the CoM, and propulsive force) in the anticipatory phase, while the mean amplitudes of the anticipatory EMG activities of the TA of the swing leg did not correlate significantly with mechanical parameters in the anticipatory phase. The present results suggest that the duration parameters of the APAs associated with single step forward motion are dependent on the displacement of the CoM estimated by the initial cutaneous messages from the swing leg prior to initiation of the single step, and that the APAs may be directly involved not only in the increase in propulsive force towards the supporting leg, but also increasing the forward propulsive force at heel-off.

Anticipatory control related to the upward propulsive force during the rising on tiptoe from an upright standing position.

The purpose of the present investigation was to explore whether and how the amplitude and/or duration parameters of anticipatory postural adjustments (APAs) affect the upward propulsive force (Delta FZamp) during rising on tiptoes from upright standing position. Seven subjects initiated the movement of rising on tiptoe from a strictly regulated initial body position at various velocities at the subjects' own spontaneous pace. In this experiment, electromyographic (EMG) activities of the muscles in the tibialis anterior (TA) and soleus, the goniogram in the ankle joint, and the anteroposterior and vertical ground reaction forces were simultaneously recorded. The average amplitude and the duration of the EMG activities and ground reaction force were measured, and the displacement of the center of body mass and the center of foot pressure (CP) were calculated and reported as the mean value plus its standard deviation. Delta FZamp correlated positively and significantly with the maximum backward CP shift, the average amplitude of the backward loading and the average EMG amplitude in the TA in the anticipation phase, whereas Delta FZamp did not correlate positively or significantly with the anticipatory duration of the backward CP shift of the backward loading and of the EMG activity in the TA. These results suggest that the amplitude parameters of the APAs associated with rising on tiptoes are dependent on the upward propulsive force, and that APAs may be directly involved not only with compensation of postural disturbance but also with increasing performance of the focal movement.

Anticipatory control in the initiation of a single step under biomechanical constraints in humans.

It is generally known that both the duration and amplitude parameters of the anticipatory postural adjustments (APA) in the sagittal plane co-vary with the progression velocity in step or gait initiation. The purpose of this study is to elucidate how the duration and/or amplitude parameters of the APA are associated with the performance of the initiation of a single step forward in cases where the step displacement of the center of body mass are strictly regulated. Seven male subjects performed the initiation of a single step at two speeds (as fast as possible, F; normal speed, N). The APA amplitudes in the F condition showed significantly higher values than those in the N, while the APA durations showed no significant difference between the F and N conditions under the biomechanical constraints. The present results suggest that the central nervous system might scale the APA amplitudes and durations according to the intended forward velocity and the forward displacement of the center of body mass in step initiation, respectively.