Clinical anatomy of the pelvic floor

The study presented here comparing cross-sectional anatomy of the fetal and the adult pelvic connective tissue with the results of modern imaging techniques and actual surgical techniques shows that the classical concepts concerning the subdivision of the pelvic connective tissue and muscles need to be revised. According to clinical requirements, the subdivision of the pelvic cavity into anterior, posterior, and middle compartments is feasible. Predominating connecting tissue structures within the different compartments are: Paravisceral fat pad within the anterior compartment (Fig. 17, I), rectal adventitia or perirectal tissue within the posterior compartment (Fig. 17, II), and uterosacral ligaments within the middle compartment. The nerve-vessel guiding plate can be found in all of these compartments; it starts within the posterior compartment and it ends within the anterior one. It constitutes the morphological border between the anterior and posterior compartments in the male. This border is supplied by the uterosacral ligaments in the female. Whereas in gross anatomy no further border is discernable between anterior and posterior or middle compartment, the rectal fascia (hardly visible in embalmed cadavers) demarcates the rectal adventitia and is one of the most important pelvic structures for the surgeon. In principle, the outlined subdivision of the pelvic connective tissue is identical in the male and in the female; facts that become clear from early human life and that are already established during this period (Fig. 18). The uterus is interposed between the bladder and rectum and subdivides the pelvic peritoneum into two pouches thus establishing the only real difference between male and female pelvic cavity. The preferential direction of the pelvic connective tissue fibers is not changed by the interposition of the uterovaginal complex. The pelvic floor muscles are composed of the portions of the levator ani muscle, the muscles of the cavernous organs and the deep transverse perineal muscle in the male. The latter does not exist in the female. We have clearly shown that the different muscles can already be found in early human life and that they are never intermingled with the muscular walls of the pelvic organs. The levator ani muscle of the female, however, is intermingled with connective tissue long before the female sexual hormones exert influence. We have also shown that the distinct sexual differences within the pelvic floor muscles as well as within the sphincter muscles can already be found in early human life. Both the external urethral and the external anal sphincter muscles are not completely circular. The external anal sphincter is intimately connected with the internal sphincter as well as with the longitudinal muscle. Whereas the innervation and function of the urethral sphincter muscles are mostly clear, cloacal development, innervation, and function of all parts of anal sphincter complex are not completely clarified. As to the support of the pelvic viscera, we believe that intact pelvic floor muscles, an undisturbed topography of the pelvic organs, and an undisturbed perineum are of more importance than the so-called pelvic ligaments. Our hypothesis points to the fact that the support of pelvic viscera is multistructural. Thus in pelvic surgery, a lot of techniques have to be revised with the aim to preserve or to reconstruct all the structures mentioned. This is a multidisciplinary task that can only be solved by cooperation of morphologists, urologists, gynecologists, and coloproctologic surgeons or by creating a multidisciplinary pelvic floor specialist.

Cartilage canals in the chicken embryo: ultrastructure and function

In this study the detailed morphology and the function of cartilage canals in the chicken femur are investigated. Several embryonic stages (e 13.5, 16, 19, and 20) are examined by means of light microscopy, electron microscopy (TEM), and immunohistochemistry (VEGF, type I and II collagen). Our results show that cartilage canals originate from the perichondrium and form a complex pattern. Two types of canals are distinguishable: shell canals and communicating canals. Shell canals are in the reserve zone and are arranged in successive layers. Communicating canals spring from the shell canals and pass down into the proliferative zone and into the hypertrophic zone. These canals are conical shaped and are orientated nearly in parallel to the long axis of the femur. Cartilage canals comprise venules, arterioles, capillaries (mature and immature), and undifferentiated mesenchymal cells. No canal wall in the sense of an epithelium is elaborated. VEGF is detected in both types of canals and macrophages are found at the end of the cartilage canals. We conclude that the growth factor stimulates angiogenesis and that the latter cells erode the matrix ahead of the canals and thus enable the advancement of the vessels. The results clearly show that the canal matrix differs from the remaining cartilage matrix. The canal matrix contains type I collagen, few type II collagen fibrils and proteoglycans are lacking. In contrast, in the cartilage matrix type II collagen and proteoglycans are abundant but no type I collagen is found. Communicating canals are surrounded by a distinct layer of type I collagen indicating that osteoid is formed around these canals. Hypertrophic chondrocytes label for type I collagen and it seemed possible that chondrocytes adjacent to the communicating canals differentiate into bone-forming cells. Our results provide evidence that cartilage canals are involved in nourishment of the cartilage as well as in the ossification process.

The trapezoid form of the trochlea tali

The wedge-shaped superior surface of the trochlea tali may be seen in a proximal view as a trapezium. The angle of this trapezium was calculated by measuring the length, and the smallest and largest widths of the trochlea, and was found to be 16.04 degrees for the left talus and 12.48 degrees for the right talus, respectively. The difference between these angles is highly significant. Due to biomechanical features of the talocrural joint an increase in the angle of the trochlea tali also intensifies the incongruency of this joint in plantar-flexion. Thus, this incongruency is larger on the left side. With this diminution of the joint-surface contact, increased internal rotation or "wobbling" movements are possible. An explanation for these facts might be found in footedness, similar to handedness. When constructing a prosthesis one has to consider that the trochlea tali cannot be exactly mirrored from one side to the other but may have to be calculated separately for each side. The fact that footedness seems to correlate with the angle of the trochlea tali can be also helpful.

Lateral arm flap: analysis of its anatomy and modification using a vascularized fragment of the distal humerus

Soft tissue injuries with associated bone defects are difficult to manage and often require prolonged treatment with repeated interventions. Frequently, a free flap is applied as a first step and bone grafting is carried out in a second procedure. Ideally, these two procedures are combined in one operation, utilizing a soft tissue flap with an attached vascularized bone fragment. The lateral arm flap can provide such an osteoseptocutaneous flap and has been utilized clinically with success; however, the vascular anatomy of the flap, especially the humeral fragment, has not been described in detail previously, and there is broad disagreement concerning its innervation. In this study, the arteries and nerves of 24 fresh cadaver arms were dissected after injection of colored latex. The levels of origin of the periosteal arteries of the humerus were also documented. The lateral arm flap has a consistent arterial supply from three septocutaneous perforating branches that are arranged in a predictable pattern. The lateral supracondylar ridge of the humerus is vascularized by direct branches of the posterior branch of the radial collateral artery and by arteries that arise from muscular branches supplying adjacent muscles. The innervation of the lateral arm flap is by the inferior lateral cutaneous nerve of the arm. Knowledge of the consistent vascular anatomy of the lateral humerus and soft tissue of the donor site allows an osteoseptocutaneous flap to be raised safely with an appropriate technique. We recommend use of the lateral arm flap with a humeral fragment for the treatment of combined soft tissue and bone defects when a single step surgical solution is indicated.

The intersesamoidal ridge of the first metatarsal bone: anatomical basics and clinical considerations

The first metatarsal shows a ridge at the plantar side of the head, aligned nearly longitudinally. On 100 macerated first metatarsals (53 right, 47 left) the existence and alignment of this ridge was examined. On the basis of a regression formula, the specimens were assigned to the genders; accordingly, 29 bones were female, the remaining 71 bones male. The intersesamoidal ridge existed in 95 cases (50 right, 45 left); all 29 female bones showed this ridge, male ones in 66 cases. The ridge deviated on average 7.99 degrees from the longitudinal axis of the first metatarsal towards distal-lateral (from -3 degrees to 19 degrees ). Significant differences ( p=0.001) were found for side (left: 6.04 degrees, right: 9.74 degrees ) but not for gender (female: 8.14 degrees, male: 7.92 degrees ). Noticeable correlations with the length of the first metatarsal and the size of the head could not be determined. The mean values of the alignment of the intersesamoidal ridge seem also not to correlate with the metatarsophalangeal angle. The ridge separates the joint surfaces for the sesamoid bones, which are built-in to the tendons of the two heads of the flexor hallucis brevis muscle. Thus, from the alignment of the ridge, the functional direction of this muscle can be concluded. Since the alignment deviates from the longitudinal axis of the first metatarsal, an adduction, in addition to the flexion, can be concluded. Operative techniques for the correction of hallux valgus often change the alignment of the ridge, and therefore also the biomechanical properties of the flexor hallucis brevis muscle. This could explain failures in several surgical therapies.

Relationship between the descending branch of the inferior gluteal artery and the posterior femoral cutaneous nerve applicable to flap surgery

Flap surgery in the distal part of the gluteal region has to deal with a lack of detailed descriptions of the inferior gluteal artery and the posterior femoral cutaneous nerve. The existing papers are mainly clinical studies, based on low numbers of observations. Our study includes 118 cadaveric gluteal regions. The descending branch was present in 91% and gave rise to a cutaneous branch. When the descending branch was absent, this cutaneous branch came from the medial or lateral femoral circumflex artery or as a perforator of the deep artery of the thigh. The posterior femoral cutaneous nerve was found in a common sheath of connective tissue with the descending branch of the inferior gluteal artery in 72% of cases. Nerve loops around the vessel are present in 29%. Our results show that a cutaneous or fasciocutaneous flap, either local or free, in this region can be reliably lifted on a cutaneous branch of the descending branch of the inferior gluteal artery without loss of sensitivity. However, the close relationship of the artery and nerve limits the arc of rotation in the case of a local flap.

Ossification in the human calcaneus: a model for spatial bone development and ossification

Perichondral bone, the circumferential grooves of Ranvier and cartilage canals are features of endochondral bone development. Cartilage canals containing connective tissue and blood vessels are found in the epiphysis of long bones and in cartilaginous anlagen of small and irregular bones. The pattern of cartilage canals seems to be integral to bone development and ossification. The canals may be concerned with the nourishment of large masses of cartilage, but neither their role in the formation of ossification centres nor their interaction with the circumferential grooves of Ranvier has been established. The relationships between cartilage canals, perichondral bone and the ossification centre were studied in the calcaneus of 9 to 38-wk-old human fetuses, by use of epoxy resin embedding, three-dimensional computer reconstructions and immunhistochemistry on paraffin sections. We found that cartilage canals are regularly arranged in shells surrounding the ossification centre. Whereas most of the shell canals might be involved in the nourishment of the cartilage, the inner shell is directly connected with the perichondral ossification groove of Ranvier and with large vessels from outside. In this way the inner shell canal imports extracellular matrix, cells and vessels into the cartilage. With the so-called communicating canals it is also connected to the endochondral ossification centre to which it delivers extracellular matrix, cells and vessels. The communicating canals can be considered as inverted 'internal' ossification grooves. They seem to be responsible for both build up intramembranous osteoid and for the direction of growth and thereby for orientation of the ossication centre.

New, simple, ultrasound-guided infiltration of the pudendal nerve: topographic basics

PURPOSE

We report the topographic relationship of the pudendal nerve to the accompanying pudendal vessels and the ischial spine and provide the basics for an ultrasonographic depiction of these structures.

METHODS

Twenty-nine female and 29 male adult human cadavers were positioned prone to expose the deep gluteal region. In 58 left and 58 right pelves the course of the pudendal nerve and vessels at the ischial spine were evaluated and analyzed statistically (n = 116).

RESULTS

Multitrunked pudendal nerves were found in 40.5 percent with a left-vs.-right ratio of 1:1.5. The diameters of the single-trunked nerves ranged from 1.3 to 6.8 (mean 3.6 +/- 1.1) mm. In 75.9 percent the pudendal nerve was found medial to the accompanying internal pudendal artery. The distance to the artery ranged from 17.2 mm medial to 8 mm lateral (mean, 3.4 mm medial +/- 4.1 mm). The distance to the tip of the ischial spine ranged from 13.4 mm medial to 7.4 mm lateral (mean, 2.1 mm medial +/- 3.7 mm).

CONCLUSIONS

The knowledge of the close spatial relationship between the pudendal nerve and the internal pudendal artery is important for any infiltration technique and even surgical release. It demands real-time, visually controlled infiltration techniques, such as with ultrasound.

Smooth eye movements and spatial localisation

We asked subjects to align a target that flashed as their eyes rotated to the right in pursuit of a moving ring, with a target that flashed as their eyes rotated to the left in pursuit of the ring. Subjects systematically mislocalised the targets in the direction of pursuit. When the ring and flashes were the only structures that were visible, the alignment error was about 4 cm, corresponding to a timing error of about 100 ms. The timing error was independent of the position along the ring's path, but did depend to some extent on pursuit velocity. Adding a textured background reduced the mislocalisation considerably, presumably because it enabled subjects to localise the targets relative to the surrounding. There was almost no mislocalisation if the subject was not pursuing the ring. It is suggested that the mislocalisation arises because incoming retinal signals are combined directly with outgoing oculo-motor commands, with no attempt to account for any of the involved neuronal and muscular delays.

Independent movements of the digits in grasping

Reaching out for an object is often considered to consist of the control of two components: transporting the hand to the object's position, and scaling the grip to the object's size. We recently proposed an alternative view. According to this view, grasping consists of controlling the digits, not the hypothetical transport and grip. This alternative view assumes that the opening of the hand emerges from the trajectories of the digits. We therefore studied the movements of the digits in grasping. We asked subjects to grasp disks (diameters ranging from 5 to 8 cm) at marked positions with two digits. The positions were at opposite sides of the disk, at the same distance from the starting position, so that the orientation of the surface was the same for both digits. The subjects grasped the disks either with the index finger and thumb of the dominant hand, with the same digits of the non-dominant hand, or bimanually with both index fingers. Our predictions are: that the well-known relation between object size and grip aperture holds for each digit; that the same relation holds if the object is grasped with two hands instead of with the thumb and finger of one hand; that maximum deviation, variability and duration of the digit movements are related; and that variations in the timing of the maximum deviation of one digit are independent of those in the other digit. In accordance with our predictions, we found that the maximum deviation of both digits increased with 0.75 times the object radius, independent of the hand(s) used. The movements of the thumb were more variable than those of the index finger, which was reflected by a larger deviation earlier in the movement. The timing of the maximum deviation of the two digits was independent. These results on the digits' movements are consistent with our view that grasping can be understood as the largely independent movements of the digits. The results are not in conflict with the hypothesis that the grip is controlled during grasping, but can only be explained by extending that hypothesis post hoc.

Endpoints of arm movements to visual targets

Reaching out for objects with an unseen arm involves using both visual and kinesthetic information. Neither visual nor kinesthetic information is perfect. Each is subject to both constant and variable errors. To evaluate how such errors influence performance in natural goal-directed movements, we asked subjects to align a real 5-cm cube, which they held in their hand but could not see, with a three-dimensional visual simulation of such a cube. The simulated cube was presented at one of four target locations at the corners of an imaginary tetraeder. Subjects made successive, self-paced movements between these target locations. They could not see anything except the simulated cube throughout the experiment. Initial analysis of the spatial dispersion of movement endpoints demonstrated that the major source of errors under these conditions was visual. Further analysis of the relationship between variability of the starting positions and endpoints showed that the errors were primarily in judging the endpoint, rather than the direction or amplitude of the required movement vector. The findings support endpoint control of human goal-directed movements.

The different growth zones of the fetal foot

Previous publications revealed no reliable data or models concerning the three-dimensional ontogenesis of the lower extremity. Using the method of plastination-histology in combination with 3D-computer-reconstructions we were able to produce exact, virtual 3D-specimens of 19 healthy fetal feet. The fetuses were aged between 9 to 38 weeks of gestation and age-dependently related to four defined age-groups. We compared these feet with the help of a new geometrical method. Thus, we obtained a kind of "slow-motion-picture" of the undisturbed three-dimensional development of the fetal foot. Our results show that the human fetal foot has a desultory mode of growth and that growth priorities within the foot-skeleton change dependent upon age and region. Though the growth of the fetal foot-skeleton is desultory, it is not disconnected. The result of this peculiar mode of growth is to create the foot arches and thus seems to be functionally-oriented toward the human foot's specific purposes.

Metabolite and light regulation of metabolism in plants: lessons from the study of a single biochemical pathway

We are using molecular, biochemical, and genetic approaches to study the structural and regulatory genes controlling the assimilation of inorganic nitrogen into the amino acids glutamine, glutamate, aspartate and asparagine. These amino acids serve as the principal nitrogen-transport amino acids in most crop and higher plants including Arabidopsis thaliana. We have begun to investigate the regulatory mechanisms controlling nitrogen assimilation into these amino acids in plants using molecular and genetic approaches in Arabidopsis. The synthesis of the amide amino acids glutamine and asparagine is subject to tight regulation in response to environmental factors such as light and to metabolic factors such as sucrose and amino acids. For instance, light induces the expression of glutamine synthetase (GLN2) and represses expression of asparagine synthetase (ASN1) genes. This reciprocal regulation of GLN2 and ASN1 genes by light is reflected at the level of transcription and at the level of glutamine and asparagine biosynthesis. Moreover, we have shown that the regulation of these genes is also reciprocally controlled by both organic nitrogen and carbon metabolites. We have recently used a reverse genetic approach to study putative components of such metabolic sensing mechanisms in plants that may be conserved in evolution. These components include an Arabidopsis homolog for a glutamate receptor gene originally found in animal systems and a plant PII gene, which is a homolog of a component of the bacterial Ntr system. Based on our observations on the biology of both structural and regulatory genes of the nitrogen assimilatory pathway, we have developed a model for metabolic control of the genes involved in the nitrogen assimilatory pathway in plants.

Can the dimensions of artificial tendon lesions be predicted ultrasonographically? A cadaveric study

OBJECTIVE

To prove the reliable assessment of artificial partial tendon lesions in cadavers.

METHODS

The tendon of the tibialis anterior muscle was cut twice (transversely, not standardized depths) along its dorsal surface. The dimensions were measured by using a 10-MHz linear probe and a gliding caliper. The lesions were classified as type A tears (<60%; n = 15) and type B tears (>60%; n = 28).

RESULTS

The depths of type A tears had high correlation (r = 0.827), and those of type B tears had low correlation (r = 0.415). This low correlation was due to subtotal lesions (50%-70%; r = 0.699). High-resolution ultrasonography allowed the correct detection of 14 type A tears and 21 type B tears (kappa = 0.63; accuracy, 81%; type B tears: sensitivity, 75%; specificity, 93%).

CONCLUSIONS

High-resolution ultrasonography is able to assess the dimensions of artificial partial tendon lesions in cadavers and would be an accurate tool for determining the lesion percentages in patients with partial tendon tears.

The development of the external urethral sphincter in humans

OBJECTIVE

To assess the hypothesis that during fetal development, the external urethral sphincter changes from a concentric sphincter of undifferentiated muscle fibres to a transient ring of striated muscle which regresses caudo-cranially in the posterior urethra during the first year of life, when the sphincter assumes its omega-shaped configuration.

MATERIALS AND METHODS

The anatomy and development of the external urinary sphincter was assessed in human males and females during fetal life. Plastic-embedded sections (transverse, sagittal and frontal planes; 300-700 microm) of the pelvis of 31 females and 31 males (9 weeks of gestation to newborn) were stained with azure II/methylene blue/basic fuchsin and viewed at x 4-80. The sections of interest were taken from the bladder neck to the perineum. The sections of the membranous urethra were reconstructed three-dimensionally using a computer program.

RESULTS

In both male and female an omega-shaped external sphincter was apparent in all specimens at > 10 weeks of gestation. In the early fetal period (ninth week), there was undifferentiated mesenchyme; in this period the mesenchyme was more dense in the anterior part and loose in the posterior part of the urethra. In females, there was a close connection between the urethra and the anterior wall of the vagina.

CONCLUSION

The omega-shaped configuration of the external urethral sphincter was recognisable from 10 weeks of gestation in both sexes. There was no suggestion of a change from a cylindrical to an omega-shaped sphincter in the fetal period to birth. Also, a transient 'tail' posterior to the sphincter was not apparent. The rectovesical septum was well developed in neonates. There is no reason to assume that the development of the septum leads to an apoptosis of muscle cells in the posterior part of the external sphincter in males after birth. The anatomical development of the external sphincter does not explain transient outlet obstruction during fetal life. The function of the muscle may change during development because of neuronal maturation.

The effect of expectations on hitting moving targets: influence of the preceding target's speed

When hitting a target that is moving, the time for planning the interception is limited. Instead of waiting for all the necessary information about the target's position and speed before starting to move, subjects could use their previous experience with similar targets to make initial guesses and adjust as new information becomes available. In the present study we examined whether the speed of the preceding target influences a hitting movement. Subjects hit moving targets that appeared on a screen about 40 cm in front of them. The targets moved at 6, 12 or 18 cm/s. Both the hand's initial movement direction and the final hitting error depended on the speed of the preceding target. We conclude that people control the way they hit moving targets on the basis of the speed of the preceding target.

How vertical disparities assist judgements of distance

The ratio of the vertical sizes of corresponding features in the two eyes' retinal images depends both on the associated object's distance and on its horizontal direction relative to the head (eccentricity). It is known that manipulations of vertical size ratio can affect perceived distance, size, depth and shape. We examined how observers use the vertical size ratio to determine the viewing distance. Do they use the horizontal gradient of vertical size ratio, or do they combine the vertical size ratio itself with the eccentricity at which it is found? Distance scaling (as measured by having subjects set an ellipsoid's size and shape to match a tennis ball) was no better when the judged object was 30 degrees to the right of the head (where vertical size ratios vary considerably with distance) than when it was located straight ahead. Distance scaling improved when vertical disparities were presented within larger visual fields, irrespective of where this was relative to the head. Our results support the proposal that subjects use the horizontal gradient of vertical size ratio to estimate the distance of an object that they are looking at.

Separate simultaneous processing of egocentric and relative positions

It is well established that all kinds of visual attributes are processed separately within the brain. This separation is related to differences in the information that is relevant for the different attributes. When attributes differ greatly (such as colour and motion) it is obvious that they must rely on different information. However, separating the processing of different attributes could also allow highly related attributes to evolve independently, so that they end up being judged on the basis of different types of information. Here, we examine the case of egocentric and relative localisation. For judging egocentric positions, the orientation of the eyes has to be taken into account. This is not so for judging relative positions. We demonstrate that these two attributes can be processed separately by showing that simultaneous judgements of relative and egocentric position differ in their dependency on eye orientation. Subjects pursued a moving dot. We flashed either single targets, or pairs of targets with a 67 ms interval between them, directly below the subjects' gaze. As the eyes were moving during the 67 ms interval, the retinal separation between pairs of targets was different from their actual separation. Subjects indicated the position at which they saw the targets with reasonable reproducibility, with a consistent bias in the direction of the eye movement. However, when two targets were flashed, the indicated separation between them usually coincided with their retinal separation, rather than with their actual separation. We conclude that egocentric and relative spatial positions can be estimated separately and simultaneously, on the basis of different types of information.

Comparing extra-retinal information about distance and direction

The idea that extra-retinal information about the orientation of the eyes could be used to judge an object's distance has a long history, and has been the issue of considerable debate throughout this century. We here show that the poor performance in comparison with judgements of direction has geometrical rather than physiological reasons, and discuss why previous studies have misled us into believing that information about distance is even poorer than the geometry predicts.

Motion extrapolation is not responsible for the flash-lag effect

To achieve perceptual alignment between a flashed target and a moving one, subjects typically require the flashed target to be aligned with a position that the moving target will only reach some time after the flash (the flash-lag effect). We examined how the magnitude of this misalignment changes near an abrupt change in velocity. The magnitude of the misalignment turns out to depend on the target's velocity after, rather than before, the flash. Thus, the misalignment cannot be caused by motion extrapolation. Neither can it be the inevitable consequence of a difference between the time it takes to process flashed and moving stimuli, because the magnitude of the misalignment is influenced by the extent to which subjects can anticipate the flash. We propose that it is the consequence of having to 'sample' the moving target's position in response to the flash.

Hitting moving objects. The dependency of hand velocity on the speed of the target

In previous studies, subjects did not hit slowly moving objects as quickly as fast ones, despite being instructed to hit them all as quickly as possible. In those studies the targets moved at constant but unpredictable velocities, and it has been suggested that subjects were unable to adjust the hand's path to suit the velocity of the target. To compensate for this, they adjusted the speed of their hand to that of the target (speed coupling). According to this hypothesis, speed coupling is necessary only when subjects are unable to correctly predict the next target velocity and only if they have to be accurate. We show here that decreasing the uncertainty about the upcoming target's velocity or enlarging the tip of the hitting weapon does not make speed coupling disappear. Moreover, there is a negative correlation between hand velocity and strength of speed coupling, whereas the hypothesis predicts a positive correlation. The hypothesis is therefore rejected. We propose that speed coupling is a result of different speed-accuracy tradeoffs applying to different target velocities.

Masseteric nerve: a possible donor for facial nerve anastomosis?

In the medical treatment of facial nerve paralysis a large number of different techniques have been developed to restore the function of the facial nerve. These include (a) the ipsilateral nerve grafting (e.g., partial hypoglossal-facial, spinal accessory-facial, partial glossopharyngeal-facial), (b) crossfacial nerve grafting and (c) temporal muscle flaps or even free muscle transfers. None of these techniques uses the masseteric nerve as a graft for reconstruction of the facial nerve. This preliminary report deals with the anatomical basis, which could lead to a new technique. The masseteric nerve leaves the infratemporal fossa through the mandibular notch, accompanied by the masseteric artery. At this level the nerve consists in nine of 36 cases studied of only one branch (25.0%), in 17 cases of two branches (47.0%), in nine cases of three (25.0%), and in the remaining case of four branches (2.8%). There are three main reasons for considering the masseteric nerve as a possible donor for at least the orbicular branch of the facial nerve: (1) The approach to the mandibular notch is quite simple; (2) since the nerve consists of two or more branches in 75.0% of the cases, severe dysfunction of the masseter muscle should not occur; (3) if there is complete denervation of the masseter muscle, its function may be taken over by the temporalis muscle.

Interaction between the perceived shape of two objects

The difference between the way in which binocular disparity scales with viewing distance and the way in which motion parallax scales with viewing distance introduces a potential indirect cue for viewing distance: the viewing distance is the only distance at which disparity and motion specify the same depth. The present study examines whether this information is used. Two simulated ellipsoids were presented on a computer screen in complete darkness. The two ellipsoids were 6 degrees to the left and right of straight ahead. Subjects set the width and depth of each ellipsoid to match a tennis ball, and set the distance of the one on the right to half that of the one on the left. The distance of the left ellipsoid varied between trials. On half of the trials it was static. On the other half it was rotating up and down around its frontal horizontal axis. Rotating the left ellipsoid influenced its set depth: rotating ellipsoids were set to be much more spherical. There was no influence on the set depth of the other ellipsoid, or on the set width of either. The set distance of the right ellipsoid was also unaffected. We conclude that subjects do not combine binocular disparity and motion parallax to obtain more veridical information about viewing distance.

Anatomical study of the perforating vessels of the lower leg

Difficulty of soft tissue defects of the lower leg demands the development of new methods to treat such defects. The aim of this study is the examination of perforators and the various ways of blood supply to the skin in the lower leg. Provided with certain regularity, we would be able to cure soft-tissue defects also in the difficult zone of the distal segment and on the dorsum of the foot not harming vessels and not affecting mobility of muscles. Subcutaneous island-flaps supplied by perforating vessels could replace free flaps. By saving the crural fascia of 10 lower legs we flayed layers of skin and fat, marked the perforating vessels with pins, and photographed and documented them. Specimens were divided into a proximal, an intermediate and a distal segment, each of them subdivided into a medial, lateral and dorsal section. The perforators, which can be classified as septocutaneous and musculocutaneous vessels, followed a reproducible pattern all over the lower leg. All vessels were sufficient in number as well as in size. Additionally these perforators can easily be identified by colour-coded sonography. The knowledge that perforators in the lower leg occur regularly enables the development of a new operative approach in therapy of soft-tissue defects in this region with the advantage, that the vessels used can be selected preoperatively.

A new view on grasping

Reaching out for object is often described as consisting of two components that are based on different visual information. Information about the object's position and orientation guides the hand to the object, while information about the object's shape and size determines how the fingers move relative to the thumb to grasp it. We propose an alternative description, which consists of determining suitable positions on the object - on the basis of its shape, surface roughness, and so on - and then moving one's thumb and fingers more or less independently to these positions. We modeled this description using a minimum-jerk approach, whereby the finger and thumb approach their respective target positions approximately orthogonally to the surface. Our model predicts how experimental variable such as object size, movement speed, fragility, and required accuracy will influence the timing and size of the maximum aperture of the hand. An extensive review of experimental studies on grasping showed that the predicted influences correspond to human behavior.

Insertion of the abductor hallucis muscle in feet with and without hallux valgus

Textbooks of human anatomy present different opinions on the insertion of the abductor hallucis muscle which is concerned in etiology as well as in therapy of hallux valgus. In plastic and reconstructive surgery the muscle is taken as a graft for flap-surgery. In this study 109 feet (58 right, 51 left) were examined, 18 of these with clinical hallux valgus. The tendon of the muscle may attach to the tendon of the medial head of the short flexor hallucis muscle where a subtendineous bursa can be found. At the head of the first metatarsal bone the joint capsule is reinforced by fibres arising from the medial sesamoid bone which may be called "medial sesamoidal ligament." The tendon passes the first metatarsophalangeal joint plantarily to its transverse axis. Three types of insertion could be distinguished: type A, insertion at the proximal phalanx (N = 42); type B, insertion at the medial sesamoid ligament and at the medial sesamoid bone (N = 65); type C, insertion at the medial sesamoid bone (N = 2). In all types superficial fibres of the tendon extended to the medial and plantar sides of the base of the proximal phalanx, running in a plantar to dorsal direction. Statistical analysis exposed neither significant differences between both sides nor significant difference between normal feet and feet with hallux valgus. Therefore, a specific pattern of insertion of the abductor hallucis muscle in hallux valgus cannot be stated.

Perceived distance, shape and size

If distance, shape and size are judged independently from the retinal and extra-retinal information at hand, different kinds of information can be expected to dominate each judgement, so that errors in one judgement need not be consistent with errors in other judgements. In order to evaluate how independent these three judgments are, we examined how adding information that improves one judgement influences the others. Subjects adjusted the size and the global shape of a computer-simulated ellipsoid to match a tennis ball. They then indicated manually where they judged the simulated ball to be. Adding information about distance improved the three judgements in a consistent manner, demonstrating that a considerable part of the errors in all three judgements were due to misestimating the distance. Adding information about shape that is independent of distance improved subjects' judgements of shape, but did not influence the set size or the manually indicated distance. Thus, subjects ignored conflicts between the cues when judging the shape, rather than using the conflicts to improve their estimate of the ellipsoid's distance. We conclude that the judgements are quite independent, in the sense that no attempt is made to attain consistency, but that they do rely on some common measures, such as that of distance.

Hitting moving targets. Continuous control of the acceleration of the hand on the basis of the target's velocity

Previous studies on how we hit moving targets have revealed that the direction in which we move our hand is continuously adjusted on the basis of the target's perceived position, with a delay of about 110 ms. In the present study we show that the acceleration of the hand is also under such continuous control. Subjects were instructed to hit moving targets (running spiders) as quickly as possible with a rod. We found that changing the velocity of the target influenced the speed with which the rod was moved. The influence was noticeable about 200 ms after the target's velocity changed. The extent of the influence was consistent with a direct dependence of the acceleration of the hand on the target's velocity. We conclude that the acceleration of the hand is continuously adjusted on the basis of the speed of the target, with a delay of about 200 ms.

When is a background equivalent? Sparse chromatic context revisited

Jenness and Shevell (Vision Res 1995;35:797-805) reported that a red background with white dots scattered on it has a different influence on a target's apparent colour than an equivalent uniform background. We show that this finding depends on what one considers an equivalent background. Jenness and Shevell averaged the chromaticity and luminance of the background with the dots, and 'superimposed' the target onto this new background. This changed the luminance and chromaticity of both the target and the surround. We show that if only the surround is changed, it is irrelevant whether the latter is red with white dots scattered over it, or a uniform field with the same space averaged chromaticity and luminance. Our findings are consistent with a local contrast mechanism that has a limited spatial resolution.

[Use of the internal mammary artery in reconstructive microsurgery in the thoracic region: anatomical-radiologic study]

In this study, the topographic anatomy and the diameter of the internal mammary (thoracic) vessels was investigated in regard to their potential as a recipient vessel in reconstructive microsurgery in the ventral thoracic region. Particularly for reconstruction of large thoracic wall defects as well as for female breast reconstruction with free tissue transplantation, these vessels seem to be suitable due to their location. We performed an anatomical study on 86 cadavers and a radiological investigation on 50 female patients and volunteers. We found a mean diameter on 50 female patients and volunteers. We found a mean diameter of 1.8 mm of the artery and 2.1 mm of the commitant vein at the level of the fourth rib, one to two centimeters parasternally. We conclude that the internal mammary vessels can serve as recipient vessels in reconstructive microsurgery in the ventral thoracic region at the level of the fourth rib or cranially. Hypothetically, free muscle flaps for the treatment of sternal osteitis, free fasciocutaneous flaps to replace presternal burn scars or appropriate flaps to fill up a funnel chest cavity subcutaneously may be anastomosed to the internal mammary vessels.

Judging distance from ocular convergence

Subjects misjudge distances considerably when forced to rely on extra-retinal information. Nevertheless, they can reproducibly set a target to the same distance as a reference, or to double or half that distance, even when they have to look back and forth between them because they are prevented from seeing one when looking at the other. Our explanation for this apparent discrepancy is that people have access to reasonably accurate extra-retinal information on changes in ocular convergence, but can only use this information to judge distances if they had reliable information about the orientation of the eyes before the convergence changed.

Fast Responses of the Human Hand to Changes in Target Position

If a target toward which an individual moves his hand suddenly moves, he adjusts the movement of his hand accordingly. Does he use visual information on the target's velocity to anticipate where he will reach the target? These questions were addressed in the present study. Subjects (N = 6 in each of 4 experiments) were instructed to hit a disk with a rod as soon as it appeared on a screen. Trajectories of the hand toward stationary disks were compared with those toward disks that jumped leftward or rightward as soon as the subject's hand started moving toward the screen, and with those in which either the disk or the background started moving leftward or rightward. About 110 ms after the disk was suddenly displaced, the moving hand was diverted in the direction of the perturbation. When the background moved, the disk's perceived position shifted in the direction in which the background was moving, but the disk appeared to be moving in the opposite direction. When hitting such disks, subjects adjusted their movement in accordance with the perceived position, rather than moving their hand in the direction of the perceived motion in anticipation of the disk's future displacement. Thus, subjects did not use the perceived velocity to anticipate where they would reach the target but responded only to the change in position.

Management of ingested foreign bodies within the appendix: a case report with review of the literature

A case is reported of an elective appendectomy in a patient with known ingestion of a sharp foreign body. The metal drill bit was ingested unintentionally 3 months before presentation at our institution. Plain abdominal films demonstrated the foreign body in the right lower abdominal quadrant. Because the gold dental drill bit was sharp and thought to be lodged in the terminal ileum or cecum, an attempt was made to remove the object during colonoscopy. This attempt was unsuccessful because no drill bit could be detected in the colon or terminal ileum. A laparoscopic exploration was performed, and the foreign body was found to lie in the appendix, after bowel manipulation under fluoroscopic guidance and with direct laparoscopic visualization. A laparoscopic assisted appendectomy was performed. On pathologic examination the drill bit was embedded in the tip of the appendix with signs of intramucosal acute inflammation. Management and indication for surgery of foreign bodies in the appendix are discussed, and we review the related literature. This is the second reported case of a dental drill bit in the appendix causing appendicitis.

[The conservative and surgical therapy of traumatic humeral shaft fractures]

Sixty-three patients with humeral shaft fractures were evaluated clinically and radiographically 18 months after injury; 27 patients were treated surgically (group A) and 36 patients conservatively (group B). Analysis of the results according to a score by Kwasny revealed 6.2 points in group A and 2.2 points in group B (P < 0.0001; F = 46.9). The results of these two comparable groups suggest that conservative treatment of humeral shaft fractures is superior regarding mobility of the shoulder and elbow, strength, the incidence of neurological complications, pain, subjective rating and cosmesis. There were no differences on roentgenograms between the two groups (P = 0.48).

Holding an object one is looking at: kinesthetic information on the object's distance does not improve visual judgments of its size

Visual judgements of distance are often inaccurate. Nevertheless, information on distance must be procured if retinal image size is to be used to judge an object's dimensions. In the present study, we examined whether kinesthetic information about an object's distance--based on the posture of the arm and hand when holding it--influences the object's perceived size. Subjects were presented with a computer simulation of a cube. This cube's position was coupled to that of a rod in the subject's hand. Its size was varied between presentations. Subjects had to judge whether the cube they saw was larger than, smaller than, or the same size as a reference. On some presentations, a small difference was introduced between the positions of the rod and of the simulated cube. When the simulated cube was slightly closer than the rod, subjects judged the cube to be larger. When it was farther away, they judged it to be smaller. We show that these changes in perceived size are due to alterations in the cube's distance from the subject rather than to kinesthetic information.

Continuous Use of Perceived Velocity While Hitting Running Spiders

From previous studies examining how we hit moving targets we concluded that the speed and the direction of the hand are determined independently, the former being based on the perceived velocity of the target and the latter on its perceived position. It is known that the direction in which the hand moves is continuously adjusted on the basis of the perceived target position, with a delay of about 110 ms. In the present study we examined whether the speed of the hand is also under such continuous control, or whether it is determined in advance.

Subjects were instructed to hit targets (spiders) as quickly as possible with a rod. They were presented with moving targets that appeared at unpredictable moments on a screen in front of them. Some time within 400 ms of their appearing on the screen, the velocity of the target abruptly changed. We found that this influenced the speed with which the rod hit the target as long as the change occurred at least 200 ms before the hit. Considering that the movement time of the hand was more than 200 ms, the perceived velocity must have influenced the speed of the hand during its motion. We conclude that the speed of the hand is continuously adjusted to maintain its relationship with the speed of the target.

Seroma as a common donor site morbidity after harvesting the latissimus dorsi flap: observations on cause and prevention

This prospective study reveals that the incidence of seroma formation after harvesting the latissimus dorsi muscle by scalpel is reasonably moderate. This incidence is lower when the resulting skin flaps are tacked to the underlying structures with resorbable sutures. In contrast, electrocautery dissection shows a significantly much higher rate of seroma formation, probably because of thermal injury of the wide fascial wound layers or the subcutaneous fat tissue. Fifty-eight patients were distributed among three groups. Within each group a specific way of latissimus dorsi muscle harvesting and donor site treatment was accomplished. The group of scalpel dissection and skin flap fixation to the underlying layers with additional tacking sutures shows the lowest rate of seroma formation (9.1%, N = 2) due to the avoidance of shearing effects. A clearly higher incidence is present in the group of scalpel dissection without tacking sutures (38.1%, N = 8), whereas seromas most frequently result after electrocautery dissection without skin flap fixation (80.0%, N = 12).

Four issues concerning colour constancy and relational colour constancy

Four issues concerning colour constancy and relational colour constancy are briefly considered: (1) the equivalence of colour constancy and relational colour constancy; (2) the dependence of relational colour constancy on ratios of cone excitations due to light from different reflecting surfaces, and the association of such ratios with von Kries' coefficient rule; (3) the contribution of chromatic edges to colour constancy and relational colour constancy; and (4) the effects of instruction and observer training. It is suggested that cognitive factors affect colour constancy more than relational colour constancy, which may be an inherently more robust phenomenon.

The distance used for scaling disparities is the same as the one used for scaling retinal size

To determine the physical size and global three-dimensional (3-D) shape of an object, retinal size and retinal disparity have to be scaled in accordance with the object's distance. We examined whether the distance used for scaling retinal disparity is the same as the distance used for scaling retinal size. Subjects adjusted the 3-D shape (size and depth) of a computer-simulated ellipsoid to match a tennis ball. Analysis of the errors when only the ellipsoid was visible in an otherwise completely dark room suggests that the distance used for scaling retinal disparity is indeed the same as that used for scaling retinal size. This was confirmed by showing that the correspondence between the distance used for scaling retinal disparity and that used for scaling retinal size does not improve when more information about distance is available (room lights on), although both distances are then much closer to the simulated distance. Finally, we show that this correspondence is not due to the use of distance-invariant higher order binocular information.