Venous outflow of the leg: Anatomy and physiologic mechanism of the plantar venous plexus

AbstractPurpose: Mechanisms of venous outflow from the leg and foot have not been clearly defined. The purpose of this study was to evaluate the anatomy and physiologic mechanism of the plantar venous plexus and its impact on venous drainage from the tibial veins.Methods: Fifty phlebograms that contained complete foot and calf films were reviewed. On lateral films, the number of veins in the plantar venous plexus and its tibial outflow tract were counted. The length and diameter of the longest vein in the plantar venous system and the length of the foot arch were measured. The ratio of the length of the plantar venous plexus to the arch length was calculated. The presence or absence of valves within the plexus was recorded. Plantar venous plexus outflow was evaluated by an duplex ultrasonographic scan of the posterior tibial, anterior tibial, and peroneal veins during intermittent external pneumatic compression of the plantar surface of the foot.Results: The plantar venous plexus was composed of one to four large veins (mean, 2.7 veins) within the plantar aspect of the foot. The diameter of these veins was 4.0 ± 1.2 mm. The veins coursed diagonally from a lateral position in the forefoot to a medial position at the level of the ankle, spanning 75% of the foot arch. Prominent valves were recognized within the plantar veins in 22 of 50 patients. The plexus coalesced into an outflow tract of one to four veins (mean, 2.5 veins) that flowed exclusively into the posterior tibial venous system. Small accessory veins that drained the plantar surface of the forefoot flowed into either the posterior tibial or peroneal veins. This pattern of selective drainage of the plantar venous plexus was confirmed by duplex imaging. Mechanical compression of the plantar venous plexus produced a mean peak velocity in the posterior tibial veins of 123 ± 71 cm/sec, in the anterior tibial veins of 24 ± 14 cm/sec, and in the peroneal veins of 29 ± 26 cm/sec.Conclusions: The plantar venous plexus is composed of multiple large-diameter veins that span the arch of the foot. Compression of the plantar venous plexus, such as that which occurs during ambulation, is capable of significantly increasing flow through the posterior tibial venous system into the popliteal vein. Its function may be integral to venous outflow from the calf and priming of the more proximal calf muscle pump. (J Vasc Surg 1996;24:819-24.

Energy relations of winter roost-site utilization by American goldfinches ( Carduelis tristis )

American goldfinches ( Carduelis tristis ) were observed roosting in Colorado blue spruce ( Picea pungens ), which comprised part of a mixed stand of conifers. Their winter roost-sites were distally situated among the most densely-needled branches on the leeward sides of these trees. Heated and unheated taxidermic goldfinch mounts were placed within these sites and at the same height in an adjacent clearing. The radiative and convective characteristics of these locations were monitored simultaneously and compared to predicted power requirements of live goldfinches (based on laboratory calibration of heated mounts) and operative temperatures ( T e ; based on body temperatures of unheated mounts). The winter roost-sites significantly reduced radiative and convective heat exchanges between goldfinches and the environment. Based on body composition data for winter goldfinches, all but two birds sampled could endure a 15-h roost period at average overnight T e 's as low as-40°C. In contrast, if these birds were prevented from feeding the following day, only 30% could survive the imposition of a 39-h fast at average T e 's of-2°C. Winter roost-site selection may be more constrained by thermoregulatory considerations in small birds than in larger species.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47760/1/442_2004_Article_BF00379484.pd

Vicryl Mesh in Expander/Implant Breast Reconstruction: Long-Term Follow-up in 38 Patients

Background: Acellular dermal matrix has proven to be a useful adjunct in tissue expander or direct-to-implant breast reconstruction. Although versatile, acellular dermal matrix adds considerable cost. Vicryl (polyglactin) mesh has an established track record in many fields of surgery, and is considerably less costly than acellular dermal matrix. This study examines the use and long-term follow-up of Vicryl mesh in breast reconstruction. Methods: Vicryl mesh was used in 46 breast reconstructions (38 patients; 35 immediate and three delayed). The mesh was used along the inframammary fold to maintain position of the inferior pectoral edge, and/or along the lateral border to maintain expander position and prevent lateral migration. Eight breasts received adjuvant radiation therapy. Results: Mean follow-up at the time of review was 43 months. In the nonirradiated group (38 breasts), there was one postoperative infection (2.6 percent), which required expander removal. In the irradiated group, there were three complications requiring expander removal (37.5 percent): two infections and one device exposure after irradiation. Significant malposition was not observed in any breast where Vicryl mesh was used, and no visible mesh remained at the time of implant placement. The incidence of symptomatic capsular contracture in nonirradiated breasts was 3.2 percent. At latest follow-up, nonirradiated breasts had an average Baker capsule grade of 1.1, compared with 1.5 in the irradiated group. Conclusions: Vicryl mesh is an effective alternative to acellular dermal matrix in nonirradiated breast reconstruction and is available at approximately onetwentieth the cost. Acellular dermal matrix or full muscle coverage may be preferable in irradiated reconstructions

Quantitative morphological analysis of the sensory epithelium of the starling and pigeon basilar papilla

Several features of bird basilar papilla morphology were quantitatively studied in the starling and the pigeon in order to attempt a structure-function correlation. We confirmed and quantified several findings from earlier studies, but also obtained results contradictory to previous reports. The greatest discrepancies concerned the pattern of hair cell orientation. By including the results from other investigations, we describe a 'typical' avian basilar papilla and on this basis the specializations within individual species. These morphological specializations are discussed in the context of the available physiological data

Basilar papilla of the canary and zebra finch: A quantitative scanning electron microscopical description

Morphological parameters of the apical surface of canary and zebra finch basilar papillae were quantitatively evaluated by scanning electron microscopy. The papillar length is 1.6 mm in both species. The zebra-finch papilla has a larger number of hair cells and is wider in the apical half of the papilla as compared to the canary. These two small songbird species have the smallest number of hair cells and the smallest papillae of the bird species investigated to date. The orientation of the hair cells is much more homogenous as compared to other species. Also, the discrepancy in the number of stereovilli of neural and abneural hair cells is much larger than in other bird species. A detailed analysis of gradients across the papilla in the canary revealed that anatomical parameters change in the neural half, whereas they remain rather constant in the abneural half of the papilla. There were, however, no obvious borders that separated distinct hair cell populations in either species