Anatomical landmarks for ankle block.

We aimed to describe anatomical landmarks to accurately locate the five nerves that are infiltrated to accomplish anaesthesia of the foot in an ankle block. Twenty-four formaldehyde-fixed cadaveric ankles were studied. Photographs of cross sections of the frozen legs, cut at a horizontal plane across the most prominent points of the medial and lateral malleoli, were analysed. The curvilinear distance from the most prominent point of the closest malleolus to each of the five cutaneous nerves and their depth from the skin surface were measured. Sural, tibial, deep peroneal, saphenous and medial dorsal cutaneous nerves were located 5.2 ± 1.3, 9.2 ± 2.4, 7.4 ± 1.9, 2.8 ± 1.1, 2.1 ± 0.6 mm deep to the skin surface. The curvilinear distances from the medial malleolus to the tibial, deep peroneal and saphenous nerves were 32.5 ± 8.9, 62.8 ± 11.1 and 24.4 ± 7.9 mm, respectively. The curvilinear distances from the lateral malleolus to the sural and medial dorsal cutaneous branches of superficial peroneal nerves were 27.9 ± 6.3 and 52.7 ± 7.3 mm, respectively. The deep peroneal nerve was found between the tendons of the extensor hallucis longus and the extensor digitorum longus in the majority of specimens, while the medial dorsal cutaneous nerve was almost exclusively found on the extensor digitorum longus tendon. The sural and tibial nerves were located around halfway between the most prominent point of the relevant malleolus and the posterior border of the Achilles tendon. In conclusion, this study describes easily identifiable, palpable bony and soft tissue landmarks that could be used to locate the nerves around the ankle.

An anatomic basis for volumetric evaluation of the neck.

BACKGROUND: A better understanding of volume distribution between the superficial (subcutaneous) and deep (subplatysmal) planes of the neck may be useful when deciding on the best course of management for patients presenting for cervical contouring. OBJECTIVES: The authors investigate the normal distribution of fat in the superficial and deep planes of the neck in a cadaver model, to determine the proportion of the submandibular gland that contributes to submental fullness. METHODS: Fat in the superficial and deep neck planes of 29 adult cadavers was dissected and weighed. The submandibular glands were also dissected and the cervical portion of each gland was shaved off, weighed, and compared to the weight of the whole gland. RESULTS: The mean weight of superficial fat collected from the specimens was 15.0 g in males (n = 14; range, 2.2-35.7 g) and 14.3 g in females (n = 15; range, 1.6-37.3 g); the mean weight of subplatysmal fat was 5.5 g in males (range, 1.3-15.2 g) and 3.7 g in females (range, 0.6-15.1 g). Mean weight was not statistically significantly different between the sexes, nor between the 2 racial/ethnic groups (Caucasian, n = 14; Southeast Asian, n = 15). Approximately 40% of the submandibular gland was found to lie inferior to the lower border of the mandible in the specimens examined. The authors found no anatomical evidence of submandibular gland ptosis, even in the oldest specimens. CONCLUSIONS: The study provides a comprehensive analysis of the distribution of adipose tissue in the superficial and deep planes of the neck, as well as the contribution of the submandibular glands to submental volume. This objective evaluation of neck volume may help guide clinicians in the surgical planning process and provide a foundation for designing new cervicofacial rejuvenation techniques.

Development of a high pressure automated lag time apparatus for experimental studies and statistical analyses of nucleation and growth of gas hydrates.

Nucleation in a supercooled or a supersaturated medium is a stochastic event, and hence statistical analyses are required for the understanding and prediction of such events. The development of reliable statistical methods for quantifying nucleation probability is highly desirable for applications where control of nucleation is required. The nucleation of gas hydrates in supercooled conditions is one such application. We describe the design and development of a high pressure automated lag time apparatus (HP-ALTA) for the statistical study of gas hydrate nucleation and growth at elevated gas pressures. The apparatus allows a small volume (≈150 µl) of water to be cooled at a controlled rate in a pressurized gas atmosphere, and the temperature of gas hydrate nucleation, T(f), to be detected. The instrument then raises the sample temperature under controlled conditions to facilitate dissociation of the gas hydrate before repeating the cooling-nucleation cycle again. This process of forming and dissociating gas hydrates can be automatically repeated for a statistically significant (>100) number of nucleation events. The HP-ALTA can be operated in two modes, one for the detection of hydrate in the bulk of the sample, under a stirring action, and the other for the detection of the formation of hydrate films across the water-gas interface of a quiescent sample. The technique can be applied to the study of several parameters, such as gas pressure, cooling rate and gas composition, on the gas hydrate nucleation probability distribution for supercooled water samples.

Fluorescence spectra in lung with porphyrin injection.

The fluorescence emission spectra from human bronchial mucosa and tumors, before and after injection of dihematoporphyrin ether/ester, have been measured with an optical multichannel analyzer from 500 to 750 nm. Fluorescence was excited with a violet krypton ion laser (average wavelength 410 nm). The autofluorescence spectra decrease monotonically with increasing wavelength except for a small broad peak near 600 nm. The spectra from tumor sites, after injection of the fluorescent porphyrin, exhibit the characteristic fluorescence emission at 630 and 690 nm, added to the autofluorescence spectrum. The spectra from control or nontumor sites are similar but the magnitude of the component due to the injected porphyrin is smaller than at a tumor site. The magnitude ratio of tumor to control site fluorescence depends on concentration of the porphyrin, tumor thickness, and time after injection. Autofluorescence degrades contrast and thus makes very thin tumors difficult to image. Subtraction of the autofluorescence background is desirable.