Summary 1. Tendons are a specialized form of connective tissue uniting muscle and bone and as such have functions essential to normal mobility. 2. The structural unit of tendon is the fibre, up to 300 µ in diameter, consisting of fibrils of collagen, encircled by the anastomosing processes of fibroblasts. Fibres are arranged in fasciculi but may pass from one to another so that successive cross‐sections show slightly different appearances. Such interweaving ensures the equal distribution of muscular tension over the whole area of insertion, particularly where the movement of a joint alters the angle between tendon and bone. 3. There are two hypotheses concerning the nature of the muscle‐tendon junction. First, the tension developed within a muscle fibre might be transmitted to the helical perisarcolemmal fibres of connective tissue surrounding its length and thence to the tendon, and secondly, and more probably, the tension might be transmitted directly from the end of the myofibrils to the interdigitating fibrils of the tendon. The interdependence of muscle and tendon is further illustrated by their longitudinal growth since the changing length of the muscle belly relative to the distance between the bony attachments determines the rate of growth and relative length of tendon. 4. The orientation of fibrous tissue in the tendon supports the hypothesis of a mechanical influence upon tendon growth, but there is no strict relationship between muscle strength and tendon thickness and various muscles differ in the ratio of their total fascicular cross‐sectional area to tendon thickness. It would appear that this difference develops post‐natally and, since a red postural muscle has a relatively thick tendon, it has been suggested that the duration as well as the level of transmitted tension might influence the growth of collagen. 5. Tendon thickness may increase proportionately with muscle cross‐sectional area in conditions which cause the muscle to hypertrophy, but when the muscle is de‐nervated or excised in the young animal growth of tendon thickness occurs in such a manner as to suggest that the growth of collagen is determined by the history of the total tension transmitted. 6. The tendon has a tensile strength which is probably four times as great as the maximum tension that it has to transmit in vivo and an even greater margin of safety is present in penniform muscles which transmit less maximum isometric tetanic tension per unit fascicular cross‐sectional area than do fusiform muscles. Although the wave form seen on the surface of a tendon when at rest is eliminated by less than 10 % of the maximum tension which its muscle is liable to transmit, it is possible that the normal range of tensions transmitted in vivo might fall within that part of the stress‐strain curve where the tendon is still easily extensible.
Necrotizing soft tissue infections represent a group of highly lethal infections best treated by early and repeated extensive debridement and broad-spectrum antibiotics. Hyperbaric oxygen appears to offer the advantage of early wound closure. Certain markers predict those individuals at increased risk for multiple-organ failure and death and therefore assist in deciding allocation of intensive care resources.
The present investigation was designed to examine the influence of water temperature and prior hyperventilation on some of the potentially hazardous responses evoked by immersion in cold water. Eight naked subjects performed headout immersions of 2-min duration into stirred water at 5, 10, and 15 degrees C and at 10 degrees C after 1 min of voluntary hyperventilation. Analysis of the respiratory and cardiac data collected during consecutive 10-s periods showed that, at the 0.18-m/s rate of immersion employed, differences between the variables recorded on immersion in water at 5 and 10 degrees C were due to the duration of the responses evoked rather than their magnitude during the first 20 s. The exception to this was the tidal volume of subjects, which was higher on immersion in water at 15 degrees C than at 5 or 10 degrees C. The results suggested that the respiratory drive evoked during the first seconds of immersion was more closely reflected in the rate rather than the depth of breathing at this time. Hyperventilation before immersion in water at 10 degrees C did not attenuate the respiratory responses seen on immersion. It is concluded that, during the first critical seconds of immersion, the initial responses evoked by immersion in water at 10 degrees C can represent as great a threat as those in water at 5 degrees C; also, in water at 10 degrees C, the respiratory component of this threat is not influenced by the biochemical alterations associated with prior hyperventilation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.