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Feature Christmas 2010: Surgery

Middle ear instrument nomenclature: a taxonomic approach

BMJ 2010; 341 doi: https://doi.org/10.1136/bmj.c5137 (Published 13 December 2010) Cite this as: BMJ 2010;341:c5137
  1. John S Phillips, otology/neurotology fellow1,
  2. Matthew J Mason, lecturer2,
  3. Heather Dixon, student2
  1. 1Rotary Hearing Clinic, University of British Columbia, Vancouver, BC, Canada V6Z 1Y6
  2. 2Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
  1. Correspondence to: J Phillips john.phillips{at}mac.com

Starting from a common origin in the early 17th century, the divergent evolution of the English language between North America and Great Britain holds a great deal of interest for linguists, but is a source of confusion to the unwary traveller.1 An example of such confusion arose when the lead author of this article, trained in the UK as an otolaryngologist, found that his use of the term “crocodile forceps”—referring to the commonly used surgical instrument used to perform delicate middle ear surgery—met with bewilderment in US and Canadian hospitals (fig 1). There, as it turned out, the term “alligator forceps” was prevalent.

Figure1

Fig 1 Hartmann Alligator Micro-Forceps, model MCO13B. Manufactured by Microfrance Incorporated. Medtronic Xomed, Jacksonville, FL (reproduced with permission)

To avoid such communication problems, biologists maintain strict rules relating to their formal nomenclature. The earliest binomial for an organism, published within or since Carl Linnaeus’s Species Plantarum (1753; for plants) or the first volume of his 10th edition of Systema Naturae (1758; for animals), is by international convention considered to be the only valid name.2 On further investigation, however, an organism can be reclassified as belonging to a different genus, whereupon its scientific name can properly be changed.

In the interests of scientific clarity, a dispassionate investigation of the correct terminology for these forceps is clearly long overdue. We address this important issue both through establishing priority of nomenclature within the literature and through original investigations of jaw morphology. Modern crocodyliforms within the suborder Eusuchia appeared in the Cretaceous period3; this group includes the 23 extant species of alligators, crocodiles, caimans, and gharials. We chose to restrict our comparative focus to the two species living in the continental United States: the American crocodile, Crocodylus acutus, and the American alligator, Alligator mississippiensis. Both species inhabit Florida, where they are likely to be familiar to local clinicians.

Methods

We sought the earliest post-1758 uses of the terms “crocodile forceps” and “alligator forceps” using a web based literature search concentrating on medical textbooks and catalogues. We obtained representative specimens of the forceps in question (Microfrance Incorporated, Medtronic Xomed, Jacksonville, FL; n=13 models), and we compared measurements with those obtained from adult and juvenile skulls of C acutus (n=8) and A mississippiensis (n=12), from the collections of the University Museum of Zoology, Cambridge and the Natural History Museum, London. Snout width was measured between the positions of the most caudal teeth, while snout length was measured from the midpoint of the line connecting these teeth to the most rostral point on the snout. For the forceps, these measurements were made from the point of articulation at the most posterior tooth. Snout ratio was defined as snout length divided by snout width. We also counted the numbers of teeth in the upper jaws.

Results

The first use of the term “alligator forceps” recorded in the Oxford English Dictionary comes from Knight’s New Mechanical Dictionary,4 an American publication. We were able to extend the use of this term back to 1875, where it features in the urological work of WT Helmuth, professor of surgery in the New York Homeopathic Medical College.5 Alligator forceps were frequently referred to in the American urological literature after this date,6 7 and later appeared in otolaryngological sources from the other side of the Atlantic.8 The term “crocodile forceps” was in use at the same period, again first appearing in the American urological literature in 18759 and later the British otolaryngological literature.10 US army surgeons used modified versions of the forceps to remove arrowheads from wounds.11 The forceps were manufactured at around this time by companies including those of Louis Mathieu in Paris and George Tiemann and Company in New York. Nomenclature was evidently labile at first—some authors used both “crocodile” and “alligator” to describe the forceps8 12 13 (fig 2)—but over time “alligator” became much the more popular term worldwide: a Google search generated 67 600 hits for “alligator forceps” but only 5560 hits for “crocodile forceps”.

Figure2

Fig 2 “Crocodile lever ring forceps” as illustrated by MacNaughton Jones (1889). Reprinted with permission from The Lancet

Turning to the morphology (fig 3), the mean snout ratio in C acutus was 2.19 (SD 0.24, n=8); in A mississippiensis it was 1.59 (0.28, n=12). In the Microfrance forceps it was 5.58 (1.53, n=13 models). The number of teeth in the upper jaw of C acutus ranged from 17 to 19 (modal number 19), in A mississippiensis from 14 to 21 (20), and in the forceps it ranged from 11 to 27 (11).

Figure3

Fig 3 Dorsal view of the skulls of C acutus (spec. no. R6053; left) and A mississippiensis (spec. no. R6301; right), to illustrate the differences in snout morphology. Scale bar represents 10 cm. Specimens from the University Museum of Zoology, Cambridge

Discussion

Our literature search suggests that the terms “alligator forceps” and “crocodile forceps” appeared at around the same time, but “alligator” has become the preferred term worldwide. However, our morphological comparison shows that the snout ratio and the modal tooth number of the forceps are actually closer to that of the crocodile than to the alligator. The tooth number was very variable in the forceps, however, and is therefore not very informative.

Notably, even the lowest snout ratio observed in the forceps (4.69) was still almost twice the maximum found in any American crocodile (2.59). Such a long, pointed snout is actually more reminiscent of that of the gharial (Gavialis gangeticus), a rare crocodilian found on the Indian subcontinent (fig 4). In his study of crocodilian snout evolution Brochu states, “Some crocodyliform snouts resemble a pair of toothed forceps,”14 referring the reader to an illustration of the fossil gavialoid Thoracosaurus. Some important differences remain, however; notably the fact that in the forceps it is the upper jaw that moves, whereas in crocodilians—despite Aristotle’s assertions to the contrary in his History of Animals—it is the lower.

Figure4

Fig 4 Dorsal view of the skull of a juvenile gharial, Gavialis gangeticus (spec. no. R5793). Scale bar represents 10 cm. Specimen from the University Museum of Zoology, Cambridge

As Wilkinson has argued, the rule of priority must be flexible when applied to scientific ideas, which evolve over time.15 Mindful of this, and of the potential for offending the sensibilities of clinicians on one side of the Atlantic or the other, we propose that the ethnologically neutral and morphologically more accurate alternative name of “gharial forceps” should be introduced for these vital implements—subject to confirmation following a more detailed study.

Notes

Cite this as: BMJ 2010;341:c5137

Footnotes

  • We thank Matt Lowe of the University Museum of Zoology, Cambridge; Colin McCarthy of the Natural History Museum; and Jessica Rudd of Medtronic, Canada, for granting us access to their specimen collections. We also thank John Kirkup and Alan Humphries for help and advice regarding the history of scientific instrument manufacture. JP would like to thank B Westerberg and his team at St Paul’s Hospital, Vancouver, Canada for their inspiration.

  • Contributors: JP was involved in the concept, study design, research, and production of the text. MM and HD were involved in the study design, research, and production of the text. All authors have seen and approved this final version. JP is guarantor.

  • Competing interests: All authors have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; Medtronic was one of many companies that sponsored JP through his fellowship, this support was not conditional on producing any research or submitting any work for publication.

  • Provenance and peer review: Not commissioned; externally peer reviewed.

References

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