目录
这是一篇发表在Clinical Anatomy的文章: The historical evolution of the understanding of the submandibular and sublingual salivary glands – PubMed，文章对舌下腺和颌下腺的解剖发现历程进行了回顾。
Abstract
The discovery of the major salivary glands was primarily a story of the establishment of the glands major excretory ducts. Occurring during the Renaissance: religious, political, and philosophical considerations played a role in defining the structure’s function. We describe the history and background of these political, religious, and philosophical factors. Next, we present a translation of the original texts, describing the establishment of the submandibular and sublingual salivary glands. We place these translations into historical context and comment on their naming propriety. Initially we translate the works of the 15th century anatomists. Next, we look at the discovery and description of the submandibular gland’s duct by Thomas Wharton (1614–1673) in his landmark book, Adenographia sive glandularum totius corporis descriptio (Adenographia or the description of the glands of the entire body) (1656). Next, the somewhat unexpected discovery of the duct of the parotid gland by Nicholas Stenson (1638–1686) and his publication, De glandulis oris et novis earundum vasis (On the glands of the mouth and their new ducts) (1661), done primarily for his discussion of the submandibular and sublingual gland anatomy. Finally we outline the description and discussion by Caspar Bartholin (1655–1738), in De ductu salivali, hactenus non descripto observatio anatomica (Anatomical observation of a salivary duct not hitherto described) (1685) of the origin of the complex drainage system of the sublingual gland. The honor of naming these glands rested with the discoverer of their ducts. All original works were published in Latin, and we have translated these texts to more fully understand the author’s perspectives and historical context for a more interesting and complete story.
Introduction
The anatomical establishment of the major salivary glands occurred between 1650 and 1685, toward the end of the Renaissance. The establishment of much of the structural anatomy of the human body had occurred since the introduction of systematic human dissection in the 15th century by Andreas Vesalius (1514–1564), and others. We begin with a review of the state of the art knowledge of the anatomy of the major salivary glands from the mid sixteenth century to the mid seventeenth century when the Adenographia was published by Wharton (1614–1673), translating several major anatomists’ writings on the major salivary glands from this period. These include the works of Andreas Vesalius (1514–1564), De humani corporis fabrica (1543); Realdus Columbus (1516–1559), De re anatomica(1558); William Harvey (1578–1657), The anatomical lectures of William Harvey, Prelectiones anatomie universalis de musculis (1614); and Bartholomaeus Eustachius (1500–1574) from the plates published in the Tabulae anatomicae (1714) of Johannes Maria Lancisius (1654–1720).
The Latin and Greek terms for a gland come from the words to describe an ‘‘acorn.’’ Galen mentions the ‘‘glands’’ of the mesentery, but Merke (1984) states that Galen’s descriptions are at times confused and that he probably had no concept of the glands as a separate functional entity. A curious paragraph, however, is quoted in Merke’s book History and Iconography of endemic goiter and cretinism, taken from Galen’s De Voce et anhelitu, Complete Edition Basileae 1562 (Merke, 1984, p. 84):
Collum autem habet duas glandulas, in quibus generatur humiditas. In epiglottide vero generatur humor phlegmaticus viscosus ad hoc, ut humectat illa instrumenta. Sed ex duabus glandulis, quae sunt in collo, et ex corpore, quod est in epiglottide, non perveniunt venae, in quibus currit humor, sicut perveniunt ex duabus glandulis linguae. Sed illae, quae sunt in collo sunt in natura spongiae, ex quibus pertransit humor ille, qui currit superne deorsum, sine hoc, quod indigeat eis, aut sint ei necessariae venae, in quibus currat. . .
The neck, however, has two glands in which fluid is produced. However, in the epiglottis (larynx) a viscous, heavy fluid is produced for the purpose of moistening those instruments (larynx). But no ducts with fluid running in them come from the two glands which are in the neck and from the material which is in the epiglottis (larynx) in the way ducts come from the two glands of the tongue. But those which are in the neck, are of a spongy nature, through which percolates that humor which runs down from above, without this, because it lacks those or the ducts necessary in which it flows
On the one hand Galen seems to be stating it as a known fact, that the glands by the tongue, by which he must mean the submandibular and/or sublingual, have ducts and therefore must be salivary glands. On the other hand, by the other glands that moisten the larynx, he must mean the two lobes of the thyroid gland. This is consistent with our findings in studying the thyroid gland history. Galen, however, did not dissect humans, and further evidence for these ducts in humans did not appear to occur until the studies of Wharton, Stenson, and Bartholin. The most probable conclusion is that Galen refers to anatomical conditions witnessed in the dissection of animals. We must also keep in mind that here we see the text of Galen through the possibly distorting lens of a Latin translation out of the original Greek.
Another provocative paragraph appears in Bartholin’s writings, De Ductu Salivali, Hactenus non descripto Observatio Anatomica, (Anatomical Observations About the Saliva’s Duct, that has not to This Point Been Described), which we discuss later at greater length (Bartholin, 1685, p. 8–9):
Antiqui Medici, Galenus, Halii Abbas, Avicenna & Isaacus, qui quidem vasa salivae nobis aliquo modo indigitasse videntur, obscura admodum illorum nobis reliquerunt vestigia. Descripserunt vero illa accuratius inter recentiores Anatomici Celeberrimi Stenonius & Warthonus, quorum insuper diligentiae & hoc nostrum jam addimus Spicilegium.
The ancient physicians, Galen, Halii Abbas, Avicenna and Isaacus, who indeed some proclaimed to us to have seen the vessels of saliva, left faint traces of them for us. More recently, the very celebrated anatomists Stenson and Wharton have more accurately described those, and to their diligence I now add our results.
The Fifteenth Century Anatomists and the Concept of the ‘‘Salivary Gland’’
Nahlieli et al. credited Vesalius as the first to use the term salivary gland. Vesalius discusses the presence of ‘‘glands’’ in the Fabrica in several places including the abdomen and the neck. He also clearly recognizes that there must be different structures producing different types of secretions. Some secretions would be salivary and some thicker, perhaps to be used in vocalization. He also comments on the appearance and anatomical structure of these glands, as their structure may portend a different function (Vesalius, Fabrica, p. 578):
Huc quoque faciunt asperae arteriae ad laryngis radicem utrinque appositae glandes, humore siquidem meatum imbuunt, non fluido quidem, sed viscido et pingui, quemadmodum & ipsae crassiores spissioresque caeteris humorem procreantibus glandulis sunt.
Here also the glands are fashioned next to the rough artery on both sides at the base of the larynx, in that they wet the meatus, with a liquid, not runny but sticky and fat, just as they are also thicker and denser than the rest of the little glands that produce liquid.
He is referring above to the thyroid gland, although the duct to the larynx was, of course never found. He speculates below on what probably is the salivary gland, although he is not more specific (Vesalius, Fabrica, p. 389):
Neque perfecto sufficit Naturae, stomacho ductu eum modum obliquato ad uelocem ciborum transitum eas quas innuebam tribuisse fibras uerum ut ipsius concauitas semper humecta ac uelut uncta esset, glandulas adiunxit, alias quidem ad fauces, stomacho & laryngi communes, quae saliuam humoremque illis organis ne exiccentur, praeparantes, Latinis tonsillae appellantur.
Nor, to be sure, is it sufficient for nature to have granted those fibres which it has eaten to the stomach by a tube so inclined as to facilitate the swift transit of food, but it also added glands in order that its cavity might be moistened and, as it were, lubricated. Some at the jaws, common to the stomach and the larynx, furnishing saliva and fluid to those organs so that they do not get dried out, are called tonsils in Latin.
Vesalius has rightfully concluded that the glands would be in the head and neck region to secrete the saliva into the mouth. In his description of the glands around the mandible he remarks that in apes these glands may be responsible for the production of saliva (Vesalius, Fabrica, p. 579):
Substantia costat alijs glandibus simili, at impensius fungosa, in hocque propria, ut saliuam procreet, acasperam arteriam & stomachum quoque cum tota oris amplitudine humectet. Has glandulas Graeci paqiaulia(此为希腊语，无法正确插入) vocarunt.
It resembles the other glands in its substance, while more spongy, and in this characteristic, in order to produce saliva, and moisten the trachea and stomach along with the entire length of the mouth. The Greeks called these glands pariathmia.
The final establishment of these glands as salivary would require the discovery of the duct system. This would need to wait until the next century.
Realdo Columbus was the first to devote a chapter or ‘‘book’’ to the subject of the glands. It was just two pages. Although much of the chapter reflects the intracranial fluid drainage and controversies he had with Vesalius’ concept of this drainage, he does have some interesting general considerations about glands (Columbus, 1559, p. 213):
Glandula nihil aliud est (ut ad eius descriptionem immediate deueniamus) quam corpus rotundum, oblongumque, quod plurimum est rarum, & poris refertum diuersis in locis varias ob causas positae fuere adenes, siue gladulae. est enim earum multiplex usus, aliae venis, & arteriis instar lectuli sternuntur, ut illas detineant, ne ue laedantur aliae ut sedes vacuas repleant; non enim datur in natura vacuum; aliae ut humiditates suscipiant, & contineant; ne ob motum loca exiccarentur; aliae ut excrementa suscipiat atque id genus glandulas, siue adenes in variis corporis nostri partibus reperias.
The gland is nothing other (to come immediately to its description) than a round oblong body, which for the most part is of a loose texture, & filled with pores. The glands were placed in different places for different reasons. Their functions are diverse: some are scattered with veins and arteries like a bed, to hold things in place; others function to keep things from suffering damage; others fill an empty space: indeed in nature there is no vacuum; others take up and contain fluids, in order that a location not dry up on account of movement; others function to collect discharge. You could find this type of glands (glandulas), or ‘adenes’ in the various parts of our bodies.
Glands fill space, protect, and take up secretions. As Vesalius implied a decade or so earlier, glands may exist to produce secretions like saliva. In addition, this teleological viewpoint of ‘‘Nature’’ as always working toward a purpose and perfection was extremely important to the anatomists of the sixteenth and seventeenth centuries. Nature and religion become paramount in the anatomist’s view concerning the function of these glands. The protestant reformation and the Catholic Church’s counter-reformation played an interesting role in defining this function. We (Lydiatt and Bucher, 2010, 2011) have discussed it previously. A century later Wharton took a mostly Aristotelian look at the function and purposes of these glands, that is to say he described what he saw from his dissections, and therefore, for a gland to be established as a salivary gland, the excretory duct would need to be found. We discuss this more fully below in the sections dealing with the specific glands.
Columbus states the following about the thyroid and its effects on the voice (Columbus, 1559, p. 213):
Binas alias glandulas habet pharynx paristhmias dictas cerebri humiditatem suscipientes, partesque illas humectantes, qua humectatione maxime indigent, cum continenter laborent nobis nunc loquentibus, nunc edentibus, aut inspirantibus, aut expirantibus.
The pharynx has two other glands called paristhmian, which take up the fluid of the brain and moisturize those parts with the fluid they particularly lack, since they work continuously, now as we speak, now as we eat, or inhale, or exhale.
This was part of a larger ongoing argument with Vesalius about the thyroid gland and its function. Most anatomists of the time believed the thyroid contributed to lubrication of the larynx and thus the voice, but of course, an excretory duct was never found. Other glands, including the tonsils, were likewise a mystery as they had no discoverable duct, and therefore their function was in question. Columbus includes glands that may represent the tonsils or perhaps the submandibular glands in this category (Columbus, 1559, p. 213):
Alias insuper sub radice linguae comperies, quae in nobis paruulae sunt, quarum eadem est cum praedictis utilitas.
You will discover the others above the base of the tongue, which are small in us, whose use is the same as those mentioned above.
The Seventeenth Century Anatomists and the Establishment of the Submandibular Salivary Glands
All the glands in the head and neck would have been candidates for inclusion as salivary glands. The thyroid gland and tonsils were thought at different times to produce saliva. William Harvey, writing seventy-five years later in the Prelectiones about the upper aerodigestive tract structures, included the following (Harvey, 1614, p. 222):
Fauces: uvula, tonsillae istae antiades, epiglottis, glottis, larinx et eius partes, os hyoides.
The fauces (throat): the uvula, tonsils, (that which is tonsils covered with a pellicle due to tonsillitis), epiglottis, the glottis, larynx and its parts, and the hyoid bone.
In his description of the fauces he comments on the tonsils as the origin of saliva. He makes no other references to the salivary glands that we found and this seemed to be the state of the art concerning knowledge of the salivary glands before the establishment of the excretory ducts (Harvey, 1614, p. 228):
Tonsillae, amigdalae, antiades, glandulae spongiosae circa radicem linguae ante aesophagi principium. Salivam ori ministrant. Hic plurima ulcera lue venere. Hic exit tota materia inunctione et corrodit aliquando unde cicatrice contrahuntur musculi masseteres.
The tonsils, amigdala (amygdala- almond), and antias, are spongy glands around the base of the tongue [lingual tonsils] and before the beginning of the esophagus [palatine tonsils]. They supply saliva to the mouth. Here are many ulcers from sexual affliction. Here all the material comes out, spreads out and sometimes has a corrosive effect from which the masseters are contracted by scarring, [he seems to be describing trismus caused by contracture or scarring of the muscles of mastication like the medial pterygoid].
The discovery of the submandibular gland duct and its description by Wharton was published in 1656 in the Adenographia. His description will be detailed below as well as his discussion as to why this must be a salivary gland. Wharton’s Adenographia was published as part of a systematic study of the ‘‘glands’’ of the body. Wharton had performed dissections and researched the topic as part of a Gulstonian lecture that represented a series of lectures partly establishing candidates’ credentials for inclusion into the London College of Physicians. Wharton delivered his lecture in 1652 (Freer, 1996). The Adenographia was published in 1656. In the book he established the term thyroid for that gland for the first time, advanced theories of glandular function and established the submandibular gland as a salivary gland by finding and describing the duct that bears his name.
The submandibular glands were known to exist for many years, but their function was unknown. A text written in 1714 by Johannes Maria Lancisius (1654– 1720) concerning anatomical studies done by Bartholomaeus Eustachius (1500–1574) points out in fact that Eustachius had included the submandibular glands in one of his copper plates produced over a century and a half previously, about the time Vesalius and Columbus were working. Eustachius’ anatomical studies resulted in several publications and ultimately 42 copper plates etched by Petrus Matthaeus Pinus. The first eight plates were published in 1564 in the Opuscula anatomica, but the entire group of 42 plates including the plates showing the submandibular glands was not published until 1714 in the Tabulae anatomicae, 58 years after the publication of the Adenographia. When Eustachius died in 1574, his scientific estate, including the copper plates, was deeded to Pinus. The plates were lost during the next century and a half. Lancisius discovered the plates and pointed out their relevance in his 1714 publication (Lancisius, 1714, p. 96):
Octavo: observatione dignum censemus, quod Auctor glandulam ad menti latera demonstravit 43. 17.
The eighth point: we think it is worthy of observation, that the author (Eustachius) showed a gland lateral to the chin. (Fig. 1)
Lancisius was an avid supporter of Eustachius’, and for reasons based on his religious beliefs, the importance of the function of an organ was thought to reflect the highest or ‘‘final cause’’ for which God or nature would have created that organ. Although these glands were known for many years, Lancisius was anxious for Eustachius, a previous and famous physician at the Sapienza, the Vatican University, to receive part of the credit for their discovery. Ultimately, however, the credit for establishing the true function of the gland would require the discovery of the duct to prove the salivary origin of the gland.
Wharton’s description of the submandibular gland is the most complete and informative on several levels. The maxillary glands as they were known at the time appear to have included both the submandibular/sublingual salivary glands and the facial lymph nodes (Wharton, 1656, p. 128):
Quarto maxillares glandulae vel in externas vel internas dividuntur. Externae exiguae admodum sunt & minoris momenti, sitae sunt exterius in media ferum longitudine maxillae inferioris, ubi exterior ramus arteriae carotidis, venaque jugularis externa, & ramus conspicuus nervi tertii paris in musculos faciei ascendunt.
Fourth, the maxillary glands are divided as external or internal. The externals are of very small size and of lesser importance, they are placed more outside, pretty much in the middle of the length of the lower maxilla, where the outer branch of the carotid artery, and external jugular vein & the conspicuous branch of the nerve of the third pair ascend into the muscles of the face.
The internal maxillary glands would represent the submandibular and sublingual salivary glands and the external glands the facial lymph nodes in today’s nomenclature. The external glands (facial nodes) are insinuated between and around the outer branch of the carotid (facial artery) and the external jugular (common facial vein). He also mentions the branch of the third nerve, which would represent the marginal branch of the facial nerve (seventh cranial nerve) in today’s designation. This is a good description of the lymphatic anatomy involving the inferior border of the mandible, the vascular structures, and the location of the marginal branch of the facial nerve.
The understanding of the function of the glands in general and the salivary glands in particular requires some background information. Andrew Cunningham (Freer, 1996) states that the mid-seventeenth century was a time of fresh interest in glands, and that Wharton’s book was a symptom of that interest. Glisson, a previously mentioned colleage and mentor of Wharton’s, had done recent work on the ‘‘lymphatics’’ and the role that nerves may have played in draining tissues. These lymphatics were newly discovered and the valves within the lymph vessels would imply that flow of any liquid would be one way and a corresponding vessel or method of flow would need to be hypothesized. This would be similar to the situation with arteries and veins that had been outlined by the landmark studies on the circulation of blood by Harvey (Whitteridge, 1964). Although no vessels within nerves had been identified, this was the pre-microscopic era. The nerves were, however, incident to all areas and could be candidates for efferent or afferent channels. Glisson had done much of the work with the liver and the lymphatics and Wharton had worked with him as discussed previously. Wharton considered and described the theoretical notion that the glands may be involved in removing wastes from tissues and nerves. He pointed out that the anatomical arrangement of the submandibular area makes this possible (Wharton, 1656, p. 128):
Credibile est, eas dicti nervi superfluitates aliquas excipere, & in venam proximam transmittere, qui pluriarum glandularum mos est.
It is possible, they removed some overflow of the said nerve, and that they transmit it into the nearby vein, which is the custom of most glands.
The anatomical arrangement of the nerves in the face may have predisposed it to more swelling with pathological conditions such as dental infections. The intimate relationship of the submandibular and sublingual salivary glands to the facial and submandibular lymph nodes and the lingual, hypoglossal and facial nerves makes this a plausible consideration.
Forsitan majore concitato fluxu per nervos ad faciem, quam qui per habitum parpercollari, perque lymphaeductus ad glandulum hanc remitti possit; facies subtumida apparet; nempe oedemaroso tumore inflari, quemadmodum frequenter cernimus in odontalgiae declinatione.
Perhaps the face appears a bit swollen because more flow is discharged through the nerves to the face, than that which could percollate through the tissues, and could be sent back through the lymph ducts to this gland; the face appears a little swollen, certainly to be puffed out with edematous swelling, just as we frequently see in the divergence of a toothache.
Wharton’s description of the internal maxillary (salivary) gland suggests a difference between it and the external maxillary glands (facial lymph nodes) and the parotid (salivary) gland. A gland’s function was frequently thought to be related to the glands appearance, and glands were classified according to size, texture and color. Again the definition of a true duct was the sine qua non of labeling the gland salivary (Wharton, 1656, p. 128):
Glandulae maxillares internae immediate intra maxillam inferiorem sitae sunt; Earum pars posterior, ubi parotidi & glandulis jugularibus appropinquat multo crassior & rotundior ist, ut & rubicundior;
The internal maxillary glands are positioned immediately within the lower maxilla; their posterior part, where they are close to the parotid & jugular glands is much thicker and rounder, and even ruddier;
In addition to breaking new anatomical ground by establishing the submandibular gland and its duct, Wharton had much to say about the glandular tissue that will later be known as the sublingual gland. We believe his description described the sublingual salivary gland for the first time. The establishment of the duct and thus the naming of the sublingual as a salivary gland was not usually considered established until the publication of Bartholin in 1685, described below. As we will see, however, he described and presaged very accurately a modern understanding of the complex ductal anatomy of the sublingual and submandibular glands. Wharton description continues with (Wharton, 1656, p. 128–129):
anterius progressa, paulatim attenuatur; media autem via, videtur primo aspectu ab anteriore parte quasi discontinuari & recedere, reipsa tamen exiguo ramento continuatur; dein vero nonnihil iterum crassescit & cunei instar inter maxillam & linguae musculos ad mentum usque protenditur.
As it goes forward gradually it becomes thinner; but half way along, first it seems at first sight to be sort of discontinuous from the anterior part and to be separated from it, yet in fact it is connected by a small branch; but then it thickens again somewhat and like a wedge, is extends between the mandible & the muscles of the tongue all the way to the chin.
Wharton will return to his description of this portion of the internal jugular glands. The description continued under the presumption that the submandibular and sublingual glands represented one complex. Next follows his original description of the submandibular duct, establishing this portion of the internal jugular glands as the submandibular salivary gland (Wharton, 1656, p. 129):
Habet arterias, venas, & nervos, item vas quoddam diversi generis sibi proprium: arterias a carotidibus; venas a jugularibus; nervos insignes a tertio praesertim, quarto & septimo paribus, anastomoses inter se evidentes habentibus.
It has arteries, veins, and nerves, also a certain vessel of a different type particular to itself: it contains arteries from the carotids; veins from the jugulars; nerves particularly notable from the third [trigeminal/ lingual], fourth [facial is V, IV was earlier part of trigeminal] & seventh [hypoglossal] pairs [of the cranial nerves] with anastomoses apparent between them.
Naming and numbering the cranial nerves has changed throughout history. According to Shaw (1992), Galen recognized the cranial nerves as paired structures, and although he worked from nonhuman species, he described the optic, oculomotor, and hypoglossal nerves. The trochlear, trigeminal, and abducent were problematic throughout history. Again, according to Shaw (1992), the trigeminal was not established as the fifth until Thomas Willis in 1664. Wharton may well have been adhering to the systems of Vesalius and Columbus, (Shaw, 1992), which considered the trigeminal the third and fourth, and the hypoglossal the seventh cranial nerves. Although Vesalius and Columbus (Shaw, 1992) considered the facial to be the fifth cranial nerve, Wharton may be considering the marginal branch of the facial to be part of the trigeminal and thus part of a fourth cranial nerve.
Wharton knew he was describing this duct for the first time and was therefore establishing the function of the gland for the first time as well (Wharton, 1656, p. 129):
Vas huic parti propruim, Anatomicis hactenus incognitum fuit. Verum haud difficulter in conspectum proferas si praemonitus advertas illud, ortum ducere e crassiore & posteriore huius glandulae parte; rectaque tendere mentum versus.
The vessel for this particular part has been hitherto unknown to Anatomists. But you will have no difficulty seeing, if you are forewarned and pay attention to it, seeing that it begins with the thicker & posterior part of this gland, and stretches straight toward the chin.
Next, Wharton described what must have been the multiple sublingual ducts that frequently join the submandibular duct. He does not seem to recognize the fact that these ducts come from the portion of the internal jugular glands that was ultimately called the sublingual gland (Wharton, 1656, p. 129):
Antequam vero ad anteriorem eiusdem partem pervenit, ramulos subinde novos ab eadem excipit; adeoque protenditur ad medium menti spacium, ubi immediate intra gingivas in papillam quamdam utrinque terminatur, qua se facile exoneret, nihil vero ab ore refluum admittat.
Before, however, it reaches to the anterior part of the same gland, it receives new small branches one after another from the same gland; and indeed extends all the way to the middle of the chin, where it ends immediately within the gingiva in a certain papilla on each side, by which it easily discharges itself, however, permitting nothing flowing back from the mouth.
This would not be unanticipated given the modern knowledge of the sublingual duct anatomy. The sublingual gland is classically described as having multiple small ducts that empty into the sublingual fold. Zhang et al. (2010) described the fact that the sublingual gland may empty into Wharton’s duct or have a single duct separate from Wharton’s and the sublingual fold. They studied the duct systems of the submandibular and sublingual glands in sixty sides of thirty cadavers and compared them to their clinical series that contained 63 patients with keratoconjunctivitis and had undergone submandibular duct transfers. They found only 23% of the cadavers and 10% of the patients in the clinical series to have a single separate duct from the sublingual glands. The remainder of the glands had a mixed anatomical arrangement with connections to the major submandibular duct and smaller ducts connecting directly to the floor of the mouth (Zhang, 2010). This arrangement is more in line with that described by Wharton than the later description of a single sublingual duct as proffered by Bartholin.
The following is from Wharton and is the discussion of the duct system. Some of the measurements probably indicate that some of the anatomy was not human. Leppi (1967) studied the relationships of the submandibular and sublingual glands in various monkeys and found that the relationships were less complex than in the human, but did vary considerably and were different between Rhesus and squirrel monkeys. The end result, however, was that Wharton recognized that the anatomy of the duct follows a complicated and variable course (Wharton, 1656, p. 130):
Vas hoc radices suas capillares in omnes hujus glandulae partes aequaliter spargit; & in aliquibus geminum ramum, in aliis plures ramulos emittit. Cum geminum; e glandulae capite, alter; altere causa prodit.
(Posterior ramus, spacio trium vel quatuor digitorum e glandula egreditur, priusquam cum anteriore caudice conjungitur.)
This vessel scatters its capillary roots into all parts of this gland evenly; & in some are sent out two branches, in others many branches. It appears that when it is two, one is from the head of the gland; the other from the other source.
(The posterior branch comes out from the little gland, with a span of three or four finger widths, before it is connected with the anterior trunk.)
The duct extends forward as Wharton’s duct, named above, in a more consistent fashion (Wharton, 1656, p. 131):
Hinc canalis dictus recta anterius tendit, & a linguae lateribus, nimirum in inferiore ejus parte, cute & pinguedine glandulosa tectus, ductu tredecim pollices longo provehitur, & inter gingivas in maxillae extremitate, inter ipsam & papillas quasdam compressas & rigidas ei pertinaciter adhaerentes in os aperitur, eidem quoties usus postulae humorem salivalem impertit.
From here the designated canal extends straight anteriorly, & by the side of the tongue, evidently in the inferior part of this, covered with membrane & glandular fat, it proceeds by a duct thirteen thumbs (inches) long, & opens out into the mouth within the gingival at the perimeter of the maxilla, between this & this certain papilla it is tenaciously compressed & rigid, and this imparts the liquid saliva as often as the use requires.
Caspar Bartholin (1655–1738) in De Ductu Salivali, Hactenus non descripto Observatio Anatomica, (1685) fully recognizes the importance of establishing the duct. We believe the complex anatomy of the sublingual ducts that Wharton had described, although more in line with modern concepts, differed from that described by Bartholin. We believe Bartholin considered his description to be more logical and anatomically correct and thus presented it as new. He hypothesized as to why his predecessors thought as they did (Bartholin, 1685, p. 8):
Et, ut alia taceam, certe fontes salivae & vasa illam ad cavitatem oris deducentia non plane ignota fuisse videntur veteribus, licet saltem quasi per nebulam observata. Non tamen ideo sua laus detrahenda est Recentioribus, qui ulterius progressi, manifestius has glandulas descripserunt, & vasa Salivalia ab illis prodeuntia in lucem protraxerunt.
And, to omit the rest, certainly the sources of saliva and the vessels leading it out toward that cavity of the mouth seem not to have been completely unknown to previous writers, rather as it were they saw it as though through a fog. Still due praise must not be withheld for this reason from the more recent writers. Who having progressed further clearly described these glands and they publicized the salivary ducts coming from them.
He recognized the ancients and then singles out Wharton and Stenson as being especially diligent (Bartholin, 1685, p. 8,9):
Descripserunt vero illa accuratius inter recentiores Anatomici Celeberrimi Stenonius & Warthonus, quorum insuper diligentiae & hoc nostrum jam addimus Spicilegium.
Indeed among the recent anatomists the most celebrated Stenson and Wharton have more accurately described those, to whose diligence I have now added this learning of ours.
Bartholin recognizes the complex anatomy of various glands emptying into the mouth, and this would presumably include the sublingual (Barthholin, 1685, p. 9):
Glandulae omnes, quae oris cavitati salivam subministrant, & ejusdem generis vasa excretoria in os emittunt, numero vasorum distincta accuratissime proponuntur a Stenonio in Observationibus Anatomicis de Glandulis Oris. Quaedam enim unico duntaxat excretorio vase praeditae sunt, quaedum pluribus. Illa vasa, quae numero plura, sed exigua, in oris cavitatem confluunt, propria sunt iis glandulis, quae varie sparsae reperiuntur in buccis sublingua, in palato & tonsillis.
All the glands, which supply the oral cavity’s saliva, and which emit their excretory ducts into the mouth are most accurately set out, distinguished by the number of ducts by Stenson in Anatomical Observations about the Glands of the Mouth. Indeed only certain ones are provided with one excretory duct, others have more. These vessels, which number many, but are small, flow together into the oral cavity, they are characteristic of those glands, those which are found, variously scattered in the mouth under the tongue (sublingual sulcus), in the palate, and the tonsils.
Bartholin gives credit to Stenson for the discovery of the parotid duct and then credits Wharton for the
discovery of the submandibular duct (Bartholin, 1685, p. 9):
. . . cujus primam delineationem Warthoni diligentiae debemus, quod a glandula maxillari inferiori provenit
. . . however, we owe this first delineation [of this duct], which comes from the inferior maxillary gland (submandibular) to the diligence of Wharton,.
Bartholin now seems to be describing the sublingual duct and insisting on a single duct as the true anatomical condition. This consideration along with the fact that Wharton never described the sublingual gland as a separate gland appears to encourage Bartholin to think his is the original description (Bartholin, 1685, p. 9,10):
Sed duobus illis hactenus descriptis vasis tertium, ejusdem plane generis, addi debet, jam primum, quantum quidem ego scio a me descriptum & delineatum, quodque inferius etiam dici meretur, quippe a sublinguali glandula ortum. Warthoni ductum comitatur, & sub lingua eodem, quo Warthonianum, loco aperitur, ostio aeque manifesto.
But to these two vessels described so far, a third must be added, of entirely the same type, it ought to have been added long ago, since it was described and drawn by me, and which also deserves to be mentioned below namely that it comes from the sublingual gland. It accompanies the duct of Wharton, and it opens up in that same place where Wharton’s duct opens up, with an opening which is equally obvious.
He believes Stenson has described this complex anatomy, but thinks it is inaccurate. Bartholin did not believe the small ducts described by Stenson and Wharton, the ducts of Rivinus, were from the sublingual gland. He believed they were from smaller separate glands and that Stenson had simply not identified the main duct from the sublingual gland, and therefore did not realize it was a separate gland. In the pre-microscope era this would be understandable, and Bartholin’s claims to be the first to describe and name the gland would be reasonable (Bartholin, 1685, p. 10):
Glandulam quidem, a qua tertium hoc vas originem repetit describit Stenonius de Gland Oris, & sublingualem nominat, sed illi immerito plura & angusta vasa excretoria tribuit, quae huic glandulae adjacentibus minutis aliis & ab ipsa reveram distinctis glandularum glomeraminibus jure debentur, quia scilicet verum hoc sublingualis glandulae vas excretorium nondum ipsi fuit perspectum.
Indeed, Stenson in the Glands of the Mouth [in Anatomical Observations about the Glands of the Mouth] describes again the gland, from which this third vessel arises, and he calls sublingual, but he assigned to it without justification many narrow excretory ducts, which are owed rightly to others tiny ones lying next to the sublingual gland and to groups of glands distinct from it, because this true excretory duct of the sublingual gland was not yet seen by him.
Bartholin quotes Stenson [italicized below] from De glandulis oris & novis inde prodeuntibus salivae vasis, page 27 (Bartholin, 1685, p. 10,11):
Est autem sublingualis haec glandula, quae tertium illum promit ductum, ex illarum genere, quae conglomeratae, recepta hactenus distinctione Sylviana, nominantur, sita utrinque ad latera linguae, & illi adjacent dispersae nonnullae glandulae minutae, quae angusta illa excretoria vasa obtinent, de quibus in sublingualium descriptione Stenonius, & quae a sublinguali hac glandula oriri credidit, ubi ita: Ejusdem generis cum proxime praecedentibus sunt (se sublinguales glandulae) nisi quod vasa excretoria obtinuerint, non quidem breviora, set angustiora.
However, this sublingual is that gland, which sends out this third duct, out of the type of those, which are called conglomerate (accepting Slyvius’ distintinction), situated on both sides [bilaterally] to the side of the tongue, and a number of scattered small glands lie next to it, which receive those small excretory ducts about which Stenson [says] in his discription of the sublinguals, and which he had believed to have arisen from this sublingual gland, (where he says this): They are of the same type as those mentioned immediately before [sc. sublingual glands] except that they receive excretory vessels, not shorter, but narrower.
Further, Stenson [italicized] states that (Bartholin,1685, p. 11):
Oriuntur intra ipsam exiguis rivulis, & hinc sibi invicem parallela, a lingua versus gingivas recedunt, ubi ad digiti fere a dentibus distantiam, vix conspicuis, nisi premantur, ostiis, per tunicam hiant. Nullae ostiis, nisi ad aliquod itervallum, protuberantiae adsunt, sed, ut in buccae vasis dictum, ubicunque vascula praedicta tunicam penetrant, ibi aequalis est & plana.
They arise within this same (sublingual) gland from small rivulets, and from here, mutually parallel to one another, they pass from the tongue toward the gingiva, where,about a finger’s breadth from the teeth, they open up through the tunic, though their mouths are barely visible, unless compressed. No protuberances are present to the mouths, except at some interval, but, as in the ducts in the mouth mentioned above, wherever the aforenamed vessels penetrate the tunica, it is level and flat.
Bartholin responded that when Stenson and indeed Wharton described many small ducts or rivlets coming out of the sublingual gland and draining directly into the floor of the mouth, they really were small ducts derived from many small glands next to the sublingual. Bartholin believed that a single duct from the sublingual gland drained into the mouth, but that it had not been previous discovered or described (Bartholin, 1685, p. 11, 12):
Recte quidem hic describuntur illi ductus, qui a parvulis glandulis ad latera sublingualium satis oriuntur; At habet ipsa sublingularis glandula peculiarem alium ductum, nondum descriptum, sed mihi primo observatum Anni 1682 d. 13. Martii. Etenim cum in capite Vitulino extremitate styli inquirerem & prosequerer ductum a glandula maxillari inferiori progredientem, a Warthono descriptum, forte in alium ductum adactus stylus aperuit ea quae mihi ante ignota erant. Credideram enim eundem ductum me ad Warthonianam glandulam perducturum, & ecce eo loco, circa mediam scilicet linguae longitudem,
Those ducts here are correctly described, which come from the little glands pretty much to the side of the sublinguals; On the other hand, the sublingual gland itself has its own peculiar duct, not yet described, but first observed byme on March 13, of the year 1682. In fact when I was exploring with tip of a stylus in the head of a calf and I was following the duct leading fromthe lower maxillary gland described by Wharton, by chance the stylus moved into another duct opened up those which had hitherto been unknown to me. I had believed that I was going to go through that same duct to the gland Wharton mentioned and behold in that place, that is to say, around themiddle of the length of the tongue (Fig. 2)
Although it appears, as we view the writings from the perspective of modern anatomy that Wharton and Stenson were correct in their descriptions to have included the small ducts extending from the sublingual gland to the floor of mouth or to Wharton’s duct, Bartholin was also correct in establishing a single duct to extend from the gland to an opening by the papilla of Wharton’s duct. As we have emphasized in this paper, the establishment of a duct was the sine quo non of a salivary gland.
It is interesting to note that the dissection in Figures 2 and 3 are that of a non-human specimen. Throughout the descriptions of the anatomy, the dissections of the salivary glands are frequently of a horse or cow or sheep. This would certainly have contributed to the confusion of the anatomy. We (Lydiatt and Bucher, 2010) have discussed the difficulties in limiting dissection to human specimens.
Wharton previously had discussed the fact that he felt obligated to discover the duct in order to truly call this gland salivary. After outlining information gained about this gland as to color, consistency, and taste, he writes the following about his experiences with his friend and mentor Glisson. His rationale for the use of an animal that was bigger and would presumably have bigger structures that they could more readily observe are interesting and again highlight the difficulties of working in the pre-microscopic era (Wharton, 1656, p. 130):
Quo certius hujus glandulae genium & usum deprehenderem ipsemet, praesente Collega nostro celeberrimo D. Glissono, aperui caput bovis, in quo sperabamus, ob animalis magnitudinem, omnia ut ampliora, ita conspicua magis futura essa; summa autem diligentia quaerebamus vas excretorium huic parti proprium, idque demum invenimus.
In order to discover more certainly the special function and use of this gland, I myself opened the head of a cow in the presence of our most celebrated college Dr. Glisson, in which I hoped, from the size of the animal, since all things are larger, that it would be all the more obvious; also we searched with the greatest diligence for the excretory duct which belongs to this part, and in the end we found it.
He had discovered the duct system for the maxillary glands (submandibular and sublingual) in humans and the cow. He also was able to see salivary flow from this animal’s gland, confirming it as a salivary gland (Wharton, 1656, p. 134):
Huiusmodi vero humorem ex hac glandula per suum vas in os expui oculari experientia testari possumus. Enimvero in partis (partibus) hujus canali, tam in homine, quam in bove, & humorem salivalem manifeste deprehendimus, neque quicquam praeterea inerat.
Truly we have been able to testify by the experience of our own eyes that a humor of this type is expelled from this gland through its own vessel into the mouth. Certainly in the area of this channel, as in man, so, too, in a cow, we have also noted fluid saliva, nor was there anything else inside it.
Wharton confirmed this structural relationship in the horse, and commented about other glands that also discharge into the duct (Submandibular duct). These glands may be minor glands or may have been the associated ducts of the then unnamed sublingual gland. Wharton wondered how further comparative anatomical studies would contribute in the future (Wharton, 1656, p. 131, 132):
In equo circa mediam linguae longitudinem utrinque aliae glandulae conspicuae in ductum salivalem sese exonerantes occurrunt. De quibus forsan uberius dicetur posthac, cum earum varitates in caeteris animalibus examinatae fuerint.
In a horse other conspicuous glands occur on both sides around the middle of the tongue, discharging themselves into the salivary duct. Perhaps more will be said about this in the future when the varieties of these glands have been examined in other animals.
To this end Wharton has found a single excretory duct from the submandibular gland, but also seems to have accurately described the complex variations in the sublingual gland duct system. This appears to represent the first description of the sublingual gland. Although credit for the discovery of the sublingual gland is generally given to Bartholin for his 1685 publication as he himself indicates in the passage translated above, we think Wharton’s description below rightfully supports him as the original discoverer (Wharton, 1656, p. 130, 131):
Anterior ramus mox ab egressu extrorsum fertur versus glandulam quandam minorem, sitam inter intimam maxillae partem, & hanc glandulam majorem; estque diversi generis, cineritii coloris, substantiae compactioris, minusque granulatae, & figurae ovalis, quae interno latere impressura levi & rotunda excavatur, e qua prodit, vas peculiare, quod recta fertur, & in glandulam hanc maxillarem distribuitur circa locum dictum.
Next the anterior branch is carried out from the mouth toward a certain smaller gland, positioned between the innermost part of the maxilla, & that larger gland; and it is of a different type, of an ashen color, a more compact and less granular, & an oval shape which on the internal side which is hollowed out with a slight & round impression, from which, a peculiar vessel, projects which is carried straight, & is distributed into this maxillary gland around the area mentioned.
Wharton continued by describing the anatomy in more detail, further presaging more modern thoughts on the submandibular and sublingual gland duct anatomy (Wharton, 1656, p. 131):
Simulac vero e glandulae substantia prodiit, fertur sub musculo maxillari tereti biventri, vel digastrico, qui eidem ramo quasi trochlea vicem praestat: Exinde reflectitur fere ad glandulae medium, ubi cum anteriore ramo descripto & pluribus ramulis eidem quasi sociis, unitur; & inde canalis communis ex horum concursu aliquanto auctior redditur.
But as soon as it goes out from the substance of the gland, it is carried under the tapering two-bellied maxillary, or digastric muscle, which sits in front of this same branch in a sort of pulley: then it is bent back practically to the middle of the gland, where it is united with the anterior branch which has been described & many small branches, which are as it were associated with it, & from there the common duct returns from the meeting of these somewhat enlarged. (Fig. 3) (Wharton, 1656, p. 132).
Wharton has in fact described the sublingual gland as a separate gland, outlined the varied duct system of the gland to include a separate duct, ducts joining the submandibular duct, and the multiple sublingual ducts ending at the plica sublingularis. This accurately reflects the true anatomical situation. Not only were these ducts the sine qua non of a salivary gland, and thus established the submandibular and sublingual glands as salivary, but their existence had teleological considerations as well (Wharton, 1656, p. 133).
Etenim ubicunque vas excetorium peculiare reperitur, non putandum est, frustra; conditum fuisse sed speciali cuidam excretioni destinari. Cumque excretio quaelibet determinati excrementi, humorum residuorum depurationi inserviat, quod in emolumentum totius cedit: sequitur hoc ipsum esse officii
publici.
For in fact, wherever a special excretory vessel is discovered, it must not be believed that it was put there in vain, but that it is intended for a certain particular excretion. Since whatever excretion is excreted serves to purify the remaining fluid, which passes for the benefit of the whole: it follows that this very thing which conduces for the betterment of the whole.
He established the fluid as saliva and differentiated it from other excretory fluids in the upper aerodigestive tract. This may have been a reference to his famous predecessor William Harvey’s comment, seen earlier, that the tonsils emitted saliva (Wharton, 1656, p. 134):
Certissimum est, humorem hunc salivam esse; at per salivam non intelligo crassum illum viscidumque humorem, qui e tonsillis screatu aut tussi (sputum dicimus) exprimitur: sed illum tenuem & aquosum, quem, Greci riakom & riekom vocant; de quo, sic Gorraeus, riakom saliva videtur esse similaris, mediocriter fluida & aquosa, est enim ei naturalis aquae qualitas, quae est apoio1.
It is most certain, that this fluid is saliva; but by saliva not that which I understand as thick and viscus fluid, which is expressed from the tonsils by hawking or by a cough (we call it sputum): but the thin and watery type, which the Greeks call (sialon) & (sielon) ‘‘about which, as Gorris writes, sialon (riakom) seems to be similar to saliva, moderately liquid and watery, indeed it has the natural quality of water, which is (neutral) (apoior) (apoios).
After documenting the fact that he had seen saliva coming from this duct clinically in humans and animals, Wharton proclaims the right to name the submandibular duct and established it as a source of saliva (Wharton, 1656, p. 134):
Quare cum vas hoc adhuc nomine careat, licebit appellare canalem sive ductum salivalem; siquidem tenuem illum humorem, quem proprie salivam dicimus, quique ad masticationem necessaries est, sub anteriore inferioreque linquae parte in os effundit.
Therefore since this vessel lacks a name to date, one may call it a salivary channel or duct: since this thin fluid, since it pours out that thin fluid which we properly call saliva, and that is necessary for chewing, into the mouth under the anterior and inferior part of the tongue.
Much of the rest of Wharton writing about the submandibular and sublingual glands discussed the possibility of how nerves could be involved in the production of saliva. Wharton also discussed the other various glands including the maxillary and thymus and how they varied throughout an animal’s life. He noticed that the thymus was initially larger in the young and then became smaller as the animal aged, and that the maxillary glands did the opposite. He correctly hypothesized that they probably had different functions (Wharton, 1656, p. 133):
Vsus harum glandularum scriptores hactenus latuit, ut & ipsae glandulae. Utcunque certum videtur, esse partes excretorias, munereque publico fungi.
The use of these glands has thus far escaped writers, as have also the glands themselves. However it seems certain that parts are excretory, and that they serve the whole structure.
He definitively considered salivary production to be part of the function of these glands, and rightly believed the establishment of an excretory duct to be necessary. Other functions such as their relationship with the nerves and the concentration or removal of wastes remained to be discovered (Wharton, 1656, p. 133, 134):
Restat autem adhuc inquiramus, quem peculiarem humorem haec glandula secernat & excernat, unde eundem excipiat, & quis sit eiusdem post excretionem usus.
But it still remains that we investigate, what special fluid this gland separates and excretes, from where it takes up the same, & in fact what is its use after excretion.
SUMMARY
We present a short history of the discovery of the anatomy of the submandibular and sublingual salivary glands. Various functions and ‘‘causes’’ for the glands to exist were professed through out the ages. The 16th century anatomists began to write about the glands as a separate anatomic entity, and the production of saliva was speculated to be a function of the glands in the neck and anatomic region of the submandibular triangle. The existence of a specific salivary gland would require the discovery and description of a duct. This was a difficult undertaking in the premicroscopic era.
The 17th century anatomists were the first to describe this anatomy, with Wharton describing and naming the submandibular gland duct. Although Bartholin is credited with the discovery and description of the sublingual gland duct, Wharton’s description of a ‘‘part’’ of the submandibular gland and it’s complex ductal system accurately describes the modern conception of the anatomy. We believe he deserves at least partial credit for the discovery of the sublingual gland as a salivary gland.
REFERENCES
Please refer to the original article