The bishop and anatomist Niels Stensen (1638-1686) and his contributions to our early understanding of the brain

Abstract

Many physicians are familiar with the parotid duct and the Danish physician/anatomist's name associated with it. However, most are unaware of Niels Stensen's life and his significant contributions to the early study of the brain. This physician of the Medici court was clearly ahead of his time and found errors in the publications of such giants as Varolius and Willis. The present review discusses the life of this seventeenth century anatomist, physician, and priest/bishop and highlights his contributions to neuroanatomy.

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COVER PICTURE
The bishop and anatomist Niels Stensen (1638–1686)
and his contributions to our early understanding
of the brain
R. Shane Tubbs &Martin M. Mortazavi &
Mohammadali M. Shoja &Marios Loukas &
Aaron A. Cohen-Gadol
Published online: 11 August 2010
#Springer-Verlag 2010
Abstract Many physicians are familiar with the parotid
duct and the Danish physician/anatomist's name associated
with it. However, most are unaware of Niels Stensen's life
and his significant contributions to the early study of the
brain. This physician of the Medici court was clearly ahead
of his time and found errors in the publications of such
giants as Varolius and Willis. The present review discusses
the life of this seventeenth century anatomist, physician,
and priest/bishop and highlights his contributions to
neuroanatomy.
Keywords Brain anatomy .Neuroanatomy .Stensen
“Fair is what we see, Fairer what we have perceived,
Fairest what is still in veil.”
Niels Stensen
Early life
The Dane Niels Stensen (Latin Nicolaus Stenonis)was
born on January 11, 1638, and died on November 25,
1686, and was a pioneer in both anatomy and geology
(Fig. 1). A native of Copenhagen, Denmark, Stensen
began his education in the country's most exclusive
school, the grammar school Vor Frue (1647–1656). In
1654–1655, when Stensen was 16, over 200 students of
his school died of the plague that killed approximately
one third of Copenhagen's population [1]. Stensen was
born during the 30 Years War, and interestingly, was
relatedtothefamedDanish-bornanatomistJames
Benignus Winslow (foramen of Winslow). He was the
son of parents of the upper middle class, Sten Pedersen
and Anne Nielsdatter, who came from the Danish
province of Fyn [2]. His father was a goldsmith who
worked regularly for King Christian IV of Denmark and
whose family derived from Lutheran ministers in Skåne.
In 1644, his father died, after which his mother,
interestingly, remarried another goldsmith. Stensen was
very astute and considered by some to be a savant,
speaking fluent German, Dutch, French, Italian, Latin,
R. S. Tubbs :M. M. Mortazavi
Section of Pediatric Neurosurgery, Children’s Hospital,
Birmingham, AL, USA
M. M. Shoja :A. A. Cohen-Gadol (*)
Department of Neurological Surgery, Indiana University,
Clarian Neuroscience, Goodman Campbell Brain and Spine,
1801 North Senate Blvd # 610,
Indianapolis, IN 46202, USA
e-mail: acohenmd@gmail.com
M. Loukas
Department of Anatomical Sciences, St. George’s University,
St. George, Grenada
Childs Nerv Syst (2011) 27:1–6
DOI 10.1007/s00381-010-1236-5

Greek, Hebrew, and Arabic [2]. He eventually attended
the university in Copenhagen (Københavns Universitet)
(1658–1660) studying medicine, mathematics and philos-
ophy, and in 1660, left Copenhagen to study at the
University of Leiden in the Netherlands for 3 years.
After brief visits to Paris and Montpelier, Stensen moved
to Florence, Italy in 1665–1666. In Italy, Grand Duke
Ferdinand II of the Medici palace appointed Stensen to a
hospital post that left him time for research [3]. Later, he
was elected to the Academia del Cimento (Experimental
Academy), a body of researchers inspired by Galileo's
experimental and mathematical approaches to science.
Stensen traveled through Europe visiting France, Germany,
and the Netherlands. In Leiden, he met renowned individ-
uals such as Jan Swammerdam, Frederik Ruysch, Reinier
de Graaf, François de la Boë Sylvius, and the famous
Jewish philosopher Baruch Spinoa [2]. In Montpellier, he
met Royal Society members Martin Lister and William
Croone, who introduced Stensen's work to this group [1].
While in Rome, he met Alexander VII and Marcello
Malpighi, the founder of microscopic anatomy [2].
Anatomical contributions
Eventually, fellow Dane and teacher Thomas Bartholin,
persuaded Stensen to study in Rostock and Amsterdam
where he excelled in anatomy with anatomist Gerard Bläes.
In fact, a physician visiting Paris in 1665 stated “he
(Stensen) could count the bones of a flea- if fleas have
bones”[1]. As an anatomist, he made multiple discoveries
that included determining that the heart was simply a
muscle. He also described tongue muscles, the esophagus,
and named the levator costae muscles. Stensen's name is
also associated with the discovery of the lateral foramina
(incisive foramina) of the anterior hard palate that carry
branches of the descending palatine vessels (Stensen's
foramina) [4] and the vorticose veins of the eye (Stensen's
veins). He discovered the tarsal glands of the eyelids and
understood that the lacrimal glands and not the brain
produced tears [2]. Stensen rediscovered the vitelline duct
in 1664 and discovered and named the follicles of the ovary
in 1667, although he did not publish this discovery
regarding the follicles until 1675, 3 years after his colleague
de Graaf. In 1667, he postulated that the ovary in the
female was not a female testis but was a distinct organ that
corresponded to the egg-producing organs of birds and
reptiles. He verified the existence of Peyer's patches in
1673 and demonstrated that a ligature placed around the
descending aorta resulted in paralysis of the lower limbs
and that removing the ligature restored function (Stensen's
experiment). He found that glands produced the cerumen of
the ear canal [2]. His best known anatomical works
included Anatomical Observations and Elementary Mylog-
ical Specimens published in 1662 and 1669, respectively [5,
6]. Serendipitously, Stensen discovered the parotid duct
(Stensen's duct) in sheep, dog, and rabbit heads and is most
remembered for this observation. In a letter to Thomas
Bartholin, he stated,
“having been allowed to dissect on my own, I
succeeded in the first sheep’s head which I purchased
and dissected by myself in the study hall on April 7 in
finding a duct which—as far as I know—has not
previously been described. It was my intention after
removing the ordinary outer parts to do a section of
the brain when I happened to decide first to examine
the vessels running through the mouth. Examining
with that intention the course of the veins and arteries,
by inserting a probe I observed that the point is no
longer enclosed in the narrow sheath but moves freely
in a spacious cavity; and pushing the instrument
further forward, I at once heard it clink against the
teeth themselves [7].”
Elsewhere in his letter to Bartholin, Stensen referred to
his discovery as an inventiuncula—a small observation.
Conflict
Although the parotid duct was discovered by Stensen, his
teacher, Bläes, laid claim to its discovery in 1661. This
dispute with Bläes resulted in Stensen enrolling at the
University of Leiden on July 27, 1661. It was here that he
Fig. 1 Stensen (1638–1686) as Bishop
2 Childs Nerv Syst (2011) 27:1–6

began compiling his Anatomical Observations, which he
published in 1662 and dedicated to his professors in
Copenhagen and Leiden, a group that included the
mathematician Jakob Golius (1596–1667) who was a
student of Galileo's (as was Ferdinando II, the brother to
Stensen's Medici benefactor, and Vincenzio Viviani (1622–
1703), a future collaborator) [2]. Two years later, Bläes
again attempted to convince others that he had discovered
the parotid duct; however, this time Stensen publically
dismissed his claim in an official publication in 1663.
Although earlier in his career, Stensen's former professor
Thomas Bartholin, had referred to him as the “royal
anatomist”and the century's “new Democritus,”Bartholin
later became envious of Stensen and tried to block his
academic ascent by, for example, hiring his own nephew
Mathias Jacobsen instead of Stensen [2]. As anatomist,
Stensen became well known across Europe by his public
demonstrations of anatomical dissections in the Theatrum
Anatomicum. In 1664, from the University of Leiden, came
the news that due to Stensen's “uncommon learning,”he
had been made a doctor of medicine in absentia [8].
Neuroanatomy
While in Paris and lodging in the house of Melchisédech
Thévenot (Louis XIV's chamberlain, librarian, and former
French ambassador to the republic of Genoa) [2], Stensen
attended academic sessions that later led to the establish-
ment of the Académie royale des Sciences in 1666 [2]. It
was in 1665 and to this precursor of the Académie royale
des Sciences that Stensen presented, in perfect French, his
renowned lecture on the anatomy of the brain (Fig. 2)[7].
He began by saying how ignorant he was of the brain, this
“the most beautiful masterpiece of nature,”that is the
principal organ of our mind. “Our mind thinks that nothing
can set a limit to its knowledge, but when it withdraws to
its own habitation it is unable to give a description of it, and
no longer knows itself.”With good reason, he criticized
earlier theories that the brain was connected with the mind
through an egg-shaped gland. That sort of thing was no
more than “ingenious speculation,”Stensen declared. He
compared the brain with a machine that one could
understand only by taking it to pieces down to its smallest
parts. He opposed Descartes, arguing that it was erroneous
to speculate about cerebral function when so little was
known about the anatomy of the brain. In his dissertation
on the brain, Stensen stated
“It would be a great blessing to mankind if this most
delicate part, and which is liable to so many
dangerous diseases, were as well understood as the
generality of anatomists and philosophers imagining it
to be…as if they had been present at the formation of
this surprising machine, and had been let into all the
designs of the Great Architect. We need only view a
dissection of the large mass, the brain, to have ground
to bewail our ignorance. Let us without flattering
ourselves any longer, freely acknowledge our igno-
rance, that we may not first deceive ourselves and
others afterwards, by promising to show them the true
structure of this organ”[7].
Ventricles
“The ancients were so far prepossessed about the
ventricles as to take the anterior for the seat of
common sense, the posterior for the seat of
memory, that the judgment which they said was
lodged in the middle, might more easily reflect on
the ideas which came from either ventricle. Why
should we believe them? Willis lodges common
sense in the corpora striata, the imagination in the
corpus callosum, and the memory in the cortical
substance. How can he then be sure that these three
Fig. 2 Title page of Stensen's work on the brain, Discours sur
l’anatomie du, 1669
Childs Nerv Syst (2011) 27:1–6 3

operations are performed in the three bodies which
hepitchesupon?Whoisabletotelluswhetherthe
nervous fibers begin in the corpora striata, or if
they pass through the corpus callosum all the way
to the cortical substance? We know so little of the
true structure of the corpus callosum that a man of
tolerable genius may say about it, whatever he
pleases (Fig. 3)”[7].
Pineal gland
Stensen rejected Descartes' idea that the pineal gland was
the link between the body and soul stating
“The supposed connection of this gland (pineal) with
the brain by means of arteries is likewise groundless:
for the whole basis of the gland adheres to the brain,
or rather the substance of the gland is continuous with
that of the brain, though the contrary be affirmed by
Descartes (Fig. 3). (Moreover), it is not known
whether the pituitary gland acts in any respect on
the pituita (mucous)”[7].
Brain in general
“The best figures of the brain are those of Willis; but
even these contain a great number of important
mistakes, and they want many things to perfect them.
I have seen but three figures of Varolius, which
express in a wretched manner, the best observations
that have ever been published on the brain. The
principal reason why a great many anatomists have
remained in their mistakes, and why they have gone
no greater a length than the ancients in dissection, is
because they believe that everything has been already
taken notice of, and that there is nothing left for the
moderns to do (Fig. 4)”[7].
Geologic contributions
In addition to his significant contributions to the field of
anatomy, Stensen is also regarded as the Father of Geology,
and interestingly, the root of his surname means “rock”[2].
Stensen's work on shark teeth led him to question how one
solid could come to reside within another solid. While
examining these specimens, Stensen was struck by their
resemblance to glossopetrae or “tongue stones”[7]. Ancient
authorities, such as the Roman author Pliny the Elder, had
suggested that these stones fell from the sky or from the
moon and some believed that these structures were serpent
tongues turned to stone by St. Paul. Stensen argued that
glossopetrae were simply fossilized shark teeth. With such
discoveries, Stensen is credited with developing the principles
that led to the science of stratigraphy and for establishing the
foundation on which Darwin's theory of natural selection
would be based [8]. Stensen's writings in this field continue
to be used by geologists and paleontologists today.
Religious convictions
While in Florence, Stensen began to question his Lutheran
upbringing. After intense comparative study, he decided
that Catholicism, rather than Lutheranism, was more
Fig. 4 Drawing of a parasagittal section of the brain from Stensen's
Discours sur l’anatomie du cerveau
Fig. 3 Drawing made of a sagittal section of the brain from Stensen's
Discours sur l’anatomie du cerveau noting his appreciation for
anatomical relationships
4 Childs Nerv Syst (2011) 27:1–6

consistent with his religious views and, therefore, converted
to Catholicism on All Souls' Day November 4, 1667 to
become one of the leading figures in the Counter-
Reformation [3]. Not long after his epiphany, Stensen
returned to Florence and was ordained a priest in Florence's
Cathedral on Easter Eve 1675 [2]. Despite his accomplish-
ments, Stensen's fellow Dutchman refrained from promot-
ing him to the level of professor at the University of
Copenhagen. This resulted in Stensen moving to Florence,
where he was cordially received by the Medici and
appointed as anatomist at the Santa Maria Nuova hospital
[7]. Shortly after Stensen's conversion to Catholicism, a
royal letter from the Danish king Frederick III arrived
announcing his appointment at Copenhagen University, but
while Stensen awaited free religious worship status, the
king died [1]. It was, therefore, not until 1672 that Stensen
was able to return to Copenhagen. In Denmark he was
appointed anatomicus regius since a Catholic could not
hold the position of professor [1]. Stensen wrote: “This is
the true purpose of anatomy: To lead the audience by the
wonderful artwork of the human body to the dignity of the
soul and by the admirable structure of both to the knowledge
and love of God”[2].
Stensen went to Rome where he was appointed apostolic
vicar of northern missions by Pope Innocent XI on August
21, 1677 and was consecrated titular bishop of Titiopolis in
Asia Minor (present day Turkey) on September 19 [2,3].
Later the same year after being appointed Apostolic Legate
for Northern Germany and Scandinavia, he left Rome to
minister to the minority Roman Catholic populations in
northern Germany, Denmark, and Norway [2]. Stensen
worked in Hannover until 1680 when he accepted a
position in Münster. As an example of his devotion to his
religion, Stensen sold his bishop's ring and cross to help the
needy and is said to have dressed like a beggar and ate
little, becoming so malnourished that one friend described
him as a “living corpse”[1].
In 1684, Stensen moved to Hamburg and again studied
the brain and the nervous system with his friend, the
famous Dutch anatomist Theodor Kerckring. Stensen was
invited to Schwerin and spent some of the last years of his
life ministering to the Catholics who had survived the
protracted 30 Years War [1]. He had wished to return to
Italy but became seriously ill and died in Germany at the
age of 48 [7]. At the request of Grand Duke Cosimo of
Tuscany, his body was taken by his friend Kerckring to
Florence and buried in the Medici tombs in the Basilica of
San Lorenzo (Figs. 5,6)[7].
Fig. 5 Tomb of Stensen from San Lorenzo, Florence. Courtesy of
Luca Borghi, Himetop—The history of medicine topographical
database
Fig. 6 Stained-glass depiction
of Stensen from San Lorenzo,
Florence. Courtesy of Luca
Borghi, Himetop—The history
of medicine topographical
database. (This figure is used
as cover picture)
Childs Nerv Syst (2011) 27:1–6 5

Stensen's piety and virtue have been evaluated with the
goal of eventual canonization, and centuries after his death,
Danish pilgrims appealed to Pope Pius XI to make Stensen
a saint [8]. In 1953, as part of this process his corpse was
exhumed and reburied in the Capella Stenoniana, a chapel
within San Lorenzo. On October 23, 1988, Stensen was
beatified (the first step to becoming a saint) by Pope
John Paul II and attained the status and title of Blessed
(Blessed Nicolas Steno). His day of celebration in the
Catholic Church is November 25 [3]. Stensen's name is
remembered by the Steno Museum in Århus, Denmark,
craters on Mars and the Moon, the Steno Diabetes Center,
a research and teaching hospital in Gentofte, Denmark,
and the Istituto Niels Stensen, which was founded in
1964 in Florence, Italy and administered by the Jesuit
Order.
Stensen's life was short-lived but full of discovery both
academically and spiritually. Although he lives on primar-
ily as the eponym “Stensen's duct,”it is his contributions
to neuroanatomy that should perhaps be most remem-
bered. It is on the shoulders of giants such as Niels
Stensen that we base our current understanding of the
nervous system.
References
1. Cutler A (2003) The seashell on the mountaintop: a story of
science, sainthood, and the humble genius who discovered a new
history of the earth. Dutton, New York
2. Kermit H (2003) Niels Stensen, 1638–1686: the scientist who was
beatified. Gracewing, Leominster
3. Sobiech F (2005) Blessed Nicholas Steno (1638–1686) Natural-History
research and science of the cross. Austral E J Theol (5):1448–1632
4. Thane G (1890) Osteology. In: Schafer E, Thane G (eds) Quain's
anatomy, vol II, Part I. Green and Co, London, pp 1–146
5. Stensen N (1664) De musculis et glandulis observationem
specimen. M. Godicchenii, Hafnia
6. Stensen N (1667) Elementorum myologicae specimen. Stellae,
Florentiae
7. Stensen N (1950) A dissertation on the anatomy of the brain with a
preface and notes by Edv Gotfredsen. Nyt Nordisk Forlag Arnold
Busch, Copenhagen
8. Cioni R (1662) Niels Stensen: scientist-bishop. PJ Kenedy & Sons,
New York
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