B/o/r?edf
WE
70S
I9Q5
THE LIBRARY
OF
THE UNIVERSITY
OF CALIFORNIA
LOS ANGELES
Gift of
Dr. C-ustav F. Ruediger
WORMIAN BONES
OHARIjES A.f PARKER, M. D,
INSTRUCTOR IN 8TJRQERY AND IN -A.NA/POMY, RtlSH MBDIOAL Cor.r.EGB,
IN AFFILIATION A^TTH THE UNTVBRS TTY OF CHIOACJO
f
WORMIAN BONES
CHARLES A. PARKER, M. D.,
INSTRUCTOR IN SURGERY AND IN ANATOMY, RUSH MEDICAL COLLEGE,
IN AFFILIATION WITH THE UNIVERSITY OF CHICAGO
CHICAGO
ROBERTS PRESS
1D05
CONTENTS.
PAGE
DEFINITION 5
SYNONYMS 5
HISTORY 5
Letter of Olaus Worm, establishing claim to priority G
Others mentioned — Hippocrates, Paracelsus, Vesalius, Guin-
ter d'Andernach, Goethes 7
CLASSIFICATION 8
Pozzi's— True and false — suturaux, fontanellaires, and insu-
laires 8
GENERAL FEATURES— Structure, shape, size, sutures 8
FREQUENCY AND SITE 9
Frequency in infants, apes, and in pathological conditions... 9
Table based on Chambellan's observations on 485 skulls, show-
ing size, number and location per hundred skulls 11
Greatest frequency in lambdoid suture 12
Increased frequency in coronal suture in artificially deformed
skulls 12
Almost entirely limited to sutures bordering parietal bones. 13
Rare varieties and unusual sites. Os antiepilepticum 13
DEVELOPMENT 17
Development of membrane bones 17
Two modes of origin 17
Time of appearance 18
Frequent in fetal crania 18
May be synchronous with earliest centres 19
Diminish with obliteration of sutures 20
FUNCTION — Supplementary to regular bones 20
MORPHOLOGY . . 20
Low morphological value of membrane bones 20
Development of occipital bone 21
Os interparietal 23
Os Inca 24
Os epactal 25
ANTHROPOLOGICAL SIGNIFICANCE 26
Relation between number of Wormian bones and cubage of
cranium — comparative tables 26
Dextral preponderance 27
Relation of sutural length to cranial capacity— increase of
one accompanied by increase of the other 28
Greater dextral sutural length 28
Incidental. Variations in transverse and squamous sutural
lengths in different types of skulls 28
Relation of jaws to cranial types 29-
4 CONTENTS
PAGE
CAUSES .............................................................. 29
Usually of physiological origin ............................... 29
Pathological — Severe dyscrasiae, fetal or maternal, degenera-
tive influences, possibly a few specific diseases .......... 29
Relative importance of pre- and postnatal influences ......... 30
Author's case unique, showing characteristics of both osteo-
genesis imperfecta and chondrodystrophia felalis.
Changes in face distinctly degenerative in type. No
maternal dyscrasia known .............................. 31
MEDICAL ASPECTS — Very limited ..................................... 32
Possibility of causing confusion in fractures. Saucerotte'u case. 32
Influence on childbirth. Three cases of pathological influence
— only ones recorded in literature ....................... 32
AUTHOR'S CASE OF EXTRAORDINARY DEVELOPMENT OF WORMIAN
BONES.
GENERAL DESCRIPTION OF SKULL ................................... 33
Origin, shape, measurements, capacity, cephalic index, class,
structure ................................................. 34
BASE — Measurements, development, comparison with normal
skull, absence of premature ossification and shortening. 35
Asymmetry, slight, no important mensural variations. . . ........ 35
SPECIAL FEATURES ................................................... 35
RECESSION OF FACE ............................................. 35
Comparison of profiles — vertical and horizontal ............... 35
Cause — Imperfect development of jaws .............. ......... 36
Jaws and dentition ............................... ............ 37
Superior maxilla1 — Dentition incomplete and asymmet-
rical with deformity ................................. 37
Mandible — Dentition incomplete and asymmetrical with
deformity ............................................. 37
POSTERIOR NARES — Infantile in type ........................... 38
WORMIAN BONES ................................................. 39
Number, 172 .................................................. 39
Location and area involved, base free ........................ 39
Size, shape, and other characteristics. The one in the frontal
the largest true Wormian bone yet recorded ............ 39
Separate bones involved — limited to membrane bones ......... 39
Distribution by number in different regions .................. 40
Sutures involved — adventitious sutures ...................... 40
Fontanelles — rare occurrence in fontanelle orbitaire .......... 41
PRESERVATION OF CRANIAL ANLAGE ................................ 42
REPORTS OF OTHER CASES ........................................... 42
GENERAL SUMMARY ............................ ..................... 44
CHAMBELLAN'S CONCLUSIONS ............................. ....... 44
H YRTL'S RULES .................................................. 44
AUTHOR'S CONCLUSIONS .......................................... 45
BIBLIOGRAPHY.
WORMIAN BONES.
CHAELES A. PARKER.
DEFINITION. — Wormian bones may be defined as those accidental or
intercalated bones found in the cranium having no regular relation to its
normal ossific centres. They are of frequent occurrence in man, and
generally occupy the sutures. In other animals they occur with much
greater rarity.
SYNONYMS. — According to discoverer, ossicula Andernaci, ossa
G-oethiano; shape, ossa triquetra, ossa triangularis, ossa quadratum: loca-
tion, suturaux, fontanellaires, insules, intercalaria, raphogeminantia,
apicis; function, complementaria, ossa accessorii.
Schaltknoclien and Nahtknochen are the terms in common use by the
German writers, while the French writers have occasionally called them
clefs de route, or "keys of the vault."
One occupying the upper part of the occipital bone, the subject of
considerable controversy among the anthropologists of the latter part of
of the last century, is frequently alluded to as the os epactal, or os Inca.
The latter name originated with the description of Tschudy, who, with
Rivero, considered it a special racial characteristic of the ancient Peru-
vians— a contention, however, that was soon completely refuted by the
larger observations of Jacquart, showing its more comprehensive generic
value, and its occurrence in others than the Incas, and its very frequent
absence in the race of which it was supposed to be characteristic.
HISTORY.
Occurring so frequently, and often of considerable size, they were no
doubt noticed by many observers long before we had specific accounts of
them. The first special description we have of them is by Olaus Worm,
a Danish anatomist, 1588-1654, who described them at some length in a
letter to Thomas Bartholin.
In turn Bartholin named them Ossa Wormiana, their present name.
As this letter is of historical importance in establishing the author's
claim to priority of description it is introduced into evidence here. The
6 CHARLES A. PARKER
few prefatory and closing remarks are of course not relevant here, but
the complete text is given to avoid mistakes that have occurred in partial
transcriptions.
Thomae Bartholini epistolarum medicinalium, a doctis vel ad doctos
scriptarum, centuria 1. Hagae Comitum, apud PetrumGosse, bibliopolam,
MDCCXL. 9 1., 416 pp. sm. 8. pp. 122-124.
EPISTOLA XXIX.
De ossiculis in sutura lambdoidea.
Thomae Bartholino. Patavium.
Librum tuum de Luce Viventium videndi maximp teneor desiderio.
Omnibus innatum lumen, unde ortum trahat, cur se in tarn paucis pro-
dat, scire gestit animus. Cocui historiam eleganter tradidit Moufettus
in Theatre Insectprum lib. I. cap. 15. quern si consulueris, invenies quas
ad rem faciant: etiam de liquore ex iis praeparato, noctu lucente. Cum
Lugduni Batavorum adhuc haereres & Anatomiae Parentis editionem
meditareris, de ossiculis lambdoideis me tibi scripsisse memini; sed quia,
quae, turn exarabam, excidisse videntur. jam repeto, modo usus alicujus
esse possunt. Anno 1628. cum frequent! auditorum coronas ossa sceleti
humani demonstrarem atque exponerem; in ipsa sutura lambdoidea
ossicula sex inveni, quae utrumque tabulatum cranii perforabant, a
nemine, quod sciam, ante animadversa. Diversissima enim sunt ab iis,
in quas os ipsum quandoque dispescitur, quod sutura lambdoidea circum-
scribitur, Triquetra quibusdam dictis. Tria in dextro, totidem in sinis-
tro ejus extant ductu, magnitudine, figura & situ discrepantia. Infimum
ad processum mamillaremconspicitur, medium paulosuperius, vixdimidii
digiti intervallo, tertium aliquanto longius a secundo distat. Figura
sunt varia, triquetra, oblonga, ovalia. In sinistro ductu majora omnia
apparent, quam in dextro. Maximum unguem pollicis non excedit. In
concava cranii superficie distincte magis quam in convexa apparent,
quocirca ablata calvaria melius observantur. Ut omnia sint clariora,
iconem addo. A. portio est sutune sagittalis. B. sutura lambdoidea. C.
sectio serra facta. D. primum os sinistri ductus. E. secundum. F. ter-
tium. Gr. primum dextri ductus. H. secundum. I. tertium. K. mag-
num cranii foramen, per quod medulla in spinam descendit. LL. Pro-
cessus mammillares. Dissimulare interim hie nequeo, in diversis craniis,
tarn numero, quam magnitudine & figura, item situ, variarehaec ossicula.
Dum haec scribo, mihi ad manum quinque sunt crania; quorum duo
suturam sagittalem per qs frontis in nasum usque protendunt. Horum
alterum, quatuor saltim istorum ossiculorum ostentat, atque ex iis unum
in ipsa junctura sagittalis cum lambdoidea, quo in loco Triquetrum dic-
tum, conspici solet: in altero vero duo saltim extant, eaque in dextro
ductu tantum. Verum haec crania integra erant; si calvariam auferre
licuisset, forsan plura ostendisset interior superficies. Sed cum Naturam
in pssibus majoribus, suturis ipsis, & aliis humani corporis partibus,
varie ludere videamus, quid mirum si in hisce antiquum obtineat? In
monumentis ac sepulchris majorum nostrorum licet res varias reperian-
tur, ut lib. 1, cap. 7. Monumentorum nostrorum docuimus, lucernarum
tamen perpetuarum nulla prorsus vestigia. Inter veterum inventa
deperdita eas, ni fallor, refert Pancirollus, qui de iis ex professo agere
videtur. Vale & bono publico feliter vive. Hafniae 6, April, 1643.
T. T.
Olaus Worm D.
WORMIAN BONES 7
Of the earlier mention of these bones, Sappey refers to Hippocrates,
but does not cite the instance, and a very careful search by the writer
through all of the accessible editions of the works of that celebrated
teacher fails to establish the claim of his priority. It is true he deals
with bones and sutures, and even mentions in his fifth book of The
Epidemics the case of Autonomus of Omilos, wherein he mistook a frac-
ture near the bregma for a suture — not a suture for a fracture — with a
fatal result because of delay of proper treatment. He explains his error
in diagnosis as being due to the proximity of the fracture to the known
sutures of that region, and in another place warns against the possibility
of such mistakes being made in the neighborhood of sutures, but in no
way can this be construed as an instance of an adventitious suture or an
intercalated bone.
Eambaud and Renault, in their work on the "Origin and Develop-
ment of Bones," mention Gonther d'Andernach, or as his biographer, E.
Turner calls him, Jean Guinter d'Andernach, a German anatomist,
1487-1574, as having "discovered the os Wormiens, and Olaus Wormius
gave their name."
Testut says Tourtefois claims that both Andernach and Vesale,* the
•celebrated Belgian anatomist, of 1514-1564, gave good descriptions of
them, particularly in relation to their medical importance in cerebral
affections, epilepsy, etc. Hence, the designation ossicula Andernaci as
one of the synonyms mentioned by Hyrtl.
This latter author also says Paracelsus, 1460-1541, mentioned the one
in the posterior fontanelle, which was called the ossiculum Antiepilep-
ticum, on account of its supposed relation to epilepsy.
These three teachers were contemporary in the first half of the 16th
century.
Yet again, Peckham, in the "Reference Handbook of the Medical
Sciences," says Fischer credits an account preceding Worm's to one
Goethes, in an article "De ossa epactala seu Goethiana," Moscow, 1811.
Still, it is evident that Worm's careful observations entitle him to
the same distinction of practical priority that Columbus' voyage does
that worthy mariner to the discovery of America, though neither, in
point of fact, was actually first in his respective claim.
*Zeller mentions Vesalius as having found the squama occipitalis divided In two
parts by the continuation of the sagittal suture from the lambda to the foramen mag-
niim. Thfl a*rp wa.K not, iriv^n
num. The age was not given.
CHARLES A. PARKER
CLASSIFICATION.
Pozzi, in the Dictionnaire Encydopedique des Sciences Medicales.
divides the Wormian bones into two main groups, the false and the true,
the former including those resulting from anomalous development of
normal centres, as double parietals, double squamosals and interparietal
bones, the os supplementaires of Manouvrier, the latter, the os inter-
calaires, the variety usually observed, comprising those having no such
relation to the regular ossific centres, and usually situated along the
margins of the bones in the sutures and fontanelles, suggesting their
further division into os suturaux and os fontanellaires. To these Ma-
nouvrier adds a third variety, the os endocraniens, or insules, of Hyrtl.
This division of the true Wormian bones into three classes, suturaux,
fontanellaires and insules, or endocraniens, is followed by Porier et Char-
pey, Testut, Debierre and others.
Os endocraniens are usually small isolated fragments occurring exclu-
sively in the inner table, and are designated by position as endofrontal
and endoparietal, etc.
They are also called insular or peninsular according as they are com-
pletely enclosed in a bone or are contiguous to a suture. Manouvrier
found endofrontal bones 15 times in the crania of 58 Parisians, and Hyrtl
describes them in the parietal bone near the squamous margin. They
have also been mentioned by Zermak, Henle and others.
Pozzi divides the os fontanellaires into the following obvious classes
named in the order of frequency of their occurrence, the normal fonta-
nelles preceding the abnormal, or infrequent ones, described by Hamy.
Normal. Os Wormien fontanellaire asterique,
Os Wormien fontanellaire pterique,
Os Wormien fontanellaire lambdatique,
Os Wormien fontanellaire bregmatique,
Os Wormien fontanellaire orbitaire, at the junction of the
frontal, os planum, and lesser wing of the sphenoid.
Abnormal. Os Wormien obelique — at the obelion.
Os Wormien glabellaire — at the glabella.
To this last class Hrdlicka adds a group occupying the sites of the
somewhat numerous primary fissures, occasionally remaining as super-
numerary fontanelles in the margins of the developing parietal bones.
GENERAL FEATURES.
In structure Wormian bones resemble the other bones of the cranium
and involve both the external and internal layers, but not infrequently
they are limited to the outer layer only, much more rarely, as the os
insules, to the inner.
WORM i AN BONES 9
They articulate with the surrounding bones by sutures, the denta-
tions of which are more complex on the outer than on the inner surface
of the skull.
In shape they are round, oval, oblong, triangular, quadrilateral and
polygonal, and they vary in size from less than a millimeter in diameter
to the one measuring 5 by 9 cm. in the skull presented by the author at
the close of this article, the largest true Wormian bone whose measure-
ments were obtainable, although the false Wormian, or interparietal
bone, may even considerably exceed this.
Quain says, '-They may exceed an inch in diameter'1: John and
Charles Bell, that "they are sometimes full size of a crown": Ilyrtl,
that they "vary in size from a flaxseed to a dollar": Zeller, "from the
size of a lentil to two inches or more": Merkel, that they "vary in size
even to the upper half of the occipital"; and Gruber reported one in the
anterior fontanelle measuring 5 cm. by 6.5 cm.
FREQUENCY AND SITE.
The number of Wormian bones varies in different classes of skulls,
and in different parts of the same skull, according to apparently well
established laws. In this connection a synoptic study of the unique and
comprehensive tables of Chambellan is of the greatest interest.
Victor Chambellan, to whose inaugural thesis reference has already
frequently been made, who studied Wormian bones both from an anthro-
pological and an anatomical standpoint, gives, in his extensive tables
arranged from the examination of widely diversified groups of human and
simian skulls, the size, location and number of Wormian bones in the
several groups of the series, and, by clever comparisons and contrasts,
establishes quite definite laws in regard to the relative frequency of their
occurrence.
The following groups were comprised in his observations:
Auvergnats ... Males 56 Females 47
Parisians " 124 " 56
Neo-Caledonians " 46 " tt
Negroes " 89 " 11
Incas " 44 " (>
TOTAL 485
Foetuses 10
I nf ants 12 months or less 14
Infants 2 years 1
Microcephales 5
Hemi-microcephales 15
Hydrocephales, adults 13
Hydrocephales, foetuses, infants of several months, one 5 years 8
Apes, anthropoid 52
Apes, inferior 73
10 CHARLES A. PARKER
Tor the purpose of determining the sites of predilection and relative
numbers and sizes in different regions, the data from the 485 normal
adult human skulls, male and female, are here condensed from Chambel-
lan's separate catagories into one general table arranged in decreasing
order of their frequence. No attempt is made to separate the male from
the female skulls, nor those of different races.
The size is designated by the nomenclature of Broca, which is as
follows:
No. 1 comprises all those bones which measure from 1-2 mm. in their
smallest diameters.
No. 2 comprises all those bones which measure from 3-5 mm. in their
smallest diameters.
No. 3 comprises all those bones which measure from 6-10 mm. in their
smallest diameters.
No. 4 comprises all those bones which measure from 10-20 mm. in their
smallest diameters.
No. 5 comprises all those bones which measure over 20 mm. in their
smallest diameters.
For example, if the sagittal suture of a skull contain four Wormian
bones measuring 1.5 mm. in their smallest diameters, and two 3.5 mm.
in their smallest diameters, they would be designated, Sagittal suture,
4 (1), 2 (2). To these Chambellan has added the designation, +1 (plus 1),
for those bones less than a millimeter in their smallest diameters, but
which he thinks should be recorded in an exhaustive study.
Furthermore, as the number of skulls examined varied in the different
races and sexes, the results were originally given for each group in terms
of 100 skulls for purposes of ready comparison, a method which for the
same practical reason will be made use of here.
WORMIAN BONES
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estimated from a
their numerical fre
Lambdoid suture, rigl
Lambdoid suture, left
Coronal suture, right
Coronal suture, left.. .
Mastoparietal, right..
Mastoparietal, left . . .
Asterion, right
Asterion, left
Pterion, right
Pterion, left
Squamoparietal sutur
Squamoparietal sutur
Sagittal suture
Masto-occipital sutun
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Sphenofrontal suture,
Sphenofrontal suture,
Obelion
TOTAL
12 CHARLKS A. PARKER
The greatest frequency of Wormian bones in the lambdoid suture is
attested by all observers: containing as it does, with the addition of the
asterion and masto-occipital sutures, as its continuations, 271.12 bones,
or one-half of the whole number present in all the skulls. Hyrtl observed
300 in this suture in the skull of a cretin, the largest number found
recorded in a single skull. Liston reported 100 in a hydrocephalic skull,
but no reference is given of the sutures involved. That the coronal
suture should stand second as a site of predilection for these bones in
normal skulls is a source of some surprise, as this region is not usually
considered as specially favoring their existence (Humphrey), though
Dorsey has particularly remarked their increased frequency in this
suture in artificially deformed skulls. Sandifort observed them in this
suture.
Hrdlicka distinguishes a number of the Wormian bones occurring in
the sutures surrounding the parietal as fontanelle in origin, and else-
where their frequency is given, but no other statistics based upon such
a distinction are available.
In an illustrated article entitled "Wormian Bones in the Artificially
Deformed Kuaikuitl Crania," appearing in the American Anthropologist
for June, 1897. Dorsey comments upon the frequent occurrence of Worm-
ian bones in the coronal sutures of the deformed skulls of this race.
They were found 10 times in 60 skulls, occurring rather more fre-
quently in females than in males, and oftener on the left side than on
the right. In one case there were 5 bones on the right side, and 2 on
the left.
With this article in mind an analysis was made of the cases in the
museum of the Royal College of Surgeons, England, given in the cata-
logue of 1879, Part I.
Total number of crania mentioned, 1010.
Total number mentioned as having Wormian bones, 79, including
cases of epactal and epipteric bones.
Number containing Wormian bones in coronal suture, 15.
Further analysis of these 15 showed the following:
They occurred 9 times in males, once in a female, and 5 times in
crania of unknown sex, some being children. They were present on the
right side in 14 cases, on the left in 10, and on both sides in 8. Their
numbers were not given frequently enough for study.
In 20 skulls of flat head Indians, 7 contained Wormian bones, and in
5 they occurred in the coronal sutures, the frequency of occurrence in
this suture being 71 per cent, of the skulls containing these ossicles.
Taking out these 5 cases from the special total of 15, and the 7 cases
from the general total of 79, there remain 10 examples of coronal occur-
rence in 72 cases of Wormian bones, a frequency of 14 per cent. A com-
WORMIAN BONES 13
parison of the 71 per cent, of frequency in the flat heads with the 14 per
cent, in other skulls shows the predilection of this site in the former to
be five times as great as in the latter.
In explanation of this striking peculiarity Dorsey says, "These skulls
are deformed by bandages and flattened in front, projecting behind,
often showing a groove just behind the coronal suture from the bandages
* * * * They are probably due to elongation of the skull, and con-
sequent faulty union of the parietals with the frontal."
Next in frequency to the coronal are the mastoparietal sutures, and
the asterions, the points of divergence of the former from the lambdoid.
Following these in decreasing succession are the pterion, thesquamo-
parietal, sagittal and masto-occipital sutures, the orbits, themetopic and
sphenofrontal sutures, the bregma and obelion.
Ninety-three per cent, of the whole number, or 501.52 of these bones,
are situated in the sutures bordering the parietal bones, a distribution
quite proportionate to the greater relative extent of these over the
remaining sutures of the membranous cranium.
Gruber observed their presence in the squamous suture on one or
both sides in 5 per cent, of 4,000 skulls, and Humphrey mentions that they
may here be two or three rows deep.
In the skull later presented by the writer, the whole squamae tem-
porales and adjacent portions of the parietals consist of numerous
Wormian bones, completely obliterating this suture, and rendering sepa-
rate distinction of asterion and pterion ossicles impossible.
Although they are very rare in the face, and between the sphenoid
and neighboring bones, according to Merkel they are frequently met
along the orbital margin, and Ward has observed them in the ethmo-
sphenoidal suture and in the lesser wing of the sphenoid.
Hyrtl records one in the internasal suture, and one in the crucial
suture of the palate. Gegenbauer mentions their occasional occurrence
at many points in the articulation of the bones of the wall of the nose or
the maxillary region.
Mitchell and LeCount, at a necropsy on a case of acromegaly, ob-
served two Wormian bones in the roof of the right orbit and four in the
roof of the left. Their numerous occurrence in the orbits of the skull,
previously mentioned by the writer will later be noted. (Figs. 21, 22.)
Metopic Suture. Simon reports numerous Wormian bones through-
out the length of this suture in the skull of an adult male. Chambellan
reports two cases of Wormian bones in this suture, and Gruber an os
interfrontal at the site of the bregma, but in front of the coronal suture.
Kobert Harrison, in the "Dublin Dissector," says that "the os frontis
may develop in three parts, the third being ovoid and situated in the
median line separating the two lateral halves, a specimen of which is in
the museum."
14
CHARLES A. PARKER
Intraparietal Suture. A very unusual site is the abnormal
intraparietal suture in divided parietals. Hrdlicka, in his recent exten-
sive work on the parietal bone, records seven cases, collected from litera-
ture, of these bones situated in this suture in man. Five were on the
left side, and two on the right. (Fig. 1.)
Here, also, should be mentioned the isolated observation of Gruber,
who found in the petro-spheno-basilar sutures of 100 skulls, 119 extra
bones varying in
length from 2 to 26
mm., and in width
from 1 to 9 mm.,
and from the thin-
ness of paper to 5
mm. thick. They
were spongy or corn-
pact in structure.
The frequency
given them here
would place them
fourth in rank, or
next to the masto-
parietal suture.
Their occurrence
in the fontanelles
has been noted in
the following order
of their frequency:
asterion, pterion,
lambda, bregma, and
orbital fontanelle.
FIG. 1. — Wormian bones In anomalous parietal su-
ture. (After Hrdlicka, "Parietal Bone in Man and
Other Mammals," p. 258, drawn from photograph of
Putnam's first case of parietal division.)
Os Wormien Asterique. Chambellan found 36 cases in 110 skulls
of Parisians. When single they usually range in diameter from 4 to 8
mm., but they may be found measuring but 1 or 2 mm.
They are not rarely symmetrical in their presence on the two sides,
though this is not at all constant.
Os Wormien Pterique. The same author observed this bone but
14 times in 110 Parisians.
These bones vary in size, number and distribution, similar to those
at the asterion, and may extend variable distances along the upper bor-
der of the squama temporalis even as far as the posterior border.
(Fig. 2.)
WOBMIAN BONES
15
Os Wormien Lamdatique. This bone is situated, as its name im-
plies, in the posterior fon-
tanelle, and is mentioned
by Worm as frequently
assuming a triangular
shape. Hyrtl says it was
mentioned by Paracelsus,
and called os antiepilepti-
cum on account of its
supposed relation to epi-
lepsy. In 100 Bavarian
skulls Ranke found this
bone present four times.
Os Wormien Bregmatique.
This bone was flrst de-
scribed by Bertin, and is
situated in the anterior FIG. 2.— Worm ian bones In the squamous suture.
fontanelle. In the skulls of 198 Parisians Chambellan encountered it but
twice. In one case it was oval, and in the other quadrangular in form.
They were single and of nearly equal dimensions, measuring 8 to 9 mm.
in width by 2 cm. in length, their
long axes corresponding in direc-
tion with the sagittal suture.
(Fig. 3.)
Gruber, in a series of contribu-
tions to Virchow's Archives, re-
ports 70 cases found in the exami-
nation of 11,928 skulls — an average
of 1 in 170. One of these measured
5 cm. by 6 cm., the largest he had
ever seen. In two instances there
were three bones, one being the
skull of a hydrocephalic boy; and in
one case they were double.
Quoting Humphrey, "Bertin
Cruveilhier and Cuvier, each de-
scribe the os bregmatique, and
Tiedemann, in the Ztschr, f Phys.
Ill, gives plates of two in this sit-
uation; also Sandifort in his "Mus.
Anat." Tab. VIII. There are sev-
eral examples in the museum of
Bonn. Blandin, "Anat." I describes
Tiedemann mentions Stehelin
FIG. 3.— Os Wormien bregmatique, occu-
pying the anterior fontanelle. (After
Cha ' -
lambellan.)
them in each of the fontanelles."
Doveren, Tarin and Sandifort also having observed bregmatic bones.
16
CHARLES A. PARKER
Os Wormien Orbitaire. This is situated at the junction of the frontal,
O9 planum of the ethmoid and lesser wing of the sphenoid. Chambellan
had not seen a single instance in the nearly five hundred skulls he had
observed. They are present in both orbits of the skull presented by the
writer, along with numerous others in the neighboring sutures. (Figs.
21 and 22.)
Abnormal Fontanelles. In the abnormal fontanelles, Chambellan
records two cases of os Wormien obelique occurring at the site of the
obelion in the skulls of 198 Paris-
ians. They occurred singly, and
were somewhat smaller than the
ones previously described at the
bregma, their long diameters ex-
tending transversely instead of
sagittally. (Fig. 4.)
Hamy applies to the same bone
the name os sagittal, but os obelique
is the preferable designation, as it
refers to a definite place.
In the descriptive catalogue of
the Warren Museum "a Wormian
bone the size of the finger nail in
the middle of the sagittal suture,
an unusual situation, in the skull of
a child four or five years old" may
possibly be an example of this bone.
M. Pozzi observed one instance
of os Wormien glabellaire in the nasof rontal fontanelle in 485 skulls; but
Chambellan never encountered it in the nearly 500 he examined.
In this class are included the fontanelle bones mentioned by Hrdlicka,
referred to in a previous chapter, which heretofore have been considered
sutural rather than fontanelle in location. Few observers have at-
tempted this distinction, and occasionally the multiplicity of bones
makes the differentiation quite impossible, but the attempt is justified
by the author in the following assertion: "The recognition of the fon-
tanel bones adds considerably to our proper understanding of the
subject of intercalated bones and diminishes very much the numbers of
the purely accidental of these ossicles."
In the examination of 45 complete skulls he found 33 of these bones
in 17, the majority being along the posterior border of the parietals and
usually classed as lambdoidal. In 105 calvaria, upon which observations
were necessarily limited to the remaining portions, 9 examples were
seen.
FIG. 4.— Os Wormien obelique, at the site
of the abnormal fontanelle obelique.
(After Chambellan.)
WORMIAN BONES
17
DEVELOPMENT.
Kolliker describes the development of the parietal bone as follows:
"In the region of the parietal bone is first seen a number of small
isolated ossific centres which become more numerous and blend with one
another. * * * It grows partly through the enlargement
of the existing osseous framework, and partly by isolated centres, while
at the same time the interspaces are tilling up with an osseous material,
till at the end a thin com-
pact bone is formed."
(Fig. 5.) What is here
said with reference to the
parietal bone may be ap-
plied with equal truth to
the other membrane bones
of the cranium. The fur-
ther development, accord-
ing to Gegenbauer, "is
accomplished b y small
bony crests radiating
toward the periphery. Be-
tween the parts already
formed, new ones appear,
or else distinct bony pieces
may be formed outside the
growing borders of the
bones, and later fuse with
the principal piece. How-
ever, this fusion of isolated
pieces does not always
occur, and it sometimes
happens that these pieces
remain independent, form-
ing little bony fragments
FIG. 5. — Embryonal parietal bones, showing two
centres of ossification. (After Kanke.)
in the dentations of the sutures. These are found regularly in the occipi-
tal sutures. When they are found at an advanced stage of development
these little bony pieces may grow without joining the neighboring bones.
We then find distinct bones in the sutures, relatively large, and articu-
lating by dentate sutures with the adjoining bones. These are the so
called intercalary or Wormian bones."
The origin of Wormian bones by supernumerary centres or by division
of primary centres is axiomatic, since they must either arise by separate
18
CHARLES A. PARKER
centres and remain distinct, or develop as a part of the regular centres
and in some manner later be severed from their origin.*
A later development of occasional small Wormian bones is mentioned
by Chambellan, Sappey, Porier et Charpey and others, as due to the
gradual compression and final obliteration of the pedicle of a denticule by
its adjacent denticules. This is but another method of origin by separa-
tion from a primary centre.
Their mode of growth is similar to that of the larger bones, taking
place by radiation from the centre to the periphery.
Time of Appearance. Beclard
says they do not develop till five or
six months after birth, a statement
with which Humphrey apparently
agrees; but it is a matter of common
observation that they are not in-
frequent in infants at birth. Cham-
bellan, in the skulls of ten fetuses
observed six in the lambdoid suture,
all of small size. In the crania of
fourteen infants under twelve
months, and one child of two years,
he observed ten instances, occurring
in the lambdoid suture, pterion, as-
terion and obelion. In the Museum
of Obstetrics and Gynecology, Hush
Medical College, are a number of
fetal skulls showing minute osselets
in the lambdoid and other sutures. The skull of an infant in the first post-
natal months shows two bones occupying the site of the parietal foramina.
One, triangular, measures 7 by 8 mm. in its longest diameters, the other,
oblong, 4 by 7 mm. (Fig. 6.)
In the same collection, ISTo. 77, is the skull of a somewhat older in-
fant, showing the large Wormian bones occupying the right half of the
lambdoid suture, materially changing its course, and developed at the
expense of both the parietal and adjacent occipital bones. The larger
bone measures 4 by 5 cm. and the smaller 2 by 3 cm. They are not the
result of fracture. The posterior fontanelle is inlaid with a mosaic of
numerous thin flat bones from 1 to 2 mm. wide, and 5 to 10 mm. long,
arranged in quite definite vertical lines. (Fig. 7.)
A few similar shaped ones are present in the anterior and lateral
fontanelles.
FIG. 6. — Skull of an infant, showing two
Wormian bones, occupying the site of the
parietal foramina— fontanelle obelique.
(From the Gyn. and Obstet. Mus., Bush
Medical College.)
*See Cruveilhier, Rauber, Humphrey, Hyrtl, Macalister, Merkel. Cunningham,
Wistar, Chambellan, Rambaud et Renault, Porier et Charpey, Sappey.
WOKMIAN BONES
19
FIG. 7.— Skull of ;i newborn child showing largn Wormian
bones, A and B, in the right lambdoid region. Many smaller
bones are also present in the posterior fontanelle. (From the
Gyn. and Obstet. Museum of Rush Medical College, No. 77.)
This striated or radiating arrangement is mentioned by Humphrey
as having been
observed by him
in hydrocephalic
skulls where they
appeared like ex-
tensions of the
radiations of the
normal bones,
from which, how-
ever, they were
quite separate.*
This form of
growth results
from the linear
arrangement o f
separate centres
in a suture ren-
dering lateral
development un-
necessary and im-
possible, permitting only extension in a vertical direction, producing
a palisade formation across the gap to the opposite bone.
Peckham, in the "Reference
Handbook of the Medical Sciences, "
gives a cut showing two Wormian
bones of considerable size in the
posterior fontanelle of a newborn
infant. (Fig. 8.)
In some cases they doubtless
arise synchronous with the larger
normal centres, as for instance,
the large Wormian bone occupying
such a considerable portion of the
frontal region of the skull later pre-
sented in this article, having a
greater area than the largest piece
in the parietal region; but, just as
under normal conditions some cen-
tres of ossification appear later
Fig. 8.— Skull of an infant whose still- than nrhpr« whpn rhp npppccitv
birth is ascribed to the influence of the tnan Otners— wnen tne necessity
Wormian bones in the posterior fonta- arises for them— SO it is probably
nelle. (Grace Peckham "Ref. Handbook
Med. ScL," 1894, Art. "Wormian Bones.") true of these bones that their
*Examples of this are referred to by Humphrey in the Museum of the College of
Surgeons No. 3842, and in Sandifort's "Mus. Anat." Tab. VII. Fig. 2.
20 CHARLES A. PARKER
period of origin extends over considerable intervals of time, even a num-
ber of years, in some instances.
It is evident, that with the exception of the few small ones men-
tioned as occasionally formed by inclusion of adenticule, and obliteration
of its pedicle, as may occur almost any time during adult life, the most
of these bones appear during the earlier years of cranial development,
while the fontanelles are open and the bones separable at the sutures,
as the only time when they may be of service or can obtain room. Cham-
bellan says they are most frequent in adults in those skulls with open
sutures, becoming fewer as the sutures are obliterated. Cruveilhier
says their sutures are the first of all cranial sutures to be effaced. This
is more particularly true for those of smaller dimensions than for the
larger ones which seldom disappear entirely, though they may be par-
tially united to the neighboring bones. Their diminution in number
with the obliteration of the sutures is the natural consequence of the
disappearance of the conditions — sutures — which originally distinguished
them from the adjacent bones, causing them eventually to become
integral parts of the latter.
FUNCTION.
With reference to their function Cruveilhier says:
"They are looked upon as supplementary points of ossification, and
not as playing an important role in the mechanism of the solidity of the
cranium, as would be supposed from the name, 'Keys of the vault,' or
'Clefts de route,' given them by some anatomists." Ward expresses simi-
lar views, though he quotes Bichat as saying they are designed to
strengthen the cranium. According to Humphrey; "They are evidently
stop-gaps developed in the membranous covering of the brain when the
extension of the regular osseous nuclei is likely for some reason to be
insufficient to cover the cranial cavity." Wistar says practically the
same, and Manouvrier, "They are due to an insufficiency of the normal
centres."
MORPHOLOGY.
As to their morphological value they are not reversional types as a
rule, the more numerous bones of the skulls of other animals having
their representatives in the separate ossific centres from which the
larger bones of the human cranium are regularly formed, and not in the
occasional Wormian bones. (Humphrey, Manouvrier.) According to
Macalister, "They are a testimony of the low morphological value of
centres of ossification in membrane bones." Merkel says, "For the most
part they are the product of a development with too little energy."
WOKMIAN BONES 21
Yet, at times division of the parietals or irregular development of the
occipital and other bones may present features of considerable morpho-
logical interest, often making it difficult or impossible to distinguish
between those bones developed separately from normal centres, and
those arising from true supernumerary ossific areas. The peculiar man-
ner of development of the squama occipitalis affords opportunity for a
great variety of examples of irregular development with consequent con-
fusion of morphological relations. The lower part of the squama occipi-
talis, including the inion, is developed in cartilage, while the remaining
upper portion is developed in membrane. As formerly taught by Broca,
1875, and most other anatomists, the entire squamous portion is devel-
oped by four centres of ossification placed in two superimposed symmet-
rical pairs, the upper in membrane and the lower in cartilage. The
adjacent portions of each pair fuse, and then the upper part unites with
the lower, beginning at the inion, leaving at first vertical and horizontal
incisures at the margins.
The horizontal incisures are frequently present at birth. Failure of
union of the upper portion with the lower results in the formation of
the socalled interparietal bone, the analogue of a separate bone of that
name constant in many of the mammalia. This bone is developed from
normal centres, and is therefore not a true Wormian bone.
Since then Merkel and Kolliker, 1879, and Hagen and Anoutchine,
1879 and 1880, have described eight centres of ossification instead of four
for the squama occipitalis; the first two authors arranging them four on
a side, one above the other, the last two arranging them three on a
side, one above the other, with the fourth placed lateral to the third,
or uppermost one, which makes the summit of the bone. In 1881 Hann-
over of Copenhagen, reduced the number to two, one for the membranous
portion and one for the cartilaginous portion, thus reverting to the views
of Sappey in 1867. Debierre in 1895 gave six centres of ossification for the
squama occipitalis. (Porier et Charpey.)
Wiedersheim in the same year, in his "Structure of Man," gives the
same number of centres, and arranged in a similar order as follows:
supraoccipital, from the cartilaginous portion, interparietal and pre-
interparietal, the latter according to the author, being constant as a
separate bone only in the horse.
According to Debierre its occurrence in man constitutes the os
epactal.
22
CHARLES A. PARKER
The accompanying diagrams from Wiedersheim's work, show very
clearly this morphology. (Fig. 9.)
A B
FIG. 9.— Development of the occipital bone. (After Dr. K. Wiedersheim, "The
Structure of Man." 1895, p. 56.) A Development of the squama occipitalis by six cen-
tres. 8 O. supraoccipital; I p, interparietal ; i PP. pre-interparietal; B o. basioccipital;
E O, exoccipital. B Later stage of development. C Interparietal bone formed from
the upper four centres. D Pre-lnterparietal bones formed from the upper pair of
nuclei. These remain normally separate only in the horse. (Wiedersheim designates
these_ latter as interparietals, though the view expressed here appears to be the proper
one, judging from the plan of development.)
WORMIAN BONES
23
Figures 10, 11 and 12 are instances of irregular development of this
region. (For Fig. 12 see page 24.)
FIG. 10.— Wormian bones in the lamb-
doid suture. (From the Anatomical Labo-
ratory of Rush Medical College.)
FIG. 11.— Quadrangular bone occupying
the apex and adjacent portion of the
squama occipitalis, apparently represent-
ing the enlarged and ununited pre-inter-
parietal portion. (From the Anatomical
Laboratory of Rush Medical College.)
With this evident confusion as to the exact number and arrangement
of the centres in this region of the skull, further "testimony of the low
morphological value of centres of ossification in membrane bones," the
frequent impossibility of accurate distinction between true and false
Wormian bones is manifestly apparent. Still, certain special terms are
applied to more or less regular formations commonly observed here.
They are the os interparietal, os epactal and os Inca.
IXTERPARIETAL BONE.
By many authors these terms are synonymous and cover a consider-
able range of variation from all of the membranous portion of the squama
occipitalis to a small os lambdatique. The following description by
Broca probably best represents this special formation, including as it
does all of the membranous portion of the occipital bone, the line of the
adventitious suture, the interparietal, corresponding exactly with the
lower posterior limit of the development of Wormian bones in the skull
later described in this article.
"L' interparidtal se distingue par la position de sa suture qui aboutit
de chaque cote" a la partie inferieure de la suture lamdoide et qui, sur la
ligne mediane passe a peine a un centimetre et demi au dessus de 1'Inion. "
24
CHARLES A. PARKER
r,
FIG. 12 — Peculiar development of the occipital bone observed in two skulls in the
Osteological Collection at the University of Chicago. In A the two symmetrical lateral
areas apparently represent a divided interparietal separated by the sagittal suture
above, and by a tongue of bone extending from below. In B the separation is more
complete, the tongue of bone entirely separating the two portions. In both cases the
"interparietal" suture is present the greater part of the distance from the mastoid
process to the inion.
Os INCA.
Eivero and Tschudi in their "Peruvian Antiquities" described abone
later designated under this name. As much confusion exists as to its
morphological position the following quotation from these authors is
here introduced:
"In conclusion it may be proper to notice an osteologic anomaly, very
interesting, which is observed in the crania of all the three races (Chin-
cas, Aymares, Huancas) and it is this; that those children of tender
years, in the first months after birth, present an interparietal bone (os
interparietal) perfectly distinct: a bone which, as its name indicates, will
be found placed between the two parietals, and having a form more or
less triangular, whose sharpest angle is above, and is bounded by the
posterior edges of the parietal bones, while its base attaches itself to the
occipital bone by a suture which runs from the angle of union of the tem-
poral with the occipital bone, a little above the semi-circular line, to the
similar angle on the opposite side. It follows that this interparietal
bone occupies precisely that part of the occiput which in the other crania
is occupied by the upper portion of the occipital, and which is connected
with the parietals by the lambdoid suture. At four or five months this
bone is regularly united to the occipital. It is a circumstance worthy of
attention of learned anthropologists, that there is thus found in one
section of the human race a perpetual anomalous phenomenon, which is
WOKMIAN BONES
wanting in all others, but which is characteristic of the ruminant and
carnivorous animals."
The exposition of the fallacy of this premature conclusion, by Jac-
quart. lias already been mentioned. Gosse came to similar conclusions
regarding their morphological significance, although he believed they
more frequently remained separate in the Peruvians.
This accurate description, together with the accompanying figure
(Fig. 13.), from the same source, leave
absolutely no room for doubt as to its
morphology, that it represented the
generally recognized interparietal
bone of today developed from the en-
tire membranous portion of the
squama occipitalis.
Os EPACTAL.
Broca makes no distinction between
the os epactal and the os Inca, which
he describes as follows:
'•L'os des Incas est un os Wormien,
triangulaire, qui est vraiment surnu-
meraire, qui est symetrique de grande
dimension et qui occupe le lambda."
Chambellan also considers the two
terms synonymous, and asserts that it
maybe single or double, or even divided in three parts. According to
these authors it is not an interparietal, which is a false Wormian bone.
These conclusions must be based on entirely erroneous conceptions of the
os Inca as just described, and detract from the force of their opinions
with regard to the os epactal.
Topinard, Jacquart, Kambaud et Benault, Milne Edwards, Testut,
Porier et Charpey, Cunningham and many other writers use the word
interparietal and epactal as synonymous terms designating varying pro-
portions of the squama occipitalis, making no endeavor to apply them
separately to different formations; thus probably best avoiding the con-
fusion naturally arising from too much specialization in a region nor-
mally of such doubtful morphology.
The writer believes that the term interparietal, in its true sense,
should be applied only to the bone developing from the whole mem-
branous portion of the squama occipitalis, the lower boundary of which
has already been described by Broca, as a suture converging from either
side at the lower part of the lambdoid to pass in the median line scarcely
one and one-half centimetres above the inion.
As it is evident that the terms os Inca and os epactal, as they are
generally used, are rather suggestive of authority than of morphology,
further consideration of them need not be given.
FIG. 13.— Skull of a, youth of the
Chincas, 10 to 12 years old, in which the
"occipital" suture may be seen open
throughout its whole length. (From
"Peruvian Antiquities." p. 38.)
26 CHARLES A. PARKER
ANTHROPOLOGICAL SIGNIFICANCE.
Especially interesting from the anthropological standpoint is the
significant relation between the number of Wormian bones and the
cubage of the skulls selected for study. This is shown in the following
tables from Chambellan, the number of bones being on a basis of 100
skulls for each group.
No. or SKULLS TOTAL NUMBER OF
OBSERVED. NAME OF GROUP. WORMIAN BONES.
MALES
56 Auvergnats 626
124 Parisians .587
46 Neo-Caledonians 519
89 Negroes 501
44 Incas 481
FEMALES
17 Auvergnats 600
56 Parisians 551
6 Neo-Caledoriians 455
11 Negroes 427
6 Incas 493
CUBAGE OF MALE SKULLS.
No. OF SKULLS
OBSERVED. NAME OF GROUP. CAPACITY.
44 Auvergnats 1,535 cc.
40 Parisians 1,511 cc.
38 Neo-Caledonians 1,471 cc.
38 Negroes 1,410 cc.
37 Incas 1,324 cc.
The Auvergnats have the most Wormian bones, 626 to 100 skulls, the
Parisians, Neo-Caledonians and Negroes following in order of decrease to
the Incas with but 481.
Comparing these numbers with the cubage of the corresponding
skulls a similar regular decrease in capacity is shown from the Auver-
gnats to the Incas, thus establishing the general conclusion that the
number of Wormian bones is greatest in the skulls of the largest capacity,
and correspondingly diminishes as the cubage decreases. See the follow-
ing table:
Auvergnats 626 Wormian bones. Capacity, 1,535 cc.
Parisians 587 " " " 1,511 cc.
Neo-Caledonians 519 " " " 1,471 cc.
Negroes 501 " " " 1,410 cc.
Incas 481 " " " 1,324 cc.
WORMIAN BONES 27
The cubage of the female skulls was neglected, yet a diminished total
in each of the groups except the last, probably accounted for by the small
number of skulls (six) observed, shows here also the same definite corre-
spondence between the numbers and the well known smaller capacity of
these skulls.
Analagous and equally interesting results corroborative of this
relation are obtained by examination of the data relating to the other
groups of skulls examined by this writer.
Hydrocephales, adults. 13 1092 Wormian bones. Capacity 3,727 cc.
Hemi-microcephales . . .15 366 " " " less than 1,100 cc.
Apes, anthropoid 52 96 " " " in gorilla 531 cc.
Microcephales 5 40 " " " 433 cc.
Apes, non-anthropoid. .73 17 " " "much less than
microcephales.
The commonly observed increase of these bones in hydrocephalic
skulls is here very apparent.
Comparing these with the skulls of the Auvergnats, the largest nor-
mal skulls studied, the relation of number to capacity is very strikingly
shown.
Auvergnats 600 Wormian bones Capacity, 1,535 cc.
Hydrocephales 1,092 " " " 3,727 cc.
Equally noticeable is the diminished number in the crania of small
cubage as the anthropoid apes and microcephales.
Chambellan also studied their occurrence in brachycephalic and
dolichocephalic skulls, examining fifty of the former and twenty-five of
the latter, with the result of finding the equivalent of 676 Wormian bones
to the hundred skulls in the former, and 362 in the latter.
A comparison of the cubage of some of these skulls gave the follow-
ing results:
No. OF SKULLS. TOTAL CAPACITY. AVERAGE.
Brachycephales, 12 18,311 cc 1,525 cc.
Dolichocephales, 28 42,145 cc 1,505 cc.
The number of skulls is too small to furnish the most desirable proof,
but from all that has been shown the evidence is very conclusive that in
spite of numerous isolated exceptions, the general rule for groups holds
good, that the number of Wormian bones increases with the capacity of the
skull, regardless of the cause of the enlargement.
Finally their occurrence on the two sides of the head was separately
recorded with the following results:
Parisians Right side 281 Left side 255
Auvergnats " " 307 " " 288
Neo-Caledonians " " 299 " " 197
Negroes " " 295 , " " 215
Incas.. " " 257.. " " 230
28 CHARLES A. PARKER
Showing their greater frequency on the right side in all the groups
examined.
SUTURAL, LENGTHS. — With the object of establishing a probable
direct relation between the increase in Wormian bones, and the general
increase in sutural length, and between their preponderence on the right
side and a greater corresponding dextral sutural length, careful measure-
ments were made by the writer upon 50 normal skulls to obtain data
upon which conclusions might be based. Measurements were made of
the coronal, lambdoid, squamous, (including the sphenoparietal and
mastoparietal), and sagittal sutures, as they comprised most of the
sutures bearing Wormian bones. In the first three, including the two
transverse sutures, the two sides were recorded separately. The cephalic
index was also taken in each case, and the skulls divided into dolicho-
cephalic, mesaticephalic and brachycephalic classes. The average total
sutural length in 22 dolichocephalic skulls was 78. cm., in 16 mesati-
cephalic skulls 78.7 cm., and in 12 brachycephalic skulls 79.8 cm., or
including the last two in one group, in 28 brachycephalic skulls 79.2 cm.
Chambellan determined that the brachycephales have a greater cranial
capacity than the dolichocephales— he did not distinguish a middle class
— and that they also have a larger number of Wormian bones correspond-
ing to their increase in cubage, agreeing with his previously mentioned
law that as a class the larger the cranial capacity the greater the number
of Wormian bones. A comparison of his results with those obtained
from the foregoing sutural measurements suggests certain fundamental
relations; first, as the brachycephalic skulls have a greater number of
Wormian bones and also a greater sutural length, that the greater the
sutural length of a skull the greater the number of Wormian bones; and, second,
as the brachycephalic skulls have a greater cranial capacity with a
greater sutural length, that the larger the cranial capacity of a skull, the
greater its sutural length. In other words, in man at least, the number of
Wormian bones and the capacity of a skull bear a direct relation to the
length of its sutures.
These relations thus established by tangible data are such as we
would a priori expect to obtain, since the Wormian bones develop in the
sutures and the longer the suture the greater the opportunity for increase
in their numbers, and the greater the cranial capacity the longer the
sutures necessary to unite the enlarged parts. In the first principle
also is to be found the explanation of their greater frequency on the
right side, as the total sutural length of the right side of the 50 skulls
was 1,666.2 cm., as compared with a total of 1,643.5 cm., on the left, the
excess being limited to the squamous and coronal sutures. Although of
secondary importance to the main subject, certain interesting observa-
tions appear in the comparison of the coronal and lambdoid sutures in
the two general classes of skulls. In the 22 dolichocephales the coronal
WORMIAN BONES 29
sutural length averaged 22.7 cm., and in 28 brachycephales 23.4 cm.,
while the lambdoid in 22 dolichocephales averaged 19.5 cm., and in 28
brachycephales 19.3 cm., showing a very definite increase in sutural
length, associated with a corresponding increased cranial capacity, in
the anterior and lateral regions of the brachycephalic skulls with a
stationary or slightly diminished capacity in the posterior region of the
same skulls. The lateral increase is particularly emphasized by similar
comparisons of the squamous sutures in the three classes of skulls, as the
average length in 22 dolichocephales was 23.2 cm., in 16 mesaticephales
23.5 cm., and in 12 brachycephales 24.9 cm., a progressive increase from
the first to the last. At the same time the sagittal suture is shortened
from an average of 12.6 cm., in dolichocephales to an average of 12.4 in
brachycephales. The direct relation of the increase in size in this
region — the temporal fossa — to brachycephaly, with special reference to
the causative factor of the jaws in its production, is admirably demon-
strated in an exceedingly interesting scientific paper by Arthur Thom-
son, presented before the recent International Medical Congress, at
Madrid.
CAUSES.
The larger number of Wormian bones doubtless arises from local
metabolic variations entirely physiological and compensatory in charac-
ter. Their innocuous occurrence in practically all normally developed
skulls is opposed to an essentially pathological origin, and only when
presenting particularly abnormal features should it come into considera-
tion. Their occasional association with definite pathological processes
may be secondary or incidental, and rarely a direct or specific result of
the primary affection. Pathological or physiological variations can
directly produce Wormian bones in but two ways; either by permanently
segregating offshoots from pre-existing centres, or by causing an excess
of original centres themselves. As the distinction between physiological
and the milder pathological fetal nutritional variations is frequently
so obscure the difficulty of positively ascribing these effects on osteogene-
sis to definite pathological causes is plainly apparent. A physiological
excess of primary ossific nuclei, possibly sometimes hereditary or atavistic
is well known to occur, and it is possible that some of the definite patho-
logical processes, or the more subtle so called degenerative influences
may also occasionally produce similar results; but there is no doubt that
most of the Wormian bones properly ascribed to specific pathological
processes directly affecting osteogenesis are produced by the permanent
segregation of nuclei from pre-existing centres.
Rachitis, scrofula, violent pressure, heredity, syphilis, and in addi-
tion, in the writer's case, osteogenesis imperfecta, chondrodystrophia
fetalis, and cretinism, have all been considered in the pathology of their
30 CHARLES A. PARKER
development. Lombroso and Ferrero assert their increased frequency in
the crania of criminals. Of the pathological conditions in which the
occurrence of Wormian bones is but incidental or secondary to the pri-
mary affection, hydrocephalus is probably the best known. Other affec-
tions gradually producing great cranial enlargement would probably lead
to equally excessive development of these bones.
Their production by pressure is evidenced by their increased fre-
quency in the coronal suture in the skulls of the flat head or similarly
deformed Indians reported by Dorsey, and those referred to by the author
in a previous paragraph. Whether flattened by direct pressure on the
occiput and forehead, or by compressing bands around the back of the
head, the compensatory lateral enlargement is especially effective in the
coronal region, correspondingly increasing its predilection for Wormian
bones. Their occurrence is secondary to the sutural diastasis.
The role of heredity in their production without the relative occur-
rence of pathological features is distinctly physiological.
Their association with stigmata of degeneration, tuberculosis, syphi-
lis and similar dycrasiae must be considered quite incidental to the pri-
mary affection, and only possessing a possible aetiological relation when
presenting distinctly unusual or abnormal local features.
Chondrodystrophia fetalis and osteogenesis imperfecta are prenatal
in origin, rachitis and cretinism are essentially postnatal affections,
though possibly occasionally occurring earlier under the influence of
maternal dycrasiae similar to their own specific pathologies. Except in
the latter extremely rare instances, the influences of these two chrono-
logical classes of affections on osteogenesis must differ considerably in
their opportunities, if not in their effects; the prenatal affections alone
being capable of profound fundamental disturbances of osteogenesis, the
postnatal diseases being limited in the production of separate nuclei to
their action on the margins of the bones only.
Osteogenesis in cretinism exhibits a similar characteristic sluggish-
ness or inhibition in its course to that observed in the growth of other
tissues in this disease, a condition apparently most unfavorable to the
development of supernumerary ossiflc nuclei; although in the single case
mentioned by Hyrtl the extraordinary number of 300 was found in the
lambdoid suture of a cretin.
On the other hand, however, the notably irregular osteogenesis of
rachitis would appear to specially favor the separation of such nuclei
from pre-existing centres, and this disease is particularly mentioned by
Gosse as one of the causes of Wormian bones. Yet its postnatal occur-
rence and usually short duration necessarily reduce its direct aetiological
relation to narrow chronological and mensural limits.
Chondrodystrophia fetalis is a fundamental disease of chondrogenesis,
secondarily affecting only bones of chondral origin so that while the base
WORMIAN BONES 31
of the skull may present gross deformities the membrane bones show no
specific alterations. It thus bears no aetiological relation to Wormian
bones.
Osteogenesis cranii imperfecta, or aplasia cranii, with its irregular
development of isolated patches of bony tissue, appears to be the best
known pathological condition to favor excessive development of these
bones. A beautiful specimen of this condition is the fetal skull described
by Vrolik in a later paragraph. (Fig. 23.)
Back of these fetal dystrophias commonly lie parental, usually ma-
ternal, dyscrasiae, and, in the Vrolik case syphilis apparently played an
important part. In the writer's case Prof. Hektoen, in a separate article
more especially concerning the general dystrophy, considers rachitis,
cretinism, chondrodystrophia fetalis and osteogenesis imperfecta as
possible causes of the various body changes. As neither the changes in
the skull nor in the body conform to those of rachitis or cretinism, they
were excluded as aetiological factors, and the preference given to osteo-
genesis imperfecta and chondrodystrophia fetalis. The body changes
with the short and misshapen limbs correspond closely with those ob-
served in the latter disease, and differ from those of the former in the
apparent absence of multiple fractures. On the other hand, the changes
in the cranium correspond to those of osteogenesis imperfecta, while the
base of the skull presents none of the lesions of chondrodystrophia
fetalis.
The successive occurrence of the two diseases is doubtless possible,
but the restriction of the two processes to separate and distinct areas
instead of each acting generally, develops an apparently unique variation
from the usual types. Considering the analogy between this skull and
the one described by Vrolik, its excessive number of Wormian bones can
best be ascribed to the changes occurring in osteogenesis imperfecta. On
account of the incomplete history it is impossible to determine any
parentalldyscrasiae.
The changes in the face of this skull, of a distinctly degenerative
character, are in all probability due to the same general dyscrasia
variously affecting the^different regions of the body.
32 CHARLES A. PARKER
MEDICAL ASPECTS.
Their specific medical importance is exceedingly limited. By simu-
lating normal sutures or fractures, the occurrence of adventitious sutures
may occasion confusion in examination of the skull.
Nicolas Saucerotte, in his "Melanges De Chirurgie," mentions the
case of a clergyman who was thrown from his horse and suffered an
injury in the occipital region. The first attendant on examining the
wound, pronounced it a fracture of the skull, and suggested trephining
as the proper treatment. Dr. Nouvelle, a clever surgeon of the time,
was called in consultation, and opposed the diagnosis of fracture. He
contended that the apparent line of fracture was the adventitious suture
of a Wormian bone. The skull was not trephined. Upon his recovery
the grateful clergyman promised, should he die first, that the doctor
whose knowledge and skill had saved his skull intact while he lived
should have the opportunity of examining it after his death. Some
years later he died, and the doctor found at the site of the injury a tri-
angular shaped Wormian bone measuring one inch and ten lines in its
greatest diameter, by one inch and a half in its lesser, occupying the
upper angle of the occipital bone, its transverse suture having previously
been mistaken for a fracture of the. skull. This is the only instance I
have found recorded of a Wormian bone becoming of surgical importance,
although it is highly probable that such confusion has not been so rare
as this single record would indicate.
In the "New York Medical Record" for 1888, Grace Peckham reports
three cases occurring during her internship in the New York Hospital
for Women and Children, in which Wormian bones in the posterior fonta-
nelle gave rise to confusion in the examination of the presenting head,
and were considered responsible for the death of all three children, as
no instruments were used in the deliveries. These are the only recorded
instances in which pathological influences are ascribed to these bones.
AUTHOR'S CASE OF EXTRAORDINARY DEVELOPMENT OF
WORMIAN BONES.*
This interesting skull was obtained by Prof. Hektoen at an autopsy
on a white man about 45 years of age. The man had been a resident of
Chicago, and possessed only a fair degree of intelligence. He had always
been a cripple, the most noticeable deformities being a marked dorso-
lumbar kyphosis and very imperfectly developed and misshapen limbs.
The special body changes have been described by Prof. Hektoen in a
separate article, t
The skull presents on lateral view an unusually high cranium over-
towering a small, receding face, and protruding lower jaw. In front it
has a narrow oval outline with high orbits and irregular teeth.
(Figs. 14 and 15.)
Various measurements were made and compared with the average of
ten normal skulls, and are given in the following table. The measure-
ments are in centimetres unless otherwise stated.
SPECIMEN AVERAGE
CRANIUM. SKULL. SKULL.
Greatest length 17.2 18.3
Greatest breadth 13.2 14.6
Cephalic index 76.7 80.1
Circumference 49.5 52.6
Biauricular distance over bregma 35.
Basio-bregmatic height 15. 12.4
Vertical height from external auditory meatus to
bregma , 13.5 12.1
Capacity 1450 cc. 1450 cc.
Basion to foramen caecum 9.7 8.3
Distance from inion to vertical dropped to basion 8. 7.9
Basion to spenocribriform junction, Huxley's base
line.. . .6.6 6.4
*The skull was presented at the fifteenth annual session of the Association of
American Anatomists, at the University of Chicago, Dec. 31, 1901 to Jan. 2, 1902, and a
brief abstract was later published in the proceedings of the society.
tL. Hektoen. Anatomical Study of a Short Limbed Dwarf, with Special Reference
toOsteo^euesis Imperfecta and Uhondrodystrophia Foetalis. — Amer. Jour. Med. Sci..
May. 1903.
34 CHARLES A. PARKER
SPECIMEN AVERAGE
SPHENOID. SKULL. SKULL.
Occipitosphenoidal synchondrosis to spheno crib-
riform junction— length of spbenoid 4.4 4.3
Postsplienoid 2. 2.3
Presphenoid 2.5 2.2
Pituitary fossa, depth 1. .9
diameter, transverse 1.5 1.3
diameter, antero-posterior 1. 1.2
Foramen magnum, length 3.7 3.7
breadth 3.4 3.1
FACE.
Basion to nasion 10.1 10.1
Basion to posterior inferior angle of nasal bone 9. 9.7
Basion to prosthion 7.5 9.6
Basion to gnathion 9.2 11.6
Basion to supraorbital notch 10. 10.2
Basion to middle of infraorbital margin 7.5 8.6
Basion to posterior nasal spine 3.7 4.
Nasion to prosthion 6.2 7.1
Nasion to gnathion 10.7 12.
Nasion to gonion 10.5 12.5
Prosthion to gnathion 4.3
MANDIBLE.
Gonion to gonion 9. 9.9
Gonion to gnathion 6.5 9.1
PALATE.
Length 3.4 4.9
Breadth, interalveolar 3.7 3.8
NASAL CAVITIES.
Anterior nares, height 3. 3.1
width 2.1 2.3
Posterior nares, height 2.5 2.7
width 3.5 3.
The maximum length is 17.2 cm., the maximum breadth 13.2 cm.,
with a corresponding circumference of 49.5 cm.
The height from the basion, or anterior margin of the foramen mag-
num, to the bregma, is 15 cm. Although a comparison of these figures
with those averaged from ten normal skulls shows both the breadth and
length to be slightly over 1 cm. short of the average, yet the height, which
is increased by over 2 cm., completely compensates for the circumferen-
tial constriction, as shown by the capacity of 1450 cc., that of the aver-
age normal male skull. The cephalic index is 76.7, hence the skull is of
the mesaticephalic type.
WORMIAN BONES 35
The internal surface of the base presents little variation from the
average sic a 11 in form or measurements; the foramen magnum is normal
in size, shape and location, as are also neighboring parts of the occipital
bone, except that the upper part of the tabular portion is composed of
Wormian bones.
The thickness varies from 2 mm. laterally in the temporal region, to
9 mm. in the frontal and occipital, the average being 4 to 5 mm.
The distance from the basion to the foramen caecum is 1 cm. above
the average, which, considering the shortness of the skull and normal
location of the basion, appears disproportionate, but is explained by the
absence of the frontal sinus and crest. The foramen is situated 1 to 2
cm. nearer the anterior surface of the skull and correspondingly farther
from the basion.
It is not unusual to find the distance from the glabella to the fora-
men more than 2 cm., while in this skull it is less than 1 cm.
The distance from the basion to the occipitosphenoidal synchon-
drosis is normal, as is also the distance from the latter to the anterior
superior angle of the sphenoid at the cribriform suture. The cerebral
surface of the presphenoid measures 2.5 cm., while the postsphenoid
measures but 2 cm., giving an index of 125, obtained by dividing 100
times the former by the latter, the average being very close to 100, or
both parts equal. In a series of skulls examined the maximum was 113,
and the minimum 87.
While the total length of the cerebral surface of the sphenoid is not
affected, the disproportion between the two parts is unusual, and con-
stitutes the only noteworthy variation from the ordinary measurements
in this region.
Although somewhat asymmetrical in general outline, the entire
cranium presents but slight variations from the normal measurements,
the moderate circumferential constriction being accompanied by vertical
elongation with undiminished capacity, and the disproportion between
the pre- and postsphenoid making no difference in the length of the floor.
The peculiar shape of the skull with the recession of the face may be
represented by superimposing an outline of a median section of the skull
upon a similar outline of an average skull, so that a line from the basion
to the sphenocribriform junction, the base line of Huxley, in one, exactly
corresponds with a similar line in the other, their uppermost ends being
at the same point. (Fig. 19.)
RECESSION OF FACE: — If the facial profiles be represented by two
irregular curves drawn through the nasion, posterior inferior angle of the
nasal bone, prosthion and gnathion, a comparison of them will show that
they lie quite near at their upper ends at the nasion, and progressively
diverge to the prosthion the point of maximum separation of 2.4 cm.,
36 CHARLES A. PARKER
from whence they continue nearly parallel or slightly converging to the
gnathion, where the difference from the average skull is about the same
as at the prosthion.
The curves are obtained by joining the arc connecting the three
upper points with that connecting the three lower at their point of
intersection. (Fig. 20.)
A series of measurements from the basion successively to the afore-
mentioned parts compared with a similar series the average of ten nor-
mal skulls confirms the results obtained by direct comparison of profiles
showing no recession at the nasion, agreeing with the measurements of
the base of the skull, a slight foreshortening at the posterior inferior
angle of the nasal, the portion most commonly present of the lower
extremity of that bone, and most marked at the prosthion where the
difference as above stated is over 2 cm.
Although the lower jaw protrudes beyond the upper, and relieves in
some measure the appearance of recession, it also shares in the general
defective development of the face, and is decidedly shortened, the
gnathion, or most prominent part of the symphysis menti, being 2.4 cm.
nearer the basion than normally, and its intrinsic length from gonion to
gnathion 2.6 cm. below the average.
A series of horizontal profiles drawn through the various levels men-
tioned compared with those of a normal skull show in each plane concen-
tric curves with increasing recession of the lateral regions of the face
similar to that in the median line.
The vertical curves are eccentric, the horizontal concentric. There
is a vertical shortening of the face of 1.3 cm.
As the face is but slightly narrowed the main fault of development is
in the sagittal plane with but little, if any, in the coronal, and as the
recession is symmetrical, affecting both sides of the face alike, it is evi-
dently the result of some general cause exerting its principal influence in
a sagittal direction. The recession is not due to the premature ossifica-
tion of the basiosphenoid cartilage with consequent shortening of the
base of the skull, as has already been shown, nor to an excessive flexion of
the face on the cranium from any other possible cause, as the normal
distance separates the basion and the posterior nasal spine, the meeting
point of the vomer and palate bones, which from their relation to the
base of the skull would be the ones most influenced by its flexion. It is
therefore necessarily due to the changes in the bones of the face itself,
and principally and primarily in the maxilla?, as the ones most influencing
its form. The true facial profile is formed by the nasal and maxillary
bones, with the former resting upon the superior maxillae; so that changes
in the latter affecting their nasal processes produce corresponding varia-
tions in the positions of the nasals, the upper ends of which remain with
the cranium proper, wbile the lower ends follow the changes of the ma-x-
WORMIAN BONES 37
illas and swing on the upper as on a pivot. The increasing recession from
above downward reaching its acme at the maxillaa is co-ordinate evidence
of the primary responsibility of these bones for this feature of the skull.
As the evolution of the teeth is the most important factor in the
growth of the jaws, and perversions in this process produce irregularities
in the development of the maxillas, a consideration of the dentition is
essential to a proper appreciation of the maxillary changes.
DENTITION.
SUPERIOR MAXILLAE.
Incisors. The upper jaw contains two large, well spaced median in-
cisors, and one small lateral incisor on the right side, half the normal
width, and separated from the median by a space equal to its own width,
Canines. The canines are well developed, the left being shifted one
centimeter nearer the median line through non-development of the lateral
incisor. Its ridge also participates in the shifting and borders the lateral
margin of the anterior nares. The intermaxillary suture is deflected
slightly to the left as it approaches the alveolar margin.
Premolars. Two well developed and partially rotated premolars are
present on the left side, and one, the distal, well developed and partially
rotated, on the right. Two unoccupied alveoli, one lateral and one
medial, are present behind this single premolar, the former probably
being for the absent second premolar, and the latter of small size, of
unknown function.
Molars. The first molars only are present on either side, the second
and third never having erupted.
There are six teeth on the right side, and five on the left. The ab-
sence of the left lateral incisor with mesial shifting of the canine is
accompanied by marked left sided flattening, producing considerable
asymmetry of the alveolar arch. Vertically they are much shortened,
and the nasal processes separated from the frontal by intervening
Wormian bones.
MANDIBLE.
Incisors. Two shallow alveoli mark the place of two missing central
incisors that were of fair size, judging from the space left for them.
One lateral incisor is present on the right side but none on the left,
corresponding with the same condition in the upper jaw.
Canines. The two canines are present, the left being 5 cm. nearer
the symphysis than the right.
Premolars. The first premolars are present on either side.
The second premolars are absent on both sides.
On the left side is a narrow interval between the first premolar and
the first molar with no alveolar absorption; on the right an interval of
38 CHARLES A. PARKER
two centimeters exists between the first premolar and the second molar
with absorption of the alveolar process, which probably once contained a
well developed second premolar and a first molar.
Molars. The first and second molars are present on the left side; and
the second with an erupting third on the right, the first as just men-
tioned probably having formerly occupied the region of the absorbed
alveolus.
Counting the two median incisors whose alveoli are present, there are
six teeth remaining in each lateral half, the total number erupted on
the leftside, while on the right side there were eight, the full number.
This excess of the right side over the left of eight to six, is similar to
that in the upper jaw, which is as six to five. As in the upper jaw, the
absence of the left lateral incisor, and mesial shifting of the canine,
determine a flattening of the curve on the same side accompanied here
by an abrupt bend at the canine tooth. The muscles of the cheeks and
lips evidently were important acessories, producing the reciprocal
changes in the jaws for the articulation of the teeth.
The length of the right half from the symphysis to the posterior
border of the ramus exceeds the left by 1 cm. As there is no backward
displacement of the ramus and the normal curve is maintained, the in-
creased length causes a slight displacement of the symphysis to the left
of the median line.
A slightly increased relative deficiency over that of the lower jaw
exists in the length of the upper, corresponding to the more incomplete
dentition. The distance between the condyles corresponds with the
normal measurements of the base of the skull.
This study of the dentition renders very apparent the role of the
teeth as an important causative factor in the production of the facial
deformity; and, as the permanent teeth are the ones more evidently in-
volved, the disturbing process, doubtless prenatal in origin isseen to have
extended through a considerable number of postnatal years, in this
respect corresponding with the changes occurring in the growth of the
chondro-skeleton as shown in the fragile and misshapen bones of the
trunk and limbs.
POSTERIOR NARES. The posterior nares measures 2.5 cm. in height
and 3.5 cm. in width. In the average normal skull the two measurements
are practically equal.
This great disproportion between the height and width of the post-
erior nares gives a broadening effect, which with the incomplete dentition
already noticed, stamps the face anatomically of the infantile type ren-
dering the general deformity particularly conspicuous because of the
adult cranium,
WOKMIAN BONES 39
WORMIAN BONES.
By far the most interesting feature of this skull is the extraordinary
development of Wormian bones, numbering 172. (Figs. 14, 15, 16, 17, 18.)
These bones are most numerous in the posterior and lateral regions
of the skull, supplanting the larger portion of the parietals, the squamous
portions of the temporals, and the upper half of the tabular portion of
the occipital.
Several occur in the vertical and orbital plates of the frontal, partic-
ularly in the vicinity of the nasal notch. The portions of the cranium
free from them are the lower half of the tabular, the condyles and basilar
portions of the occipital, the mastoid and petrous portions of the tempo-
rals, the sphenoid and ethmoid bones, or those parts developed primarily
from cartilage, the chondro-cranium.
They range in size from 3 mm., and even less in the posterior and
lateral regions, to one measuring 5 by 9 cm. in the upper part of the
frontal bone.
They are mostly irregularly circular in form, with coarse and fine
dentations for articulation with similar adjacent bones. All layers of
the bones are affected, the outer surface presenting the most irregular
and uneven serrations, the inner showing fewer irregularities combining
with the others, making a smooth, even surface next the dura.
Parietal bones. Three-fourths of each parietal bone are represented
by various sizes of Wormian bones, ranging in diameter from 3 mm. to
3cm., the remaining fourth consisting of a single quadrilateral segment
measuring 4 by 8cm., occupying the anterior superior angle, separated
from its fellow by the sagittal suture, and forming with the frontal the
upper part of the coronal suture. Bordering the coronal suture on either
side below the larger segments are three or four of smaller size ranging
from 2 cm. to 3 cm. in diameter. The temporal ridges are indistinct or
absent. On the inner surface the grooves for the meningeal arteries are
weil marked. The average thickness is 3 to 4 mm.
Temporal bones. The squamae temporales consist almost entirely of
various sized Wormian bones, their slender interlocking processes pre-
senting an appearance resembling a delicate pattern of lace work. As
previously mentioned the mastoid and petrous are not involved.
Occipital bom. The line of separation between the membranous and
cartilaginous portions of the squama occipitalis is distinctly marked by a
curved denticulated suture extending from one mastoid region to the
other, rising in the middle 1}£ cm. above the inion, corresponding exactly
to the lower boundary of the interparietal bone as outlined by Broca.
The part above this suture is composed entirely of Wormian bones, as is
well shown in the posterior view of the skull. (Fig. 17.)
Frontalbone. The unusually high frontal bone is divided into two
nearly symmetrical halves by the persistent metopic suture. The entire
40 CHARLES A. PARKER
upper portion of the right half exists as a separate bone, cut off from the
lower part by a suture extending from the metopic laterally to the coro-
nal. This large Wormian bone is somewhat quadrilateral in form, and
measures 9 cm. in length by 5 cm. in width.
Twelve small Wormian bones are located in the suture between the
orbital plates and the alto parvie of the sphenoid, the cribriform plate,
and lateral masses of the ethmoid, the lachrymal, and the nasal processes
of the superior maxillae, forming a considerable portion of the upper and
inner walls of the orbit. None, however, exists in the nasofrontal suture.
The distribution by numbers in the different regions may approximately
be given as follows:
Frontal bone, 12.
Parietals, each, 40.
Temporals, each, - - - - - - . 25.
Occipital, 30.
Sutures. The sagittal suture extends uninterruptedly from the nasion
to within one and a half centimeters of the inion, or throughout the
total median extent of the membranous cranium, a condition normally
present only in intrauterine life.
This suture is quite distinct throughout, the Wormian bones that
border i t for the greater part of its extent not attempting to cross it
more than the usual dentations common to the normal suture. In the
frontal region its dentations are least developed, towards the lower part
becoming a sutura harmonia.
The persistence of the frontal portion of the sagittal suture is of very
frequent occurrence, but its persistence through the membranous por-
tion of the squama occipitalis is exceedingly rare, when present being
almost, if not quite always, accompanied by a bisected interparietal.
The coronal suture is well marked and bounded behind by Wormian
bones from one temporal fossa to the other.
The squamoparietal suture is completely obliterated by the confusion
of Wormian bones in its vicinity, and the sphenoparietal, squamosphe-
noidal and mastoparietal sutures are only defined by the limitation of
development of these supernumerary bones at the borders of the great
wing of the sphenoid and mastoid portion of the temporal, as these are
the lines of separation between the membranous and thechondrocranium.
The lambdoid suture is also obliterated, as it is impossible to trace it
with any degree of precision through the mosaic of bones occupying this
region.
As before mentioned, a well marked suture extends in a curved direc-
tion from one mastoid region to the other, crossing the center of the
occipital just above the inion, marking out the lower limit of develop-
ment of Wormian bones, or the separation in this region of the membra-
nous and chondro- or primordial cranium.
WORMIAN BOXES
41
The adventitious suture extending from the metopic to the coronal,
and separating the large Wormian bone from the right half of the fron-
tal, is long enough to merit special mention. It is reciprocally bevelled
and feebly denticulated.
The rest of the cranial sutures are distinct, though a number of
Wormian bones are intercalated in those surrounding the nasal notch of
the frontal.
Fontanelles. As the whole squamae temporales and adjacent portions
of the parietals consist of Wormian bones, it is impossible to separately
distinguish pterion and asterion ossicles.
A similar profusion of these bones in the posterior region of the skull
makes it equally impossible to distinguish an os Wormien lamdatique in the
posterior fontanelle. This complication does not exist at the bregma,
where no bregmatic bone is present.
In each orbit there is an os Wormien orbitaire occupying the angle of
junction of the frontal, os planum of the ethmoid and lesser wing of the
sphenoid.
FIG. 21.— Right orbit,
fontanelle.
A, B, C, I. D. Wormian bones; A, occupying the orbital
The one in the right orbit measures 1 cm. wide by 2 cm. long, the
long axis being obliquely vertical. (Fig. 21.) The one in the left orbit
measures 7 mm. by 12 mm. and has the same relative direction as the
right. (Fig. 22, page 42.)
This bone was not observed a single time in the nearly 500 skulls
examined by Chambellan.
In the accompanying figures are shown other accessory bones in the
orbits, four being visible in the right, and three in the left in the suture
surrounding the nasal notch.
42 CHARLES A. PARKER
In the so-called abnormal fontanelles at the site of the nasof rental
suture, the fontanelle glabellaire, and at the obelion, the fontanelle
FIG. 2:2.— Left Orbit. A, B,0, D, Wormian bones; A, occupying theorbital fontanelle.
obelique, no example can be said to be present; in the tirst instance being
definitely absent, and in the second, although the number of adventitious
bones apparently leaves some room for doubt, none crosses the sagittal
suture, demonstrating here also the absence of a special bone, or true
os Wormien obeliqw.
Although so much of the cranium is composed of Wormian bones, yet
the cranial anlage are well preserved, the principal sutures and bony
areas being present and in their proper relations, showing that whatever
general influences affected the skeleton, they were, in the skull at any
rate, limited to osteogenesis, and not of earlier origin or farther reaching
in their effects disturbing the fundamental elements and interfering
with the type of development as is observed in the perverted chondro-
genesis of chondrodystrophia foetalis, and frequently seen in monsters.
The same may be said of the rest of the skull; all the bones are pres-
ent with their usual relations though the imperfect development of
some produces considerable deformity, most marked in the recession of
the face.
No similar condition in an adult skull has been recorded, and but two
of a like nature have been observed in infants. These are the cases of
Jung and Vrolik. Quoting from Hrdlicka, (%Jung published in 1827 an
observation on the skull of a new born male child, which showed, besides
an extreme number of Wormian bones, irregular divisions in both parie-
tals. The right bone was separated into five, the left into three por-
WORMIAN BONES 43
tions," and in referring to the same instance, Zeller remarks, ''Jung says
the disintegration of the whole cranium into intercalary bones is very
rare."
In regard to the second case, Vrolik says, "The skeleton is from anew
born infant of syphilitic parents.
"It died the third day; the following year the mother bore a healthy
child. The whole osseous system was vitiated. This was most noted in
the cranium, where no bone could be said to be intergrate. The frontal
bone, the parietal bones, for the most part, and also the occipital bone,
consisted of very many nuclei with irregular bones, which were joined
by serrate margins, and gave to the cranium the appearance of being
composed of very many little Wormian bones put together.
'•Without doubt
the cranium was
expanded by hy-
drocephalous with
a short and nar-
row face. The
rest of the
skeleton showed
an imperfect
state of the osse-
ous system, with
many fractures
occupying all the
ribs and long
bones, some re-
cent, some cured
by callus. No
doubt this was
FIG. 23. — Osteogenesis imperfecta cranii. (After Vrolik.) from imoerfecfc
osteogenesis, both as to form and texture of the bones."
The accompanying figure shows this infantile skull with its rich
mosaic of supernumerary ossiflc nuclei to be an almost perfect minature
of the one presented with this article. (Fig. 23.)
44 CHARLES A. PARKER
GENERAL SUMMAEY.
CHAMBELLAN'S CONCLUSIONS.
Chambellan at the close of his exhaustive work presents the follow-
ing conclusions:
The real name of Olaus Wormius is Olaiis Worm.
We may establish two categories of Wormian bones.
(1) The os Wormien suturaux.
(2) The os Wormien fontanellaires.
The os epactal and os interparietal should still be considered as
different bones.
There are more Wormian bones in the lambdoid suture than in the
others; they are also here the most voluminous. Following in order of
frequency are the coronal, sagittal, squamous, masto-occipital and masto-
parietal.
There are occasionally met in the sagittal suture certain Wormian
bones of quite considerable size, and occupying always a place in the
vicinity of the bregma, the obelion, or the lambda. In consequence they
should be given the names os parabregmatique, paraobelique and para-
lamdatique, or better, sagittal-lambdoidien.
The skulls with obliterated sutures contain fewer Wormian bones
than those in which the sutures are open or present.
There are more Wormian bones on the right side than on the left.
The Wormian bones are developed in two ways; the first, the usual
manner, by the development of separate ossific nuclei, the second, by the
absorption of pedicles of denticules leaving the minute extremities free.
In general they are more numerous in the larger crania.
This appears constant in all the groups examined, Auvergnats,
Parisians, Neo-Caledonians, Negroes, Incas, microcephales, hemi-micro-
cephales, apes and hydrocephales.
They are more numerous in brachycephales than in dolichocephales.
This is notable, as the former have a greater average capacity than the
latter.
In the Parisians, Auvergnats, Neo-Caledonians, Negroes, and Incas
they are more abundant on the right side than on the left.
HYRTL'S RULES.
Hyrtl gives the following rules:
(1) They are found only in the cranium, and more in the true than
in the false sutures. In the face but two examples have been personally
observed, one in the crucial suture of the palate, the other in the inter-
nasal suture.
WOBMIAN BONES 45
(2) They are more frequent in large skulls than in small.
(3) Their size varies from a flax seed to that of a dollar, which was
observed in the anterior fontanelle.
(4) Paired Wormian bones on the cranial vault are more frequently
symmetrical than not, but in the temporal fossa are as often asymmetri-
cal as otherwise.
(5) The/ coasist usually of two layers with diploe, their inner sur-
face as a rule being smaller than the outer.
(6) Rarely they are found on the inner surface and not on the outer,
more frequently do they appear only on the outer surface when they are
always small. A rare form is the os insulare observed in the parietal
near the margo squamosa.
AUTHOR'S CONCLUSION*.
Wormian bones are properly named after Olaiis Worm, and his claim
to priority of description is established by his letter to Thomas Bartholin.
To the two categories of Cliarnbellan should be added the os insules
of Manouvrier and Ilyrtl.
The os interp;irietal should be limited to those single, or rarely
several, elements representing the complete anlage of the membranous
squama occipitalis.
The os Inca of Rivero and Tschudi is identical with the true inter-
parietal; but the os epactal and os Inca as commonly defined have no
definite morphological limits, and therefore no absolutely distinctive
characteristics.
All observers agree to the preponderance of Wormian bones in the
lambdoid suture. Their almost complete limitation to the sutures bor-
dering the parietal bones is also noteworthy.
They develop either from original centres themselves or by segrega-
tion from pre-existing centres.
They vary in size from a millimetre in diameter to the one measuring
5 cm. by 9 cm. in the accompanying skull, probably the largest true
Wormian bone ever recorded.
They are frequent in the crania of infants, and at times are doubt-
less synchronous in origin with the normal ossiflc centres.
The obliteration of the sutures by age or other causes diminishes
their number by effacing the characteristic feature that distinguishes
them from the adjacent bones.
True Wormian bones have no morphological value.
Their increased frequency in crania of large capacity is an apparently
well established fact, the same rule applying whether enlarged from
physiological or pathological causes.
Brachycephalic skulls have the greatest total sutural lengths. With
Chatnbellan's observations that the brachycephalic skulls have the
46 CHARLES A. PARKER
greatest average capacity and the largest number of Wormian bones,
this establishes a direct ratio between the number of Wormian bones,
and the total sutural length.
In the 50 skulls examined by the writer the total dextral considerably
exceeded the total sinistral sutural length. As Chambellan observed a
dextral preponderance of Wormian bones in the skuils he examined,
their excess on the right side further evidences the relation between the
sutural length and the frequency of these bones.
Incidental. There is a definite increase in length of the coronal
suture in brachycephalic skulls, and a slightly diminished length of the
lambdoid and sagittal sutures. The lateral or squamous length shows a
progressive increase from dolichocephales to brachycephales.
The great majority of Wormian bones are physiological in origin and
compensatory in nature, and only when presenting distinctly unusual or
abnormal features should a pathological origin be considered.
There are but three recorded cases in which Wormian bones are
reputed to have exerted a pathological influence, causing still-birth of
the fetus in each of the reported instances.
The case reported in this article is unique.
BONES 47
BIBLIOGRAPHY.
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48 CHARLES A. PARKER
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WORMIAN BONES 49
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Schadels, 8°, Tiibingen, 1862.
WORMIAN KONES
PLATK I
Fm. 14. — FRONT VIEW
CHARLES A. PARKER
WOK MIAN BOXES
PLATE II
FIG. 15.— LATERAL, VIEW.
CHARLES A. PARKER
WOKMIAN BONES
PLATE III
FIG. 16.— LATERAL VIEW
CHARLES A. PARKER
WORMIAX BONES
PLATE IV
FIG. 17. — POSTERIOR VIEW
CHARLES A. PARKER
WOKMIAN BOXES
PLATE V
FIG. 18. — VIEW OF VERTEX.
CHARLES A. PARKER
WOKMIAN BONES
PLATE VI
FIG. 19
SUPERIMPOSED OUTLINES OF Two SKULLS WITH THE LINE ab COM-
MON TO BOTH; THE PRESENT SKULL BEING REPRESENTED IN BLACK,
THE NORMAL SKULL IN RED.
CHARLES A. PARKER
WORMIAN HONES
I'LATK VII
FIG. 20
COMPARISON OF FACIAL PROFILES. THE HEAVY BLACK LINE REPRE-
SENTING THAT OF THE PRESENT SKULL. THE HEAVY RED LlNE THAT
OF A NORMAL SKULL.
CHARLES A. PARKEB
University of California
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