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Full text of "Wormian bones"

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 maxilla 1 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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Table showing 
estimated from a 
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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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a 
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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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BELL,, JOHX AND CHARLES. Anatomy and Physiology of the Human 

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BROCA, PAUL. Bui. Soc. D'Anthrop., 1875, p. 138. 
CHAMBELLAN, VICTOR. Etude Anatomique et Anthropologi<iue sur les 

os Wormiens. Inaugural Theses Paris, 1883, pp. 66. 
CRUVEILHIER, J. Traite d'Anatomie Descriptive, 3rd Ed., Paris, 1851, 

Tome I, p. 162. 

CUNNINGHAM, D. J. Text Book of Anatomy, 1902, pp. 103, 127, 154. 
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DORSEY, GEO. A. The Amer. Anthropologist, Washington, D. C., June, 
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EDWARDS, H. MILNE. Lecons sur La Phys. et L'Anat. Com p. De 
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FISCHER, G. De ossa epactal sen Goethiano, Moscow, 1811. Quoted by 
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GEGENBAUER, C. Lehrbuch d. Anat. des Menschen, 1899, 7 Aufhige, 
Bd. I, p. 254. Also French translation, p. 265.' 

GRUBER, WEXZEL. Ueber Ossicula Wormiana an Saugetheire 
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Nachtrag zu den Stirnfontanellknochen beim Menschen. Archiv. 
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No. 7. Quoted from Testut. 



48 CHARLES A. PARKER 

GUIXTER, (JEAN GUINTER D'AXDERXACH). Gazette Hebdum. de Med. 

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Turner, Welcker, Dorsey, Calori, Terry; Fig. 8, p. 258, Wormian 

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HYRTL, JOSEPH. Lehrbuch d. Anat., 1878, p. 288. 
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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 



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