From the Mortonian collection, other illustrations of this fact might
be drawn; but neither space nor time permits their introduction here.
In the study of the sutures, considerations of a highly philosophical
character are involved. Their history enables us to perceive why
the cranium was not formed of one piece, and why there should be
two frontal and two parietal bones, and only one occipital. Such an
arrangement obviously allows the fullest development of the anterior
and middle lobes of the cerebrum,—the organs, according to Carus,
of intelligence, reflection, and judgment.82 That the sutures are
tutamina cerebri, that in the foetus they permit the cranial bones to
overlap during parturition, and thus, by diminishing the size of the
head in certain of its diameters, and producing anaesthesia, facilitate
labor, curtailing its difficulties and diminishing its dangers to both
mother and child, there can he no doubt. Such provisions are of
high interest, as exhibiting the harmony of nature. But when we
call to mind that the skull is a vertebra in its highest known state
of development; that the enclosed brain, as the organ of intellection,
is the distinguishing mark of man; that the development of the
cranium goes on pari passu with that of the encephalon; that the
various degrees of human intelligence are definitely related to certain
permanent skull-forms; and that the cranial sutures, in conjunction
with the ossific centres, are the -guiding agents in the assumption of
these forms—it will be evident that a higher and far more comprehensive
significance is attached to these bony interspaces. Again,
no extended investigation has been instituted, as far as I am aware,
to determine the period at which the different cranial sutures are
closed in the various, races of men. The importance of such an inquiry
becomes apparent, when we ask ourselves the following questions
:—1. Does the cranium attain its fullest development in all the
races at the same, or at different periods of life ? and 2. To what
extent are race-forms of the cranium dependent upon the growth and
modifications of the sutures ?
“ The most obvious use of the sutures,” according to Dr. Morton, “ is to subserve the
process of growth, which they do by osseous depositions'at their margins. Hence, one of
these sutures is equivalent to the interrupted structure that exists between the shaft and
epiphysis of a long bone in the growing state. The shaft grows in length chiefly by accretions
at its extremities; and the epiphysis, like the cranial suture, disappears when the
perfect development is accomplished. Hence, we may infer that the skull ceases to expand
whenever the sutures become consolidated with the proximate bones. In other words, the
growth of the brain, whether in viviparous or in oviparous animals, is consentaneous with
that of the skull, and neither can be developed without the presence of free sutures.” 83
82 “ Das besondere Organ des erkennenden, vergleichenden und urtheilenden Geistesleben.”
r- Symbolik der menschlichen Gestalt, von Dr. C. G. Carus, Leipzig, 1858.
83 See article on Size of the Brain, &c., quoted above, p. 303.
From investigations of this nature, and from other - considerations,
Dr; M. concluded that the growth of the brain was arrested at the
i P i l w f consolidation of the sutures was an indication of
the full development of both cranium and brain, and that any increase
or decrease in the size or weight of the brain after the adult
period wquld not be likely to affect the internal capacity of the cra-
n.1Uf1f ’ ^ lch’ S B R indicates the maximum size of the encephalon
at the time of its greatest development, Combe, however, affirms
that when the brain contracts in old age, the tabula vitrea of the
cranium also contracts, so as to keep itself applied to its contents,
the outer or fibrous table undergoing no change.84 It is, to some
extent, true that m the very aged, even when the skull-bones become
consolidated into one piece, some changes may result from an undue
activity of the absorbents, or some defect in the nutritive operations
Fnder such cmcumstances, the cranial bones maybe thinned and
altered slightly m form. D avis gives an example of this change, in
the skull of an aged Chinese in his collection, in which the cfntral
area of the parietal bones is thinned and depressed over an extent
equal to four square inches to about one-third of an inch deep in the
central part. Such changes, however, are too limited in their extent
to demand, more than a passing notice.
The pressure of the brain, exerted through its weight, is felt
mainly upon the base and inferior lateral parts.
Prof. E ngel, in a valuable monograph upon skull-forms,86 particularly
calls attention to the action of the muscles in determining these
forms. He considers the influence of the occipito-frontalis as almost
• aPPreeiable, — bo slight, indeed, that it may be neglected in our
nquines. R e action of the temporal and pterygoid muscles and of
ffie group attached to the occiput, though more evident, is still not
worthy of much consideration. To the action of the musculus
sterno-cleido-mastoideus, he assigns a greater value.
“ This muscle,” says he, “ tends to produce a downward displacement at the
bon of the temporal bone, which will he the more considerable, as the lower point of its a t ^ T
ment- t h e sternum and c la v ic le -is able to offer much greater resistance than t,S
In addition to this, the unusual length of the muscle produces hv it. * • npper'
effect, and, hence, favors a greater displacement of the hones tb which it isa tteh ed '’
bone upon which it exerts its influence is also very loose in earlv life j .'
firstyear of our existence, when extensive motions o “ h e n 2 e 2 e T d v t T
»ot as firmly fixed as the other hones; hence, it becomes g S £
muscle upon the position of the hones of the skull will he a demonstrable one 6 °
may, however, be admitted à priori, that in spite of all these favorable circumstances,
84 System of Phrenology, p. 83. , ~ ~ ■ '------- --------
“ Op C if’’ P‘ 6' 866 aIS0'Ga11’ I S” les Fonctions Cerveau,” III, 53, 1825.