Freiburger historische Bestände - digital

60

Cunningham Memoirs.

who have sought to localize the position of the parieto-occipital fissure
with reference to the cranial wall are largely due to the measurements
having been made in some instances from the lambda, and at other
times from the suture to the outer side of this.

Of course a considerable amount of difficulty is experienced in localizing
in the foetal head the position of the lambda, owing to the presence
of the posterior fontanelle. We cannot judge this by the anterior end
of the supra-occipital; it can only be done accurately by prolonging
upwards on the two sides of the head the lines of the lambdoid sutures, and
noting the point on the mesial line of the cranium where they intersect.
This point I have taken as representing the lambda in the foetal
skull-capsule.

The results which I have obtained I shall express in indices, so that
we may the more readily be able to detect the true relationships which
exist between the fissure in question and the cranial wall at different
periods of life. This index we may term the lambdo-parieto-occipital;
and it is obtained by comparing the distance between the lambda and
the fissure with the mesial length of the hemisphere reckoned as 100.
The results which I have obtained are as follows :—

(i.) Adults.—Position of parieto-occipital fissure determined in 22 hemispheres
; 14 male and 8 female; 13 right and 9 left.

Fissure in front of lambda, . . . 18 times; index 3'5.
Fissure coinciding with lambda (i. e. the
point where it reaches the upper

border of the hemisphere), . . 3 times (all male hemispheres, 1 left and 2 right).
Fissure behind the lambda, . . . 1 hemisphere; index 1*7 (male ; left).

(n.) Children, 11 to 15 years old.—Position of parieto-occipital fissure
determined 5 times; three times in the male; twice in the female; three
times on the right side; and twice on the left side.

Fissure in front of the lambda, . . 3 times; index 2-5.

Fissure coinciding with lambda, . . 1 hemisphere (male, and right side).

Fissure behind the lambda, . . 1 hemisphere ; index 2-8 (male, and left side).