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The attachments of the dura mater over the base of the skull.

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THE ATTACHMENTS O F THE DURA MATER OVER
THE BASE O F T H E SKULL1
A. E A R L WALKER
ONE FIGURE
To the surgeon operating in the intracranial cavity the
attachments of the dura mater to the cranium have considerable practical importance, yet detailed descriptions of them
are difficult to find. For this reason the present investigation
was made at a series of necropsies. The ages of the subjects
varied and they had died from a variety of causes. However,
from the anatomical standpoint these factors seemed not to
be very important. The method used was simply to strip
the membrane from the inner surface of the skull, carefully
noting the points to which it was attached and the structures
which were involved in these attachments. The findings are
not entirely constant, but the essential variations are few,
T H E ATTACHMENT TO T H E CONVEXITY
The strongest attachment to the cranium on the convexity
is in the midline. Here the superior sagittal sinus is firmly
attached by fibrous processes of the outer dural layer to the
midline of the skull. Less firmly it is attached t o the lambdsidal and coronal sutures. Between these points it is easily
stripped with only scattered unimportant attachments principally along the branches of the middle meningeal artery.
From the Division of Neurology and Neurosurgery, University Clinics, University of Chicago. This work has been conducted under a grant from thc Douglas
Smith Foundation for Medical Research at The University of Chicago.
291
THE ANATOMIC.kL RECORD, T O L .
55,
NO.
292
A. EARL WALKER
THE ATTACHMENT TO T H E BASE
The arzterior fossa
The beginning of the superior sagittal sinus is frequently
small vein from the nose which passes up through the foranien caecum. a r o u n d this vein the dura mater is firmly attached. Posteriorly, in the midline of the base, the membrane
is firmly attached t o the crista galli of the ethmoid bone, on
either side of which lie the grooves for the olfactory bulbs.
I n this region are the many small foramina through which
pass the olfactory nerves. Around them and also around the
cthmoidal foramina, which communicate with the orbit, the
dura mater is firmly attached. Inconstantly, lateral to the
olfactory grooves, small branches of the meningeal vessels
enter the inner table of the skull. I n the posterior part of the
anterior fossa there are a number of attachments. On either
side of the midline the optic nerves enter the orbit through
the optic foramina and around these nerves the dura mater
is prolonged forward to the orbital wall. Between the nerves
and from the anterior clinoid processes the membrane can
be stripped, although usually with some difficulty. The sheet
which forms a thin capsule f o r the pituitary body is usually
easily stripped from the hypophysial fossa, but is frequently
so thin on the posterior part of the hypophysis that it cannot
be followed to the posterior clinoid processes. To the most
lateral tips of the lesser wings of the sphenoid bone the dura
inater is attached by folds around the anterior branch of the
middle meningeal artery which frequently tuiineIs the bone
at this point. Extending medially along the wing, it is less
firmly attached along the sphenoparietal sinus. Stretching
across the midline in the posterior part of the floor of the
anterior fossa is a strong band about 2 em. in width which
gains attachment to the jugae cerebralee in the middle part
of each anterior fossa.
R
ATTACHNENTS O F THE DUXA MATER
293
The middle fossa
Stripping the dura mater from the lateral to the medial
side of the middle fossa, we first often note firm attachments
to the jugae cerebrales between the digitations on the floor
of the fossa. Around the structures entering the superior
orbital fissure-the oculomotor, trochlear, ophthalmic division of the trigeminal, abducens nerves with the ophthalmic
veins, sympathetic branches to the ciliary ganglion, and small
orbital branches of the middle meningeal artery-the membrane forms a sheath which runs into the orbital cavity,
merging with the periosteum of the bony orbit.
Along the medial side of the middle fossa the dura mater
forms a thick mass in which lie the cavernous sinus, the
abducens nerve, the maxillary and ophthalmic divisions of the
trigeminal nerve, and the internal carotid artery. Around
the maxillary nerve it forms a sheath continued into the
foramen rotundum; similarly it is carried into the foramen
ovale around the roots of the mandibular nerve, and the accessory meningeal artery. As these nerves and vessels pierce
the dura mater, sheaths follow them for a short distance.
From the anterior surface of the petrous pyramid it can be
readily stripped as far as the foramen lacerum, where it is
firmly attached to the vessels and nerves passing through.
The posterior f ossa
To the midline of the occipital bone, above the transverse
sulcus, the dura mater is irregularly attached along the line
of the sagittal sinus. The attachment of the lateral sinuses
to the transverse sulcus is not very firm. The attachments to
the inferior occipital fossa are very feeble and easily broken.
It is better attached to the ridge from the internal occipital
protuberance to the foramen magnum, along the posterior
border of the foramen magnum and around its sides to the
canales hypoglossi.
I n the anterior part of the posterior fossa the dura mater
is rather firmly attached to the posterior clinoidal processes.
294
A. EARL WALKER
Backward from them along the clivus it is attached by dense
fibrous tissue and is separated only with difficulty. I n the
upper part of the posterior fossa, on either side, the dura
mater accompanies the acoustic and facial nerves as they sink
into the internal acoustic meatus, and is rather firmly attached
to the superior petrous sulcus for a centimeter or more along
the superior margin of the temporal bone behind the acoustic
meatus. Immediately below this region it is attached to the
sulcus for the sigmoid portion of the transverse sinus and
more anteriorly follows around the ninth, tenth, and eleventh
cranial nerves as they enter the jugular canal. The dura
mater is further attached to the sulcus for the transverse
sinus where the posterior temporal diploic vein passes
through the mastoid foramen to empty into the transverse
sinus.
The attachments over the base of the cranium described in
the foregoing paragraphs are illustrated in the accompanying
diagram (fig.1).
ATTACHMENTS O F T E E DVRA MATER
Figure 1
295
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