The vessels were unusually numerous and highly engorged, and lymph and pus were effused in considerable quantity, the arachnoid was opaque, and the cerebral substance was somewhat softened.
If the dura mater is torn, and the blood passes into the sub-arachnoid space, it may spread over the whole surface of the brain.
The larger arteries run in the sub-arachnoid space and give off branches which ramify in the pia mater before entering the cerebral substance.
In the acquired form the communication between the ventricles and the sub-arachnoid space, by way of the foramen of Magendie, is obstructed, so that the cerebro-spinal fluid is pent up in the ventricles and gradually distends them.
Thus a localised meningitis spreading to the brain may set up a cerebral abscess; a sinus phlebitis may give rise to a purulent lepto-meningitis; or a cerebral abscess bursting into the sub-arachnoid space may produce meningitis.
Through the foramen of Magendie in the roof of the fourth ventricle the sub-arachnoid fluid of the cranial cavity communicates with that of the vertebral canal.
The needle usually encounters some resistance as it pierces the interspinous ligament, and then enters the sub-arachnoid space.
The membranes gradually become lost in the fibrous sheaths of the nerves, and the sub-dural and sub-arachnoid spaces become continuous with the lymph spaces of the nerves.
Situated under the dura mater, or between the dura mater and the arachnoid membrane.
Inflammation of thepia mater or of the arachnoid membrane.
The three membranes that envelop the brain and spinal cord; the pia mater, dura mater, and arachnoid membrane.
The arachnoid space is also in some cases similarly filled.
The arachnoid has also shown slight congestion, and in other cases the membranes showed a slight thickening.
It may also be due to an extravasation of blood or to exudation in the subdural or arachnoid spaces.
Paralysis of certain sets of muscles is a very common result of chronic, subacute, and acute encephalitis, and is due to softening of the brain or to exudation into the cavities of the brain or arachnoid space.
In milder cases effusion may take place in the arachnoid spaces and ventricles of the brain, followed by paralysis and other complications.
Neither is the arachnoid often affected with acute inflammation, except as a secondary result.
The cerebral arachnoid was all opaque, the lateral ventricles were filled with serum, and the blood in all the cavities was very fluid and dark colored.
In a case reported by Gordon[51] the entire duration of the illness was under five hours, and after death the cerebral arachnoid was more or less opaque, and in some spots had a layer of very thin purulent matter beneath it.
On examination pus was found between the arachnoidand the pia mater.
On examination there was found beneath the arachnoid a thin layer of lymph and abundant exudation over the posterior lobes of the cerebrum, and also at the base of the brain and on the medulla oblongata.
In other cases there may be an increased amount of serum beneath the arachnoidand into the lateral ventricles, but not more than is often seen after death from other causes.
Serum abounds in the arachnoid cavity and in the ventricles of the brain; it may be clear or milky, and sometimes it is quite purulent.
Occasionally the cavity of the spinal arachnoidcontains blood.
The dura mater is often very dark, its blood-vessels engorged, its arachnoid cavity distended with serum more or less bloody, turbid, or purulent.
In some Ophidians the same physiological purpose is served by the manner in which the convolutions of the long intestine are bound together by a subperitoneal arachnoid membrane.
Perhaps the earliest tendency to structurally modify the intestine in the direction named is found in the manner in which the intestinal coils are bound together by the subperitoneal arachnoid in many Ophidians (Fig.
Thus, one layer of the arachnoid envelopes the brain and spinal cord, and the other lines the dura mater.
The space between the internal and the external layers of the arachnoid membrane of the brain is much smaller than that enclosed by the corresponding layers of the arachnoid membrane of the spinal column.
Between the dura mater and the subjacent arachnoid membrane is a fine space containing a minute quantity of limpid serum, which moistens the smooth inner surface of the dura and the corresponding smooth outer surface of the arachnoid.
The sub-arachnoid space is more distinctly marked beneath the spinal than beneath the cerebral parts of the membrane, which forms a looser investment for the cord than for the brain.
The arachnoid is a membrane of great delicacy and transparency, which loosely envelops both the brain and spinal cord.
The sub-arachnoid space is subdivided into numerous freely-communicating loculi by bundles of delicate areolar tissue, which bundles are invested, as Key and Retzius have shown, by a layer of squamous endothelium.
In quite young specimens the collector will notice two well defined arachnoid veils, the lower one being much more dense.
The chest of one of them enclosed a small quantity of serosity; a similar fluid was between the dura mater and the arachnoid membrane, and the same was the case in the larger ventricles of the encephalon.
The dura mater, the two leaves of the arachnoid membrane, and the pia mater did not constitute more than one membrane of the usual thickness, and presented a somewhat yellow colouring.
The fluid ran out freely, and the space was evidently in free communication with the general arachnoid cavity.
Escape of cerebro-spinal fluid was not so prominent a feature as might have been expected, considering how freely the arachnoid space was opened up in many cases.
No doubt a similar vicarious arachnoid space develops in all cases in which a soft pulsating swelling fills an aperture in the bones of the skull.
On separating the skin it was found directly adherent to the cicatrised dura, and when this was incised a large vicarious arachnoid space was opened up.
Defn: Inflammation of the pia mater or of the arachnoid membrane.
Defn: The three membranes that envelop the brain and spinal cord; the pia mater, dura mater, and arachnoid membrane.
Defn: Situated under the dura mater, or between the dura mater and the arachnoid membrane.
The arachnoid membrane was, in many parts, without its natural transparency: the pia mater was generally suffused with blood, and its vessels were enlarged: the consistence of the brain was firm.
All the ventricles of the brain were dilated with serum, and there was a good deal of effusion into the arachnoid and pia mater.
There are numerous large plates of bone on the arachnoid of the lumbar portion, and of the cauda equina.
All these branches lie on a spherical face, and form by communications the irregular, very delicate, arachnoid network of the outer shell, quite unlike that of the inner, with large polygonal meshes of very different size.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "arachnoid" in a variety of sentences. We hope that you will now be able to make sentences using this word. Other words: cerebellum; cerebrum; convolution; fissure; lobe; mantle
