Cerebrospinal fluid

Japanese: 髄液 - ずいえき

Cerebrospinal fluid, also called cerebrospinal fluid, is a fluid that fills the ventricles and subarachnoid space, with a total volume of 100-150 milliliters, which circulates continuously while bathing the brain and spinal cord. Most of it is produced in the choroid plexus of the ventricles (mainly the lateral ventricles), enters the subarachnoid space from the ventricular system through the small Magendie and Luschka foramen in the fourth ventricle on the dorsal side of the medulla oblongata, circulates through the subarachnoid space of the brain and spinal cord, and is absorbed into the venous sinus via the arachnoid granulations that protrude into the superior sagittal sinus. CSF surrounds the brain and spinal cord, acts as a lubricant between the bones and the brain, and acts as a cushion against mechanical shocks from the outside, mainly playing a role in protecting the brain and spinal cord.

In cases of central nervous system diseases, cerebrospinal fluid is an important source of information for diagnosing the disease, so a needle is inserted into the subarachnoid space at the lumbar or suboccipital area (lumbar puncture or cisternal puncture) to measure cerebrospinal fluid pressure, or to collect a sample of cerebrospinal fluid to examine its appearance, such as whether it is turbid or coagulated, and its color, and to examine the cells and various reactions.

[Shinichiro Ebihara]

Cerebrospinal fluid pressure

Measurements are taken with a manometer (pressure gauge) attached to a needle inserted into the subarachnoid space. In a healthy adult, cerebrospinal fluid pressure is 70 to 150 millimeters of water when in a supine position, but if the person coughs, strains, or compresses the jugular vein while measuring the pressure, the pressure will rise. Cerebrospinal fluid pressure increases in the acute stages of brain tumors, meningitis, and cerebrovascular disorders. If there is a central nervous system disease that causes blockage of the subarachnoid space, pressure will not rise even when the jugular vein is compressed.

[Shinichiro Ebihara]

Cloudy cerebrospinal fluid

Normal cerebrospinal fluid is watery and transparent, but if a large number of white blood cells are mixed in due to meningitis, the cerebrospinal fluid becomes cloudy. In addition, if the protein content of cerebrospinal fluid increases, the fluid will turn yellowish and may spontaneously clot after collection. If red blood cells are mixed in due to cerebral hemorrhage or subarachnoid hemorrhage, the cerebrospinal fluid will turn bloody or yellowish.

[Shinichiro Ebihara]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

脳脊髄(せきずい)液ともいい、脳室およびくも膜下腔(かくう)を満たしている液で、その総量は100～150ミリリットルといわれ、脳および脊髄を浸しながら絶えず循環している。その大部分は脳室（おもに側脳室）の脈絡叢(そう)で生成され、延髄背側の第四脳室にある小さいマジャンディMagendie孔およびルシュカLuschka孔とよばれる出口を通って脳室系からくも膜下腔に入り、脳と脊髄のくも膜下腔を循環し、上矢状(じょうしじょう)静脈洞の中に突出しているくも膜顆粒(かりゅう)を経由して静脈洞に吸収される。髄液は脳と脊髄を包み、骨と脳との間にあって滑剤のように作用し、また外からの機械的衝撃に対しては、クッションのように作用するなど、主として脳と脊髄を保護する役割を果たしている。

　中枢神経系の病気の際には、髄液は病気の診断の重要な資料となるので、腰椎(ようつい)あるいは後頭下の部位でくも膜下腔に針を刺し（腰椎穿刺(せんし)あるいは大槽穿刺）、髄液圧を測定したり、髄液を採取して混濁や凝固の有無、色調など外観を見たり、細胞や各種反応を検査したりする。

［海老原進一郎］

髄液圧

くも膜下腔に穿刺した針にマノメーター（圧力計）を接続して測定する。健康成人の髄液圧は臥位(がい)で70～150ミリメートル水柱であるが、圧測定中に咳(せき)をしたり、力んだり、頸(けい)静脈を圧迫すると、圧は上昇する。髄液圧は脳腫瘍(しゅよう)や髄膜炎、脳血管障害の急性期に高くなる。くも膜下腔が閉塞(へいそく)するような中枢神経系の病気があると、頸静脈を圧迫しても圧は上昇しない。

［海老原進一郎］