{"id":9356,"date":"2026-01-06T13:06:01","date_gmt":"2026-01-06T12:06:01","guid":{"rendered":"https:\/\/neurohirurgija.in.rs\/?page_id=9356"},"modified":"2026-06-10T12:42:58","modified_gmt":"2026-06-10T10:42:58","slug":"subarachnoid-space-simply-explained","status":"publish","type":"page","link":"https:\/\/neurohirurgija.in.rs\/en\/subarachnoid-space-simply-explained\/","title":{"rendered":"Subarachnoid Space \u2014 Simply Explained for Patients"},"content":{"rendered":"<div style=\"line-height:1.35; margin:0 0 18px 0;\">\n  <div>\n    <span style=\"font-weight:600;\">Author:<\/span>\n    <a href=\"https:\/\/neurohirurgija.in.rs\/en\/cv-en\/\" \n       style=\"color:#004a80; font-weight:600; text-decoration:none;\"\n       onmouseover=\"this.style.textDecoration='underline';\"\n       onmouseout=\"this.style.textDecoration='none';\">\n       Dr. Zeljko Kojadinovic, MD, PhD\n    <\/a>\n    \u2014 Neurosurgeon and Pain Management Specialist\n  <\/div>\n\n  <div>\n    <span style=\"font-weight:600;\">Specialized Experience:<\/span>\n    30 years of clinical expertise in neurosurgery and neurocritical care.\n  <\/div>\n\n  <div>\n    <span style=\"font-weight:600;\">Last medically reviewed:<\/span>\n    January 6, 2026\n  <\/div>\n<\/div>\n\n\n\n<p class=\"wp-block-paragraph\">The <strong>subarachnoid space<\/strong> is a thin, fluid-filled space that surrounds the brain and spinal cord.<br>It lies <strong>between two protective layers of the brain coverings (meninges)<\/strong> and plays a key role in cushioning and protecting the nervous system.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Where is the subarachnoid space located?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The brain and spinal cord are covered by three layers called meninges:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Dura mater<\/strong> \u2013 the tough outer layer<\/li>\n\n\n\n<li><strong>Arachnoid mater<\/strong> \u2013 the delicate middle layer<\/li>\n\n\n\n<li><strong>Pia mater<\/strong> is the thin inner layer that lies directly on the brain surface.<br>There is no space between the brain and the pia mater \u2014 when the brain is seen, what you see covering it is the pia mater itself.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\ud83d\udc49 The <strong>subarachnoid space<\/strong> is located <strong>between the arachnoid mater and the brain surface.<\/strong><\/p>\n\n\n\n<figure class=\"wp-block-image size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"480\" height=\"241\" src=\"https:\/\/neurohirurgija.in.rs\/wp-content\/uploads\/2026\/01\/SA-space.jpg\" alt=\"The subarachnoid space is shown between the arachnoid mater (one of the brain\u2019s protective membranes) and the brain itself. It is filled with cerebrospinal fluid (CSF), a clear liquid that cushions the brain and spinal cord. This space is crisscrossed by delicate connective tissues called trabeculae and contains the brain\u2019s blood vessels. The subarachnoid space follows the contours of the cerebral cortex, extending into the sulci (the grooves or folds between the ridges of the brain known as gyri).\" class=\"wp-image-9361\" style=\"aspect-ratio:1.9917655449653116;width:744px;height:auto\" srcset=\"https:\/\/neurohirurgija.in.rs\/wp-content\/uploads\/2026\/01\/SA-space.jpg 480w, https:\/\/neurohirurgija.in.rs\/wp-content\/uploads\/2026\/01\/SA-space-300x151.jpg 300w, https:\/\/neurohirurgija.in.rs\/wp-content\/uploads\/2026\/01\/SA-space-18x9.jpg 18w\" sizes=\"auto, (max-width: 480px) 100vw, 480px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Image: The subarachnoid space is shown between the arachnoid layer (one of the brain\u2019s protective membranes) and the brain itself (covered with pia mater). It is filled with cerebrospinal fluid (CSF), a clear liquid that cushions the brain and spinal cord. This space is crisscrossed by delicate connective tissues called trabeculae and contains the brain\u2019s blood vessels. The subarachnoid space follows the contours of the cerebral cortex, extending into the sulci (the grooves or folds between the ridges of the brain known as gyri). <\/strong><\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">What is inside the subarachnoid space?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The subarachnoid space contains:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Cerebrospinal fluid (CSF)<\/strong> \u2013 a clear fluid that cushions the brain. It is continuously produced within the <strong>ventricles<\/strong> (four interconnected cavities inside the brain: the two lateral ventricles, the third, and the fourth ventricle). From there, the CSF flows out of the ventricles and enters the <strong>subarachnoid space<\/strong>, where it circulates around the entire brain and spinal cord, providing buoyancy and waste removal.<\/li>\n\n\n\n<li><strong>Major blood vessels<\/strong> supplying the brain<\/li>\n\n\n\n<li><strong>Nerve roots<\/strong> (especially along the spinal cord)<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">This space allows the brain to \u201cfloat\u201d and reduces the impact of everyday movements or minor trauma.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"697\" height=\"480\" src=\"https:\/\/neurohirurgija.in.rs\/wp-content\/uploads\/2026\/01\/SA-space-spine.jpg\" alt=\"The subarachnoid space is shown between the spinal cord, the spinal nerves, and the arachnoid membrane. Cerebrospinal fluid (CSF) flows through this space, and spinal nerves pass through it before they receive their individual nerve coverings.\" class=\"wp-image-9363\" srcset=\"https:\/\/neurohirurgija.in.rs\/wp-content\/uploads\/2026\/01\/SA-space-spine.jpg 697w, https:\/\/neurohirurgija.in.rs\/wp-content\/uploads\/2026\/01\/SA-space-spine-300x207.jpg 300w, https:\/\/neurohirurgija.in.rs\/wp-content\/uploads\/2026\/01\/SA-space-spine-18x12.jpg 18w\" sizes=\"auto, (max-width: 697px) 100vw, 697px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Image: The subarachnoid space is shown between the spinal cord, the spinal nerves, and the arachnoid membrane. Cerebrospinal fluid (CSF) flows through this space, and spinal nerves pass through it before they receive their individual nerve coverings.<\/strong><\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Why is the subarachnoid space medically important?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Problems involving the subarachnoid space are often <strong>clinically significant<\/strong> because this space contains both <strong>CSF and blood vessels<\/strong>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Common conditions include:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Subarachnoid hemorrhage (SAH)<\/strong> \u2013 non-traumatic bleeding into this space<\/li>\n\n\n\n<li><strong>Traumatic subarachnoid hemorrhage (tSAH)<\/strong> after head injury<\/li>\n\n\n\n<li><strong>CSF circulation disturbances<\/strong><\/li>\n\n\n\n<li><strong>Inflammation or infection<\/strong> affecting the meninges<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Even small changes in this space can cause symptoms such as headache, neck stiffness, or altered consciousness.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"680\" height=\"421\" src=\"https:\/\/neurohirurgija.in.rs\/wp-content\/uploads\/2025\/11\/image.png\" alt=\"Brain CT showing blood in the subarachnoid space. Fresh blood appears white (red arrow).\" class=\"wp-image-8392\" srcset=\"https:\/\/neurohirurgija.in.rs\/wp-content\/uploads\/2025\/11\/image.png 680w, https:\/\/neurohirurgija.in.rs\/wp-content\/uploads\/2025\/11\/image-300x186.png 300w, https:\/\/neurohirurgija.in.rs\/wp-content\/uploads\/2025\/11\/image-18x12.png 18w\" sizes=\"auto, (max-width: 680px) 100vw, 680px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Image: Brain CT showing blood in the subarachnoid space. Fresh blood appears white (red arrow).<\/strong><\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">How does bleeding occur in the subarachnoid space?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Bleeding into the subarachnoid space happens when a blood vessel, an aneurysm, or an arteriovenous malformation (AVM) ruptures.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This can occur due to:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Head trauma<\/strong> (traumatic SAH)<\/li>\n\n\n\n<li><strong>Ruptured brain aneurysm<\/strong> or AVM (non-traumatic SAH)<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">The presence of blood irritates the brain coverings and may increase intracranial pressure.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Is the subarachnoid space the same as brain ventricles?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">No.<br>They are connected but <strong>not the same<\/strong>.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Ventricles<\/strong> are cavities inside the brain where CSF is produced<\/li>\n\n\n\n<li>The <strong>subarachnoid space<\/strong> surrounds the brain and spinal cord and allows CSF to circulate<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Both are part of the normal CSF system.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Related topics<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"https:\/\/neurohirurgija.in.rs\/en\/tsah-traumatic-subarachnoid-hemorrhage\/\">Traumatic subarachnoid hemorrhage (tSAH)<\/a><\/li>\n\n\n\n<li>Cerebrospinal fluid (CSF)<\/li>\n\n\n\n<li><a href=\"https:\/\/neurohirurgija.in.rs\/en\/intracranial-pressure-icp-explained\/\">Intracranial pressure (ICP)<\/a><\/li>\n\n\n\n<li>Brain meninges explained<\/li>\n\n\n\n<li><a href=\"https:\/\/neurohirurgija.in.rs\/en\/ruptured-brain-aneurysm-sah-treatment-prognosis\/\">Ruptured brain aneurysm and SAH<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/neurohirurgija.in.rs\/en\/spontaneous-csf-leak-intracranial-hypotension\/\">Spontaneous CSF leak<\/a><\/li>\n<\/ul>\n\n\n\n<nav aria-label=\"Pages in this hub\" class=\"hub-mini\"\n     style=\"background:#f4faff;border:1px solid #cce5ff;border-radius:8px;            padding:9px 11px;margin:14px 0;font-size:13.5px;line-height:1.5;\">\n  <div style=\"font-weight:700;color:#005c99;margin:0 0 6px 0;font-size:14px;\">\n    Pages in this Hub\n  <\/div>\n\n  <ul style=\"list-style:none;margin:0;padding:0;             display:flex;flex-wrap:wrap;gap:8px 18px;\">\n    <li><a href=\"https:\/\/neurohirurgija.in.rs\/en\/neuroanatomy-simply-explained\/\">Neuroanatomy \u2014 Hub<\/a><\/li>\n    <li><a href=\"https:\/\/neurohirurgija.in.rs\/en\/brain-anatomy-simply-explained\/\">Brain anatomy<\/a><\/li>\n    <li><a href=\"https:\/\/neurohirurgija.in.rs\/en\/spine-anatomy-simple-explanation\/\">Spine anatomy<\/a><\/li>\n    <li><a href=\"https:\/\/neurohirurgija.in.rs\/en\/nerve-anatomy-simply-explained\/\">Nerve anatomy<\/a><\/li>\n    <li><a href=\"https:\/\/neurohirurgija.in.rs\/en\/cranial-nerves-simply-explained\/\">Cranial nerves<\/a><\/li>\n    <li><a href=\"https:\/\/neurohirurgija.in.rs\/en\/cerebral-blood-circulation-simply-explained\/\">Cerebral circulation<\/a><\/li>\n    <li><a href=\"https:\/\/neurohirurgija.in.rs\/en\/ventricular-system-cerebrospinal-fluid-csf-simple-explanation\/\">Ventricular system &#038; CSF<\/a><\/li>\n    <li><a href=\"https:\/\/neurohirurgija.in.rs\/en\/subarachnoid-space-simply-explained\/\">Subarachnoid space<\/a><\/li>\n    <li><a href=\"https:\/\/neurohirurgija.in.rs\/en\/skull-anatomy-simple-explanation\/\">Skull anatomy<\/a><\/li>\n  <\/ul>\n<\/nav>\n\n<script>\n(function(){\n  var here = location.pathname.replace(\/\\\/+$\/,'') + '\/';\n  document.querySelectorAll('nav.hub-mini a').forEach(function(a){\n    var ap = a.pathname.replace(\/\\\/+$\/,'') + '\/';\n    if (ap === here){\n      var span = document.createElement('span');\n      span.textContent = a.textContent;\n      span.setAttribute('aria-current','page');\n      span.style.fontWeight = '700';\n      span.style.color = '#005c99';\n      span.style.textDecoration = 'none';\n      a.replaceWith(span);\n    }\n  });\n})();\n<\/script>","protected":false},"excerpt":{"rendered":"<p>Author: Dr. Zeljko Kojadinovic, MD, PhD \u2014 Neurosurgeon and Pain Management Specialist Specialized Experience: 30 years of clinical expertise in neurosurgery and neurocritical care. Last medically reviewed: January 6, 2026 The subarachnoid space is a thin, fluid-filled space that surrounds the brain and spinal cord.It lies between two protective layers of the brain coverings (meninges) [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_seopress_titles_title":"Subarachnoid Space \u2014 Simply Explained for Patients","_seopress_titles_desc":"The subarachnoid space is a fluid-filled space surrounding the brain and spinal cord. 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