View source for Biology:Epidural space

{{Short description|Space between the dura mater and vertebrae}}
{{hatnote|For the anesthetic procedure and route of drug administration, see [[Medicine:Epidural administration|Epidural administration]].}}
{{Infobox anatomy
| Name        = Epidural space
| Latin       = spatium epidurale, <br>spatium extradurale, <br>cavum epidurale
| Image       = Gray767.png
| Caption     = The medulla spinalis and its membranes
| Width       = 120
| Image2      =
| Caption2    =
| Precursor   =
| System      =
| Artery      =
| Vein        =
| Nerve       =
| Lymph       =
}}

In [[Biology:Anatomy|anatomy]], the '''epidural space''' is the potential space between the [[Medicine:Dura mater|dura mater]] and vertebrae ([[Biology:Vertebral column|spine]]).<ref name=":0">{{Cite book|title=Clinical neuroanatomy|last=Waxman|first=Stephen G.|date=2010|publisher=McGraw-Hill Medical|isbn=9780071603997|edition=26th|location=New York|oclc=435703701}}</ref><ref name=":1">{{Cite book|title=Neuroanatomy through clinical cases|last=Blumenfeld|first=Hal|date=2010|publisher=Sinauer Associates|isbn=9780878930586|edition=2nd|location=Sunderland, Mass.|oclc=473478856}}</ref>

The anatomy term "epidural space" has its origin in the [[Social:Ancient Greek|Ancient Greek]] language; {{Lang|grc|ἐπί}}, "on, upon" + [[Medicine:Dura mater|dura mater]] also known as "epidural cavity", "extradural space" or "peridural space". In humans the epidural space contains lymphatics, spinal nerve roots, loose connective tissue, adipose tissue, small arteries, dural venous sinuses and a network of internal vertebral venous plexuses.<ref>{{Cite journal|last1=Richardson|first1=Jonathan|last2=Groen|first2=Gerbrand J.|date=2005-06-01|title=Applied epidural anatomy|url=https://academic.oup.com/bjaed/article/5/3/98/278715|journal=Continuing Education in Anaesthesia, Critical Care & Pain|language=en|volume=5|issue=3|pages=98–100|doi=10.1093/bjaceaccp/mki026|issn=1743-1816|doi-access=free}}</ref>

==Cranial epidural space==
In the [[Biology:Skull|skull]], the periosteal layer of the dura mater adheres to the inner surface of the skull bones while the meningeal layer lays over the arachnoid mater. Between them is the '''epidural space'''. The two layers of the dura mater separate at several places, with the meningeal layer projecting deeper into the brain parenchyma forming '''fibrous septa''' that compartmentalize the brain tissue. At these sites, the epidural space is wide enough to house the epidural venous sinuses.<ref name=":1" /><ref name=":2">{{Cite book|title=A Textbook of Neuroanatomy|last1=Patestas|first1=Maria|last2=Gartner|first2=Leslie P.|date=2013|publisher=John Wiley & Sons|isbn=9781118687741|edition=1st|location=New York, NY|oclc=899175403}}</ref><ref name=":3">{{Cite book|title=Neurology & neurosurgery|last1=Collins|first1=Dawn|last2=Goodfellow|first2=John|last3=Silva|first3=Dulanka|last4=Dardis|first4=Ronan|last5=Nagaraja|first5=Sanjoy|isbn=9781907816741|location=London|publisher=JP Medical Publishers|date=2016|oclc=945569379}}</ref>

There are four fibrous septa:<ref name=":2" />

# '''Falx cerebri''', that separates the left and right [[Biology:Cerebral hemisphere|hemispheres]] of the [[Biology:Cerebrum|cerebrum]]. It contains the superior sagittal sinus and inferior sagittal sinus.
# '''Tentorium cerebelli''', which separates the cerebrum from [[Biology:Cerebellum|cerebellum]] and contains the [[Medicine:Transverse sinuses|transverse sinus]], straight sinus and superior petrosal sinus.
# '''Diaphragma sellae''', that encloses the hypophyseal fossa from the superior side, cushioning the [[Medicine:Pituitary gland|pituitary gland]]. It contains the anterior and posterior intercavernous sinuses.
# '''Falx cerebelli''', which separates the left and right cerebellar hemispheres and contains the occipital sinus.

In pathological conditions fluid such as blood can fill this space. For example a torn meningeal artery (often the middle meningeal artery) or dural venous sinus (rarely) may bleed into this potential space and result in an [[Medicine:Epidural hematoma|epidural hematoma]].<ref name=":3" />

== Spinal epidural space ==
In the spinal canal, the periosteal layer adheres to the inner surface of the spinal canal which is formed by the bodies of [[Biology:Vertebra|vertebra]]e. The meningeal layer lays over the spinal arachnoid mater.<ref name=":1" /> Between the vertebrae and the dural sheath is the '''spinal epidural space'''. Unlike the cranial epidural space, the spinal epidural space contains adipose tissue, the internal vertebral venous plexuses and the spinal nerve roots.<ref name=":0" /> The spinal epidural space spans the length of the spinal cord, from the foramen magnum superiorly to the sacral hiatus inferiorly.<ref name="Moore-20112">{{cite book |last1=Moore |first1=Keith L. |title=Essential Clinical Anatomy |last2=Dalley |first2=Arthur F. |last3=Agur |first3=Anne M. R. |publisher=Lippincott Williams & Wilkins |year=2017 |isbn=978-1496347213 |page= |pages=132}}</ref>

Epidural space is the smallest at the cervical region, measuring 1 to 2 mm. At L2 to L3, enlarges until 5 to 6 mm. It then enlarges progressively until lower lumbar and sacral region.<ref>{{cite book |last1=Mathis |first1=JM |last2=Golovac |first2=S |title=Image Guided Spine Interventions |date=2010 |publisher=Springer Science & Business Media |isbn=9781441903518 |page=14 |url=https://books.google.com/books?id=3DJVAElCmQYC |access-date=5 March 2022}}</ref> However, some authors stated that it decreases in size after mid-lumbar region until 2 mm at S1 level.<ref name="pmid16868616">{{cite journal | vauthors = Botwin KP, Natalicchio J, Hanna A | title = Fluoroscopic guided lumbar interlaminar epidural injections: a prospective evaluation of epidurography contrast patterns and anatomical review of the epidural space | journal = Pain Physician | volume = 7 | issue = 1 | pages = 77–80 | date = January 2004 | pmid = 16868616 | doi = 10.36076/ppj.2004/7/77| url = | doi-access = free }}</ref>

==See also==
* Subarachnoid space
* Subdural space
* [[Medicine:Meninges|Meninges]]

== References ==
{{Reflist}}


[[Category:Spinal cord]]

{{Sourceattribution|Epidural space}}