View source for Medicine:Cavernous sinus

{{Short description|Sinus in the human head}}
{{Infobox vein
| Name        = Cavernous sinus
| Latin       = sinus cavernosus
| Image       = Gray488_blue.gif
| Caption     = Cavernous sinus (center, labeled "SIN. CAVERN.")
| Image2      = Cavernous sinus.png
| Caption2    = The sinuses at the base of the skull.  Cavernous sinus labeled in red
| DrainsFrom  =
| Source      = middle cerebral vein, sphenoparietal sinus, superior&nbsp;ophthalmic&nbsp;vein, Inferior ophthalmic vein
| DrainsTo    = inferior petrosal sinus, superior petrosal sinus
}}
The '''cavernous sinus''' within the human head is one of the dural venous sinuses<ref name="auto">{{cite journal | last1 = Yasuda |display-authors=et al | date = Jun 2008 | title = Microsurgical anatomy and approaches to the cavernous sinus | journal = Neurosurgery | volume = 62 | issue = 6 Suppl 3| pages = 1240–63 | doi = 10.1227/01.neu.0000333790.90972.59 | pmid = 18695545 | s2cid = 21204727}}</ref> creating a cavity called the '''lateral sellar compartment''' bordered by the [[Medicine:Temporal bone|temporal bone]] of the skull and the sphenoid bone, lateral to the sella turcica.

==Structure==
The cavernous sinus is one of the dural venous sinuses of the head. It is a network of veins that sit in a [[Biology:Sinus (anatomy)|cavity]]. It sits on both sides of the sphenoidal bone and [[Medicine:Pituitary gland|pituitary gland]], approximately 1&nbsp;×&nbsp;2&nbsp;cm in size in an adult.<ref name="GRAYS2008" /> The carotid siphon of the internal carotid artery, and cranial nerves III, IV, V (branches V<sub>1</sub> and V<sub>2</sub>) and VI all pass through this blood filled space. Both sides of cavernous sinus is connected to each other via intercavernous sinuses. The cavernous sinus lies in between the inner and outer layers of [[Medicine:Dura mater|dura mater]].<ref name="Ryan 2011"/>

===Nearby structures===
* Above: [[Biology:Optic tract|optic tract]], optic chiasma, internal carotid artery.<ref name="Ryan 2011"/>
* Inferiorly: foramen lacerum, and the junction of the body and greater wing of sphenoid bone.
* Medially: pituitary gland (hypophysis cerebri), and sphenoidal air sinus.<ref name="Ryan 2011">{{cite book |last1=Ryan |first1=Stephanie |title=Anatomy for diagnostic imaging |date=2011 |publisher=Elsevier Ltd |isbn=9780702029714 |page=88 |edition=Third |chapter=2}}</ref>
* Laterally: [[Biology:Temporal lobe|temporal lobe]] with [[Biology:Uncus|uncus]].
* Anteriorly: [[Medicine:Superior orbital fissure|superior orbital fissure]], and the apex of the orbit.
* Posteriorly: apex of petrous temporal bone.

===Venous connections===
The cavernous sinus receives blood from:<ref name="GRAYS2008" />

* Superior and inferior ophthalmic veins<ref name="Ryan 2011"/>
* Sphenoparietal sinus<ref name="Ryan 2011"/>
* Superficial middle cerebral veins<ref name="Ryan 2011"/>
* Inferior cerebral veins

Blood leaves the sinus via superior and inferior petrosal sinuses as well as via the emissary veins through the foramina of the skull (mostly through foramen ovale). There are also connections with the pterygoid plexus of veins via inferior ophthalmic vein, deep facial vein and emissary veins.

=== Contents ===
Apart from the blood which passes through a venous sinus, several anatomical structures, including some cranial nerves and their branches, also pass through the sinus.<ref name="GRAYS2008" />

Structures within the outer (lateral) wall of the compartment from [[Biology:Anatomical terms of location|superior to inferior]]:<ref name="GRAYS2008" />

*[[Biology:Oculomotor nerve|Oculomotor nerve]]
*[[Biology:Trochlear nerve|Trochlear nerve]]
*[[Biology:Ophthalmic nerve|Ophthalmic]] and maxillary branches of the [[Biology:Trigeminal nerve|trigeminal nerve]]

Structures passing through the midline (medial) wall:<ref name="GRAYS2008">{{cite book|editor1=Susan Standring  |editor2=Neil R. Borley |display-editors=et al.|title=Gray's anatomy : the anatomical basis of clinical practice|date=2008|publisher=Churchill Livingstone|location=London|isbn=978-0-8089-2371-8|edition=40th}}</ref>

*[[Biology:Abducens nerve|Abducens nerve]]
*Internal carotid artery accompanied by the internal carotid plexus

These nerves, with the exception of CN V<sub>2</sub>, pass through the cavernous sinus to enter the orbital apex through the [[Medicine:Superior orbital fissure|superior orbital fissure]]. The maxillary nerve, division V<sub>2</sub> of the trigeminal nerve travels through the lower portion of the sinus and exits via the foramen rotundum. The maxillary branch passes external to, but immediately adjacent to, the lateral wall of the sinus.<ref name="auto" />

The [[Biology:Optic nerve|optic nerve]] lies just above and outside the cavernous sinus, superior and lateral to the [[Medicine:Pituitary gland|pituitary gland]] on each side, and enters the orbital apex via the optic canal.

==Function==

=== Venous drainage ===
As a venous sinus, the cavernous sinus receives blood from the superior and inferior ophthalmic veins and from superficial cortical veins, and is connected to the basilar plexus of veins posteriorly. The cavernous sinus drains by two larger channels, the superior and inferior petrosal sinuses, ultimately into the internal jugular vein via the sigmoid sinus, also draining with emissary vein to pterygoid plexus.

==Clinical significance==
It is the only anatomic location in the body in which an [[Biology:Artery|artery]] travels completely through a venous structure. If the internal carotid artery ruptures within the cavernous sinus, an ''arteriovenous fistula'' is created (more specifically, a carotid-cavernous fistula). Lesions affecting the cavernous sinus may affect isolated nerves or all the nerves traversing through it.

The [[Medicine:Pituitary gland|pituitary gland]] lies between the two paired cavernous sinuses. An abnormally growing pituitary adenoma, sitting on the bony sella turcica, will expand in the direction of least resistance and eventually invade the cavernous sinus.<ref>{{cite journal |last1=Dhandapani |first1=S |last2=et |first2=al. |title=Cavernous Sinus Invasion in Pituitary Adenomas: Systematic Review and Pooled Data Meta-Analysis of Radiologic Criteria and Comparison of Endoscopic and Microscopic Surgery. |journal=World Neurosurg |date=Dec 2016 |volume=96 |pages=36–46 |doi=10.1016/j.wneu.2016.08.088 |pmid=27591098 |url=https://doi.org/10.1016/j.wneu.2016.08.088}}</ref> '''Cavernous sinus syndrome''' may result from mass effect of these tumors and cause ophthalmoplegia (from compression of the oculomotor nerve, trochlear nerve, and abducens nerve), ophthalmic sensory loss (from compression of the ophthalmic nerve), and maxillary sensory loss (from compression of the maxillary nerve). A complete lesion of the cavernous sinus disrupts CN III, IV, and VI, causing total ophthalmoplegia, usually accompanied by a fixed, dilated pupil. Involvement of CN V (V<sub>1</sub> and variable involvement of V<sub>2</sub>) causes sensory loss in these divisions of the trigeminal nerve. [[Medicine:Horner's syndrome|Horner's syndrome]] can also occur due to involvement of the carotid ocular sympathetics, but may be difficult to appreciate in the setting of a complete third nerve injury.<ref name="auto1">Blumenfeld, H, Neuroanatomy through clinical cases. Sinauer Associates, Inc., 2002.</ref>

Because of its connections with the facial vein via the superior ophthalmic vein, it is possible to get infections in the cavernous sinus from an external facial injury within the danger area of the face. In patients with [[Medicine:Thrombophlebitis|thrombophlebitis]] of the facial vein, pieces of the clot may break off and enter the cavernous sinus, forming a cavernous sinus thrombosis. From there the infection may spread to the dural venous sinuses. Infections may also be introduced by facial lacerations and by bursting pimples in the areas drained by the facial vein.<ref>Kumar, P. & Clark, M. Clinical Medicine, 6th ed. Londonn: W.B. Saunders; 2005.</ref>

Potential causes of cavernous sinus syndrome include metastatic tumors, direct extension of nasopharyngeal tumours, [[Medicine:Meningioma|meningioma]], pituitary tumors or pituitary apoplexy, [[Medicine:Aneurysm|aneurysm]]s of the intracavernous carotid artery, carotid-cavernous fistula, bacterial infection causing cavernous sinus thrombosis, aseptic cavernous sinus thrombosis, idiopathic granulomatous disease ([[Medicine:Tolosa–Hunt syndrome|Tolosa–Hunt syndrome]]), and fungal infections.  Cavernous sinus syndrome is a medical emergency, requiring prompt medical attention, diagnosis, and treatment.<ref name="auto1"/>

==See also==
{{Anatomy-terms}}
* Cavernous sinus thrombosis
* Dural venous sinuses

==References==
{{Reflist}}

==External links==
{{Commons}}
* {{LoyolaMedEd|grossanatomy/h_n/cn/dvs/dvs3.htm}}
* {{SUNYAnatomyFigs|28|03|06}}{{snd}} "Venous dural sinuses."
* {{MeshName|Cavernous+Sinus}}
* {{NormanAnatomy|lesson2}}
* {{UMichAtlas|n3a8p1}}


[[Category:Medical mnemonics]]

{{Sourceattribution|Cavernous sinus}}