Anterior clinoid process

The anterior clinoid process is a pyramid-shaped bony projection of the lesser wing of the sphenoid bone and forms part of the lateral wall of the optic canal. Between each ACP lies the sella turcica, which holds the pituitary gland. Additionally, the ACP is part of the anterior roof of the cavernous sinus. The posterior and inferior portions of the ACP border the internal carotid artery.{{Cite book |last=Waxman |first=S.G. |title=Clinical Neuroanatomy |publisher=McGraw Hill |year=2024 |edition=30th |location=New York |language=English |chapter=Chapter 11: Ventricles and Coverings of the Brain}}{{Cite journal |last1=da Costa |first1=Marcos Devanir Silva |last2=de Oliveira Santos |first2=Bruno Fernandes |last3=de Araujo Paz |first3=Daniel |last4=Rodrigues |first4=Thiago Pereira |last5=Abdala |first5=Nitamar |last6=Centeno |first6=Ricardo Silva |last7=Cavalheiro |first7=Sergio |last8=Lawton |first8=Michael T. |last9=Chaddad-Neto |first9=Feres |date=September 2016 |title=Anatomical Variations of the Anterior Clinoid Process: A Study of 597 Skull Base Computerized Tomography Scans |url=https://journals.lww.com/01787389-201609000-00009 |journal=Operative Neurosurgery |language=en |volume=12 |issue=3 |pages=289–297 |doi=10.1227/NEU.0000000000001138 |pmid=29506115 |s2cid=3743429 |issn=2332-4252}}

The free border of the tentorium cerebelli extends anteriorly on either side beyond the attached border of the same side (which ends anteriorly at the posterior clinoid process) to ultimately end by attaching onto the anterior clinoid process.{{Cite book |last=Sinnatamby |first=Chummy S. |title=Last's Anatomy |publisher= Elsevier Australia|year=2011 |isbn=978-0-7295-3752-0 |edition=12th |pages=440}}

The anterior clinoid process projects over the internal carotid artery, which supplies the majority of blood to the brain. Because of the "spear-like" shape of the ACP and the large size of this artery, it is possible (though rare) that as a complication of major head trauma, the ACP may puncture the vessel and cause intracranial hemorrhage.{{Cite journal |last1=Cheong |first1=Jin Hwan |last2=Kim |first2=Jae Min |last3=Kim |first3=Choong Hyun |date=2011 |title=Bony Protuberances on the Anterior and Posterior Clinoid Processes Lead to Traumatic Internal Carotid Artery Aneurysm Following Craniofacial Injury |journal=Journal of Korean Neurosurgical Society |language=en |volume=49 |issue=1 |pages=49–52 |doi=10.3340/jkns.2011.49.1.49 |issn=2005-3711 |pmc=3070895 |pmid=21494363}} Additionally, when an aneurysm forms below the ACP, the projection may create a flat or pointed area of compression that may rupture the vessel.{{Cite journal |last1=Nishizaki |first1=Takafumi |last2=Ikeda |first2=Norio |last3=Kurokawa |first3=Yasushi |last4=Okamura |first4=Tomomi |last5=Abiko |first5=Seisho |date=October 2005 |title=Ruptured Internal Carotid Artery Anterior Wall Aneurysm Identified During Vasospasm: Case Report |url=https://journals.lww.com/00006123-200510000-00024 |journal=Neurosurgery |language=English |volume=57 |issue=4 |pages=E811 |doi=10.1227/01.neu.0000178238.36637.43 |pmid=17152665 |s2cid=220563820 |issn=0148-396X}}

More frequently, this positioning means that the ACP is an important surgical access point for correction of aneurysms, tumors, and other operations in the structures adjacent to it. It is particularly common for surgery to involve the ACP when operating on giant pituitary adenomas and giant meningiomas, a type of meningioma which may originate at the ACP or spread to it from other structures.{{Cite journal |last1=Attia |first1=Moshe |last2=Umansky |first2=Felix |last3=Paldor |first3=Iddo |last4=Dotan |first4=Shlomo |last5=Shoshan |first5=Yigal |last6=Spektor |first6=Sergey |date=October 2012 |title=Giant anterior clinoidal meningiomas: surgical technique and outcomes |url=http://dx.doi.org/10.3171/2012.7.jns111675 |journal=Journal of Neurosurgery |volume=117 |issue=4 |pages=654–665 |doi=10.3171/2012.7.jns111675 |pmid=22900847 |issn=0022-3085}}

Endovascular surgery has become an increasingly common procedure for lesions and aneurysms around the ACP, as the complex anatomy makes it difficult and dangerous to access via other surgical methods. However, endovascular surgery in the clinoid region is also relatively high-risk, so only serious injuries and diseases are indicated for this procedure.{{Cite journal |last1=White |first1=A |last2=Roark |first2=C |last3=Case |first3=D |last4=Folzenlogen |first4=Z |last5=Kumpe |first5=D |last6=Ding |first6=D |last7=Seinfeld |first7=J |date=August 2021 |title=E-001 Endovascular management of traumatic intracranial aneurysms from closed head injury |url=https://jnis.bmj.com/lookup/doi/10.1136/neurintsurg-2021-SNIS.97 |journal=Journal of NeuroInterventional Surgery |volume=13 |issue=Suppl 1 |publisher=BMJ Publishing Group Ltd. |pages=A62.1–A62 |doi=10.1136/neurintsurg-2021-SNIS.97}}

The anterior and posterior clinoid processes surround the sella turcica like the four corners of a four poster bed. Cline is Greek for bed. –oid, as usual, indicates a similarity to.{{Cite web |title=Anterior clinoid process of the sphenoid bone |url=http://www.anatomyexpert.com/structure_detail/609/1856/ |access-date=20 March 2013 |publisher=AnatomyExpert}} The term may also come from the Greek root klinein or the Latin clinare, both meaning "sloped" as in "inclined".

Image:Anterior clinoid process.jpg|Anterior clinoid process

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• {{cite web|url=http://www.tk.de/rochelexikon/pics/s34257.000-2.html |title=Anatomy diagram: 34257.000-2 |work=Roche Lexicon - illustrated navigator |publisher=Elsevier |archive-url=https://web.archive.org/web/20130622050647/http://www.tk.de/rochelexikon/pics/s34257.000-2.html |archive-date=2013-06-22 |url-status=dead }}
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Category:Bones of the head and neck

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