Internal carotid artery
Internal carotid artery | |
---|---|
Carotid arteries. | |
Details | |
Precursor | 3. aortic arch |
Source | Common carotid artery |
Branches | Ophthalmic, anterior choroidal, anterior cerebral, middle cerebral and posterior communicating artery |
Vein | Internal jugular vein |
Identifiers | |
Latin | arteria carotis interna |
MeSH | D002343 |
TA98 | A12.2.06.001 |
TA2 | 4463 |
FMA | 3947 |
Anatomical terminology] |
The internal carotid artery (Latin: arteria carotis interna) is an artery in the neck which supplies the anterior circulation of the brain.[1]
In human anatomy, the internal and
Classification
Terminologia Anatomica in 1998 subdivided the artery into four parts: "cervical", "petrous", "cavernous", and "cerebral".[3][4] In clinical settings, however, usually the classification system of the internal carotid artery follows the 1996 recommendations by Bouthillier,[5] describing seven anatomical segments of the internal carotid artery, each with a corresponding alphanumeric identifier: C1 cervical; C2 petrous; C3 lacerum; C4 cavernous; C5 clinoid; C6 ophthalmic; and C7 communicating. The Bouthillier nomenclature remains in widespread use by neurosurgeons, neuroradiologists and neurologists.
The segments are subdivided based on anatomical and microsurgical landmarks and surrounding anatomy, more than
The segments of the internal carotid artery are as follows:
- Cervical segment, or C1, identical to the commonly used cervical portion
- Petrous segment, or C2
- Lacerum segment, or C3
- C2 and C3 compose the commonly termed petrous portion
- C2 and C3 compose the commonly termed
- Cavernous segment, or C4, almost identical to the commonly used cavernous portion
- Clinoid segment, or C5. This segment is not identified in some earlier classifications and lies between the commonly used cerebral or supraclinoid portion.
- Ophthalmic, or supraclinoid segment, or C6
- Communicating, or terminal segment, or C7
- C6 and C7 together constitute the commonly used cerebral or supraclinoid portion.
- C6 and C7 together constitute the commonly used
Course/part
The internal carotid artery is a terminal branch of the common carotid artery; it arises around the level of the fourth cervical vertebra when the common carotid bifurcates into this artery and its more superficial counterpart, the external carotid artery.
C1: Cervical segment
The cervical segment, or C1, or cervical part of the internal carotid, extends from the carotid bifurcation until it enters the carotid canal in the skull anterior to the jugular foramen.
At its origin, the internal carotid artery is somewhat dilated. This part of the artery is known as the carotid sinus or the carotid bulb. The ascending portion of the cervical segment occurs distal to the bulb when the vessel walls are again parallel.
The internal carotid runs vertically upward in the
It is relatively superficial at its start, where it is contained in the
Unlike the external carotid artery, the internal carotid normally has no branches in the neck.
C2: Petrous segment
The petrous segment, or C2, of the internal carotid, is that which is inside the petrous part of the temporal bone. This segment extends until the foramen lacerum. The petrous portion classically has three sections: an ascending, or vertical, portion; the genu, or bend; and the horizontal portion.
When the internal carotid artery enters the canal in the
The named branches of the petrous segment of the internal carotid artery are:
- the vidian arteryor artery of the pterygoid canal
- the caroticotympanic artery
C3: Lacerum segment
The lacerum segment, or C3, is a short segment that begins above the foramen lacerum and ends at the petrolingual ligament, a reflection of periosteum between the lingula and petrous apex (or petrosal process) of the sphenoid bone. The lacerum portion is still considered "extradural" since it is surrounded by periosteum and fibrocartilage along its course. It is erroneously stated in several anatomy textbooks that the internal carotid artery passes through the foramen lacerum. This at best has only ever been a partial truth in that it passes through the superior part of the foramen on its way to the cavernous sinus. As such it does not traverse the skull through it. The inferior part of the foramen is actually filled with fibrocartilage. The broad consensus is that the internal carotid artery should not be described as travelling through the foramen lacerum.[8]
C4: Cavernous segment
The cavernous segment, or C4, of the internal carotid artery begins at the petrolingual ligament and extends to the proximal dural ring, which is formed by the medial and inferior periosteum of the anterior clinoid process. The cavernous segment is surrounded by the cavernous sinus.
In this part of its course, the artery is situated between the layers of the dura mater forming the cavernous sinus, but covered by the lining membrane of the sinus. It at first ascends toward the
The named branches of the cavernous segment are:
The cavernous segment also gives rise to small capsular arteries that supply the wall of the cavernous sinus.
C5: Clinoid segment
The clinoid segment, or C5, is another short segment of the internal carotid that begins after the artery exits the
The clinoid segment normally has no named branches, though the ophthalmic artery may arise from the clinoid segment.
C6: Ophthalmic segment
The ophthalmic segment, or C6, extends from the distal dural ring, which is continuous with the falx cerebri, to the origin of the posterior communicating artery. The ophthalmic segment courses roughly horizontally, parallel to the optic nerve, which runs superomedially to the carotid at this point.
The named branches of the ophthalmic segment are:
- the ophthalmic artery
- the superior hypophyseal artery
C7: Communicating segment
The communicating segment, or terminal segment, or C7, of the internal carotid artery passes between the optic and oculomotor nerves to the anterior perforated substance at the medial extremity of the lateral cerebral fissure. Angiographically, this segment extends from the origin of the posterior communicating artery to the bifurcation of the internal carotid artery.
The named branches of the communicating segment are:
The internal carotid then divides to form the anterior cerebral artery and middle cerebral artery. The circle of Willis provides a collateral pathway for blood supply to the brain.
Branches
The following are the branches of the internal carotid artery, listed by segment:[9]
- C1: Branches from the cervical portion - none
- C2: Branches from the petrous portion
- Caroticotympanic arteries
- Artery of pterygoid canal (vidian artery)
- C3: Branches from the lacerum portion - none
- C4: Branches from the cavernous portion
- Branches of the meningohypophyseal trunk:
- Tentorial basal branch
- Tentorial marginal branch
- Meningeal branch - helps supply blood to the meninges of the anterior cranial fossa
- Clivus branches - tiny branches that supply the clivus
- Inferior hypophyseal artery
- Capsular branches - supplies wall of cavernous sinus
- Branches of the inferolateral trunk:
- Branches to trigeminal ganglion - provide blood to trigeminal ganglion
- Artery of the foramen rotundum
- Branches to nerves
- Branches of the
- C5: Branches from the clinoid portion - none
- C6: Branches from the ophthalmic portion
- Ophthalmic artery
- Superior hypophyseal artery
- C7: Branches from the communicating portion
- Posterior communicating artery
- Anterior choroidal artery
- Anterior cerebral artery (a terminal branch)
- Middle cerebral artery (a terminal branch)
Carotid plexus
The sympathetic trunk forms a plexus of nerves around the artery known as the carotid plexus. The internal carotid nerve arises from the superior cervical ganglion, and forms this plexus, which follows the internal carotid into the skull.
Diagnostics
The state and health of internal carotid arteries is usually evaluated using
Typically internal carotid artery blood flow velocities are measured in peak systolic velocity (PSV) and end diastolic velocity (EDV) and according to Society of Radiologists in Ultrasound in healthy subjects without stenosis must be below 125 cm/sec at PSV and below 40 cm/sec at EDV.[10]
One study found that for
Additional images
-
Circle of Willis
-
Diagram of the arterial circulation at the base of the brain (inferior view).
See also
References
This article incorporates text in the public domain from page 566 of the 20th edition of Gray's Anatomy (1918)
- ^ "Carotid artery". WebMD. Retrieved 28 July 2015.
- PMID 21452447.
The arterial input to the eye is provided by several branches from the ophthalmic artery, which is derived from the internal carotid artery in most mammals.
- ^ "Internal Carotid Artery". www.meddean.luc.edu. Retrieved 2021-07-09.
- ^ "Internal carotid artery" at Dorland's Medical Dictionary
- PMID 8837792.
- ^ Lasjaunias P, Santoyo-Vazquez A. Segmental agenesis of the internal carotid artery: angiographic aspects with embryological discussion. Anat Clin 1984;6:133–41
- ^ Fischer E. Die Lageabweichungen der vorderen Hirnarterie im Gefa¨ssbild. Zentralbl Neurochir 1938;3:300 –13
- ^ TAUBER M, VAN LOVEREN H. R et al. The enigmatic foramen lacerum. Commentaries. Neurosurgery. 1999, vol. 44, no2, pp. 386-393 [1]
- ISBN 0-397-58404-0.
- ^ Weerakkody, Yuranga. "Ultrasound assessment of carotid arterial atherosclerotic disease | Radiology Reference Article | Radiopaedia.org". Radiopaedia. Retrieved 2024-03-08.
- ^ "Blood-flow velocities and their relationships in carotid and middle cerebral arteries".
External links
- Anatomy photo:28:09-0212 at the SUNY Downstate Medical Center
- Atlas image: n3a8p1 at the University of Michigan Health System
- The Anatomy Wiz. Internal Carotid Artery
- Aneurysms of the Internal Carotid Artery