Internal carotid artery

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The internal carotid artery (or internal carotid artery , ACI for short ) is one of the arteries supplying the brain . In humans and some other mammals, it supplies not only the brain but also the eye . The branch is called the ophthalmic artery .

Course in humans

Cervical arteries

It arises from the splitting of the common carotid artery , the other branch is the usually somewhat weaker external carotid artery , which supplies the outer parts of the head and partly the cervical organs as well as the meninges in the skull . There are many connections ( anastomoses ) between the two . In the embryo, the internal carotid artery is connected to the longitudinal neural artery (the later basilar artery ) via the trigeminal artery .

At the exit of the internal carotid artery, the carotid sinus , there are pressure receptors (also called presso- or baroreceptors ) that monitor the blood pressure in the arterial system and transmit the information to the cardiovascular center in the brain and represent the receptor area for the carotid sinus reflex . In addition, the internal carotid artery can be found at the origin chemoreceptors in the so-called carotid body that the content of carbon dioxide , oxygen and pH in blood monitor.

The internal carotid artery is of a sympathetic accompanied plexus, the from the upper border strand derived.


The course of the internal carotid artery can be divided into four sections: pars cervicalis, pars petrosa, pars cavernosa, pars cerebralis.

Pars cervicalis

The pars cervicalis ("neck part") extends from the outlet from the common carotid artery to the point of entry into the base of the skull through the outer opening of the carotid canal (carotid canal ). In its initial section, the internal carotid artery is usually behind (dorsal) the external carotid artery , it then progresses medially (towards the center) and reaches the base of the skull. Throughout the cervical part of the available internal carotid artery from any branch.

Pars petrosa

The pars petrosa ("petrous bone") runs within the part of the temporal bone of the same name and is about 3 cm long in humans. It first moves cranially, i.e. upwards, but then describes an arc in the front wall of the tympanic cavity ( paries caroticus ) to the front and to the middle (anteromedial) towards the sphenoid body . The arch is also known as the "carotid knee". The pars petrosa releases several branches to the tympanic cavity ( Arteriae caroticotympanicae ) and in 30% of the cases one branch to the canalis pterygoideus ( Arteria canalis pterygoidei ). In the area of ​​the inner opening of the carotid canal, the internal carotid artery is usually only covered by hard meninges ( dura mater ) and rests on the foramen lacerum . The space between the wall of the Karotiskanals and the internal carotid artery is of a as venous plexus internal carotid designated venous plexus ingested. This venous plexus connects the cavernous sinus located inside the skull with the pterygoid plexus located outside the skull . This connection can play a decisive role in the development of meningitis ( meningitis ).

Pars cavernosa

Immediately on the inside of the base of the skull, the internal carotid artery runs through the cavernous sinus . This section is known as the pars cavernosa ("sponge work part"). The artery here makes another "S" -shaped arch from the back and bottom to the front and top, which is called a siphon or "carotid siphon ". In this section, the internal carotid artery gives off a branch to the neurohypophysis ( arteria hypophysialis inferior ), branches to the trigeminal ganglion ( Rami ganglionares trigeminales ), to the surrounding hard meninges ( Ramus meningeus ) and to the cavernous sinus ( Ramus sinus cavernosi ).

Pars cerebralis

After breaking through the hard meninges medial to the anterior clinoid process , the internal carotid artery merges into its cerebral pars (“brain part”). The pars cerebralis lies in the subarachnoid space at the base of the brain . It runs in this section from the back bottom to the top front. Immediately after passing through the hard meninges, it gives off the ophthalmic artery as a branch . This runs with the optic nerve ( nervus opticus ) to the eye. Most comes from the pars cerebral and the posterior communicating artery out that part of the circle of Willis , and the front combines with the rear basin. Other branches are the anterior choroid artery , which supplies blood to various brain structures, and the superior hypophysial artery . The internal carotid artery then divides into the anterior ( anterior cerebral artery ) and the middle cerebral artery ( media cerebral artery ), which together supply large parts of the cerebrum . The point of division is called the "carotid T".


As a rare variant, the posterior cerebral artery ( arteria cerebri posterior ) also arises primarily from the arteria carotis interna . Connections of the vessels on both sides and the basilar artery form the Circulus arteriosus cerebri (Circulus Willisii).

Comparative anatomy

In horses and dogs, the internal carotid artery also supplies the brain. In horses, the artery runs caudodorsal to the medial air sac , an extension of the ear trumpet ( tuba auditiva ). In articulated ungulates, cats and guinea pigs, the internal carotid artery recedes outside the cranial cavity and is functionally replaced by other vessels. In artifacts and cats, this is the maxillary artery , a branch of the external carotid artery , which also forms miracle networks at the base of the brain. The cerebral artery supplying the brain is formed by the union of the miracle nets and the internal carotid artery . In guinea pigs, around 40% of the inflow to the cerebral arterial circle comes from the internal ophthalmic artery ( internal ophthalmic artery ).


The initial segment of the internal carotid artery , in particular, is a predilection for the formation of atherosclerotic plaques . These can either narrow the vessel ( carotid stenosis ) or, in extreme cases, close it completely, or cause a cerebral infarction through an embolism .

The dissection is a crack that can also lead to acute vascular occlusion. The cause is often trauma.

In the intracranial course (within the skull), small bulges ( aneurysms ) sometimes develop , which, if ruptured, lead to the highly acute subarachnoid hemorrhage .


  • Helga Fritsch, Wolfgang Kühnel: Inner organs (= pocket atlas anatomy. Vol. 2). 10th, revised and expanded edition. Georg Thieme, Stuttgart et al. 2009, ISBN 978-3-13-492110-6 , p. 50.
  • Uwe Gille: Cardiovascular and immune system, Angiologia. In: Franz-Viktor Salomon, Hans Geyer, Uwe Gille (Ed.): Anatomy for veterinary medicine. 2nd, revised and expanded edition. Enke, Stuttgart 2008, ISBN 978-3-8304-1075-1 , pp. 404-463.
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Web links

Commons : Internal carotid artery  - Collection of images, videos and audio files

Individual evidence

  1. FCAT - Federative Committee on Anatomical Terminology: Terminologia Anatomica. Thieme, Stuttgart et al. 1998, ISBN 3-13-114361-4 .
  2. DH Padget: The development of the cranial arteries in the human embryo . (1948) Carnegie Inst. Wash. Pub. 575, Contrib. to embryol. 32: 205-261.
  3. a b Horst Erich König, Hans-Georg Liebich (Ed.): Anatomy of domestic mammals. Textbook and color atlas for study and practice. 4th, revised edition. Schattauer, Stuttgart et al. 2008, ISBN 978-3-7945-2650-5 , p. 455.
  4. Hans Mauer: Angioarchitektonische Investigations on the arteries in the cranial cavity of the guinea pig Cavia cobaya . Vet. Med. Diss. Munich 1986