The aorta (aorta) is the largest vessel in the human body. It gives rise to all the arteries of the systemic circulation.

Aorta (aorta)

The ascending aorta (pars ascendens aortae)

Arch of the aorta (arcus aortae)

The descending aorta (pars descendens aortae)

Three major arteries arise from the arch:

The brachiocephalic trunk (truncus brachiocephalicus)

The left common carotid artery (arteria carotis communis sinistra)

The left subclavian artery (arteria subclavia sinistra)

The right common carotid artery (arteria carotis communis dextra) arises from the brachiocephalic trunk.

At the level of the superior border of the thyroid cartilage, the common carotid artery divides into the external carotid artery (arteria carotis externa) and the internal carotid artery (arteria carotis interna).

In this video, we will walk through the anatomy of the internal carotid artery and its branches, as well as the areas of blood supply and anastomoses.

The internal carotid artery (arteria carotis interna) is the main branch of the common carotid artery that supplies the head with blood.

There are two internal carotid arteries, one on each side of the neck. They pass upwards along the neck and enter the skull through the external opening of the carotid canal. Along its course, the internal carotid artery gives rise to many branches, eventually dividing into two terminal branches.

According to the Cincinnati Classification, the internal carotid artery is divided into 7 segments:

The cervical segment (C1), which doesn’t give off branches.

In this segment, the artery goes in the superior direction through the carotid triangle of the neck and passes anteriorly from the transverse processes of the cervical vertebrae

The petrous segment (C2)

This segment passes inside the carotid canal

The lacerum segment (C3), which doesn’t give off branches.

It is a short segment passing over the cartilage covering the foramen lacerum

The cavernous segment (C4)

In this segment, the artery passes in the cavernous sinus The clinoid segment (C5)

It begins after the artery leaves the cavernous sinus. The opthalmic (supraclinoid) segment (C6)

It begins from the distal dural ring. This segment ends in the area of the posterior communicating artery.

The communicating (terminal) segment (C7), which doesn’t give off branches.

In this segment, the internal carotid artery divides into two terminal branches

These are the anterior cerebral artery (arteria cerebri anterior)

And the middle cerebral artery (arteria cerebri media).

Along its length, the internal carotid artery gives off a number of branches. Let’s consider them according to the segments from which they arise.

There are 2 branches in the petrous segment:

1. The caroticotympanic artery (arteria caroticotympanica)

2. The pterygoid artery (arteria pterygoidea)

• The caroticotympanic artery (arteria caroticotympanica) passes through an opening in the carotid canal into the tympanic cavity.

  It supplies the tympanic cavity with blood

• The pterygoid artery (arteria pterygoidea), also called the Vidian artery, passes through the pterygoid canal together with the nerve of the pterygoid canal.

  It supplies the superior wall of the pharynx, the auditory tube, and the tympanic cavity with blood.

  The cavernous segment also gives off 2 branches:

  1. The meningeal artery (arteria meningea)

     

  2. The inferior hypophysial artery (arteria hypophysialis inferior)

• The meningeal artery (arteria meningea) supplies the dura mater of the anterior cranial fossa with blood.

• The inferior hypophysial artery (arteria hypophysialis inferior) also arises from the cavernous segment (C4), supplies the neurohypophysis and the posterior part of the pituitary gland with blood, and ends in the portal system of the pituitary gland.

  The ophthalmic segment also has 2 branches:

  1. The superior hypophysial artery (arteria hypophysialis superior)

  2. The ophthalmic artery (arteria ophthalmica)

  

• The superior hypophysial artery (arteria hypophysialis superior) supplies the infundibulum, the median eminence of the hypothalamus, and the tuberal part of the anterior pituitary lobe with blood.

• The ophthalmic artery (arteria ophthalmica) passes through the optic canal and enters the orbital cavity together with the optic nerve. Along its medial wall, it goes to the medial corner of the eye and divides into terminal branches.

  It gives off a number of branches along its course:

• The lacrimal artery (arteria lacrimalis), which passes to the lacrimal gland between the superior and lateral rectus muscles of the eye, supplying them with blood;

  

• Lateral palpebral arteries (arteriae palpelrales laterales), which give off long and short posterior ciliary arteries (arteriae ciliares posteriores longi et breves) passing through the sclera into the vascular layer of the eye;

  

  

  

• The central retinal artery (arteria centralis retinae), which enters the optic nerve and reaches the retina with it;

  

• Muscular arteries (arteriae musculares), which supply the oculomotor muscles with blood. The terminal branches of the muscular arteries are the anterior ciliary arteries (arteriae ciliares anteriores) and episcleral arteries (arteriae episclerales) that supply the sclera with blood, as well as anterior conjunctival arteries (arteriae conjunctivales anteriores);

  

  

• The posterior ethmoidal artery (arteria ethmoidalis posterior), which passes through the posterior ethmoidal opening to the posterior ethmoidal cells, supplying their mucous membrane with blood;

  

  

• The anterior ethmoidal artery (arteria ethmoidalis anterior), which passes through the anterior ethmoidal foramen and divides into its terminal branches;

  

  

• The anterior meningeal artery (arteria meningea anterior), which enters the cranial cavity and supplies the cranial dura mater with blood.

  

  

• The supratrochlear artery (arteria supratrochlearis), which exits from orbital cavity through the frontal foramen together with the nerve of the same name, supplying the skin and muscles of the frontal region with blood;

  

• The medial palpebral arteries (arteriae palpebrales mediales), which pass to the medial corner of the eye, where they anastomose with the branches of the lateral palpebral arteries arising from the lacrimal artery. This is how the superior and inferior palpebral arches (arcus palpebrales superior et inferior) are formed.

  

  

  

• The dorsal nasal artery (arteria dorsalis nasi), which goes to the medial corner of the eye, pierces the orbicular oculi muscle and anastomoses with one of the terminal branches of the facial artery called the angular artery (arteria angularis).

  

  The terminal segment is the called the communicating segment. It fives off four branches, two of which are terminal:

  1. The posterior communicating artery (arteria communicans posterior)

     

  2. The anterior choroidal artery (arteria chorioidea anterior)

     

  3. The anterior cerebral artery (arteria cerebri anterior)

     

  4. The middle cerebral artery (arteria cerebri media)

  

  Let’s consider these branches in greater detail.

• The posterior communicating artery (arteria communicans posterior) arises from the internal carotid artery immediately after the branching of the ophthalmic artery. It goes posteriorly heading to the pons. At the anterior border of the pons, this artery communicates with the posterior cerebral artery arising from the basilar artery.

  

• The anterior choroidal artery (arteria chorioidea anterior) arises behind the posterior communicating artery. It enters the inferior horn of the lateral ventricle, from where it follows into the third ventricle, where it participates in the formation of vascular plexuses. It supplies the optic tract, lateral geniculate body, internal capsule, basal nuclei, nuclei of the hypothalamus, and red nucleus with blood.

  

• The anterior cerebral artery (arteria cerebri anterior) is one of the two terminal branches. It arises from the trunk of the internal carotid artery above the ophthalmic artery, goes in the anterior direction, then superiorly and posteriorly along the medial surface of the cerebral hemisphere in the sulcus of the corpus callosum to the parieto-occipital sulcus. The right and left anterior cerebral arteries communicate with each other by the anterior communicating artery (arteria communicans anterior). It supplies the medial surface of the frontal, parietal and, partially, occipital lobes, the superior part of the dorsolateral and, partially, the basal surface of the cerebral hemisphere (cortex, white matter), the genu and trunk of the corpus callosum, the olfactory bulb, the olfactory tract, and, partially, the basal nuclei with blood.

  

  

• The middle cerebral artery (arteria cerebri media) is another terminal branch. It goes posteriorly in the depth of the lateral sulcus of the cerebral hemisphere. In the middle cerebral artery, according to its topography, there are three parts: the sphenoid, which is attached to the greater wing of the sphenoid bone, the insular, which is attached to the insula, and the terminal, or cortical, which branches on the superior lateral surface of the cerebral hemisphere. It supplies the superior lateral side of the frontal, parietal and temporal lobes, as well as the insular lobe (cortex and white matter) with blood.

Dictionary

The internal carotid arteryand its branches

Internal carotid artery

a. carotis interna

Pterygoid artery

a. pterygoidea

Caroticotympanic arteries

a. caroticotympanica

Meningeal artery

a. meningea

Inferior hypophysial artery

a. hypophysialis inferior

Superior hypophysial artery

a. hypophysialis superior

Ophthalmic artery

a. ophthalmica

Lacrimal artery

a. lacrimalis

Lateral palpebral arteries

aa. palpebrales laterales

Central retinal artery

a. centralis retinae

Muscular arteries

aa. musculares

Anterior ciliary arteries

aa. ciliares anteriores

Episcleral artery

aa. episclerales

Anterior conjunctivalarteries

aa. conjunctivales anteriores

Posterior ethmoidal artery

a. ethmoidalis posterior

Anterior meningeal artery

a. meningea anterior

Supratrochlear artery

a. supratrochlearis

Medial palpebral arteries

aa. palpebrales mediales

Anterior choroidal artery

a. chorioidea anterior

Anterior cerebral artery

a. cerebri anterior

Middle cerebral artery

a. cerebri media