Video: Arteries of the head

A mighty and powerful brain – that supercharged center of nervous potential which oversees the regulation of physiological balance or homeostasis – is in charge of executing all your cognitive functions and micromanages just about almost every body function there is quite literally without even having to think about it. It's no small feat by any means. In doing all of this, our brains zap up around twenty percent of the body's energy every day, meaning it requires a huge volume of oxygenated blood in order for it to meet this high physiological demand. But how does this blood get there in the first place? In today's tutorial, we will look at some of the blood vessels responsible for supplying this much-needed oxygen and nutrient-rich blood to the brain and much more as we explore the arteries of the head.

So in today's tutorial, we're going to be looking at how arterial blood reaches the head using this illustration which is a right lateral view of the head and the neck. Now before we get started, I want to let you know that this tutorial is jam-packed with detail. In fact, we're going to be speaking about over seventy arteries today. But don't let that put you off. We're going to be taking it slow and steady and we're going to divide this huge family of vessels into three main groups. We've also included lots of mnemonics and other memory devices to help you memorize all you need to know.

So today we'll be looking at the anatomy and branches of the external carotid artery, the internal carotid artery, and finally, the vertebral artery. Feel free to watch this video in parts to make sure that you've mastered the anatomy of one group before moving on to the next one. Alright so let's get straight to it and kick things off with this large vessel here highlighted in green which is the brachiocephalic trunk.

Also known as the innominate artery or brachiocephalic artery, this blood vessel is a major supplier of oxygenated blood to the right side of the head and neck as well as the right upper extremity. It arises directly from the aorta as you can see here at the aortic arch as the first unpaired branch of the aorta. It courses superiorly crossing the trachea and bifurcates at the level of the right sternoclavicular joint into the right subclavian artery and the right common carotid artery, the latter of which continues to the head and neck.

So here you can see the common carotid artery highlighted in green. Unlike the brachiocephalic trunk, this large artery is a bilateral artery which means that it has right and left counterparts. That being said, despite the fact that it is bilateral, it's important to know that it has different origins on the left and right side.

As we have already seen on the right side, the right common carotid artery arises from the bifurcation of the brachiocephalic trunk at about the level of the right subclavian joint. It also courses superiorly through the neck towards the head. On the left side, the left common carotid artery arises directly from the aortic arch as the second branch from the aortic arch. It travels superiorly passing through the superior mediastinum and courses through the neck on the left side.

From here, the right and left common carotid arteries follow a similar course and branching pattern. Both examples travel superiorly to their bifurcation which is variably around the level of the fourth cervical vertebra into the internal and external carotid arteries. Interestingly, the bifurcation of the left common carotid artery is higher than its right counterpart in fifty percent of the population.

This next structure is situated just inferior to the carotid bifurcation and it is known as the carotid body. The carotid body is an oval-shaped structure that acts kind of like an antenna measuring the chemical composition of blood flowing through the common carotid arteries. This information is then relayed to the respiratory center in the brainstem and it's quite small which can make it difficult to find in gross anatomy dissection.

So what makes this small structure so special? Well, it is composed of chemoreceptors called glomus cells and sustentacular cells. These chemoreceptors are responsible for monitoring blood pH, oxygen, and carbon dioxide levels and, therefore, are able to detect hypoxia, acidemia, and hypercapnia. The carotid body is innervated by the nerve of the carotid sinus which is a branch of the glossopharyngeal nerve which, as you probably know, is the ninth cranial nerve.

The carotid sinus is a dilation situated at the base of the internal carotid artery just above the carotid bifurcation. It is an important structure which is involved in the relaying of information about arterial blood pressure to the hypothalamus. It contains baroreceptors which are mechanoreceptors that detect changes in systemic blood pressure and it is innervated by the nerve for the carotid sinus known as Hering's nerve, which is a branch of the glossopharyngeal nerve.

As we saw, the common carotid bifurcates into two branches and we're going to explore each of them in detail now beginning first with the external carotid artery. The external carotid artery courses superiorly passing under the submandibular gland and into the parotid gland giving off branches to the head and neck along its course. The external carotid generally gives off eight branches along its course which supply the head, the neck, and the structures of the face. These are the superior thyroid artery, the ascending pharyngeal artery, the lingual artery, the facial artery, the occipital artery, the posterior auricular artery, the maxillary artery, and the superficial temporal artery.

To remember these eight branches of the external carotid artery, why not try using the mnemonic Some Anatomists Like Freaking Out Poor Medical Students. Here, the first letter of each word stands for the first letter of each branch that you need to memorize. Remember this and you'll be off to the best start when learning the anatomy of the external carotid artery.

So now let's look at these branches beginning first with the superior thyroid artery, seen here highlighted in green. This artery arises from the external carotid artery at about the level of the hyoid bone. It makes its way inferiorly to the superior portion of the thyroid gland giving off branches along its course that go on to supply the infrahyoid muscles and the sternocleidomastoid muscle.

Next, we'll look at the superior laryngeal artery, a branch of the superior thyroid artery. This vessel courses beneath the thyrohyoid muscle accompanying the internal laryngeal branch of the superior laryngeal nerve along its course. The superior laryngeal artery which is seen here from a posterior view of the neck with tissue and muscle removed to expose the larynx, trachea, and epiglottis supplies the larynx as well as the mucosa, muscle, and glands of the larynx. You get an idea of this just by looking at the distribution of the branches of this artery. Like many vessels of the neck, the superior laryngeal artery forms an anastomosis with its counterpart on the opposite side of the body.

The next branch we will look at is the ascending pharyngeal artery, which is the smallest branch of the external carotid artery. It ascends superiorly along the pharynx giving off branches along its course that go on to supply the prevertebral muscles, the pharynx, the middle ear, and the cranial meninges.

The lingual artery courses deep to the hyoglossus muscle giving off two branches – the deep lingual artery and the sublingual artery. As its name suggests, the lingual artery, via its branches, supplies the tongue, the sublingual gland, the gingiva, and the oral mucosa of the floor of the mouth.

The next branch of the external carotid artery is a biggie so pay close attention to this one. This is the facial artery which, as the name suggests, supplies the structures of the face. It courses initially around the inferior border of the mandible before turning superiorly across the cheek and towards the angle of the mouth and terminating near the medial aspect of the eye. The facial artery, like the other arteries we've discussed so far, also gives off several branches which can be described as cervical branches or facial branches of the artery depending on which region they supply.

We won't discuss all the branches of the facial artery in detail in this tutorial; however, we will look at some of the major ones beginning first with the submental artery, which is this small artery seen here running along the inferior aspect of the jaw bone or the mandible. The submental artery, which is the largest cervical branch of the facial artery, courses anteriorly over the mylohyoid muscle passing underneath the anterior belly of the digastric muscle and then inferior to the body of the mandible where it goes on to supply the muscles and the skin over the submental region.

The next artery we'll look at – the inferior labial artery – arises close to the angle of the mouth. It runs deep to the depressor anguli oris muscle piercing the orbicularis oris muscle and goes on to supply the muscles and mucous membrane of the lower lip as well as the labial glands. The inferior labial artery forms an anastomosis with its counterpart on the opposite side and with the mental branch of the inferior alveolar artery which we will meet shortly.

Finally, let's look at the superior labial artery. This artery, seen here from the anterior aspect, supplies the upper lip as well as gives off branches to supply the nasal septum and the ala of the nose.

That brings us to the terminal branch of the facial artery which is the angular artery. You can see in this magnification of the image the angular artery ascends the face towards the medial angle of the eye. Here, it anastomosis with the branches of the ophthalmic artery forming an anastomosis between the internal and external carotid arteries. Moving around to look at it from an anterior perspective, we can better see the course of the artery as it travels over the maxilla towards the medial angle of the eye. The angular artery supplies various structures of the face including the lacrimal sac and the nasal area as well as the orbicularis oculi muscle.

Let's move on from the facial artery now and look at the last four branches of the external carotid artery beginning first towards the posterior aspect of the head where we have the occipital artery. This vessel arises from the external carotid artery close to the inferior border of the posterior belly of the digastric muscle. In this image, we can only see this small proximal end of the artery, but if we look at the artery as seen from the posterior aspect of the skull, we can see that this artery branches across the posterior surface of the skull.

Next up is the posterior auricular artery. Here we see the proximal part of the artery. The posterior auricular artery arises above the digastric and stylohyoid muscles, courses superiorly and posteriorly behind the external acoustic meatus, and goes on to supply the parotid gland, the facial nerve, the auricle of the ear, the scalp behind the ear as well as adjacent musculature.

Onto the two terminal branches of the external carotid artery now, the first of which that we'll look at being the superficial temporal artery. Here we see the proximal end or origin of the artery but it actually arises deep to the parotid gland. In this illustration, we can get a clearer view of what this looks like when the parotid gland is in its anatomical position. Once the superficial temporal artery arises, it courses superiorly over the zygomatic process of the temporal bone to supply the scalp in the temporal region. The pulse of this artery can actually be palpated and you can feel its pulse just anterior to the tragus of the ear.

Let's turn our attention now to the other of the two terminal branches of the external carotid artery which is the maxillary artery. Of the two terminal branches, the maxillary artery is the larger one of the two and it supplies both the hard and soft tissue of the maxillofacial region with oxygenated nutrient-rich blood. The maxillary artery also gives rise to roughly fifteen defined branches. To help us keep track of all of these, we can divide the maxillary artery into three parts. The first part is known as the mandibular part which is the first part of the artery which courses deep to the neck of the mandible. The second or pterygoid part is found between the two heads of the lateral pterygoid muscle. And finally, the third or pterygopalatine part of the maxillary artery enters the pterygopalatine fossa.

Let's quickly zoom through the branches of the maxillary artery beginning with the first branch of the mandibular part which is the deep auricular artery. This vessel passes through the bony wall of the external acoustic meatus via the squamotympanic fissure and supplies the skin of this canal and part of the tympanic membrane. The anterior tympanic artery is a tiny artery which also passes via the squamotympanic fissure of the temporal bone and supplies the middle ear. The reason it's not shown on our main illustration today is due to the fact that the anterior tympanic artery may sometimes arise as a branch of the deep auricular artery which we looked at a moment ago. Remember, all anatomy is subject to variation.

Next, let's look at the middle meningeal artery which typically arises as the third branch from the first part of the maxillary artery. From its origin, the artery passes superiorly through the foramen spinosum and then goes on to supply the bones of the skull as well as the cranial dura mater. It should be noted that the middle meningeal artery gives off two branches before it divides into its anterior and posterior divisions. These branches are known as the superior tympanic branch and the ganglionic branch.

Next up is the accessory meningeal artery. This artery arises as a branch of the maxillary artery but it can also arise from the middle meningeal artery where it is then referred to as the accessory branch of the middle meningeal artery. The accessory meningeal artery courses upwards from its origin and enters the cranial vault through the foramen ovale. It goes on to supply the meninges, specifically, the dura matter that covers the floor of the middle cranial fossa as well as that of the trigeminal cave, also known as Meckel's cave. The accessory meningeal artery is also the primary source of blood supply to the trigeminal ganglion.

The inferior alveolar artery also arises from the mandibular part of the maxillary artery. It courses anteriorly and inferiorly towards the inferior alveolar foramen through which it passes along with the inferior alveolar nerve. It travels anteriorly to supply the mandibular teeth or lower dentition as well as the body of the mandible. The inferior alveolar artery bifurcates around the region of the first premolar into the incisive and mental branches, the latter of which you can see here highlighted in green.

This next artery – the masseteric artery – also arises from the second or pterygoid part of the maxillary artery. This small artery is superficial to the lingual nerve passing laterally via the mandibular notch where it goes on to supply the masseter muscle.

Up next are the pterygoid branches of the maxillary artery which also arise from the second part of the maxillary artery. They are somewhat variable in number and origin and supply both the lateral and medial pterygoid muscles.

Next, we look at the buccal artery which also arises from the pterygoid part of the maxillary artery. Also known as the buccinator artery, the buccal artery travels obliquely from its origin between the medial pterygoid muscle and the insertion of the temporalis muscle until it reaches the outer surface of the buccinator muscle which it supplies as well as the overlying cheek tissue.

The deep temporal arteries arise from the superior aspects of the maxillary artery and descend deep to the temporalis muscle which they supply. They also deliver oxygenated blood to the squamous part of the temporal bone as well as the pericranium, which is the outer covering of the skull. The branch most proximal along the maxilla is known as the posterior deep temporal artery while the more distal example is referred to as the anterior deep temporal artery. The third middle deep temporal artery may also occasionally be present.

Let's move on to the final part of the maxillary artery now which is the pterygopalatine or the third part. Our first artery of interest here is the descending palatine artery arising from the third part or the pterygopalatine part of the maxillary artery. It divides into the greater and lesser palatine arteries which supply the hard and soft palates respectively.

The posterior superior alveolar artery, sometimes referred to as the posterior dental artery, is our next branch of interest. This one descends along the posterior surface of the maxilla and supplies the premolar and molar maxillary teeth as well as the maxillary sinus and gingiva or gums of the upper oral cavity.

Following along the pterygopalatine part of the maxillary artery, our next vessel of interest is the infraorbital artery. This vessel passes via the inferior orbital fissure, infraorbital groove of the orbit, and infraorbital foramen where it gives off the middle and anterior superior alveolar arteries. These supply the canine and incisor maxillary teeth as well as parts of the nose, the lower eyelid, and the upper lip.

Next, let's look at this small vessel here which is the sphenopalatine artery. It arises from the third part of the maxillary artery – the pterygopalatine part. Also known as the nasopalatine artery, the sphenopalatine artery travels through the sphenopalatine foramen entering the nasal cavity at just the back of the superior meatus. Here the artery supplies the nasal cavity and gives off posterior nasal branches. The sphenopalatine artery terminates on the nasal septum where it gives off its posterior septal branches.

The next artery we will look at is this vessel here which is the pharyngeal branch of the maxillary artery. This vessel also arises from the pterygopalatine part of the maxillary artery and goes on to supply the nasopharynx as well as the roof of the nose.

And, finally, the last branch of the maxillary artery is the artery of the pterygoid canal. This somewhat variable branch courses posteriorly through the pterygoid canal and gives off branches to the auditory tube, the tympanic cavity, and upper portion of the pharynx. And it can also anastomose with the pharyngeal, ethmoidal, and sphenopalatine arteries in the pterygopalatine fossa, while in the oropharynx and around the pharyngotympanic tube, it can often anastomose with the ascending pharyngeal, accessory meningeal, ascending palatine and descending palatine arteries.

If trying to remember all fifteen branches of the maxillary artery is giving you more grief than what it's worth, why not try using the mnemonic Detailed Anatomy Makes Interesting Art, (however) Maybe People Don't Bother, Since Decor Is Pretty Pricey Always. In this mnemonic, the first letter of each word stands for the first letter of each branch of the maxillary artery. Note that the commas also help by dividing the list of branches according to the three segments of the maxillary artery.

And with that marathon of arterial branches, we've covered the external carotid artery and its major branches. If you need a break, now's not a bad time to do so, but if you're ready for more, let's keep our momentum going and go back to the carotid bifurcation and learn about the internal carotid artery.

So we're going back to the bifurcation of the common carotid artery which gives off the external carotid artery which we've already looked at, and the internal carotid artery, which you can see here highlighted in green. The internal carotid artery courses superiorly from its origin at the carotid bifurcation within a fascial covering known as the carotid sheath and goes on to enter the neurocranium at the base of the skull via the appropriately named carotid canal. Within the cranial vault, it plays an important role in cerebral circulation which we will see as we explore its branches.

Anatomically, this artery can be divided into segments. One way to describe or classify the segments of the internal carotid artery was described in 1996 by Bouthilliers et al. known as Bouthilliers segments. Basically, this divides the internal carotid into seven segments based on the position of each part of the artery. These segments are the cervical segment, the petrous segment, the lacerum segment, the cavernous segment, the clinoid segment, the ophthalmic segment, and the communicating or terminal segment.

How about another mnemonic to help you remember this list of terms? To memorize the seven segments mentioned of the internal carotid artery, try using the mnemonic Charlie Please Let Children Consume Our Candy. As always, the first letter of each word stands for a segment of this artery.

Like many other large arteries, the internal carotid artery gives off several branches which can be classified according to their respective segments. Fortunately, the branches of the internal carotid artery are a little more straightforward compared to the external carotid artery. The first thing to note is that the odd-numbered segments, with the exception of C7, generally present no branches. The even-numbered segments have branches; however, these are mostly small and variable in the cases of C2 and C4 segments.

The main vessel you need to know for these segments is the meningohypophyseal trunk which you can see highlighted here arising from the C4 segment. This is a relatively small caliber of vessel but is typically consistent in its presence so it's worth looking at for a moment. As its name suggests, it supplies to two main structures. The first of these is the meninges via various meningeal branches, and secondly, supply is brought to the pituitary gland, also known as the hypophysis via the inferior hypophyseal artery. These branches may alternatively rise directly from the fourth segment of the internal carotid artery instead of the meningohypophyseal trunk being present.

Let's continue on now to the C6 or ophthalmic segment and look at one of the more prominent branches of the internal carotid artery which is the appropriately named ophthalmic artery. This vessel arises after the internal carotid artery exits the cavernous sinus and medial to the anterior clinoid process. It courses anteriorly through the optic canal accompanying the optic nerve and enters the bony orbit. The ophthalmic artery gives off numerous branches which are divided into the orbital and ocular group based on the structures they supply.

We're not going to look individually at each of the branches of the ophthalmic artery today, you'll learn about them when you study the eye and the orbit. However, I will draw your attention to two of the branches, the first of which is the supraorbital artery. From its origin, the supraorbital artery passes anteriorly traveling along the medial border of the superior rectus and levator palpebrae superioris muscles. The artery continues along its course and passes through the supraorbital notch after which it goes on to supply the muscles and skin of the forehead.

The other branch of the ophthalmic artery which we're going to quickly touch on is the supratrochlear artery. Not to be confused with the supraorbital artery, this vessel is one of the terminal branches of the ophthalmic artery and courses more medially within the orbit. It leaves the orbit at the supratrochlear notch. It then ascends to supply the forehead and the scalp, and for that reason, it's also sometimes referred to as the frontal artery.

Let's go back to the internal carotid artery now and look at another branch of the C6 segment, the superior hypophyseal artery. This small vessel arises from the posterior medial aspect of the internal carotid artery and gives off several tiny branches to the optic nerve and chiasm as well as the pituitary gland as hinted by its name.

Moving on to the terminal C7 segment of the internal carotid artery, the next vessel we're going to look at is the posterior communicating artery. Also sometimes referred to as PCOM, this vessel forms an anastomosis between the internal carotid artery and the ipsilateral posterior cerebral artery completing what's known as the circle of Willis. When you study the vessels associated with the vertebral artery, you will come across this vessel again and learn a little more about its importance.

Next up is the anterior choroidal artery which although is small in caliber is big in importance due to the structures it supplies. It arises from the posterior aspect of the C7 segment of the internal carotid artery and gives off branches to deep structures of the brain such as the basal ganglia, the thalamus, the optic tract, the hippocampus, the amygdala, and the choroid plexus of the lateral ventricles.

We're almost there with the internal carotid artery and we're now looking at the first of its two terminating branches, the anterior cerebral artery. It is a paired artery situated at the base of the brain and supplies the medial aspect of the cerebral hemispheres as far back as the parietal lobe. Now, I won't be getting into the branches of the anterior cerebral artery right now. That's a tutorial for another day. But I will mention one important vessel related to the anterior cerebral artery and that is the anterior communicating artery.

As you can see from these two images, this artery courses between the left and right anterior cerebral arteries. This small vessel forms an anastomosis between these arteries and also completes the anterior part of the circle of Willis.

And, finally, we have the middle cerebral artery which arises from the last part or the communicating portion of the internal carotid artery as the larger of its two branches. Looking at the base of the brain, we can see the middle cerebral artery coursing into the lateral sulcus where it goes on to give rise to numerous branches which supply a large portion of the lateral surface of the cerebral hemisphere as well as part of the internal capsule and basal ganglia.

And with that, we have covered the internal carotid artery and its major branches. If you're feeling like this, take a break and get some air. You're almost there. Just one last section to go. But if you're ready, let's hit the final stretch and look at the final major artery of the head which is the vertebral artery. Come on and let's find out more.

So we are right back where we started now at the brachiocephalic trunk but this time, we're moving on from the common carotid artery to this vessel here which is the subclavian artery. The subclavian artery is a bilateral vessel which supplies the head, the neck, and the upper limbs. It gives rise to several branches which supply the neck, for example, the costocervical trunk or the thyrocervical trunk. But for the purposes of this tutorial, I want to focus on this one here which is the vertebral artery.

This vessel is a paired or bilateral artery and can be divided into four parts – the cervical part which ascends from the origin of the artery within the pyramidal space formed by the scalene and longus muscles; the vertebral part which extends from vertebrae C6 to C2 passing through the transverse foramina of these vertebrae along its course; the third part known as the atlantic or suboccipital or extradural part extends from the atlas or C2 and travels in a groove on the posterior arch of the atlas towards the cranial vault as far as the foramen magnum where it pieces the dural meningeal layer; and the final part known as the intracranial or intradural part of the artery extends until the convergence of the two vertebral arteries at the inferior border of the pons to form the basilar artery.

Several muscular and spinal branches are given off as the vertebral artery ascends through its first three parts. These supply various muscles of the neck as well as the cervical vertebrae, spinal dura matter, and spinal cord. One other notable group of vessels arising from the V3 segment are the meningeal branches of the vertebral artery which supplies the dura of the cerebellar fossa.

Moving on from the V4 segment, we next come to the posterior inferior cerebellar artery, also sometimes abbreviated as PICA. It arises from the vertebral artery before it converges with its contralateral counterpart. If we look at the posterior inferior cerebellar artery as it appears from this perspective where we see the artery on the inferior aspect or the base of the brain, we can see that it gives off a network of branches along the posteroinferior surface of the cerebellum which it supplies.

The next vessel we're going to look at is the basilar artery, which is formed as a result of the convergence of the left and right vertebral arteries at the pontomedullary junction. It travels along the ventral or anterior surface of the pons within the pontine cistern. It gives off several bilateral branches which include the anterior inferior cerebellar artery; sometimes the labyrinthine artery, which supplies the cochlear and vestibular apparatus, although this will often be seen as a branch of the anterior inferior cerebellar artery; the pontine arteries of the pons; the superior cerebellar artery; and finally, the posterior cerebral artery.

Taking a closer look at the posterior cerebral artery, this is a paired vessel which arises from the bifurcation of the basilar artery. It supplies the posteromedial portion of the temporal lobe as well as the occipital lobe as you can see from the network of vessels that branch from the posterior cerebral arteries to these areas of the brain.

If you can remember the anatomy of the internal carotid artery, you'll already be familiar with this important vessel here which is the posterior communicating artery. It forms an anastomosis between the posterior cerebral artery and the internal carotid artery linking the anterior and posterior circulation of the brain. The posterior communicating arteries complete what is known as the famous circle of Willis, and truthfully, we cannot talk comprehensively about the arteries of the head without looking at this structure.

So just to remind ourselves, the circle of Willis, which is anatomically referred to as the cerebral arterial circle, refers to a ring of interconnected arteries at the base of the brain. You can see these arteries here highlighted in green.

Phew! That's a whole lot of arteries. You'll be happy to know that we've reached the end of our arterial journey today. Before we finish, let's wrap up this tutorial with a clinical note for good measure.

We just looked at the circle of Willis and described what it is. However, with all that in mind, you might be surprised to know that finding a perfect circle of Willis in clinical practice is not all that common. Yep! Like almost everything in human anatomy, the circle of Willis is subject to a great deal of variation and is only complete in about one in every five of the population due to the fact that some vessels are often absent or poorly developed. For instance, when the circle of Willis is incomplete, this could be due to hypoplasia of one or both posterior communicating arteries, hypoplasia or absence of the A1 segment of one of the anterior cerebral arteries, or absence of the anterior communicating artery.

And that is it for this marathon of head arteries. So let's quickly wrap all of this up with a short summary of what we learnt today.

First, we looked at the common carotid artery up to its bifurcation where it gives rise to the external and internal carotid arteries. Then we went on to discuss the branches of the external carotid artery which included the superior thyroid artery, the ascending pharyngeal artery, the lingual artery, the facial artery, the occipital artery, the posterior auricular artery, the maxillary artery, and the superficial temporal artery.

Next we looked at the internal carotid artery and its defined seven segments which were the cervical segment, the petrous segment, the lacerum segment, the cavernous segment, the clinoid segment, the ophthalmic segment, and the communicating segment. You'll remember that the odd segments except C7 do not have any branches and that the even segments had mainly smaller branches except for C6 which gave off the ophthalmic and superior hypophyseal arteries. The communicating or C7 segment is where most of the action was happening with the main branches mentioned here being the posterior communicating artery, the anterior choroidal artery, the anterior cerebral artery, and the middle cerebral artery.

Our last port of call was the vertebral artery and its four segments. We focused on the V4 segment which gave off the posterior inferior cerebellar artery before merging with its contralateral counterpart to form the basilar artery. We quickly looked at the branches of this vessel before ending up at the posterior cerebral artery. And, finally, we brought it all together by having a quick look at the cerebral arterial circle of Willis.

And that's it! You have definitely earned your stripes with this tutorial. Well done. Thanks for watching and happy studying!