Video: Arteries of the head and neck
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The head and neck are very important and anatomically complex regions of the body. The head houses the brain; therefore, it is the site of our consciousness – ideas, creativity, imagination, respon... Read more
The head and neck are very important and anatomically complex regions of the body. The head houses the brain; therefore, it is the site of our consciousness – ideas, creativity, imagination, responses, decision making, and memory. Our face provides our identity as individuals. The head also includes special sensory receivers, broadcast devices for voice and expression, and portals for the intake of fuel, water, and oxygen and the exhaust of carbon dioxide. The neck contains many vital structures and attaches the head to the trunk, supporting it and allowing its movements in several directions. All these structures need nutrients and oxygen to perform their vital functions which as we know is delivered through arteries.
Today, we'll learn about the path arterial blood takes to reach these structures. So let's begin this tutorial on the main arteries of the head and neck.
Let's briefly take a look at what we'll cover in this video. First, we'll take a general look at the main arterial sources of the head and neck – the common carotid arteries and the subclavian arteries. Each of these arteries are paired, meaning that there is one of them on each side of the body. After that, we'll take a look at the main branches of these arteries and the areas supplied by them. We'll finish this tutorial by taking a quick look at an important condition related to the subject – cerebrovascular disease. So let's begin with the big overall picture of the arterial supply of the head and neck.
The head and neck derive their blood supply from two main paired arteries and their branches – the common carotid artery and the subclavian artery. In some books, these two arterial tracts are referred to as the carotid system and the subclavian system. In this image, we can see the right and left common carotid arteries highlighted in green. The left one originates directly from the arch of the aorta and the right one from the brachiocephalic trunk. The common carotid arteries split into two main branches – the external carotid artery and the internal carotid artery. This bifurcation occurs at the level of the fourth cervical vertebra.
The other main arterial source for the head and neck are the structures we can now see highlighted in green – the subclavian arteries. The left subclavian artery originates directly from the arch of the aorta while the right subclavian artery originates from the brachiocephalic trunk. The subclavian arteries give rise to branches that travel superiorly into the neck and head but its main component travels into the upper limbs providing blood supply there.
Now that we have the general scheme of the main arteries of the head and neck, let's have a look at the main branches of those arteries as well as the structures supplied by them.
So let's start with the external carotid artery which you can see here highlighted in green in this lateral view of the head and neck. The external carotid artery gives some branches to the parts of the neck and supplies the external structures of the head and face. It has eight branches which can be remembered by the mnemonic ‘Some Anatomists Like Freaking Out Poor Medical Students’. The first letter of these words can help you remember the name of all of those branches. We'll work through them in the following slides.
The first branch of the external carotid artery is the superior thyroid artery. This artery's main target is the superior portion of the thyroid gland. It arises from the anterior surface of the external carotid artery and descends along the lateral border of the thyrohyoid muscle to reach the thyroid gland.
The second branch is the ascending pharyngeal artery. It is the smallest branch of the external carotid artery. It arises from the medial surface of the external carotid artery near its base and ascends between the internal carotid artery and the pharynx to reach the base of the cranium. As its name suggests, this artery arises to supply the pharynx as well as other nearby structures including the soft palate.
The lingual artery is the third branch of the external carotid artery. It arises anteromedially from the external carotid artery between the superior thyroid and facial arteries. Here we can only see the beginning of the artery because it disappears deep to the hyoglossus muscle. As you may have guessed, the lingual artery supplies the intrinsic muscles of the tongue and the floor of the mouth.
The fourth artery is the facial artery which as its name implies supplies the muscles and skin of the face. The facial artery arises anteriorly from the external carotid in the carotid triangle. It also gives rise to branches that supply the tonsils, palate, and submandibular glands.
As we can see, the ‘Out’ of our mnemonic is for occipital artery which is the fifth branch of the external carotid artery. It travels towards the occiput to supply the posterior region of the scalp. We can see the beginning of the occipital artery here highlighted in green. In this image of the skull from a posterior view, we can get a better idea of its complete path.
Next we have the posterior auricular artery arising from the external carotid artery posterior to the ramus of the mandible. We can see the beginning of this artery here highlighted in green. In this image, we're now looking at the left side of the face and neck with the posterior auricular artery highlighted in green. It's traveling posteriorly around the ear. This artery supplies the adjacent musculature, the parotid gland, and parts of the ear and scalp.
Almost there! We're on number seven of eight branches. The final two branches – the maxillary and superficial temporal arteries – are known as the terminal branches of the external carotid artery as they are formed by its terminal bifurcation. Let's take a look at the maxillary branch first.
The maxillary artery is the larger of the two terminal branches and has 17 branches itself. The maxillary artery enters and traverses the infratemporal fossa before terminating in the pterygopalatine fossa. Its branches supply many, many structures including the mandible, the teeth, the masseter muscle, and the buccinator muscle, and finally, the last branch of the external carotid artery.
The other terminal branch is the superficial temporal artery. We can see the beginning of this artery highlighted here in green. This artery ascends superficially along the temporal bone and terminates by dividing into the frontal and parietal branches. Because of its superficial location, the pulse of this artery can be easily palpated. It supplies the temporal region of the scalp as you can see here in this image of the lateral view of the face and neck.
So to wrap up our external carotid artery, let's just quickly review its eight branches and the mnemonic that will help us remember them all – Some Anatomists Like Freaking Out Poor Medical Students. S for superior thyroid artery, A for ascending pharyngeal artery, L for lingual artery, F for facial artery, O for occipital artery, P for posterior auricular artery, M for maxillary artery, and S for superficial temporal artery.
Now that we're done with the external carotid artery, let's take a look at the internal carotid artery.
You can see it here arising at the carotid bifurcation traveling superiorly in the neck and entering the skull through the carotid canal. The internal carotid arteries are one of the two main parts of vessels supplying the brain. They provide the so-called anterior circulation. We will see the other pair later in this tutorial.
An easy way to tell the external and internal carotid arteries apart is by looking at their branches. The internal carotid artery gives off zero branches in the neck and only begins to branch within the cranial cavity whereas the external carotid artery as we've already seen gives off several branches within the neck.
Let's take a look at some of the branches of the internal carotid artery now.
The first branch of the internal carotid artery is the inferior hypophyseal artery. The inferior hypophyseal artery arises from the cavernous part of the internal carotid artery and passes medially across the cavernous sinus towards the pituitary gland. It supplies the neurohypophysis or posterior part of the pituitary gland. The pituitary gland sits in this bony space – the sella turcica.
Next up is the superior hypophyseal artery which arises from the cerebral part of the internal carotid artery and passes between the optic chiasm to reach the infundibulum of the pituitary gland. It supplies part of the hypothalamus as well as the anterior pituitary gland.
The ophthalmic artery is next. This artery passes through the optic canal ultimately entering the orbit. It travels along the medial wall of the orbit between the superior oblique and medial rectus muscles supplying its contents.
The posterior communicating artery originates from the communicating segment of the internal carotid artery. It extends posteriorly and joins with the posterior cerebral artery. This artery which we can see highlighted in this inferior view of the brain contributes to the formation of the circle of Willis which is an important anastomosis between the intracranial vessels. Keep an eye out through the tutorial as we discover more components of the circle of Willis.
Just superior to the posterior communicating artery is where the anterior choroidal artery originates. It travels backwards across the optic tract and terminates in the choroidal plexus. This artery supplies several subcortical structures, parts of the midbrain, and components of the visual pathway.
As you can see here on this image, the anterior cerebral artery is one of the terminal branches of the internal carotid artery. Being located in the anterior and medial aspects of the interhemispheric fissure, the anterior cerebral artery supplies a large portion of the medial cerebral hemispheric surfaces. Through the anterior communicating artery, it anastomosis with its contralateral counterpart. This anastomosis makes the anterior component of the circle of Willis.
The middle cerebral artery, also a contributor to the circle of Willis, is the second and largest terminal branch of the internal carotid artery. It supplies many deep brain structures – the majority of the lateral surface of the cerebral hemispheres and the temporal pole of the brain. It travels from the base of the brain to the lateral sulcus of Sylvius to the lateral surface of the brain. And with the middle cerebral artery, we finish the carotid system.
Now let's go back to the neck and take a look at the subclavian system.
The subclavian artery is highlighted in this lateral view of the neck. This artery contributes to the blood supply of the neck. Moreover, it gives origin to the second main vessel that supplies the brain – the vertebral artery – which we will describe later in this tutorial. The main bulk of the subclavian artery travels distally into the upper limbs while giving off branches to the thorax, scapular region, and more. In this tutorial, though, we'll focus on the branches that supply the head and neck.
The first arteries arising from each subclavian artery are the left and right vertebral arteries. We can see the right one in this image highlighted in green. These arteries provide blood to the superior part of the spinal cord, brainstem, cerebellum, and posterior part of the brain. Each vertebral artery originates from the first part of their respective subclavian artery then courses superiorly through the neck in the transverse foramina of the cervical vertebrae as you can see here in this image. They enter the skull and once at the level of the pons, they merge with each other to form the single midline basilar artery which we can see here in this image of the brain from an inferior view.
The basilar artery then ascends along the ventral surface of the pons. This vertebrobasilar system gives origin to the other arterial circuit delivering blood to the brain – the posterior circulation of the brain. The basilar artery ends by bifurcating into the paired posterior cerebral arteries which in turn join the posterior communicating arteries from the internal carotid arteries to complete the circle of Willis. We can see then that this hexagonal arterial network called the circle of Willis connects the dual supply of the brain – the anterior circulation that you can see highlighted here and the posterior circulation highlighted in blue.
Heading back to the subclavian artery, the next branch is the thyrocervical trunk. It has a relatively short course in the anterior portion of the neck and gives off several branches. That's why this arterial trunk has a wide supply territory including the thyroid and parathyroid glands, larynx, and pharynx.
The last branch on our list is the costocervical trunk. The costocervical trunk arches posteriorly towards the neck of the first rib. After this short course in the anterior neck, it divides into two terminal branches through which it supplies structures in the root of the neck including the posterior neck muscles as well as some in the thorax.
Now it's time to get clinical.
In this clinical note, we're going to talk about a very important and prevalent condition – cerebrovascular disease. Its most acute and serious presentation is a cerebrovascular accident or stroke. A stroke occurs when the blood supply to part of the brain is interrupted preventing brain tissue from getting oxygen and nutrients. Brain cells begin to die in minutes.
There are two main types – a blocked artery which causes an ischemic stroke or a leaking or burst blood vessel which leads to a hemorrhagic stroke. Ischemic strokes are the most common type. Ischemic strokes can be further divided into thrombotic or embolic. Thrombotic strokes are usually caused by atherosclerotic plaques which are fatty deposits that gradually build up in the artery’s wall. If they get big enough to block the blood vessels, they can cause a stroke.
Embolic strokes are caused by clots that travel through the bloodstream from another source and lodge in the arteries of the brain. Emboli could break off from a plaque in the common carotid artery and travel through the pathways we looked at earlier to ultimately block one of the smaller arteries in the brain. The brain tissue that is downstream from the location of the lodged clot will be deprived of oxygen and can die within minutes.
The symptoms of a stroke depend on which area of the brain has been affected; however, the common symptoms of a stroke can be remembered with the word FAST. This acronym stands for Facial drooping, Arm weakness, Speech difficulties, and Time to call emergency services. A stroke is a medical emergency and prompt treatment is crucial. Early action can reduce brain damage and other complications.
And now you're an expert on the main arteries of the head and neck! Before we finish this tutorial, let's just do a quick review of what we learned today.
We started with a general overview of the main arteries supplying the head and neck – the common carotid artery and the subclavian artery. The common carotid artery bifurcates into the external carotid artery and internal carotid artery. Then we described the main branches of those arteries and the areas supplied by them. The external carotid artery gives some branches to the neck but mainly it supplies the external structures of the head and face.
The branches of the external carotid artery can be remembered by the mnemonic ‘Some Anatomists Like Freaking Out Poor Medical Students’. These branches 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.
The other branch of the common carotid artery – the internal carotid artery – is one of the two main vessels supplying the brain. It provides the so-called anterior circulation of the brain. The main branches of the internal carotid artery are the superior hypophyseal artery, inferior hypophyseal artery, ophthalmic artery, posterior communicating artery, anterior choroidal artery, anterior cerebral artery, and middle cerebral artery.
Finally, we looked at the subclavian artery which is the main arterial supply to the structures of the neck through the thyrocervical trunk and costocervical trunk. Moreover, it gives off the vertebral artery which unites with its counterpart to form the basilar artery – the second main system that supplies the brain through the so-called posterior circulation. Branches from the internal carotid artery and from the basilar artery contribute to the formation of the circle of Willis – the most important anastomosis between the intracranial vessels that connect the anterior and posterior circulations.
We finish this tutorial talking about cerebrovascular accidents or strokes – a medical condition in which interrupted blood flow to the brain causes cell death.
Hope you enjoyed this video. See you next time and happy studying!