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Anatomy and contents of the anatomical regions of the head and neck.
Hello everyone! It's Megan from Kenhub here, and in today's tutorial, we'll be discussing the descriptive terms used to describe the regions of the head and neck. You may be wondering why we divide the body into so many regions. Well each portion of the body such as the trunk of the body, the upper limbs, the lower limbs and of course the head and neck is divided into regions to help clinicians in the identification of injuries or pathologies to underlying organs, bones or muscles.
So the body is divided into many, many regions and we'll actually cover them across five different tutorials but today as you know our focus will be on the regions of the head and neck or the region you can see contained within the blue rectangle on your screen.
We'll begin this tutorial by looking at the regions of the head then we'll move on to the regions of the neck. The head is divided into quite a few regions and these regions are in turn grouped into either regions of the neurocranium or regions of the viscerocranium. Let me draw a line on our nice image of the skull here to show you roughly where this division occurs.
So above the blue line we have the neurocranium and below it we have the viscerocranium. So essentially the neurocranial portion of the skull protects the brain and the viscerocranial portion forms the face. So first let's look at the neurocranial portion of the regions of the head. These regions are named according to the underlying bones with the exception of the auricular region which we'll discuss later on.
As you can see here, the first region of the neurocranial portion that we'll talk about is the frontal region. This region is situated at the front of the head overlying the frontal bone and encompasses the area of the forehead. If we look at another illustration, we can see that the frontalis muscle now highlighted in green is also found in this region.
The next region of the head that we'll look at is the parietal region which refers to the area on either side of the head that overlies the parietal bones of the skull as you can see indicated by these arrows here. Now if we flip our skull to view it from above, we can see the parietal bones much clearer and that they're roughly square in shape.
Moving on, we can see the temporal region of the head which is also located on either side of the head but below the parietal region as shown by our arrows here. This region of the head overlies the temporal bones of the skull. And if we flip our skull to view it from below, we can see the temporal bones a bit better and how they contribute to the zygomatic arches of the skull.
The fourth region of the head is the occipital region. This region is located at the back of the head and is the region overlying the occipital bone of the skull. Note that the frontal and occipital regions of the head overlie unpaired bones of the skull in contrast to the temporal and parietal regions of the head which overlie paired bones of the skull.
Next we have the auricular region which you can see here highlighted in green. In the neurocranial portion of the head, the auricular region is the only region that's not named after the bone or bones it overlies. Instead, the auricular region refers to the region around the ears. This region includes the external ear which is composed of the auricle or pinna and the external acoustic meatus or canal.
So next let's look at the regions of the head found in the area of the face or the facial region – we call this the viscerocranial portion of the head. These regions of the head situated in the facial region are named according to the related superficial features, deep tissue formations and skeletal features.
The first region that we'll talk about is the orbital region. This region is one of five bilateral regions of the viscerocranial portion of the head, and if we remove the surrounding muscular tissue, we can see that it includes several structures. We can see the eye socket here also known as the bony orbit and the soft tissue organs within it such as the eyeball which we can see here and these muscles surrounding the eyeball which are the extraocular muscles. Other structures include the eyelids, the eyebrows and the list goes on. From our image, we can also see that the orbicularis oculi – the circular muscles you can see around the eyes highlighted in green – are also found in this region.
Moving on, we can see the infraorbital region which is also one of the bilateral regions of the face. Now if you don't know what bilateral means, it simply means that this region is paired and it's located on both sides of the face. So you have a left infraorbital region and a right infraorbital region. Now as the name suggests, this region of the face is located just inferior to the orbit.
The third of the five bilateral regions of the face is the buccal region. This is the region of the face situated above the buccinator muscle which we can see a bit clearer if I remove some surrounding soft tissues. So you can now see the buccinator muscle highlighted in green. Now that you've seen it, let's go back to our image of the buccal region which essentially refers to the area of the cheeks.
As you can see in the next image, the parotid region is the region of the face that overlies the parotid gland. If we change orientation slightly and view the face from an anterolateral aspect, we can see the parotid gland a bit more clearly. As you can see, this region is located just below the ear and is also one of the five bilateral regions of the face.
The fifth and final bilateral region of the face is the zygomatic region. This region of the face overlies the zygomatic bones and muscles and if you have a look at the image on the right, you'll see that I've roughly outlined these muscles for you. The zygomatic region is the area of the face were we find the so-called cheekbones.
Now that we've seen the bilateral regions of the face, let's look at the regions of the face situated along the midline starting with the nasal region. This region is named after the nose and as such includes it. The nasal region of the face comprises structures that are both important for breathing and olfaction.
The next region that we're going to see is the oral region of the face which refers to the area of the oral cavity. This region of course includes the oral cavity itself as well as structures such as the teeth, the tongue and the palate or the roof of your mouth.
The final median region of the face that we'll look at is the mental region. The word mental doesn’t only relate to your state of mind but also refers to structures relating to the chin. In other words, this region is basically the area of the chin. This is the region of the face that overlies the mental protuberance which we can now see highlighted in green.
So you'll be pleased to hear that we've finally covered the regions of the head both those found in the neurocranium and those found in the viscerocranium. So we can now move on to look at the regions of the neck.
The neck is divided into four regions and this division is defined by the commonly visible and/or palpable borders of two large and relatively superficially situated muscles – the sternocleidomastoid muscle and the trapezius muscle. The four regions of the neck can be further grouped into sub-regions or sub-triangles as we'll see across the next half of our tutorial.
So the first region of the neck that we'll take a look at is the anterior cervical region. The anterior cervical region of the neck also known as the anterior triangle of the neck is situated at the front of the neck, and if you take a look at our image on the right you can see that I've drawn the triangle on for you in green. This anatomical division of the neck is used in clinical anatomy to locate the structures that pass through it. The structures that from the boundaries of this region are the median line of the neck – an imaginary line which forms the anterior boundary of this triangle; the anterior border of the sternocleidomastoid muscle which forms the posterior boundary of this triangle, and the inferior border of the mandible which forms the superior boundary of this triangle.
The roof of the triangle is formed by the subcutaneous tissue of the platysma muscle while the pharynx, larynx and thyroid gland formed the floor. The apex of this triangle is located at the jugular notch of the manubrium, which is a dip in the manubrium that you can see contained within the dark gray circle on your screen. The anterior cervical region or triangle is further subdivided into four smaller triangles to allow for a more precise localization of structures. These sub-triangles are the submandibular triangle, the submental triangle, the carotid triangle and the muscular triangle. So as you can see, I've roughly outlined these triangles on top of our image so you can see how they relate to one another. But let's move on and be more specific about their locations and anatomical boundaries.
So let's look at the first of the sub-triangles of the anterior cervical region – the submandibular triangle. The submandibular triangle is also known as the digastric triangle because it's anterior and posterior boundaries are formed by the anterior and posterior bellies of the digastric muscle respectively. The superior boundary of this triangle is formed by the body of the mandible, and if we look to the right you can see that I've drawn around these structures in blue so that you can see how exactly they form these boundaries.
Now let's change our orientation slightly so that we can see the submandibular triangle from an anterolateral perspective. You should notice it towards the bottom of this image highlighted in green. This sub-triangle contains the submandibular gland which I'm pointing out now as well as lymph nodes and the facial artery and vein which pass through this area. The floor of the submandibular triangle is formed by the mylohyoid muscle, the hyoglossus muscle and the middle constrictor muscle of the pharynx. Please keep in mind that this triangle is a paired triangle meaning that there is a submandibular triangle located on either side of the midline of the neck.
The next triangle that we'll look at is the submental triangle. Unlike the sub-triangle we just looked at, the submental triangle is an unpaired triangle and it's the only unpaired triangle of the four sub triangles of the anterior cervical region. This triangle is located inferior to the chin in the suprahyoid area. It's bounded by the hyoid bone inferiorly as shown by the arrow, the anterior belly of each digastric muscle laterally, and its medial border is formed by the imaginary sagittal midline of the neck. The floor of this triangle is formed by the two mylohyoid muscles and its apex is located at the mandibular symphysis which is now contained within the dark gray circle on your skin. The submental triangle contains the submental lymph nodes which filter lymph draining from the floor of the mouth and parts of the tongue as well as small veins that unite to form the anterior jugular vein.
Next here we see the carotid triangle. This triangle is of clinical significance because the common carotid artery ascends into it. The boundaries of this triangle are formed by the posterior belly of the digastric muscle superiorly, the superior belly of the omohyoid muscle inferiorly and its lateral boundary is formed by the medial border of the sternocleidomastoid muscle. The main contents of the carotid triangle are the common carotid artery which bifurcates into the internal and external carotid arteries within this triangle, the internal jugular vein, the hypoglossal nerve or cranial nerve XII, and the vagus nerve or cranial nerve X. The carotid triangle is of particular clinical significance because the pulse of the carotid artery can be palpated in this region by compressing the artery lightly against the transverse processes of the cervical vertebrae. Also many of the vessels and nerves found in the carotid triangle are relatively superficially located and could be easily accessed during surgery.
The last of the sub-triangles of the anterior cervical region of the neck is the muscular triangle. This triangle which is also known as the omotracheal triangle is bounded superiorly by the hyoid bone and its medial boundary is formed by the imaginary sagittal midline of the neck. The superolateral border of this triangle is formed by the superior belly of the omohyoid muscle and its inferolateral border is formed by the inferior portion of the sternocleidomastoid muscle. As I'm sure you've noticed, this so-called triangle has four boundaries and that's because this region does not take on a true triangular shape but rather forms a sort of irregular one.
Another unique point about this region is that it's the only triangle of the anterior cervical region that does not contain important vessels, however, it does contain the infrahyoid muscle, the pharynx, the thyroid gland and the parathyroid glands.
So far we've looked at the anterior cervical region and the sub-triangles of this region. So next let's move on to another region of the neck – the sternocleidomastoid region. The sternocleidomastoid muscle which we can see highlighted in green on our image is a paired superficial muscle of the neck. It's a key muscular landmark as it visibly divides the neck into the anterior cervical region and the lateral cervical region. So the region between the anterior and lateral cervical regions corresponding to the area of the sternocleidomastoid muscle is the sternocleidomastoid region of the neck. This region has a further subdivision known as the lesser supraclavicular fossa.
As I just mentioned, the lesser supraclavicular fossa is a sub-region of the sternocleidomastoid region. This fossa is a superficial small triangular depression formed inferiorly where the two heads of the sternocleidomastoid muscle separate. Basically, the sternocleidomastoid is a two-headed muscle. Its sternal head attaches at the manubrium while its clavicular head attaches to the medial third of the clavicle and the space between these two heads is the lesser supraclavicular fossa.
As we just saw, the sternocleidomastoid muscle divides the neck into the anterior and lateral cervical regions. The lateral cervical region which is also known as the posterior triangle of the neck is bounded anteriorly by the posterior border of the sternocleidomastoid and its posterior border is formed by the trapezius muscle. Its inferior boundary is formed by the middle third of the clavicle between the trapezius and the sternocleidomastoid while its apex is situated superiorly where the sternocleidomastoid muscle and the trapezius muscle meet on the superior nuchal line of the occipital lobe. You can see the apex contained within the dark gray circle on your screen. The roof of this region is formed by the investing layer of the deep cervical fascia while its floor is formed by the muscles covered by the prevertebral layer of the deep cervical fascia.
The lateral cervical region can be further subdivided into two smaller regions – the occipital triangle and the omoclavicular triangle. The inferior belly of the omohyoid muscle crosses the lateral cervical region subdividing it into a superior and inferior part and this forms the two sub-triangles. If you look at our image, you can see that I've drawn around the inferior belly of the omohyoid muscle in blue.
Now the occipital triangle is the largest of the two triangles in the lateral cervical region and it's situated in the superior part of this region. This triangle is given its name due to the fact that the occipital artery appears in its apex. We can see it contained within the dark gray circle on your screen. The spinal accessory nerve, cranial nerve XI, also crosses this triangle and I've drawn it in yellow here on this our image.
So let's move on to the second triangle of the lateral cervical region. The omoclavicular triangle is the smaller and more inferiorly situated of the two triangles of the lateral cervical region. This triangle is also known as the subclavian triangle as it contains the distal portion of the subclavian artery. Also contained in this triangle is the inferior part of the external jugular vein which crosses it superficially. The subclavian artery and the external jugular vein are separated in this region by the investing layer of the deep cervical fascia. This triangle is also indicated on the surface of the neck by the supraclavicular fossa.
The final region of the neck that we'll talk about today is the posterior cervical region which corresponds to the area of the trapezius muscle posterior to its anterior borders. The main content of this triangle is of course the trapezius muscle and deep to this region is a sub-triangle known as the suboccipital triangle. So the suboccipital triangle as we just saw is situated deep to the posterior cervical region. It's bounded by three muscles namely the rectus capitis posterior major muscle, the obliquus capitis superior muscle and the obliquus capitis inferior muscle. And if you take a closer look at the image, you can see that I've drawn around these muscles in blue so you can see how they define this region.
So now that we've discussed its boundaries, let's zoom in and take a closer look at this triangle. The floor of this triangle is formed by the posterior atlantooccipital membrane and the posterior arch of the atlas. The contents of this triangle includes the third part of the vertebral artery, the dorsal ramus of the first cervical nerve C1 known as the suboccipital nerve and the suboccipital venous plexus.
So you'll be relieved to know we've now officially covered all of the regions of the head and neck but before I let you go, we should first summarize what exactly we've learned today.
So first we looked at the regions of the neurocranial portion of the head namely the frontal region which overlies the frontal bone, the parietal region which overlies the parietal bone, the temporal region which overlies the temporal bone and the occipital region which overlies the occipital bone. Lastly, we had our odd one out – the auricular region – which encompasses the area around the ear.
We then moved on to the regions of the face or the viscerocranial portion of the head where first we saw the orbital region. Below the orbital region, we saw the infraorbital region followed by the buccal region which encompasses the area of the cheeks. We then had the parotid region which of course overlies the parotid gland and the zygomatic region which overlies the cheekbones. Next, we had the nasal region which of course includes the nose, the oral region which includes the oral cavity, and the mental region or the region of the chin. We then moved on to the regions of the neck starting with the anterior cervical region which is divided into four regions – the submandibular triangle which contains the submandibular gland, the submental triangle which is the only unpaired triangle in this region, the carotid triangle which contains the carotid artery and the muscular triangle which is the only triangle in this region not to contain important vessels.
We then moved on to the second region of the neck – the sternocleidomastoid region – which of course contains the sternocleidomastoid muscle as well as a sub-region called the lesser supraclavicular fossa. The third region of the neck was the lateral cervical region which is divided into two triangles – the occipital triangle, and the one inferior to it, the omoclavicular triangle. Finally, we looked at the posterior cervical region which included the trapezius muscle and the sub-region called the suboccipital triangle.
So that brings us to the end of our tutorial on the regions of the head and neck. I hope you found it useful and thanks for watching.
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Now, good luck everyone, and I will see you next time.