Regional Anatomy of the Neck - SD

Introduction

Hello, my name is Fausto Lab Bruto.

I am a radiologist
and the chief of ultrasound at Linsky University Hospital
in Stockholm, Sweden.

Today's lecture will be about the
regional anatomy of the neck.

We will follow the classification of a neck lymph node,
the levels, and
for each neck region we will discuss the most important
and anatomical landmarks
and we will give some examples of pathology.

Finally, we'll shortly discuss the surgical procedure known
as a neck dissection.

Enjoy.

This is a lecture about regional anatomy of the neck.

I think ultrasound specialists must be familiar with
the anatomy of the neck for a better identification
and a description of a pathology.

This is especially true when it comes to staging head
and neck malignancies
because the exact position
of metastatic lymph nos has an enormous prognostic value
and is of great importance for planning of treatment,
surgical treatment or radiotherapy.

In the settings of lymph node pathology of the neck,
the most popular regional classification is the one
introduced by memorials Lung Kettering Cancer Center,
which divides the neck into six regions and sub regions.

This is classification originally
featured the seven regions.

However, the seventh region is in the upper meum
and it doesn't belong to the neck
and will not be further discussed today.

During the course of this lecture,
we will follow this regional classification as a roadmap
and for each region we will define the most important
anatomical landmarks and we will give examples of pathology.

Region 1

We start with region one,
which is actually divided into two sub regions, one A
and one B.

In order to fully grasp the anatomy of this part
of the neck, it is important to be familiar with the anatomy
of the di gastric muscle.

This muscle consists of two bellys, the posterior
and the anterior, which are connected
by an intermediate tendon.

The posterior belly originates from the mastoid process
of the temporal bone while the anterior belly attaches
to the body of the man bone.

The intermediate tendon,
which is located immediately superior to the hyoid bone,
may pass anteriorly posteriorly
or in a minority of cases through the distal part
of the stylo high muscle,
which is a muscle that extends from the tylo process
of the temporal bone to the OID bone.

Region one B, which is also known as a submandibular region,
is limited laterally
and posteriorly by the posterior belly of the di gastric
anteriorly and medially by the endor belly of the di gastric
while superiorly by the body of the mandible.

Region one A, which is also known as submental region,
is on the other hand a medial region limited laterally
by the anterior belly of the diagnostic inferiorly
by the higher bone and superiorly by the mandible region.

One is the drainage region for the lymphatics
of the lower lip, the anterior chin, the gum,
the anterior portion of the floor of mouth, the tip
of the tongue and the internal fascial structures

because of the position of the mandible,
which will cause acoustic shadows.

Imaging of this part of the neck
by ultrasound is mainly obtained by oblique axial
and oblique horal projections.

If we place our ultrasound probus shown in this picture,
we will be able to identify laterally an
axial section of the belly
of the stern labial mastoid muscle.

This is the muscle that extends from the mastoid process
of the temporal bone to the clavicle and to the manum stern.

More immediately we will see an axi section
of the posterior belly of the di gastric muscle.

Even more mely.

We will distinguish the parenchymal structure
of the submandibular salivary gland.

The vessels in between the belly of the digastric
and the submandibular salivary gland
is the anterior branch of the regimen.

Mandibular vein, if we rotate the ultrasound probe
and place it more medially as shown in this picture,
we will obtain an oblique projection of the belly
of the stylo oid muscle
and an almost cross-sectional projection
of the intermediate tendon which connect the posterior
and anterior belly of the diagnostic.

Those are a decent to the subular talari gland.

If we on the other hand, turn the ultrasound probe
to an almost axial position,
we may obtain a long image on the intermediate tendon
just co to the submandibular salivary gland.

This is the intermediate tendon
and if we turn the ultrasound probe exactly 90 degrees from
the former position on an oblique bleak sagittal projection,
we will obtain a perfect cross-sectional view
of the intermediate tendon.

Deep to the intermediate tendon.

We will see the thin mylohyoid muscle.

This is the muscle which extends from the body
of the mandible to the superior aspect of the hyoid bone
and together with the thicker genal hyoid, this muscle
forms the mus fluoro the mouth.

This shadow forming structure here is the
bone seen on Assal projection in this image,
which is obtained just slightly more
immediately to the former.

Beside the submandibular salivary gland,
we observe the intermediate tendon of the digastric, the
myelo hyoid than the genial hyoid
which are just cranial to their attachments
to the hyoid bone.

We can also see the acoustic shadow formed
by the body of the mandible.

An important thing to remember when intonating this part
of the neck is that beside visualizing the neck itself,
we enjoy a unique view of parts of the oral cavity
and even of the firings.

This is for example, a view of the posterior part
of region one B where we recognize the posterior belly
of the digastric, the submandibular salivary gland
and the genio iod
and the lateral part of the tongue together
with the soft tissues of the lateral pharynx.

On the other side we see an hypoechoic
ill-defined mass that abuts the lateral part of the tongue.

This was later shown to be a concealer cancer.

As we mentioned before, a region one A, which is also known
as cement region, is a median region.

Region one A is divided into right
and left by the middle line.

The difference between the right
and left region one is not just an academic one.

If we think for instance that localization
of a metastatic lymph node to the right
or to the left of the middle line will modify the staging
of the disease and its prognosis with ramifications on the surgical treatment
or on radiotherapy,

but probably the best way to image region one A
by ultrasound is to position that probe just below the chin
to obtain an exact coronary projection
and move the probe dorsally un coly
down to the higher end bone.

This way we will be able to identify the following pairs
of muscles, the anterior belly of the diagnostic,
the thin mylohyoid and the thicker genal od
and above them,
the centrally located the higher gloss which extends from
the oid bone to the root of the tongue
above this pair of muscles.

So we observe the tongue
and beneath it on both sides the parenchymatous structure
of the sublingual salivary glands.

If you have difficulties at identifying the tongue
or the sublingual salivary glands, just ask the patient
to move or to lift the tongue
in the image on the right hand side.

Here, the patient is holding a mint,
under the tongue on his left side, which makes the boundary
between the tongue
and the sublingual salivary gland, very distinct

and this is an example
of a pathological lymph no in region one A.

As usual in this corona projection
with the ultrasound proposition just below the chin,
we recognize the thick genal oid right beneath the tongue,
the thinner mylohyoid
and the diagnostic,
the anterior belly of the diagnostic.

This pathological lymph node in region one
A can also be appreciated on a contrast anset
CT scan and the Corona projection.

As we mentioned when we were talking about region one B,
it is important to realize that insin, this part
of the neck gives us a unique insights to anatomical regions
that are not strictly speaking parts of the neck
but are worth being familiar with, such
as the oral cavity and the tongue.

On this corona projection of region one A,
we recognize two pair of muscles, the thin mylohyoid
and the thicker genio hyoid together forming the floor
of mouth and we recognize the acoustic shadows, given
by the mountable on both sides immediately deep
to the mus floor of the mouth,
we observe the sublingual salivary glands
and centrally the rather hypoechoic hilos, which is covered
by the more echogenic mobile tongue.

And on the patient's right side, you may notice an
E defined mass which abuts the mobile tongue
and the right sublingual satellite gland.

This was later shown to be a lingual cancer.

This finding would've been very difficult to visualize.

On contrast, enhance the CT scan as we see on
this image and which is just taken
just one day later

and will be very subtle
on this magnetic resonance image of the same patient
obtained some days later.

However, it is rather obvious on ultrasound
and this just confirms us how ultrasound permits exquisite
to soft tissue differentiation and resolution.

This is yet another example of pathology
of the oral cavities.

In to ultrasound of the neck we are in region one A
as usually it is easy to recognize the symmetrical pairs
of muscle, the digastric, the mylohyoid and the gen oid
and the higher gloss as well as the mobile tongue
and in the area corresponding
to the sublingual salivary gland.

On the patient's right side, we observe an
koic rounded mass, which was later shown to be a hemo
of the saliva gland compared the contrast,
the CT image of the same patient.

Other reasons for asymmetry in the floor
of the mouth include iatrogenic causes

and this particular patient the difference in echogenicity
between the left
and the right side just deep to the mylohyoid muscle,
is due to the fact that this patient has undergone
hemi glossectomy,
which is the surgical removal of half of the tongue.

In this case, the right half
and the removed muscle is replaced by fatty tissue.

The higher gloss can only be identified on the left side
and these changes can be appreciated.

On the air. Comparing contrast CT image, we go
to region two.

Region 2

Lymph nodes in this region are known
as upper jugular lymph nodes or level two lymph nodes.

This is the region most frequently involved
by cervical lymph node metastasis tumors
of the oropharynx posterior oral cavity.

Supraglottic larynx
or a paric gland can metastasize initially to this region.

Carcinomas of the hypopharynx glottis
and anterior oral cavity are also frequently mes decided
to level to lymph nodes.

This region of the neck is limited superiorly
by the scalp base and inferiorly
by a transverse line passing through the higher bone

and mely by the medial border of the internal car artery
and laterally by the mar lateral margin of the belly
of the sternal mastoid muscle.

In the uppermost two centimeters of this region.

Lymph nodes may be located anteriorly,
posteriorly or laterally to the internal ular vein
but not medially because if they are located medially,
they actually are located in the paranal space,
which is a space of the SRA hyoid neck
and falls outside of this calcification from two centimeters
below the skull base down to the level of the hyoid bone.

However, lymph nodes can in differently be located
anteriorly, laterally, posteriorly
or medially to internal jaguar vein.

Here is an image of region two on the axial projection.

The flat bend like master structure located superficially is
the belly of the sternal cla mastoid.

The vascular structures located the
beneath are readily recognizable as the round pulsating
and non-compressible internal carotid artery
and the larger more flat
and more compressible internal jugular vein.

In this image you may recognize two normal lymph nodes
located the medially
and laterally to the internal jugular vein.

Level two lymph nodes that are located posteriorly
to the internal jugular vein may be a decent tweet
or separated from it by a thin layer of fat.

In the latter case, lymph nodes are described
as a level two B lymph nodes.

Region 3

We move on to region three.

Lymph nodes in this region are known
as mid jugular lymph nodes or level three lymph nodes.

This region is the first to relay for a hypo pharyngeal
glottic and subglottic carcinomas.

Region three is limited superiorly
by a transverse line passing through the OD bone
and inferiorly by a transverse line passing
through the crico cartilage mely by the medial margin
of video, the internal or the common car artery
and laterally by the lateral margin of the sternomastoid.

As you can see, on this axial CT scan,
this is what an axial ultrasound scan
through region three will look like.

On the bottom of the image you will recognize the vertebral
body of the cervical spine
with the corresponding vertebral artery.

The largest neck vessels are as well
as the stern CLE mastoid are usually read readily
recognizable and immediately
at this level you will be able
to identify the perus structure of the thyroid.

Other important muscles in this region are the SC anterior
which extends from the cervical spine to the first rib
and the long coli, which is situated deep in the neck,
just anterior to cervical spine from which it originates
and to which it attaches.

This is an example of pathologic lymph in region three.

As shown before, the most important landmarks such
as the large vessels
and the steroid mastoid are readily
recognizable laterally.

We can still see SC anterior
but also more laterally to with the scousers,
which too extends from the cervical spine to the first rib

and in the middle of the figure on enlarged central necrotic
lymph node, which was later shown to be metastasis
of squamous cell cancer of the hypo hearings compared
to the axial CT image on the same area in this particular
patient, further down in same region almost at the border
with more caliber region four

and always keeping yourself
so on an axi projection you may observe a very thin muscle
which runs from the middle line to the side

and as opposed
to all the other muscles which are rather more
vertical in their orientation.

This muscle is the homo oid,
which is circulating green here

and there is a, it is an interesting muscle which we will
also encounter when we'll discuss region five.

Similarly to the diagnostic, this muscle consists
of two belly, the superior
and the inferior, which are connected
by an intermediate tendon.

The omo higher extends from the higher bone to the scapula.

You can see it in this axial CT scan as well.

By turning the ultrasound probe 90 degrees,
we'll obtain an oblique sagittal view of the homo ide
as it passes transversly between the internal jugular vein
and the stern CLE mastoid, we carry on to region four.

Region 4

Lymph nodes in this region are known as
lower jugular lymph nos, so level four,
level four lymph nodes D drain the infraglottic region
of the thyroid gland
and the cervical esophagus carcinomas of the anterior tongue
and the non cervical tumors such
as the non cervical esophagus, lung, or breast
and stomach may also occasionally metastasize.

The region for this region is still limited superiorly
by a transverse line passing through the crico cartilage
and inferiorly by the clavicle

and mely by the medial margin of the common carotid artery
and laterally by the lateral margin
of the standard CLA mastoid.

As we can see on this axi CT scan,
this is a view of a region four on axial projection

between the common carotid artery
and the internal jugular vein.

It is possible to make out the outline of the various nerve.

The fatty area comprises between the neurovascular bundle,
the sternomastoid,
and the SC anterior, is the part of region four
where lymph nodes are usually located

and this is an example of a large
pathologic lymph node In region four as usually we
identify the caral artery, the thyroid,
and the stern Cleo mastoid.

The muscle which runs superficially
to the thyroid is the stern hyoid,
which extends from the hyoid bone to the rine stern

and the internal jugular vein is pressed
by this metastatic lymph node.

As we can also seen on the corresponding CT scan,

by turning the ultrasound probe 90 degrees,
we obtain an oblique coronary view of this region
and same patient, the pathologic lymph node is seen
immediately superior to the clavicle,
but deep to the stern CLEO mastoid
and deep to the internal jaguar vein.

The shadows on the lower part of the C image are caused
by the transverse processes of the vertebral
of the cervical spine

and we can also observe the
SC anterior muscle.

This is another typical feature of region four.

Following the SC anterior more coly consistently you will
observe an artery riding over its belly.

This is, the transverse cervical artery
and is a branch of the th glossary trunk which originates
from the subin artery.

In this view, we also recognize the omohyoid muscle
crossing the neck in between the internal jugular vein
and the sternomastoid.

Just as we saw when we were discussing region three,
this is the SC of anterior

Region 5

and in region five we observe what corresponds to
the area that surgeons like to call the posterior triangle
of the neck and includes includes both the spinal accessory
and transverse cervical lymph node chains.

Solidary lymph node metastasis are infrequent in this level,
accepting case of a nasopharyngeal cancer
and the posterior neck skin cancer.

In contrast level five nodes are
commonly involved in lymphoma.

Region five has a triangular shape
and this limited anteriorly by the lateral margin
of the stern cle cla mastoid
and posteriorly by the anterior margin
of the trapezius muscle, which is the muscle
that extends from the ular bone and the cervical
and thoracic spine down to the scapula.

As you can see from this, axial EM image
and regions five is actually,
subdivided in two sub regions, five a superior
to a transverse line passing
through the cri cartilage in region five B,
which is inferior to the same line.

This is a transverse, section of region five B.

We recognize the thyroid, the BA bundle,
the stern Cleo mastoid that the Linus anterior the omohyoid
and the sternal hyoid muscles

and laterally the traum.

The anterior limit of this region is represented
by an oblique line touching the lateral margin
of the stern Cleo mastoid

and the lateral margin of the sc anterior.

The posterior limit is represented
by a transverse line touching the anterior margin
of the trapezium.

If you have troubles that identifying the trapezium thing,
think about it as the most lateral of the muscles
of the neck and remember
that it always has a pointy medial margin, which you can
also appreciate on this
axial MR scan.

The muscle that lies immediately to it is the lator scapula,
which extends from the cervical spine to the scapula.

This muscle is usually easy to recognize thanks to its
concave shaped medial margin
where the concavity sort of, accommodates
the lateral margin of the SCS medias.

You can appreciate this same, concavity on this axi MR scan

and the muscle that lies deep to
all the mentioned muscles is the pleio coli,
which is the muscle which originates in the cervical spine
and attaches to the thoracic spine.

So for instance, in this particular patient we identify a superficial lymph
node on the lateral neck.

We notice it, as laying between the lateral margin
of the stern lato mastoid
and the medial margin of the trois.

And this, is a level five lymph node
beneath it with we will recognize from medial
to lateral thecal, anterior thecal medias
and the lero scapula with its peculiar
concave medial margin.

When scanning region five on an axial projection,
we will encounter a thin muscle
that runs almost transversely as opposed
to all other muscle running a more
or less craniocaudal direction.

This muscle is the omohyoid,
which we have seen crossing region three passing
below the stern Cleo mastoid
and now we see it continuing
through region five on its way to the scapula.

This is the stern Cleo Mastoid.

This is the external jugular vein and internal jugular vein
and this is the transversally oriented omohyoid.

These surgeons like to divide the posterior triangle
of the neck into a superior and an inferior part

and they use the omohyoid the muscle
as line dividing the two triangles.

As you can see from this image, while the jugular,
the internal jugular vein passes deep to the Omaha muscle,
the external jugular vein passes superficial to it.

This can also be appreciated.

On the corresponding CT scan we move on
to region six, which similarly
to region one A is a median region which is divided into
left and right by the middle line.

Region 6

This region is limited, superiorly
by the higher bone

and inferiorly by the manubrium sterne
and laterally on both sides by the medial margin
of the either the common or the internal caral artery.

As we can see from this, exhale CT scan at the level
of the larynx, lymph nodes in this region drain at the
supra and infraglottic regions, the perfor sinuses,
the thyroid gland, and the sags.

The most co speaker
structures in this part of the neck card.

The thyroid gland, the thyroid gland
and the parathyroid gland have
however been sufficiently discussed in other lectures
and we will not dwell upon them any longer today.

This is a STO scan.

Just immediately off the midline
we will see two large areas of shadows caused
by air in the larynx, superiorly
and the air In the traia inferiorly.

You may recognize the tra rings causing shadow
artifacts as well.

Similarly, because of the shadows that they project,
you will be able to identify the hyoid bone superiorly
and the thyroid cartilage inferiorly.

More superficially you will notice muscles extending from
the OD bone to the thyroid cartilage, which is the
hyoid muscle and extending from the
thyroid cartilage down to the sternum,
the sternal thyroid muscle.

If we look more on the detail,
we will obtain a precise view of the muscles attaching
to the od bone superiorly, the genial hyoid
and the mylohyoid

and inferiorly, the thyrohyoid
and the sternal oid, which is more superficial.

As you can see from the compounding MR image, the resolution
of ultrasound lows for a far more the type view
of the anatomy of this part of the body.

A typical pathology of this part of the neck is
theor gloss duct cyst.

This is an image of, sagittal image of a normal
hyoid bone with the muscle attachments.

This is the hyoid bone
and the muscle attachments are
superiorly the genal hyoid and malo ide
and inferiorly, the stern ide and the thyroid ide.

And this is an acomp comparing MR image

and this is an image of al
neck with a thyroglossal duct assist in the middle.

The OID bone and the muscles are the same as in the,
comparing a case

and the hypoechoic mass located just
beneath the OID bone is a thyroid loss of duct cyst.

Surgery for removal of this kind of cysts,
often include the surgical removal of the body
of the OD bone, and this is an example of an image
after the removal of the body of the OD bone, the
normal shadow given by the body of the OD bone is gone

and this area is replaced by a scar tissue.

Neck Dissection

We will now briefly discuss the surgical procedure known
as a neck dissection,
which is aimed at controlling the neck lymph
node metastasis.

This technique was first described at the beginning
of the last century by surgeons of the Cleveland Clinic

and it originally featured that the surgical removal
of all the lymph nodes on the side
of the neck affected by the malignancy.

That is, all the lymph nodes from level one
to level five together with the spinal accessory nerve,
the internal jagar vein and the sternal mastoid muscle.

The reason for removing the structure sees that
this structures are intimately connected
to the lymph node chains

and according to the American Academy of Otolaryngology
and the head and neck surgery, this version
of the procedure is defined as a radical neck dissection.

However, there exists, today less demo variance
of this procedure.

We see them listed here.

The modified radical neck dissection is procedure
that includes the removal
of all lips later lymph nodes in region one to five,
but the preservation of one
or more non lymphatic structures.

The selective neck dissection, which is a technique
of cervical lymphoadenopathy with preservation of one
or more lymph node groups
that are routinely removed in removed in
radical neck dissection.

That's for instance for oral ctic cancers, a lymphadenectomy
of region one to three, for oropharyngeal,
hypo pharyngeal and al cancer cell lymphadenectomy
of regions two to four

and in some cases the surgeon will want
to extend the area of resection

and for example to lymph no stations.

So the contralateral side
and this is defined as extended the neck dissection

and this is what, a
axial ultrasound scan looks like on a patient
who has undergone radical neck dissection.

As you can see, the stern Cleo mastoid
and the internal jugular vein,
which are readly identifiable on, the right hand side,
cannot be identified on the left side.

They are surgically removed.

There is also some scar tissue,
which is common in a patient,
who have undergone this kind of operations

and this could also be appreciated on the
corresponding CT scan.

And ultrasound has a major role in the follow up of patients
who have undergone neck dissection, with the purpose
of ruling out relapsing disease.

Any lymph node identified in a region
where a lymphadenectomy was performed regardless of the size
of the lymph node should be suspected of relapsing disease
and should be further examined, for example, with a biopsy.

Conclusion

Well, this concludes our lecture
on regional anatomy of the neck.

I hope you enjoyed it and I wish you a good day.