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Head and Neck 09 -- Infrahyoid neck


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What is the main divider of the infrahyoid neck?
The sternocleidomastoid
What does the SCM divide the neck into?
Two large triangles
What are these two large triangles?
The anterior and posterior triangles
How many subtriangles are in the anterior triangle
What are these subtriangles?
1) Carotid

2) Muscular

3) Submental

4) Submandibular
How many subtriangles are in the posterior triangle?
1) Occipital

2) Subclavian
What is in the anterior triangle?
Everything anteromedial to the SCM.
What are its compartments?
Suprahyoid and infrahyoid
What subtriangles constitute the suprahyoid compartment of the anterior triangle?
The submental and submandibular.
How are these subtriangles divided?
By the anterior belly of the digastric.
Where is the submental triangle?
Medial to the anterior belly of the diagstric, to the midline. The two submental triangles just sit right next to each other making one midline space.

Its posterior extent is the hyoid.
Where is the submandibular triangle?
Lateral to the anterior belly of the digastric, bounded posterolaterally by the posterior belly of the digastric, and anterolaterally by the body of the mandible.
What subtriangles constitute the infrahyoid compartment of the anterior triangle?
Muscular and carotid
What divides these subtriangles?
Superior belly of the omohyoid.
What is the more midline subtriangle?
What are the boundaries of the muscular triangle?

Superior belly of omohyoid
What are the boundaries of the muscular triangle?

What are the boundaries of the muscular triangle?

No medial boundary. These triangles meet in the midline
What are contents of the muscular triangle
Infrahyoid strap muscles

Hypopharynx and larynx




Recurrent larnyngeal n.
What is the cross sectional space that correlates with the anatomic muscular triangle?
Visceral space
Which is the more lateral triangle?
What are the boundaries of the carotid triangle?

Superior belly of omohyoid
What are the boundaries of the carotid triangle?

What are the boundaries of the carotid triangle?

Posterior belly of digastric
So, then what is directly above carotid triangle?
Submandibular triangle
What are contents of carotid triangle?
Carotid artery (Common)

Int. Jugular

Vagus nerve (CN X)

Cervical sympathetic trunk

Lymph nodes
Which lymph nodes
Deep cervical
What are the deep cervical nodes also called?
Internal jugular nodes
What is the infrahyoid neck space that the carotid triangle represents?
Carotid space
What is the location of the posterior triangle?
Posterolateral to SCM

Anteromedial to trapezius

Superior to clavicle

Apex at mastoid
What divides the posterior triangle into two different subtriangles?
The inferior belly of the omohyoid
What is the much larger and superior subtriangle?
What are the contents of the occipital triangle?
Spinal accessory nerve (XI)

Dorsal scapular nerves

Transverse cervical vessels

Spinal accessory lymph nodes
What is the cross sectional imaging space counterpart to the occipital triangle?
Posterior cervical space
What is the tiny triangle below the inferior belly of omohyoid
What are the contents of the subclavian triangle?
3rd portion of subclavian artery

Transverse cervical vessels

Cervical portion of brachial plexus
What is the cross sectional imaging space counterpart to the subclavian triangle?
Lower portion of the posterior cervical space
What do the deep layers of deep cervical fascia look like on imaging?
Not visible directly
What layers of deep cervical fascia are there in the infrahyoid neck
Superficial, middle, and deep, just like in suprahyoid neck
What does the superficial (investing) layer of deep cervical fascia do?
It envelops the entire head and neck, skull base to clavicles.
The superficial layer splits to enclose three spaces in the suprahyoid neck. What are they?


What does it do in suprahyoid neck?
Encircles neck completely
What does the middle layer of deep cervical fascia do in the infrahyoid neck?
Encircles the viscera of the neck
What does viscera include?




Recurrent laryngeals

Paratracheal nodes
What does the deep layer do?
Circumscribes and defines the perivertebral space
How many major spaces are there in the infrahyoid neck?
1) Perivertebral

2) Posterior cervical

3) Retropharyngeal

4) Carotid

5) Visceral
What is special about the visceral space?
It is the only one that is not also present in the suprahyoid neck
How should all of these spaces of the infrahyoid neck be viewed, for best conceptual understanding of their structure?
As tubes of circumscribed tissue
What are the major areas of the visceral space?
1) Laryngeal

2) Esophageal

3) Thyroid

4) Parathyroid
What is the appearance of thyroid lesions? What happens to the carotid space?
Displaced laterally
What happens to the trachea and esophagus?
Displaced to contralateral side
How are parathyroid lesions recognized?
Displace the thyroid anteriorly
What else do they do?
Displace longus colli posteriorly
What do they do if large?
Displace carotid space laterally
What should be remembered about parathyroid lesions?
Can be in ectopic locations
What are the ectopic locations?
1) Intrathyroid

2) In neck, from hyoid to carina
What do esophageal masses normally do to trachea?
Bow it forward
What are the first studies obtained in evaluation of suspected thyroid mass?
Ultrasound and nuclear imaging
When are CT or MRI ordered?
When questions of deep tissue extent of a lesion are asked
What CT/MRI features are suggestive of a benign thyroid lesion?
None. Cannot rule out malignancy.
What findings are consistent with malignancy?
Nodal tumor

Cartilaginous or bony destruction
What nerve malfunction is suggestive of thyroid malignancy?
What is the appearance of colloid cyst of thyroid?
Unilocular cyst
What is the differential diagnosis of this lesion?
Cannot be differentiated from either goiter or carcinoma that has undergone cystic degeneration.
What are types of goiter on non-functional imaging?
Multinodular or diffuse
What is appearance of goiter?
Well circumscribed mass involving both thyroid lobes
Where does goiter often go?
What suggests goiter versus malignancy?
Complete involvement of both lobes

Circumscribed borders
How is benign versus malignant thyroid disease evaluated?
Functional nuclear imaging. If equivocal, FNA.
What is a benign tumor of the thyroid?
What is appearance?

Well circumscribed

1-4 cm
What may it contain?
What is diferential for this appearance?
How will it appear on nucs imaging?
Cold focus
How is diagnosis made?
Are calcifications more consistent with benign or malignant thyroid disease?
Not helpful in differentiating
What are the types of thyroid carcinoma?
1) Papillary

2) Follicular

3) Medullary

4) Anaplastic
What is the recommended exam for presurgical evaluation?
When can CT be used?
Metastatic tumor comes up the thoracic duct
What is crucial in imaging of a patient with possible thryoid CA?
Any cystic neck mass should be suspected a CYSTIC THYROID NODAL METASTASIS
What is another malignancy of the thyroid not previously mentioned?
How common is this?
A typical extranodal, extralymphatic site for NHL
What is the presentation/imaging of thyroid NHL similar to?
Anaplastic thyroid CA
How is suspected parathyroid adenoma worked up?
Read a nucs book
Where is the paraesophageal/paratracheal nodal chain?
Runs along lateral esophagus into the mediastinum
What is the most common tumor to follow this nodal path into the mediastinum?
Thyroid CA
What about SCCa?
Does not follow this path
How far should a scan looking for thyroid nodal mets be continued?
To the arch
How far for SCCa?
Can stop at the cervicothoracic junction.
How commonly does SCCa involve the mediastinum?
How commonly does thyroid CA involve the mediastinum?
When is abscess of the visceral space seen?
1) Penatrating trauma

2) Superinfection of hematoma
What are examples of penetrating trauma of visceral space?
Rupture of esophagus
What is sudden onset of pain and swelling in thyroid?
Acute thyroiditis
What is most common etiology
What is nontender thyroid enlargement with low TSH?
Subacute thyroiditis
What is other name?
What are additional lesions of the carotid space in the infrahyoid neck?
1) Infrahyoid second branchial cleft cyst

2) Lesions of the deep cervical chain of nodes (also present in suprahyoid CS, though)
What is appearance of infrahyoid second branchial cleft cyst?
Cystic tubular mass along anterior border of common carotid
What is the differential diagnosis of this appearance?
Cystic metastases
When suspicious nodes of the upper deep cervical chain are seen, without a primary site, what is done?
Search for common SCCa sites
When suspicious nodes of the lower deep cervical chain are seen, without a primary site, what is done?
Search for primary tumor in the

1) thyroid

2) thorax

3) abdomen
How do you know these are not SCCa nodes?
SCCa nodes, as a rule, do not skip. If nodes in upper neck are not involved, but ones in lower neck are, its not from SCCa.
What is the most frequently involved neck node with abdominal tumor?
Left supraclavicular
What is appearance of NHL nodes?
Large non-necrotic nodes

Usually bilateral
When are they necrotic?
Aggressive NHL

Treated NHL
Who gets aggressive NHL?
AIDS related
How is a mass diagnosed as being in the posterior cervical space?
1) Center of lesion in fat of PCS

2) At least a strip of fat must separate the mass from the carotid artery/jugular complex anteriorly
Where does this second criteria become more important?
At the apex of the PCS, where the CS and PCS come close together
What if no fat can be seen?
Better to err on side of caution, and place leions within the carotid space
What are common lesions of Posterior cervical space (not including subclavian triangle region)?
1) Cystic hygroma

2) Lipoma

3) Nodal lesions (inflammation, mets, NHL)
Who gets PCS cystic hygromas?
Where else to they get cystic hygromas?
Where are larger lipomas of the head and neck found?
Always in PCS
What is the nodal chain of the PCS (occipital triangle)?
Posterior cervical chain
Where does this run?
Inferiorly, along the spinal accessory nerve
What part of the PCS are the spinal roots in?

Spinal roots are in the perivertebral space, not the posterior cervical space
What are the differences in pathology of the infrahyoid retropharyngeal space?
NO LYMPH NODES, so all related pathology is out
What is the difference in pathology of the perivertebral space in the infahyoid neck?
1) An extra pseudomass

2) The brachial plexus
What is the extra pseudomass?
Subclavian artery pseudomass
What is seen?
An enhancing mass passing between the anterior and middle scalene muscles
What is it?
The subclavian artery. Dont forget that the brachial plexus is not the only thing passing between the scalenes
What are lesions of the brachial plexus?
1) Root avulsion

2) Benign tumor

3) Malignant tumor
What is the appearance of root avulsion?
Can happen in any root, not just those associated with brachial plexus.

See contrast extravasation through the avulsed root on myelography
What is a disease of the head and neck that involves multiple contiguous spaces called?
What are the broad categories of transspatial lesions?
1) Developmental

2) Infectious

3) Benign tumors

4) Malignant tumors
What are examples of typically transspatial developmental lesions?
1) Cystic hygroma

2) Hemangioma

3) Thyroglossal duct cyst

4) Branchial cleft cyst
What are examples of typically transspatial infectious lesions?
1) Abscess

2) Diving ranula
What are examples of typically transspatial benign tumors?
1) Lipoma

2) Nerve sheath tumors

3) Juvenile angiofibroma
What are examples of typically transspatial malignant tumors?



Any lesion if vicious enough
What is a disease of the head and neck that involves multiple noncontiguous spaces called?
What are categories of multispatial disease?
1) Nodal, infectious disease

2) Nodal, noninfectious

3) Non-nodal disease
Examples of that?
Reactive adenopathy




Cat scratch
What are examples of nodal, noninfectious?

Malignant adenopathy

What are examples of non-nodal disease?

Non-nodal mets

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