A practical way to begin to evaluate cervical pathologies is to divide the neck in its different fascias.
The neck has 2 layers of fascia,
the superficial and deep layers.
The superficial cervical fascia is a thin layer that contains adipose and connective tissue,
it lies between the dermis of the skin and the deep cervical fascia and contain muscles like the platysma,
nerves,
blood vassels and lymphatics channels.
The deep cervical fascia (fascia colli),
is divided into three layers: superficial layer,
middle layer and deep layer. Fig. 1 Fig. 2
-The superficial layer.
It lies between the superficial cervical fascia and the muscles of the neck.
It goes from the base of the skull to clavicula,
acromion and sternum.
It includes the muscles sternocleidomastoid,
trapezius and parotid gland.
-The middle layer.
It extends from the skull base superiorly to the mediastinum inferiorly.
It is divided into the muscular division and visceral divisions.
- The muscular division contains the strap muscles,
the sternohyoid,
sternothyroid,
omohyoid,
and thyrohyoid,
then it forms a pulley to the intermediate tendon of the digastrics muscles.
- The visceral division (buccopharyngeal in the suprahyoid neck) encloses the visceral structures: the pharynx,
larynx,
esophagus,
trachea,
thyroid and parathyroid glands,
periesophageal lymph nodes and the recurrent laryngeal nerve.
-The deep layer.
It wraps the deep muscles of the neck and the cervical vertebrae.
It extends from skull base into the mediastinum.
- The alar layer forms the posterior and lateral walls of the retropharyngeal space and the transverse processes of the vertebrae.
- The prevertebral layer encloses and surround the paraspinal muscles and other structures like the longus colli and longus capitis muscles,
the anterior,
middle,
and posterior scalene muscles,
the brachial plexus trunks,
phrenic nerve,
cervical plexus,
vertebral artery and vein.
Neck Spaces
The cervical spaces are divided into supra and infrahyiod.
The suprahyoid neck spaces include the sublingual space,
submandibular space,
peritonsillar space,
parapharyngeal space,
pharyngeal mucosal space,
masticator space,
parotid space,
carotid space,
retropharyngeal space,
danger space,
and perivertebral space.
The infrahyoid neck spaces include the visceral space,
but the masticatory space,
parapharyngeal space and parotid space are no longer present.
The carotid space,
retropharyngeal space,
danger space,
and perivertebral space encompass the suprahyoid and infrahyoid compartments.
The content of each space and its anatomical relationships are detailed in Table 1 and 2. Table 1 Table 2
There are two other spaces:
- Anterior cervical space: a small space in the anterolateral neck.
It is not surrounded by fascia and only contains fat.
- Posterior cervical space: this space is posterolateral to the carotid space and lateral to the paraspinal space.
It contains fat,
spinal accessory nerve and spinal accessory chain of cervical lymph nodes.
My LCD
An easy way to remember what to look for when evaluating a neck study is to evaluate My LCD:
- First,
think in the “Mirror”: Is there symmetry? First,
we must look for asymmetries and then evaluate their location.
- Second,
try to find the right “Location”: Where I am? The neck has a supra and infrahyoid space,
in turn these are divided into other spaces,
some contained in both.
- Third,
try to remember the “Content”: What do you have? The different cervical spaces have different content.
Knowing what we can find we can know what to look for.
- Fourth,
the “Displacement” of different structures: Tell me where you are going,
and I will tell you who you are.
The different cervical lesions tend to distend the cervical spaces and secondarily compress or displace other adjacent spaces.
Considering the above there are some points to keep in mind:
- The parapharyngeal space: this space content FAT.
Remembering their anatomical relationships is fundamental,
since the displacement of this space can orient us on the origin of the pathology.
- The masticator space: This space contains the branch CNV3 which communicates intracranially through the foramen ovale and pterygopalatine fossa,
and then Meckel’s cave.
Therefore,
it is a way of dissemination of neural-perineural tumors.
And,
very important: sarcomas lives in this spaces
- The parotid space: This space contains the CNV7,
a way of dissemination of perineural tumors.
It is also a nodal station.
- The carotid Space: Its importance is that it contains the carotid artery and CN 9 to 12.
It is a nodal station for Squamous Cell Carcinoma.
- The sublingual space: it has no fascial margins,
so the two sides communicate anteriorly through an isthmus.
- The pharyngeal Mucosal Space: it has no fascial boundary.
It is connected to the parapharyngeal space and retropharyngeal space.
- The danger space: it has potential for fast spread of infection to the posterior mediastinum.
- The carotid space: it is enclosed by the carotid sheath and it is a route of travel of infection or malignancy from the neck into the mediastinum.
Therefore,
considering the normal anatomy,
the content of each space and its probable route of dissemination we can better guide our diagnosis,
considering and remembering My LCD. Table 3
Let's see some cases.