The Deep Fascia of the Head and Neck Revisited: Relationship with the Facial Nerve

This article1 proposes a different way of conceptualizing the fascia of the entire face and neck. The central idea is that many structures we usually learn as separate sheets—masseteric fascia, parotid capsule, deep temporal fascia, deep cervical fascia, deep fat compartments, etc.—should instead be understood as regional condensations, separations, or specializations of one continuous three-dimensional deep fascial layer.

I have based the summary below on the article itself, including its histology, plastination and dissection figures. I will distinguish the authors’ proposed anatomical model from traditional terminology, because this distinction is crucial.

1. The paper in simple terms

What question were the authors trying to answer?

Traditionally, surgeons often conceptualize the face as:

skin → subcutaneous fat → SMAS/platysma → “deep plane/spaces” → deep fascia → muscles/bone/glands

and facial nerve branches are commonly said to run deep to the deep fascia.

The authors questioned both ideas.

They specifically wanted to determine:

  1. What actually constitutes the “deep fascia” of the face and neck?
  2. Is the so-called deep fat a separate layer superficial to the deep fascia?
  3. Is the so-called layer 4/deep plane a true anatomical layer?
  4. Where exactly are the facial nerve branches relative to this fascia?

Their conclusion is essentially:

Deep fascia is not one thin sheet. It is a three-dimensional multilamellar fibrofatty connective-tissue layer, and the facial nerve branches travel within it.

The authors describe the layer as thin where little space exists and thick/fatty where there is more space.

2. Methods — simplified

They studied 50 cadavers in total, using several complementary methods rather than relying only on ordinary gross dissection.

Phase 1: feasibility study — 21 cadavers

They performed:

  • layered anatomical dissections,
  • surgical face-lift/deep-plane dissections,
  • band-saw macrosections of the head and neck in different planes.

This was essentially exploratory work to understand what they should subsequently examine systematically.

Phase 2: definitive standardized dissections — 29 cadavers

A subset underwent standardized layered dissections.

Importantly, the two sides were approached differently:

  • one side underwent a surgical deep-plane facelift dissection, reproducing what a surgeon actually sees;
  • the contralateral side underwent sharp layer-by-layer anatomical dissection.

That is an important strength of the study because it allowed them to compare the surgical plane with the actual anatomical layers.

Additional objective confirmation

They then used two especially useful techniques.

Histology: 73 full-thickness samples from 11 fresh cadavers.

Sheet plastination: 10 fresh cadaver heads/neck specimens cut in axial, sagittal and coronal planes.

In sheet plastination, water and fat are removed and the tissue slices are impregnated with epoxy resin, allowing connective tissue architecture to remain visible.

So the conclusions were based on a combination of:

surgical dissection + meticulous anatomical dissection + full-thickness histology + three-dimensional sectional anatomy.

That combination is one reason I think this paper is considerably more convincing than studies relying on one dissection technique alone.

3. Major findings — simple version

There are about seven ideas worth remembering.

1. “Deep fascia” is not simply a thin white sheet

Instead it is a multilamellar fibrofatty layer filling the space between the superficial fascia/mimetic muscles and deeper structures such as:

  • bone,
  • muscles of mastication,
  • salivary glands,
  • viscera,
  • vessels.

It consists of multiple roughly horizontally oriented connective-tissue sheets separated to varying degrees by fat/areolar tissue.

Histologically they even found numerous lamellae—up to 18 sheets in one neck specimen—and describe the appearance as “mille-feuille” architecture.

2. The deep fascia changes thickness rather than beginning and ending repeatedly

Where the underlying surface is relatively convex, the fascia is thin.

Examples:

  • cranium,
  • upper temple,
  • lower masseter,
  • SCM,
  • submandibular gland,
  • especially over the parotid.

Where the underlying anatomy creates a concavity or larger volume, it becomes thicker and more fatty.

Examples:

  • lower temple → upper masseter,
  • anterior midcheek,
  • anterior cervical triangle.

Those thicker parts correspond largely to what have previously been called deep fat compartments.

This is one of the key conceptual changes:

thin deep fascia → thick fibrofatty deep fascia → thin fascia again

rather than

fascia → separate fat compartment → another fascia.

3. Deep fat is part of deep fascia

The authors could not identify a clean anatomical boundary between “deep fat” and “deep fascia.”

Instead, connective-tissue lamellae diverge and become separated by fat in thicker regions.

Thus:

deep fat compartments = fatty portions of the deep fascia

rather than a completely independent anatomical layer.

There is one important exception:

Buccal fat pad ≠ deep fascia.

The buccal fat pad is morphologically different—more amorphous, yellow and pliable, with relatively little fibrous connective tissue—and is considered a separate structure.

That distinction is quite relevant in OMFS.

4. The traditional “layer 4” does not exist as an independent anatomical layer

Traditionally:

3 = SMAS
4 = spaces / loose areolar tissue / deep plane
5 = deep fascia

The authors propose instead:

3 = superficial fascia/mimetic muscles

then immediately:

deep fascia, whose superficial portion contains natural loose areolar interfaces that can be surgically opened.

Therefore, what surgeons call layer 4 is actually:

a potential surgical plane within the superficial part of the deep fascia,

not an independent anatomical layer.

This point is fundamental for understanding the whole article.

5. Named fasciae are regional manifestations of the same deep fascial system

When the multiple fascial lamellae converge tightly, they form recognizable thin structures such as:

  • masseter fascia,
  • SCM fascia,
  • periosteum,
  • gland capsule,
  • carotid sheath.

Where the lamellae spread apart, fat fills between them and they form structures called:

  • subplatysmal fat,
  • interdigastric fat,
  • deep cheek fat, etc.

The authors therefore argue that these are not completely independent structures.

The same connective-tissue network even extends into organs, becoming:

  • perimysium within muscle,
  • connective septa/capsula propria within salivary glands.

6. Facial nerve branches run within the deep fascia

This may be the most clinically important finding.

They found:

No facial nerve branch lying simply deep to the entire deep-fascial layer.

After exiting the parotid, the nerves initially occupy a deeper position within the deep fascia.

As they travel anteriorly, they progressively migrate superficially through the thickness of the fascia.

Near their target mimetic muscles they may lie in the most superficial portion of the deep fascia, immediately underneath those muscles.

So think:

not

fascia
———
facial nerve

but rather:

superficial fascia / muscle
deep fascia

  • superficial lamellae
  • nerve
  • deeper lamellae
    underlying muscle/bone/gland.

And its depth within that layer changes along its course.

7. Therefore “seeing fascia underneath you” does NOT guarantee that the nerve is protected

This is the surgical consequence.

Because both fascia above and below the nerve may look fibrofatty, entering too deeply into the deep fascia can put the nerve above your dissection even though the floor still looks like perfectly normal fascia.

Hence the authors recommend maintaining the dissection at the very superficial aspect of the deep fascia, immediately under platysma/SMAS.

4. Now the fascia layers in detail

I think the easiest way for an OMFS surgeon to internalize the paper is to forget the usual named structures temporarily and start from the outside inward.

Layer 1 — Skin

Nothing controversial here.

Then comes the subcutaneous superficial fascial system.

Layer 2 + Layer 3 = Superficial fascia

This nomenclature is important.

The authors use the classical anatomical idea that the superficial fascia includes the subcutaneous layer together with the mimetic muscular system.

The deepest component of this superficial fascia is therefore the mimetic muscle layer.

In conventional surgical terminology this roughly corresponds to:

subcutaneous fat + SMAS/platysma complex.

The paper emphasizes that the mimetic muscles separate:

superficial/subcutaneous fat

from

deep fascia/deep fat.

The “SMAS” — an important correction

The traditional illustration suggests that SMAS is a continuous aponeurotic sheet.

The authors explicitly challenge that interpretation.

They regard the genuine anatomical layer as primarily represented by the mimetic muscles rather than a uniform, uninterrupted aponeurosis extending everywhere.

On page 2/Figure 1 they state that SMAS is not a complete anatomical layer: the mimetic muscles exist, but a continuous aponeurosis between all of them does not.

This distinction becomes extremely important around the parotid.

Platysma

Platysma is therefore part of the:

superficial fascia / layer 3.

It represents the cervical continuation of the superficial mimetic muscular system.

Deep to it lies the deep fascia.

However, the relationship varies:

Over lower masseter / parts of neck

There may be a loose potential plane between platysma and deep fascia.

Over SCM

The deep fascia becomes closely adherent to the platysma fascia.

These attachments form what are termed:

cervical retaining ligaments.

Over parotid

The platysma continues into the platysma-auricular fascia (PAF).

This is one of the most important corrections in the paper.

Platysma-auricular fascia — PAF

This structure is frequently called parotid fascia in surgical literature.

The authors argue that this name creates confusion.

What is PAF?

It is the relatively strong aponeurotic/fibromuscular layer overlying the parotid.

Histology showed variable muscle fibers within it.

Their dissections, histology and plastination demonstrated:

platysma → PAF

as one continuous structure.

Therefore:

PAF belongs to superficial fascia / layer 3.

It is not, in their interpretation, the parotid component of the deep fascia.

This is enormously important.

What happens when you remove the PAF?

Underneath it remains:

parotid gland + thin parotid capsule.

That capsule is part of the deep fascia.

And importantly:

PAF connects to:

platysma

Parotid capsule connects to:

masseter fascia

These are two different planes.

The article therefore rejects the common idea:

parotid fascia → masseter fascia

if by “parotid fascia” one means the thick aponeurotic structure surgeons encounter superficially over the parotid.

Instead:

platysma → PAF

and beneath it:

parotid capsule → masseter fascia.

This is beautifully summarized in their parotid discussion.

Parotidomasseteric fascia: PAF versus parotid capsule–masseter fascia

The authors emphasize that the term parotidomasseteric fascia has caused confusion because two different structures over the parotid have historically been conflated. The relatively strong aponeurotic layer superficial to the parotid is the platysma-auricular fascia (PAF). It is continuous with the platysma, commonly contains muscle fibers, and belongs to the superficial fascial system. It is not continuous with the masseter fascia.

Deep to the PAF, the parotid gland is covered by a thin parotid capsule, which belongs to the deep fascial system and is continuous anteriorly with the masseter fascia. Therefore, the authors argue that the term parotidomasseteric fascia can still be used, but only for this deep continuum of parotid capsule and masseter fascia, not for the superficial aponeurotic PAF.
This distinction also explains why dissection deep to the PAF leads anteriorly into the subplatysmal plane, rather than deep to the masseter fascia.

The authors’ position is more nuanced than simply saying “parotid fascia is continuous with masseter fascia.”

Their key point is that two different structures have historically been conflated under the name “parotid fascia.”

The superficial aponeurotic layer over the parotid is what they call the platysma-auricular fascia (PAF). They argue that this layer is continuous with the platysma, commonly contains muscle fibers, and belongs to the superficial fascial system/SMAS layer. It is not continuous with the masseter fascia.

By contrast, deep to the PAF there is a thin parotid capsule, and this capsule is the structure that is continuous anteriorly with the masseter fascia.

So anatomically the authors propose:

Platysma → PAF

but separately:

Parotid capsule → masseter fascia

This is the central correction.

They specifically discuss the historical term “parotidomasseteric fascia.” Traditionally, that term implies a continuous fascial sheet extending across both the parotid and masseter regions. The authors note that classic anatomists and later surgical literature disagreed about this continuity. They cite earlier authors who argued that the apparent “parotid fascia” superficial to the gland is actually related to platysma rather than being a continuation of masseter fascia.

Their conclusion is therefore:

The term parotidomasseteric fascia can still be used, but only if it refers to the deep fascial layer consisting of the parotid capsule continuing into the masseter fascia.

It should not be used for the strong superficial aponeurotic layer over the parotid that surgeons commonly encounter and suture during facelift surgery. That superficial structure is the PAF, not the parotidomasseteric fascia.

This gives a very useful two-layer model:

SUPERFICIAL

Platysma
   ↓
PAF
   ↓
------------------
Parotid gland
   ↓
Parotid capsule
   ↓
Masseter fascia

DEEP

More precisely, because the parotid is sandwiched between these systems:

Skin
↓
Subcutaneous tissue
↓
Platysma / superficial fascia
↓
PAF
↓
Parotid gland
↓
Parotid capsule
↓
Masseter fascia
↓
Masseter

The authors also use this anatomy to explain a practical surgical observation: if one dissects deep to the PAF, the dissection proceeds into the subplatysmal plane anteriorly, rather than underneath the masseter fascia. If the PAF were truly continuous with the masseter fascia, that would not make anatomical sense.

That is a very elegant argument.

Another important point is that they explain the dense adherence around the parotid embryologically. The parotid develops within the deep fascial layer, tightly positioned between the overlying platysma/PAF and the deeper muscular fascia. This helps explain why the parotid capsule may adhere closely both to the overlying superficial fascial structures and to the masseteric fascia, even though those structures are not actually one continuous sheet.

So I would summarize the authors’ terminology as:

Structure Authors’ interpretation Continuity
PAF Superficial aponeurotic/fibromuscular structure over parotid Continuous with platysma
Parotid capsule Deep fascial covering of the gland Continuous with masseter fascia
Masseter fascia Regional condensation of deep fascia Continuous posteriorly with parotid capsule
“Parotidomasseteric fascia” Acceptable only for the deep parotid capsule–masseter fascia continuum Not the superficial PAF

And I think the most important sentence conceptually is:

The “parotid fascia” a surgeon sees superficially and the “parotid fascia” anatomists mean when discussing continuity with masseter fascia are not necessarily the same anatomical structure.

That nomenclature problem is probably one major reason why the literature appears contradictory.

For OMFS specifically, this distinction is highly relevant to parotidectomy and facial nerve dissection, because it separates the superficial platysma-derived covering from the actual deep fascial envelope containing the gland and merging with masseteric fascia.

Parotid capsule

The parotid capsule is the thin deep-fascial layer immediately surrounding the parotid parenchyma.

The authors regard it as a condensation of the overall deep fascia.

Posteriorly/anteriorly around the gland it is intimately related to the surrounding deep fascial network.

Most importantly:

parotid capsule → masseter fascia

continuously.

Therefore there are really two structures over the parotid worth keeping conceptually separate:

superficial:
platysma → PAF

deep:
parotid capsule → masseter fascia.

For parotid surgery, I think this is one of the most useful lessons in the entire paper.

Masseter fascia

Traditionally we think of this as a strong fascia covering masseter.

The article’s interpretation is slightly different.

It is the region where the lamellae of the general deep fascia become compressed/condensed over the convex masseter surface.

Therefore:

Masseter fascia is not an isolated sheet inserted into something else; it is a thin regional expression of the continuous deep fascial layer.

The authors explicitly state that the masseter fascia is continuous:

posteriorly → parotid capsule

superiorly → temporal fascia + innominate fascia

anteriorly → deep cheek fat compartments

inferiorly → deep cervical fascia.

That sentence may be the single best anatomical roadmap in the paper.

Put schematically:

deep temporal / innominate fascia
↓
masseter fascia
↙︎ ↘︎
parotid capsule deep cheek fascia/fat
↓
deep cervical fascia

All are expressions of the same deep-fascial layer.

Deep fascia proper — the authors’ central concept

Now we arrive at the most important “layer.”

The deep fascia begins immediately deep to the superficial fascia.

It is not just a fascia covering the masseter or temporalis.

The authors define it anatomically as the connective-tissue layer occupying the entire interval between:

superficial fascia / mimetic muscles

and

deep structures.

Deep structures include:

  • skull and facial bones,
  • temporalis,
  • masseter,
  • deeper cervical muscles,
  • salivary glands,
  • vessels,
  • visceral structures.

It is therefore best imagined as a 3-D connective tissue volume, rather than as wrapping paper around muscles.

Internal architecture of deep fascia

Histologically, it consists of:

connective-tissue lamella
↓
fat / loose areolar tissue
↓
connective-tissue lamella
↓
fat
↓
connective-tissue lamella

and so forth.

Hence the authors’ analogy:

mille-feuille pastry.

Where lamellae approximate each other:

→ thin dense fascia.

Where they separate:

→ fibrofatty deep fascia / “deep fat compartment.”

This model elegantly reconciles what otherwise looks like contradictory anatomy.

Deep fat compartments

Examples include:

  • deep medial cheek fat,
  • subplatysmal fat,
  • interdigastric fat,
  • other previously described deep facial fat compartments.

According to the paper:

they are not sitting superficial to the deep fascia.

They are the expanded fatty portions of the deep fascia itself.

This is extremely useful conceptually.

Imagine squeezing a multilayered sponge:

  • squeezed → looks like a fascial sheet;
  • expanded → appears like fat with septa.

Still the same structure.

Deep medial cheek fat — DMCF

The article therefore regards DMCF as a thickened fibrofatty region of the deep fascia.

This is especially clinically interesting because buccal facial nerve branches supplying the upper lip elevators progressively become superficial and eventually run in the most superficial part of the DMCF/deep fascia over the maxilla.

So DMCF is not simply “fat safely sitting over the nerve.”

The nerve may be embedded within it.

Buccal fat pad — different

The paper makes a sharp distinction:

Deep cheek fat

fibrofatty
lamellar
connective-tissue-rich
part of deep fascia.

Buccal fat pad

amorphous
soft/mobile
relatively connective-tissue-poor
a separate anatomical entity.

For an OMFS surgeon this distinction makes particularly good anatomical sense given how differently the buccal fat pad behaves during intraoral exposure.

Temporal region

This is probably the most difficult region nomenclaturally.

The paper asks us to think of the whole interval beneath the superficial temporal fascia/mimetic layer as the same deep fascial system.

From superficial to deep, in simplified form:

skin
↓
subcutaneous tissue
↓
superficial temporal fascia / temporoparietal muscular system
↓
deep fascia
 • superficial part
 • “innominate fascia” region
 • deeper fascial lamellae
↓
deep temporal fascia / temporalis.

But even here, the authors argue against treating every named sheet as an independent system.

Innominate fascia

The innominate fascia is particularly important for the temporal facial nerve branches.

The authors describe it as the region of deep fascia where the fatty layer becomes thinner and the connective-tissue lamellae become closely packed, giving the typical mille-feuille appearance.

At the inferior temporal septum the frontotemporal branches enter the most superficial portion of this deep fascia/innominate fascia, directly underneath the superficial temporal/mimetic layer.

Thus:

innominate fascia = part of deep fascia, not an entirely independent fascia.

Deep temporal fascia

The familiar deep temporal fascia is also interpreted as a deep condensation of the same deep fascial network.

In the upper temple the deep fascia is thin.

As one moves inferiorly toward the zygomatic arch, its lamellae separate and rearrange; some form the structures traditionally called the superficial and deep layers of deep temporal fascia.

Most importantly, the article emphasizes that there remains deep fascia superficial even to the superficial layer of deep temporal fascia, and the frontotemporal facial nerve branches may lie there.

So “I am superficial to deep temporal fascia” does not necessarily mean “I am outside the deep fascial system.”

That distinction is subtle but important.

Periosteum

The authors extend the same concept all the way to periosteum.

When the multiple deep-fascial sheets converge on bone:

→ they fuse to form periosteum.

Similarly:

at muscle → muscle fascia/epimysium;

at gland → gland capsule;

at vessel → vascular sheath.

Therefore periosteum is conceptually not the beginning of a completely different system but the deep-fascial connective tissue condensed at the surface of bone.

Muscle fascia / epimysium / perimysium

The same process occurs around muscle.

Deep fascia converges:

→ external muscle fascia / epimysium

and connective tissue continues inward:

→ perimysium, dividing muscle into fascicles.

This continuity is demonstrated histologically in Figure 6.

So their model is approximately:

deep fascia → epimysium → perimysium.

Again, not isolated envelopes.

Salivary gland capsule

Likewise:

deep fascia → external gland capsule → connective septa dividing the gland into lobules.

The authors use the term capsula propria for these intraglandular extensions.

This is particularly relevant to both parotid and submandibular anatomy.

Deep cervical fascia

This is perhaps the most provocative aspect for traditional head-and-neck anatomy.

We are normally taught three components:

  1. investing layer
  2. pretracheal layer
  3. prevertebral layer

with an investing layer that forms a continuous circular sheet around the neck, splitting around:

  • SCM,
  • trapezius,
  • parotid,
  • submandibular gland.

The paper says their evidence does not support that arrangement as three separable continuous sheets.

They found no single thin aponeurotic sheet encircling the neck.

Instead there is a:

continuous multilamellar fibrofatty deep fascial layer, variable in thickness.

They specifically state that dividing this into superficial, middle and deep fascial layers was not supported by either layered dissection or microscopy.

This does not necessarily mean that terms such as pretracheal fascia or prevertebral fascia cease to be surgically useful. Rather, the authors argue that these are regional specializations/condensations within a continuous connective-tissue system rather than three perfect concentric sheets.

That distinction is important.

SCM fascia

Over the convex SCM:

→ the deep fascia becomes thin and condensed.

Hence the recognizable SCM fascia.

But unlike over the lower masseter, it adheres strongly to the overlying platysma fascia in places.

Those adherent zones are the:

cervical retaining ligaments.

Figure 12 specifically depicts them as an adhesion zone between the muscle fascia of platysma and fascia over SCM.

So:

platysma [superficial fascia]
⬍ strong attachments
SCM fascia [deep fascia]

Submandibular region

Over the convex submandibular gland, the deep fascia is relatively thin.

The deep-fascial sheets converge around the gland to form its capsule, with connective-tissue extensions into the gland.

But around the surrounding anterior cervical triangle, where the space is larger, the same deep fascia becomes thick and fibrofatty.

Therefore:

SMG capsule ↔ fibrofatty deep cervical fascia

should be regarded as parts of the same connective-tissue continuum.

This is particularly intuitive surgically: the “fascia” encountered around the gland is not necessarily a discrete sheet that can be followed unchanged throughout the entire triangle.

Pretracheal fascia and carotid sheath

The conclusion explicitly includes the:

  • pretracheal fascia
  • carotid sheath

among structures formed by the same deep-fascial system.

In their words, the deep fascia encloses muscles, glands, visceral structures and vascular structures and extends into them.

So within their model:

general deep cervical fascia
→ condenses around viscera = pretracheal fascia

→ condenses around neurovascular bundle = carotid sheath

rather than these necessarily representing wholly separate membrane systems.

5. The continuity map — probably the most useful way to remember the paper

For practical anatomy, I would reduce the entire article to two continuous systems.

A. SUPERFICIAL FASCIAL SYSTEM

In the lower face/neck:

mimetic muscles / SMAS
↕
platysma
↕
PAF over parotid

Thus:

Platysma → PAF

and not

PAF → masseter fascia.

The PAF contains variable muscle fibers and is essentially the aponeurotic continuation/remnant of platysma over the parotid.

B. DEEP FASCIAL SYSTEM

A simplified craniofacial-cervical continuity is:

cranial periosteum / upper temporal deep fascia
↓
innominate fascia
↓
deep temporal fascia
↓
deep fascia around zygomatic arch
↓
masseter fascia
↙︎ ↓ ↘︎
parotid capsule deep cheek fat anterior facial deep fascia
↓
deep cervical fascia
↓
regional condensations around:

  • SCM
  • strap muscles
  • SMG
  • viscera
  • carotid sheath
  • deeper musculature.

The authors explicitly give the masseteric continuity as:

parotid capsule posteriorly → masseter fascia → temporal/innominate fascia superiorly → deep cheek fat anteriorly → deep cervical fascia inferiorly.

That is the continuity I would memorize.

6. The relationship between the two systems

Conceptually:

SKIN
│
├── Superficial subcutaneous fat
│
├── SUPERFICIAL FASCIA
│      ├── mimetic muscles
│      ├── SMAS concept
│      ├── platysma
│      └── PAF
│
│   ← potential surgical plane
│      (NOT a true independent "layer 4")
│
├── DEEP FASCIA
│      ├── loose areolar lamellae
│      ├── deep fat
│      ├── FACIAL NERVE
│      ├── masseter fascia
│      ├── innominate fascia
│      ├── deep temporal fascia
│      ├── gland capsules
│      ├── deep cervical fascia
│      └── vascular/visceral fascial condensations
│
├── muscle fascia / periosteum / gland capsule
│
└── deep structures

But the really important point is that the lower part of the diagram is not composed of independent boxes.

It is one connected, variable-thickness network.

7. Facial nerve: how it relates to this fascial architecture

For an OMFS surgeon, I would regard this as the clinically most valuable aspect of the paper.

The nerve does this:

At parotid exit

deep within the deep fascia

↓

travelling anteriorly

gradually becomes more superficial within the same deep fascia

↓

near its target mimetic muscle

lies in the superficial-most portion of the deep fascia

↓

terminal branches

cross toward/into their mimetic targets.

There is generally no single point where the nerve suddenly “pierces the deep fascia.”

That traditional question is probably anatomically wrong according to this paper.

Instead, the nerve has been inside the fascia all along and simply migrates from its deeper to its superficial lamellae.

8. Branch-by-branch transition

This part is worth learning because it makes the model clinically concrete.

Facial nerve branch Starts Becomes superficial approximately at Final relationship
Frontotemporal Deep within deep fascia after parotid Inferior temporal septum / auricularis anterior region Superficial innominate fascia, immediately under temporal mimetic layer
Zygomatic Deep within deep fascia at anterosuperior parotid Around peripheral orbicularis oculi / zygomatic ligaments Suborbicularis region
Buccal Deep within fascia over posterior masseter Progressively anteriorly, especially near anterior masseter Superficial deep fascia/DMCF beneath upper lip elevators
Marginal mandibular Deep fascia at parotid/lower masseter Near anterior masseter/facial vessels/mandibular ligament Very superficial deep fascia beneath platysma/depressors
Cervical Deep within deep fascia at parotid/SCM Terminal branches become superficial anteriorly Immediately on deep surface of platysma

The detailed observations for buccal, marginal mandibular and cervical branches are particularly well illustrated in Figure 7.

9. Something particularly interesting for OMFS: marginal mandibular nerve

The description is very clinically relevant.

The branch:

  1. exits the inferior parotid region;
  2. runs deep within the masseteric deep fascia;
  3. starts becoming more superficial near the anterior border of masseter;
  4. usually crosses the facial vessels superficially;
  5. enters the most superficial portion of the deep fascia;
  6. curves over the mandible around the mandibular ligament;
  7. continues deep to DAO/DLI toward mentalis.

So the usual concept:

“nerve superficial to facial artery/vein”
or
“nerve deep to fascia”

is inadequate.

Its three-dimensional depth within the fascial layer changes continuously.

For submandibular approaches, marginal mandibular dissection, parotidectomy and facial trauma, that seems to me much more useful than memorizing a single “nerve is superficial/deep to X” statement.

10. One point where I would be cautious

I would not yet discard conventional deep-neck fascial terminology clinically because of this single study.

The paper provides strong morphological evidence for a continuous fibrofatty connective-tissue system, but classical terms such as:

  • investing fascia,
  • pretracheal fascia,
  • prevertebral fascia,
  • carotid sheath,

remain useful because they describe surgically and radiologically recognizable regions and pathways, particularly for deep neck infection and oncologic surgery.

I therefore think the best way to interpret this paper is:

not “the traditional fasciae do not exist,” but “they may not exist as independent, perfectly separable sheets in the way textbook diagrams imply.”

Instead they may represent local condensations and configurations of a continuous fascial network.

That reconciles the paper remarkably well with what we actually see during neck dissection.

11. One-page mental model for this artilce

If you remember nothing else from the article, remember this:

SUPERFICIAL FASCIA

contains:

subcutaneous tissue + mimetic system → platysma → PAF

DEEP FASCIA

is:

one continuous 3-D multilamellar fibrofatty connective-tissue layer

that can appear as:

thin fascia
when compressed,

or

deep fat
when expanded.

It becomes locally:

innominate fascia
deep temporal fascia
periosteum
masseter fascia
parotid capsule
SMG capsule
SCM fascia
deep cervical fascia
pretracheal fascia
carotid sheath, etc.

and continues internally as:

perimysium / glandular septa.

The important discontinuity

PAF ≠ parotid capsule.

Rather:

platysma → PAF
(superficial fascial system)

while:

parotid capsule → masseter fascia
(deep fascial system).

FACIAL NERVE

Not:

deep to deep fascia.

Instead:

embedded within deep fascia

and travelling:

deep part → middle → superficial part

as it approaches its target muscle.

SURGICAL PLANE

Traditional “layer 4”:

not an independent anatomical layer.

It is a:

potential dissection plane in the superficial portion of deep fascia.

I think Figures 2, 5, 6, 7 and especially 12 are the figures worth studying repeatedly. Figure 2 resolves the platysma–PAF versus parotid capsule–masseter fascia issue; Figure 5 shows how the same multilamellar deep fascia changes appearance from forehead → temple → zygomatic arch → masseter → neck; Figure 6 demonstrates actual connective-tissue continuity into muscle and gland; Figure 7 shows the facial nerve progressively migrating through the depth of this fascial layer; and Figure 12 gives the best overall conceptual picture of the connectedness and changing thickness of the deep fascia. The latter is really the authors’ whole thesis condensed into one image.

For your OMFS practice, I think the next useful step would be to take this same paper and reinterpret it specifically for parotidectomy, submandibular approaches, transcervical mandibular access, facial nerve exploration, neck dissection, and deep neck spaces. Some of the implications are actually more interesting for OMFS than for facelift surgery, which is the context in which the authors wrote the paper.

My Opinion: Histologic Continuity versus Surgical Anatomy

Histology is very useful here as corroboration: it can show that what looks grossly like separate fascia, fat, capsule, or septa are connected by the same connective-tissue network. In that sense, it strengthens the authors’ anatomical model. But surgery is performed in macroscopic planes, not in histologic lamellae. A surgeon needs to know what can actually be seen, lifted, separated, followed, and used as a landmark.

That is where I think this paper should be read with some caution. The authors sometimes move from a histologic observation—“these tissues are continuous microscopically”—to an anatomical reclassification—“therefore they are one deep fascial layer.” That may be conceptually elegant, but it does not automatically mean that the distinction is less useful surgically.

For example, calling the masseter fascia, parotid capsule, deep cheek fat, periosteum, and deep cervical fascia parts of one continuous histologic system may be valid morphologically. But in an operation, those structures behave quite differently. The masseteric fascia can be recognized and dissected as a relatively definite surface; the buccal fat pad behaves as a separate mobile fat body; the parotid capsule has very different surgical implications; and cervical fascial planes matter because they guide access, spread of infection, and safe dissection.

So I would separate three levels of description:

  1. Histologic level: connective-tissue lamellae may be continuous.
  2. Anatomic level: regional structures may still be identifiable as distinct fasciae, capsules, fat compartments, and spaces.
  3. Surgical level: the most useful classification is based on reproducible dissection planes, tissue behavior, visible landmarks, and the relationship to nerves, vessels, glands, and muscles.

The paper itself actually provides a good example of this tension. It argues that the traditional “layer 4” is not a true independent histologic layer, but rather a potential plane in the superficial deep fascia. Yet from the surgeon’s point of view, that plane is still extremely real, because it is a reproducible dissection plane with important consequences for facial nerve safety.

Likewise, I would not say that because the authors demonstrate microscopic continuity, terms such as masseter fascia, parotid capsule, deep temporal fascia, pretracheal fascia, or carotid sheath become less useful. Those names may still describe surgically meaningful structures even if, under the microscope, they are components of one larger connective-tissue continuum.

For me as an OMFS surgeon, I would therefore reinterpret the paper this way:

Use the histology to understand continuity, but use gross surgical anatomy to decide where one operative layer ends and another begins.

And I think the strongest parts of this paper for surgical practice are not actually the histologic reclassification itself, but the gross observations that:

  • the PAF is continuous with platysma rather than masseter fascia;
  • the parotid capsule is continuous with masseter fascia;
  • the facial nerve branches are embedded within the fibrofascial layer and progressively become more superficial;
  • deep-plane dissection can therefore cross the nerve even while apparently remaining “within fascia.”

Those are directly translatable to surgery.

So yes—I would regard the paper’s histologic model as anatomically illuminating, but not necessarily the best operative classification system.

  1. Minelli, L., van der Lei, B., & Mendelson, B. C. (2023). The Deep Fascia of the Head and Neck Revisited: Relationship with the Facial Nerve and Implications for Rhytidectomy. Plastic & Reconstructive Surgery, 153(6), 1273–1288. https://doi.org/10.1097/PRS.0000000000010556 ↩