fascia-neck

FIGURE 34-9 Axial T1-weighted MR image shows a mass (medium arrow) separating the internal carotid artery (small arrow) and the internal jugular vein (large arrow). Although the fascia forming the carotid sheath cannot be seen on imaging, its presence is noted by the fact that it restrains the vessels from simply sliding away from the schwannoma and thus allows the mass to separate them.

THE FASCIAL SPACES

The fascial spaces or compartments are regions of loose connective tissue that fill the areas between the fascial layers. In some cases these compartments are readily identifiable, while in others they represent more potential spaces. The descriptions of these fascial spaces vary almost as much as those of the fasciae themselves, and there is little agreement among surgeons and anatomists as to whether the spaces communicate freely with each other, allowing unobstructed spread of infections, or whether most of these spaces are closed and separate so that infections from one space must ‘‘point’’ and penetrate in order to spread to adjacent spaces. The explanation of these differing opinions may be the normal anatomic variations of the fasciae that occur among people.

Another difficulty when discussing the spaces of the neck is that there are no officially accepted names for many of these spaces. A number of the spaces do have names that have been so commonly utilized for years that they have become acceptable terms. However, throughout the literature, a variety of less common names have been employed for some spaces. These differences in nomenclature will be mentioned throughout the discussion of the spaces.

In the previous sections, a detailed description of the fasciae that form these spaces has been given. In this section a summary of the boundaries of these spaces will be given, and Drawings 17 to 22 show the overall relationship of each of the major spaces to one another.

The Visceral Compartment and Its Spaces

Probably the most controversial and confusing terminology is for the space that contains the pharynx, cervical esophagus, trachea, thyroid gland, parathyroid glands, larynx, recurrent laryngeal nerves, and portions of the sympathetic trunk. This space is referred to by various authors as

Chapter 34 Fascia and Spaces of the Neck 1815

either the visceral compartment or the visceral space. This region extends from the skull base down to the upper thorax. In its more cranial portion it is defined by the visceral fasciae or BPF ventrally, the alar fascia dorsally, the cloison sagittale fasciae on either side, and the skull base superiorly. In its caudal portion it has two sections. There is an anterior or ventral portion enclosed by the strap muscles ventrally, the carotid sheaths laterally, and the alar fascia dorsally. There is also a caudal or posterior continuation of the more cranial portion of this region around the cervical esophagus.

Most authors today refer to this region as the visceral space. It is considered to have two subdivisions: an anterior pretracheal space and a more posterior retrovisceral space.2, 4 These spaces communicate freely between the levels of the thyroid cartilage and the inferior thyroid artery. However, caudal to this level, these spaces are separated by a fascia associated with the inferior thyroid artery. As a result, the pretracheal space extends down into the superior mediastinum, while the retrovisceral space extends into the middle mediastinum. As mentioned, the reader should be aware of the confusing terminology, as in the literature the entire visceral space is referred to by some authors as the visceral compartment, with two lower regions: the pretracheal space and the retrovisceral space.

The Pretracheal Space

The pretracheal space (itself a somewhat confusing term, as this space contains the trachea) extends from the hyoid bone and the attachments of the strap muscles and their fascia to the hyoid bone and thyroid cartilage down to the superior mediastinum about the upper border of the aortic arch and great vessels. This space contains the trachea, thyroid gland, parathyroid glands, larynx, cervical esophagus, recurrent laryngeal nerves, and portions of the sympathetic trunk. The pretracheal space communicates freely with the retrovisceral space around the sides of the larynx, the lowermost pharynx, and the upper cervical esophagus between the levels of the thyroid cartilage and the inferior thyroid artery. Caudal to this level, the pretracheal space is separated from the retrovisceral space by dense connective tissue that extends from each lateral wall of the visceral compartment to the lateral margins of the esophagus. This tissue accompanies the inferior thyroid artery on either side as it courses cranially from the thyrocervical trunk, extends ventral to the vertebral artery and the longus colli muscle, and then runs to the caudal and dorsal aspect of the thyroid gland (Drawings 3–5, 8, 9, and 17–22).2, 4

The Retrovisceral Space

The posterior portion of the visceral compartment, referred to as the retrovisceral space, is behind the pharynx and upper esophagus. It extends from the skull base down to the mediastinum, where its caudal limit is between the levels of the sixth cervical vertebra and the fourth thoracic vertebra, where the alar fascia fuses with the visceral fascia. Often the space actually stops at the more cranial of these levels, corresponding to the level of the tracheal bifurcation (Drawings 2–5, 8, 9, and 17–22).2, 4 As the retrovisceral

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space lies behind the pharynx and upper esophagus, in the upper neck it is often referred to as the retropharyngeal space.

More specifically, in its upper regions, this space lies between the BPF anteriorly (as this fascia surrounds the pharyngeal musculature) and the alar fascia posteriorly. On either side, the cloison sagittale separates the retropharyngeal space from the more laterally positioned parapharyngeal space. In the middle and lower neck, the continuation of this space surrounds the esophagus, and it is commonly referred to as the retroesophageal space. Thus the ‘‘retropharyngeal’’ and ‘‘retroesophageal’’ spaces are the upper and lower aspects of one space (the retrovisceral space or portion of the larger visceral space), which communicates freely with the pretracheal space between the levels of the thyroid cartilage and the inferior thyroid artery. This fascial anatomy explains why a retropharyngeal abscess can extend down into the pretracheal space and affect the thyroid gland and anterior mediastinum, or why a large thyroid goiter can extend behind the esophagus and grow either upward as a retropharyngeal mass or downward as a retroesophageal mass (Figs. 34-10 to 34-14).

To confuse the issue even further, a few authors have restricted the use of the term visceral space to the potential space between the visceral fascia and the enclosed viscera. However, this opinion is not held by most authors.

The Danger Space

Grodinsky and Holyoke described the danger space (their space 4) as lying between the alar fascia (ventrally) and the prevertebral fascia (dorsally).2 The space extends from the skull base down into the posterior mediastinum to a level just above the diaphragm where the fused alar and visceral fascia, in turn, fuse with the prevertebral fascia. Grodinsky and Holyoke considered this space an important potential pathway for the spread of cranial and cervical infections into the middle and lower mediastinum. Since the space is closed superiorly, inferiorly, and laterally, infections must enter the space by penetrating its walls (Drawings 2–5, 8, 9, and 17–22).2

The Prevertebral Space

This space is a potential space that exists between the prevertebral fascia and the vertebrae, extending from the skull base to the coccyx.2, 4 The prevertebral muscles are within this space (Drawings 2–5, 8, 9, and 17–22). The vast majority of the pathology that affects this space arises from the adjacent vertebral bodies, discs, and neural elements.

The Carotid Sheath

There is lack of agreement in the literature as to whether the potential cavity within the carotid sheath can act as a space that allows the spread of infections from the upper neck down into the lower neck and mediastinum. Coller and Yglesias, like Pearse, believed it to be a true pathway for the spread of infection.7, 23 However, Grodinsky and Holyoke found this space to be of limited value as a pathway for

infectious spread.2 Their experimental injections into the sheath remained confined to the sheath around the common carotid artery between the carotid bifurcation and the root of the neck, levels where the sheath is closely adherent to the vessels. They suggested that it is probably most accurate to consider the carotid sheath as a true space only below the level of the carotid bifurcation and above the root of the neck.

There is some controversy in the literature as to whether the portion of the carotid sheath about the internal carotid artery (i.e., above the hyoid bone) should be considered as part of the parapharyngeal space or as a separate ‘‘carotid space.’’ Historically, the anatomic and surgical literature is of the opinion that this portion of the carotid sheath should be considered as part of the parapharyngeal space.2, 4, 6, 9, 10, 15 The reasoning is based on three observations: (1) Grodinsky and Holyoke found that above the carotid bifurcation, the carotid sheath did not act as a space that allowed the spread of infection; (2) the anatomic literature traditionally has accepted that the posterior layers of the carotid sheath are the posterior boundary of the parapharyngeal space (Drawings 2–5, 8, 9, 15, 16, and 17–22); and (3) most importantly, during the surgical approach to the parapharyngeal space, the tensor-vascular- styloid fascia acts as a boundary between the more superficial prestyloid compartment (containing the retromandibular portion of the parotid gland) and the deeper retrostyloid compartment (containing the carotid sheath).

Harnsberger offered the concept that the carotid sheath and its contained structures should be considered as the carotid space.24 Although this may not necessarily reflect the anatomic evidence regarding the true presence of a carotid space, the benefit of this concept lies in its ability to help generate a differential diagnosis of lesions that can be localized on imaging to the carotid sheath25 (Fig. 34-9). The major limitation of this approach is that most surgeons use the prestyloid/retrostyloid terminology and are not as familiar with the carotid space concept.

The Space of the Body of the Mandible

As the SLDCF reaches the caudal border of the mandible, the fascia splits into two leaflets, with the outer leaflet firmly attaching along the lower buccal border of the mandible. The deep fascial leaflet attaches to the lingual surface of the mandible along the line of origin of the mylohyoid muscle that is 1 to 1.5 cm above the caudal edge of the mandible. This deep portion of the fascia can be elevated away from the bone, creating a potential space between the fascia and the lingual cortex of the bone. This potential space contains no loose connective tissue, is limited anteriorly by the attachment of the anterior belly of the digastric muscle, and is delineated posteriorly by the attachment of the internal pterygoid muscle.2, 4

The Space of the Submandibular Gland

This space is not a real space in the sense that the submaxillary gland can be easily shelled out of it, leaving the SLDCF behind as a capsule.2, 4 Instead, the septa of the

gland are continuous with the capsule. However, the submandibular gland has its own volume and so can be thought of as occupying a space bounded by its own capsule or thin fascia (Drawing 13).

gland is also thin or deficient in most people. However, conceptually, this space encloses the parotid gland, the parotid lymph nodes, and portions of the external carotid artery and the posterior facial or retromandibular vein (Drawings 12, 21, and 22).2, 4

The Space of the Parotid Gland

The SLDCF also splits to enclose the parotid gland. Like the submaxillary gland space, the parotid gland cannot be shelled out, leaving behind a real compartment with strong fascial boundaries. In fact, the fascia about the parotid gland is attached by septae to the gland and is inseparable from the gland. The fascia along the medial or deep portions of the

The Submandibular Space

Overall, this space is the volume described within the mandibular arch, limited above by the mucosa in the floor of the mouth and caudally by the SLDCF as it extends from the hyoid bone to the mandible. The space is divided into an upper and a lower portion by the mylohyoid muscle that

attaches to the lingual surface of the mandible along the mylohyoid line. The submaxillary (submandibular) gland is folded around the back of this muscle so that the gland lies partially above and partially below its dorsal edge. In fact, the upper and lower portions of the submandibular space communicate freely with each other around this dorsal margin of the mylohyoid muscle. In general, there is also free communication between the left and right sides of this space (Drawings 10, 13, and 20–22) (Figs. 34-15 and 34-16). As the submandibular gland lies within the submandibular space, a distinction should be made between this

FIGURE 34-12 Axial contrast-enhanced CT scan through the oropharynx shows an enhancing, thickened mucosa on the left side. There is a mucosal ulceration (arrow); however, the visceral fascia appears to prevent the tumor from spreading further into the deep spaces of the neck. This is not an uncommon imaging appearance of pharyngeal carcinomas and illustrates the potential resistance of this fascia to tumor spread.

larger space and the space for the submandibular gland, which essentially refers to the capsule of this gland (see above).

The upper or cranial portion of the submandibular space is often called the sublingual space. It is filled with loose connective tissue that surrounds both sublingual glands and their ducts, the lingual and hypoglossal nerves, the lingual arteries, and the smaller or deep portion of each submandibular gland along with its hilum and Wharton’s duct. On either side, the lower or caudal portion of the submandibular space is usually referred to as the submaxillary space, and the larger superficial portion of the submandibular gland and its lymph nodes lie within its loose connective tissue. The facial artery and vein as well as the digastric muscle are also in each submandibular space. The submental triangle and the submandibular triangles of the neck are the superficial landmarks that correspond to the region of this space.2, 4, 14

The Masticator Space

The SLDCF splits about the lower edge of the mandible, and the outer or superficial layer encloses the masseter muscle, extends over the zygomatic arch, and attaches to the calvarium about the dorsal and cranial margins of the temporalis muscle and the lateral orbital wall. The inner or deep layer of fascia covers the medial pterygoid muscle before fusing with the interpterygoid fascia and continuing to the skull base.15, 16 The split layers of the SLDCF fuse again along the ventral and dorsal borders of the ramus of the mandible and, in so doing, close this space about the muscles of mastication. The lateral pterygoid muscle lies freely within this space, while the fasciae about the masseter, temporalis, and internal pterygoid muscles con-

tribute to the boundaries of this space. The portion of the masticator space that extends cranially between the calvarium and the outer layer of the SLDCF is occasionally referred to as the temporal space, but it is probably better regarded as the cranial extension of the masticator space (Fig. 34-17). The internal maxillary artery and the third division of the trigeminal nerve run within the masticator space (Drawings 2, 10–13, 21, and 22) (Fig. 34-3); see Chapter 38.2, 4, 7, 12, 15, 16

The Parapharyngeal Space

What today is commonly referred to as the parapharyngeal space has also been referred to in the literature as the lateral pharyngeal, peripharyngeal, pharyngomaxillary, pterygopharyngeal, pterygomandibular, and pharyngomasticatory space, and it boundaries have been described with more variation than those of any other space of the neck (Drawing 2).2, 4, 6, 8, 9, 15 The parapharyngeal space is a

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FIGURE 34-17 Axial contrast-enhanced CT scan through the upper facial area shows a mucoid collection (M ) with air in the right temporal fossa adjacent to the skull. This was spread of a right masticator space abscess up into the cranial extension of the masticator space.

hatchet-shaped space on either side of the neck. Its ventral (prestyloid) compartment lies just lateral to the pharynx and deep to the masticator space and the ramus of the mandible. It is filled with fat and connective tissue, and the deep portion of the parotid gland protrudes into it. The dorsal (retrostyloid) compartment of the parapharyngeal space corresponds to the carotid sheath and its enclosed structures. The parapharyngeal space extends from the skull base down to the level of the angle of the mandible.

More specifically, the medial wall of the parapharyngeal space is formed by the BPF or visceral fascia as it extends from the skull base caudally, first covering the pharyngobasilar fascia and then the outer aspect of the pharyngeal constrictor muscles (Drawing 3).

On either side of the neck, the pterygomandibular raphe is a linear fascial condensation that extends from the hamulus of the medial pterygoid plate to the lingual surface of the mandible near the posterior margin of the mylohyoid line. This raphe serves as the point of attachment of the superior pharyngeal constrictor muscle, and it is also the origin of the buccinator muscle. In addition, the BPF (covering the pharyngeal constrictor and extending ventrally to cover the buccinator muscle) and the interpterygoid fascia (from the masticator space) both fuse with the pterygomandibular raphe. As the parapharyngeal space is between these fasciae, the pterygomandibular raphe is considered to be the anterior or ventral boundary of the parapharyngeal space.

Caudally, the parapharyngeal space has been described as extending down to the hyoid bone. However, in actuality, the fascia about the submaxillary gland, the sheaths of the styloid muscles, the fascia over the posterior belly of the digastric muscle, the fascia on the lingual aspect of the mandible, and the visceral fascia all fuse near the level of the angle of the mandible, functionally obliterating the parapharyngeal space. Running at the caudal aspect of this region is the styloglossus muscle, which is most often considered to be the inferior boundary of the parapharyngeal space.2, 4, 6, 8, 9, 15

The lateral boundary is the fascia on the medial aspect of the masticator space and the fascia over the deep surface of the parotid gland, both of which are formed by the superficial layer of the deep cervical fascia.

The posterior boundary of the parapharyngeal space is

the most controversial. As already mentioned, most anatomists and surgeons have placed the carotid sheath in the retrostyloid compartment of the parapharyngeal space, while some radiologists have referred to the sheath as representing a separate carotid space.2, 4, 6, 8–10, 15, 24, 26 In general, when communicating sectional imaging findings to surgeons, as well as for consistency with the clinical literature, the carotid sheath is considered to be the retrostyloid compartment of the parapharyngeal space. However, it should be remembered that in the literature there is no disagreement about the anatomy itself, only about the terminology used to describe this anatomy (Drawing 4).

Within the boundaries of each parapharyngeal space just described, the parapharyngeal space is usually subdivided into three compartments defined in various descriptions by the tensor-vascular-styloid fascia, the stylopharyngeal aponeurosis (aileron), and the sagittal partition (cloison sagittale) (Drawing 5).

As previously discussed, there is a well-defined, fairly thick fascial sheet, the tensor-vascular-styloid fascia, that closes the gap between the tensor veli palatini muscle and the medial pterygoid plate, the skull base, and the styloid process and its associated musculature (Drawings 3

and 5).9, 10, 16, 20

Gaughran mentioned a continuation of this fascia laterally from the styloid process to the posterior border of the mandibular ramus.9 He referred to this fascial extension as the stylomandibular fascia; a thickening in the lower edge of this fascia is the stylomandibular ligament. This ligament, along with the posterior border of the mandibular ramus and the skull base, forms the stylomandibular tunnel, through which the deep or retromandibular portion of the parotid gland protrudes into the parapharyngeal space. This stylomandibular fascia may also be thought of as a fusing of the SLDCF, as it covers both the medial aspect of the parotid gland and the styloid musculature.

There are two more fascial layers that relate to the tensor-vascular-styloid fascia and further subdivide or partition the parapharyngeal space. The first layer is a roughly coronally oriented fascia that has been variously described as extending medially from either the tensor- vascular-styloid fascia or the styloid musculature to the BPF. It attaches to the BPF near the location of the lateral pharyngeal recess or fossa of Rosenmuller.15 This fascia has been described by Testut, Zuckerkandl, and others and is most often referred to in the literature as the stylopharyngeal aponeurosis. Some French anatomists refer to it as the aileron (Drawings 3 and 5).6, 8, 9

The second fascial layer is positioned approximately in the sagittal plane and extends from the BPF, at or near the attachment of the stylopharyngeal aponeurosis, to the alar fascia and prevertebral fascia near their attachments to the transverse processes of the cervical vertebrae. This fascia is referred to by Charpy as the cloison sagittale (sagittal partition) (Drawings 3 and 5).1, 2, 6, 8, 9, 15 Probably reflecting anatomic variation, Cazalas described this cloison sagittale fascia as extending directly from the tensor-vascular-styloid fascia (rather than from the BPF) to the alar fascia.6 He also described the aileron as extending from the tensor-vascular- styloid fascia to the BPF. Cazalas used the term sphenopharyngeal ligament to identify the thickening in the tensor- vascular-styloid fascia from which, in his opinion, the cloison sagittale and the aileron had their origins.

These three fascial planes subdivide the parapharyngeal space into three compartments. The first compartment (A) is lateral to the tensor-vascular-styloid fascia and deep to the medial boundary of the masticator space. This area contains a small amount of fat, and the deep or retromandibular portion of the parotid gland protrudes into its lateral margin. The second compartment (B) is a very thin, slit-like region between the BPF medially and the tensor-vascular-styloid fascia laterally. There is only a small amount of loose connective tissue in this second compartment, which is bounded posteriorly by the stylopharyngeal aponeurosis (aileron). The third compartment (C) of the parapharyngeal region is posterior to the stylopharyngeal aponeurosis and separated from the retropharyngeal space by the cloison sagittale. This third compartment contains the internal carotid artery, internal jugular vein, and, at various levels, cranial nerves IX to XII. Thus, this third compartment is primarily the carotid sheath and its contents. Almost all descriptions of the parapharyngeal space include some or all of these compartments, albeit under a variety of names and combinations.

Gaughran referred to the region between the BPF and the medial wall of the masticator space as the lateral pharyngeal cleft.9 This cleft is analogous to the anterior part of the parapharyngeal space and includes the first two compartments (A+B) just described. Gaughran described the vascular fascia as extending from the tensor veli palatini and separating the lateral pharyngeal cleft into a very thin medial compartment and a larger, more lateral compartment called, respectively, the paratonsillar and paramasticator regions of the lateral pharyngeal cleft. This same fascial organization was described by Cazalas and Coulomb, who referred to the thin medial compartment as the meta-amygdalin space and the larger lateral compartment as the para-amygdalin space.6, 8 Amygdalin refers to the tonsil, and in this nomenclature there is also a periamygdalin space between the tonsil and the constrictor muscles (referred to today as the peritonsillar space).

Hall used the terms prestyloid and poststyloid parapharyngeal spaces.10 The poststyloid space was essentially the carotid sheath. The two spaces were separated by the stylopharyngeal aponeurosis, which indicates that the prestyloid compartment included the first two compartments described above (A+B). Hall did not describe any structure resembling the tensor-vascular-styloid fascia. Instead, he ascribed the entire region between the BPF overlying the constrictor muscles medially and the masticator space laterally to the prestyloid space. The paratonsillar and paramasticator spaces (metaand para-amygdalin) were combined.

Hollinshead referred to the parapharyngeal space as the lateral pharyngeal space, stating that it was continuous with the retropharyngeal space.4 He also stated that the area was subdivided by some authors into prestyloid and poststyloid compartments, referring to Hall, but not stating precisely which fascia, if any, divided the two compartments.

Som et al. referred to the prestyloid and retrostyloid compartments of the parapharyngeal space as being separated by the tensor-vascular-styloid fascia.20 They mentioned a fascia extending from the tensor-vascular-styloid fascia to the prevertebral fascia, separating the retrostyloid compartment from the retropharyngeal space. This fascia is analogous to the cloison sagittale, as described by Charpy. Thus Som et al. combined the spaces on either side of the stylopharyngeal aponeurosis, the second and third compart-

Chapter 34 Fascia and Spaces of the Neck 1823

ment described above (B+C), into one compartment called the retrostyloid space. The prestyloid compartment referred to the first compartment (A) described above, which is lateral to the tensor-vascular-styloid fascia and into which protrudes the deep portion of the parotid gland (Fig. 34-18).

Support for the use of this prestyloid and retrostyloid compartment terminology comes from the surgeons, who note that in their operative approach to the parapharyngeal space, the plane of the tensor-vascular-styloid fascia acts as an important landmark, with the great vessels and cranial nerves lying deep to the plane. In this sense, this fascia and its boundaries act as a protective barrier to these vital structures. Today, this terminology for the parapharyngeal space is most often used by surgeons.20

In the radiology literature, the various compartments of the parapharyngeal space have been used to help generate a differential diagnosis for lesions arising in this region. As previously discussed, two conventions are used. The first uses the prestyloid and retrostyloid configuration emphasizing the tensor-vascular-styloid fascia.16, 20 The second, discussed by Harnsberger, separates the region into the carotid space and the parapharyngeal space.24, 26 In this second convention, the separation closely approximates the stylopharyngeal aponeurosis, as discussed by Hall.10

In the opinion of most authors, the parapharyngeal space is considered as a closed space that is surrounded by a number of other ‘‘spaces.’’10 These include the pharynx, the submandibular space, the submaxillary gland space, the masticator space, the parotid gland space, the retropharyngeal space, the danger space, and the prevertebral space. However, when one considers the wide variety of descriptions of the fascial planes themselves, there is certainly a possibility that in some people, portions of these fasciae are weak or incomplete. This presumably explains why a few authors believe that the parapharyngeal space communicates freely with the submaxillary and retropharyngeal spaces.

One of the main reasons for interest in the parapharyngeal space is its critical location and anatomic relationships that allow it to act as a highway for the spread of infections and

FIGURE 34-18 Axial T2-weighted MR image shows a high signal intensity lymphangioma filling the right parotid gland and extending through the stylomandibular tunnel into the prestyloid compartment of the parapharyngeal space. The thin arrow indicates the styloid process, and the thick arrow indicates the dorsal edge of the ramus of the mandible.

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some tumors from any of the areas that surround it to any of the other bordering spaces (see Chapter 38).

The Peritonsillar Space

The palatine tonsil is surrounded by a capsule. Between this capsule and the laterally positioned superior pharyngeal constrictor muscle is a potential space that is limited anteriorly by the palatoglossus muscle and its fascia (the anterior tonsillar pillar) and posteriorly by the palatopharyngeus muscle and its fascia (the posterior tonsillar pillar). This space, called the peritonsillar or paratonsillar space, is filled with loose connective tissue. The space is inside (medial to) the constrictor muscles and the BPF and should not be confused with the paratonsillar division of the parapharyngeal space mentioned by Gaughran.9

A tonsillar infection can break through the tonsillar capsule into the peritonsillar space. Such an infection (quinsy) can produce bulging of the tissues about the tonsillar pillars, spreading cranially to the level of the hard palate and caudally to the pyriform sinus. However, these infections tend not to extend axially beyond the tonsillar pillars and their site of pointing.4

The ‘‘Paravertebral Space’’

The DLDCF extends from the spinous processes of the cervical vertebrae and the ligamentum nuchae to the left and right transverse processes of the cervical vertebrae. In so doing, this fascia covers the muscles of the upper back and the muscles of the ‘‘floor’’ of the posterior triangle. This space deep to the DLDCF has no official name; however, the term paravertebral space has been suggested as being anatomically appropriate. The space is adjacent to but separate from the prevertebral space, the danger space, and the carotid sheath structures (Drawings 2–5 and 8). (Fig. 34-4).

However, using reasoning based on imaging studies and the observation that the DLDCF surrounds both spaces, Harnsberger has suggested that this space and the prevertebral space are actually one space, the perivertebral space, and he refers to the prevertebral and paraspinal portions of the perivertebral space to describe the spaces more commonly known to the surgical community as the prevertebral and paravertebral spaces.27 It should be noted that the reluctance of most surgeons to utilize the Harnsberger classification stems from the observation that the DLDCF firmly attaches to the transverse processes of the cervical vertebrae, effectively separating the prevertebral and ‘‘paravertebral’’ spaces.

The ‘‘Posterior Triangle (Cervical) Space ’’

One final compartment or space deserves mention but lacks a common name. Grodinsky and Holyoke referred to this region as space 4A.2 This compartment lies between the SLDCF and the DLDCF, dorsal to the carotid sheath and ventral to the cervical vertebral spinous processes and the ligamentum nuchae. Its deep boundary is the DLDCF over the so-called paravertebral space, and its superficial bound-

ary is the SLDCF as it defines the posterior triangle of the neck.

This compartment contains mostly fat, hence the term coussinet adipose, or ‘‘small cushion of fat,’’ used in the French literature. The compartment also contains the spinal accessory nerve and its associated lymph node chain, and so has important surgical and radiologic significance. Potential descriptive terms include spinal accessory nodal space, posterior cervical nodal space, and posterior triangle space

(Drawings 2–5 and 8) (Figs. 34-2, 34-19, and 34-20). Harnsberger has suggested the term posterior cervical space.28

SUMMARY AND CONCLUSION

The most often quoted descriptions of the fasciae, compartments, and spaces of the head and neck have been discussed, and we have given our opinion as to the anatomy and terminology that are most widely accepted. It should be noted that some controversy still remains in the literature regarding the actual anatomy and the descriptive terminology. Some of the variations in the descriptions may be explained by the observation that these fascial sheets may be incomplete or absent in some people; dissection techniques may also account for some reported differences. In the face of such variations in the descriptions of the anatomy itself, it is difficult to expect a uniform terminology. However, the use of a common nomenclature would be an advantage in comparing information and in reporting cases. Such a standard language should use terms acceptable and recognizable to all groups interested in the field including anatomists, surgeons, and radiologists. Drawings 17 to 22 summarize the various spaces in the neck. Table 34-1 summarizes the contents of the various spaces, and Table 34-2 provides an approach to differential diagnosis based on the spaces.

FIGURE 34-19 Axial contrast-enhanced CT scan shows a cystic mass in the right neck deep to the sternocleidomastoid muscle and superficial to the muscles that comprise the floor of the posterior triangle of the neck. The mass fills this space, which has been variously referred to as the spinal accessory nodal space, the posterior cervical nodal space, the posterior triangle space, and the posterior cervical space. This lesion was a solitary lymphangioma in an adult but could just as easily have been a node in a patient with lymphoma.