The head and neck region is divided by fascial planes into a series of compartments. With the predominance of adipose tissue and its small size, the buccal space has not received an equitable representation in the literature relative to other compartments in this area. However, a variety of pathology may be seen because of its close relationship to important structures in and around this space. This article reviews the anatomy and pathology of this often-overlooked space, to help facilitate the diagnosis of lesions therein.
is a Musculoskeletal Fellow, Department of Diagnostic Radiology,
is Chief of Head & Neck Radiology, Division of
Neuroradiology, Department of Diagnostic Radiology, William
Beaumont Hospital, Royal Oak, MI.
This paper was originally presented at the American Society
of Neuroradiology 42nd Annual Meeting, Washington State
Convention & Trade Center, Seattle, WA. June 5-11, 2004.
The head and neck region is divided by fascial planes into a
series of compartments. Knowledge of these compartments and their
contents limits the daunting gamut of head and neck pathology to a
manageable differential diagnosis. The buccal space is one such
compartment that has not received an equitable representation in
the literature relative to other compartments, primarily because of
the predominance of adipose tissue and its small size. However,
because of the close relationship to important structures both in
and around this space, a variety of pathology may be seen. A
meta-analysis of the literature reveals the most common pathology
of the buccal space to be salivary gland tumors, especially
Other common etiologies of lesions are hemangiomas,
infection, and benign and malignant lymph nodes. Patients with
buccal space masses usually present with a cheek mass or swelling
that is readily apparent and palpable clinically. Although many
lesions have nonspecific characteristics on computed tomography
(CT) and magnetic resonance imaging (MRI), there are conditions
that do have distinctive findings. In general, the lack of
specificity of imaging is inconsequential, as most lesions are
excised, often for cosmetic reasons. This review is intended to
enhance the readers' knowledge of the anatomy (Figure 1) and
pathology of this often-overlooked space, thereby facilitating the
diagnosis of lesions therein.
Figure 1 presents an overview of the anatomy of the buccal space
and related spaces.
•Medial (Figure 1C)
a. Buccinator muscle
b. Pterygomandibular raphe-a fibrous band separating the oral
cavity and the oropharynx that lies between the tonsillar pillar
and the retromolar trigone. It may serve as a bridge for
pathology to extend from the retromolar trigone to the buccal
•Anterolateral (Figure 1, B and C)
a. Orbicularis oris, risorius, zygomaticus major and minor
b. Superficial layer of deep cervical fascia
•Posterior (Figure 1, B and C)
a. Masticator space
b. Parotid gland
c. Posteromedially, at the level of the hard palate (the
superior aspect of the buccal space), the superficial layer of
the deep cervical fascia (SLDCF) extending between the masseter
and the buccinator muscle is incomplete, allowing spread of
pathology between the buccal space and the masticator space. More
inferiorly, this fascia is complete.
•Inferior (Figure 1, D and E)
a. Continuous with the submandibular space
•Superior (Figure 1, D and E)
a. Continuous with the temporal fossa
•Buccal fat pad
a. Anterior compartment-superficial to the parotid duct
b. Posterior compartment-deep to the parotid duct, contains
specialized syssarcosis adipose tissue, a remnant of the
succatory fat pad that aids in muscle motion and is of lower CT
attenuation and of higher fat signal on MRI than all surrounding
fat, including the anterior compartment.
c. Four extensions
i. Lateral--follows the parotid duct to the parotid
ii. Medial--between the mandible and the maxillary sinus
iii. Superior--further divided into deep and superficial
based on relation to the temporalis muscle. The deep portion is
adjacent to the lateral orbital wall, anteromedial to the
The superficial portion is between the temporalis muscle and
iv. Anterior--superficial to the parotid duct
a. Separates the buccal space into anterior and posterior
b. Passes through the buccinator muscle at a level opposite
the second molar, causing slight retraction of the mucusa and the
a. Supplies the nasolabial region; direct branch of the
external carotid artery
a. Supplies the posterior buccal space; branch of the
b.Enters space through the incomplete SLDCF posteromedially;
anastomoses with the facial artery
a. Located just anterior to the parotid duct along the
b.Drains the nasolabial region to the external jugular vein
via the deep facial vein. Infection may spread from the deep
facial vein to the pterygoid plexus, to the inferior orbital
vein, to the cavernous sinus.
a. Buccal branch of the facial nerve CN V (sensory to skin and
the mucosa of the buccal space; originates just below the foramen
ovale and enters space through the incomplete SLDCF medially)
b.Buccal branch of CN VII (motor to muscles of facial
expression, originates within the parotid gland and courses
parallel to the parotid duct)
a. Buccal nodes to the submandibular nodes to the jugular
•Accessory parotid tissue
•Minor salivary (buccal) glands
a. Mucosa covering the inner surface of the buccinator
Pathology may arise de novo within the buccal space and spread
to surrounding structures or may arise in surrounding structures
and spread to the buccal space. As discussed above, the lack of
fascial compartmentalization superiorly, inferiorly, and
posteriorly permits the spread of pathology. Other routes of spread
include: 1) the pterygomandibular raphe and retromolar trigone and
2) the deep facial vein.
Rhabdomyosarcoma (RMS) is a malignant tumor of skeletal muscle.
Approximately 40% of cases arise in the head and neck (orbits 36%,
nasopharynx 15%, middle ear/mastoid 13%, sinonasal 8%, larynx 4%).
Rhabdomyosarcoma primarily affects children and young adults. It is
the most common sarcoma in children and the seventh most common
malignancy overall in children after leukemia, central nervous
system tumors, lymphoma, neuroblastoma, Wilms' tumor, and bone
cancer. Histological subtypes include embryonal/botryoid (75%, age
<10), alveolar (20%, nodal metastasis are most common in ages 15
to 25), and pleomorphic (5%, poorest survival, ages 40 to 60).
Prognosis correlates more closely with extent of tumor than with
histologic subtype. On imaging, skeletal muscle is invariably seen
as the site of origin (Figure 2). MRI reveals a homogenous mass
that is isointense to muscle on T1-weighted (T1W) images and
hyperintense on T2-weighted (T2W) images (Figure 2B). CT shows a
homogeneous mass that is isointense to muscle. The degree of
enhancement is similar to that of the surrounding muscle (Figure
Congenital vascular malformation
There are 2 major types of vascular lesions, true hemangioma and
vascular malformations. Vascular malformations are not neoplastic
but congenital anomalies. They are further divided into capillary
(port-wine stains or nevus flammeus), venous (cavernous), arterial
(including arteriovenous malformation and ateriovenous fistula),
and lymphatic malformations. Arterial malformations are considered
high-flow lesions, whereas malformations lacking arterial
components are low-flow. Vascular malformations are always present
at birth but may not be clinically apparent until early infancy or
childhood. They grow slowly and steadily but neither regress nor
Skeletal changes are more common than with hemangioma, and
vascular anomalies may be intraosseous or intramuscular. These
lesions may undergo rapid enlargement with trauma, infection, or
endocrine changes. Venous malformations are the subtype that most
commonly affects the oral cavity. On CT, they enhance brightly and
homogeneously and may contain phleboliths (Figure 3). Noncontrast
CT shows a lesion of muscle density. With MRI, flow voids may be
seen. The lesions are iso- to hyperintense to muscle on T1W images,
hyperintense on T2W images, and readily enhance. Treatment is
variable and includes steroid administration, laser
photocoagulation, sclerotherapy, embolization, interferon
administration, and surgical resection.
Infantile true hemangioma
This is a true neoplastic, benign condition. The term
should be applied only to lesions that present in early infancy,
enlarge rapidly, and involute by adolescence. They are rarely
present at birth, and 90% are evident by 6 months of age. Eighty
percent are solitary, and there is a 4:1 female predominance. Fifty
percent resolve completely by age 5; 70% resolve by age 7.
Clinically, hemangiomas are soft masses that may exhibit bruits and
may change in size with crying or straining. During the
proliferative phase, hemangiomas are high-flow lesions that may be
confused angiographically with high-flow vascular malformations. CT
and MRI findings are similar to those of congenital venous anomaly
(Figure 4). Hemangiomas are usually untreated unless
life-threatening complications occur. Such complications usually
occur during rapid growth and carry mortality rates as high as 30%.
They include include Kasabach-Merritt syndrome (consumption
coagulopathy), airway compression, bleeding, and ulceration.
Cystic lymphangioma (congenital lymphatic
Lymphangiomas comprise 5.6% of benign lesions of childhood and
No race or sex predilection is observed. Although 90% are detected
by age 2, 10% may present in adulthood (these are believed to be
acquired posttraumatically). They are classified clinically and
histologically into capillary lymphangioma, cavernous lymphangioma,
cystic lyphangioma (hygroma), and lymphangioma-hemangioma.
Capillary lymphangioma are cutaneous lesions that commonly affect
the oral region. Cavernous lymphangioma are subcutaneous and
commonly affect the oral cavity, neck, and tongue. They usually
present within the first months of life. Cystic lymphangioma
(hygroma) is most often present for imaging. Classically, it is
seen to insinuate between adjacent structures and appear as cystic
masses on CT and as high-intensity lesions on T2W images (Figure
5). There is a predilection for occurrence in the left posterior
neck, but they are generally cervical. Complications may arise when
mass effect is produced in places such as the submandibular and
sublingual region, the tongue, and the floor of the mouth, causing
dyspnea and dysphagia. This is especially seen in times of rapid
growth secondary to trauma, hemorrhage, or infection. On imaging,
they are large, single-or multiseptated masses of fluid
density/intensity, which exhibit variable enhancement of the
septae. Fluid-fluid levels may be seen with hemorrhage. High T1W
signal may be seen with hemorrhage or lesions with high protein or
Direct invasion by squamous cell carcinoma
Squamous cell carcinoma (SCCa) classically affects men aged 50
to 70 with a history of chronic alcohol and tobacco abuse. The
behavior of SCCa in the oral cavity is different from its behavior
in the oropharynx. The oropharyngeal mucosa, posterior to the
circumvallate papillae, is endodermal in origin and is typically
more affected by aggressive carcinomas, whereas the oral mucosa is
ectodermal in derivation and is affected by less aggressive
lesions. Oral SCCa tends to develop in 3 main areas: the floor of
the mouth, the ventrolateral tongue, and the soft palate complex
that includes the soft palate proper, retromolar trigone, and
anterior tonsillar pillar. In any of these areas or in any of the
structures around the buccal space, SCCa may invade directly.
Lesions in the retromolar trigone may extend into the masticator or
buccal space via the pterygomandibular raphe.
Squamous cell carcinoma has a variable, heterogeneous appearance on
CT and MRI (Figure 6).
Cellulitis/abscess of the buccal space
Infection is usually secondary to dental infections or
manipulation of calculi within the salivary gland duct system,
including the parotid and submandibular gland ducts. Infection can
arise de novo in the buccal space or can secondarily involve the
space from surrounding structures and compartments, especially the
masticator space and submandibular space, both of which have areas
of free communication with the buccal space. Cellulitis of the
buccal space occurs more often in patients <3 years of age, with
females and males affected equally. It commonly occurs in
fall/winter and may be associated with ipsilateral otitis media. CT
and MRI show edema and swelling of the subcutaneous fat (Figure 7).
Abscess may be seen in all ages. Diabetes mellitus and Crohn's
disease are risk factors. Crohn's patients may have recurrent
buccal space abscesses.
CT shows a hypodense mass with rim enhancement. T1W and T2W images
show signal less than and greater than muscle, respectively, as
well as rim enhancement.
Schwannoma is a nerve sheath tumor. While 13% occur in the
extracranial head and neck, most are found in the lateral cervical
region, where they originate from the sympathetic chain. The
typical age of occurrence is 30 to 40, with a slight female
predominance. On CT (Figure 8B), most of these tumors are of soft
tissue density, homogeneous, and well-circumscribed, and most
exhibit contrast enhancement. Cystic areas may be seen; they tend
to be isointense to muscle on T1W images and hyperintense on T2W
images (Figure 8A) and readily enhance.
Any benign and malignant tumor of the salivary gland primordium
may affect the buccal space. Pleomorphic adenoma is the most
common. Other pathologies include adenoid cystic carcinoma,
adenocarcinoma, acinic cell carcinoma, and basal cell adenoma.
Mucoepidermoid carcinoma accounts for 2.8% to 15.5% of all salivary
; half of these occur in major salivary glands, half in minor
salivary glands. In most series, it is the most common type of
malignant mi-nor salivary gland tumor. The age of most common
recurrence is 40 to 60, with a slight female predilection; however,
any age may be affected.
These tumors exhibit different grades of behavior and, therefore,
variable imaging characteristics (Figure 9). Previous radiation
exposure may be a risk factor for development.
These tumors are rare in the extracranial head and neck but are
common in the retroperitoneum and peripheral soft tissues. They
have been reported in the cheek, lip, soft palate, floor of mouth,
and submental regions. Their origin is from lipoblasts in or near
surrounding fascia and not from pre-existing lipomas. They occur
mostly in the fourth to sixth decades with a male predominance.
Prognosis depends on histologic subtype. On CT, their density is
greater than subcutaneous fat, and soft tissue elements are admixed
(Figure 10). The mass is of lower density than muscle, however. On
MRI, they exhibit fatty signal but of lower intensity than
subcutaneous fat. Lipoma of the buccal space is much more common
Plexiform neurofibroma, type I
Plexiform neurofibroma tumors are often seen in the subcutaneous
tissue and extend without respect for fascial planes into multiple
compartments. (The incidence of malignant transformation ranges
from 3.1% to 15%.
) Imaging findings show nodular and wormlike enhancement. Wormlike
projections are seen along the nerve ends (Figure 11). This is
pathognomonic of NF-I (Von Recklinghausen's disease).
Both Hodgkin's and non-Hodgkin's lymphoma (NHL) occur in the
head and neck. Lymph node enlargement is the most common
presentation. Non-Hodgkin's lymphoma frequently involves extranodal
sites. Primary lymphoma of the salivary glands is rare and is
classified as MALT (mucosa-associated lymphoid tissue) lymphoma, or
MALToma. Imaging findings are nonspecific (Figure 12).
Granulocytic sarcoma (chloroma)
Granulocytic sarcoma is the tissue manifestation of myeloid
leukemia and often precedes systemic relapse or progression from
the chronic to acute blast form. The term
comes from the green color of the immature myelocytes that are
imparted by the enzyme myeloperoxidase in the cytoplasm. Imaging
findings are nonspecific (Figure 13).
Ductolithiasis with sialadenitis
Most Stensen's duct stones are radio-opaque (Figure 14).
Sialolithiasis is 8 times more common in the sublingual ducts.
The buccal space often receives less attention than the other
spaces of the head and neck because of its small size and
predominantly fatty composition. However, because of the close
relationship to important structures both in and around this space,
a variety of pathology may be seen. These structures include the
parotid gland, masticator space, minor and ectopic salivary glands,
lymph nodes, muscle, sinuses, facial artery and vein, and other