Fascial spaces of the head and neck

FASCIAL SPACES OF THE FACE The fascial spaces of the face are subdivided into five spaces: the canine space, the buccal space, the masticatory space (further divided into the masseteric,

pterygomandibular, and temporal spaces), the parotid space, and the infratemporal space ( Figure 8-1, _A _). CANINE SPACE The canine space is located between the levator anguli oris and the

levator labii superioris muscles. Infection spreads to this space through the root apices of the maxillary teeth, usually the canine. Direct surgical access is achieved through incision

through the maxillary vestibular mucosa above the mucogingival junction ( Figure 8-1, _B _). BUCCAL SPACE The buccal space is bounded anterior to the masticatory space and lateral to the

buccinator muscle, with no true superior or inferior boundary, and consists of adipose tissue (the buccal fat pad that fills the greater part of the space), Stensen’s duct, the facial artery

and vein, lymphatic vessels, minor salivary glands, and branches of cranial nerves VII and IX. The buccal space frequently communicates posteriorly with the masticatory space because the

parotideomasseteric fascia is sometimes incomplete along its medial course where it joins the buccopharyngeal fascia. The parotid duct separates the buccal space into two equal-sized

anterior and posterior compartments, with the facial vein located along the lateral margin of the buccinator muscle just anterior to transversely coursing Stensen’s duct. The buccal space

may serve as a conduit as there is a lack of fascial compartmentalization in the superior, inferior, and posterior directions, which permits the spread of pathology both to and from the

buccal space. Surgical access to the buccal space infections may be easily accomplished through the intraoral approach. However, more complicated infections or masses, directed by location

within the buccal space and suspicion of malignancy, may require a preauricular or submandibular approach. PAROTID SPACE The parotid space is formed by splitting fascia of the investing

layer of the deep cervical fascia and contains the parotid gland with associated extraglandular and intraglandular lymph gland, the parotid portion of cranial nerve VII, the external

carotid, internal maxillary, and superficial temporal arteries, and the retromandibular vein. Infection in this space may spread to the lateral pharyngeal spaces, as they communicate

posteriorly and the fascia of the deep parotid space is thin and easily breached. However, primary infection in this is rare and is generally blood-borne or retrograde through the parotid

duct. MASTICATORY SPACES MASSETERIC SPACE (AND SUBMASSETERIC SPACE) The fascia that forms the borders of the masseteric space is a well-defined fibrous tissue that surrounds the muscles of

mastication and contains the internal maxillary artery and the inferior alveolar nerve. It is bounded anteriorly by the mandible, posteriorly by the parotid gland, medially by the lateral

pharyngeal space, and superiorly by the temporal space. Most masseteric space infections are of odontogenic origin (e.g., molar teeth), with trismus being the most pronounced clinical

feature, and often preclude intraoral examination. Computed tomography (CT) or magnetic resonance imaging (MRI) may be an invaluable resource in the assessment of masseteric space

infections, as it can often influence the surgical approach and distinguish abscess from cellulitis. The submasseteric space is bounded laterally by the masseter muscle, medially by the

mandible ramus, and posteriorly by the parotid gland. Infections are mostly of odontogenic origin (usually a mandibular third molar) and are often misdiagnosed as a parotid abscesses or

parotitis. Intraoral surgical access to this space for simple, isolated abscesses is generally adequate to allow for drainage, but with extension into adjacent spaces, an extraoral

submandibular approach may be required ( Figure 8-1, _C _). PTERYGOMANDIBULAR SPACE The pterygomandibular space is bounded by the mandible laterally and medially and inferiorly by the medial

pterygoid muscle. The posterior border is formed by the parotid gland as it curves medially around the posterior mandibular ramus and anteriorly by the pterygomandibular raphe, the fibrous

junction of the buccinator and superior constrictor muscles. The inferior alveolar and lingual nerves, other structures in this space, are of particular importance in the administration of

local anesthesia, including the inferior alveolar vessels, the sphenomandibular ligament, and the interpterygoid fascia. Surgical access to this space may be achieved intraorally in the case

of simple infections, but may require extraoral access when multiple adjacent spaces are involved. TEMPORAL SPACE The temporal fascia surrounds the temporalis muscle in a strong fibrous

sheet that is divided into clearly distinguishable superficial and deep layers that originate from the same region with the muscle fibers of the two layers intermingled in the superior part

of the muscle. It attaches to the superior temporal line and passes inferiorly to the zygomatic arch. Superiorly, the temporal fascia and fibers of origin of the temporalis muscle blend into

a firm aponeurosis, a flat fan of extremely dense and firm fibrous connective tissue. Communicating facial-zygomaticotemporal nerve branches piercing through the fascial and muscular planes

of the intermingled superficial and deep layers of the temporal fascia in the superior part of the muscle are important from a surgical perspective to prevent temporal hollowing that may

occur due to surgical access procedures.