A 28-year-old woman presents with a 3-day history of progressive facial swelling and pain in the left cheek. On examination, there is marked edema of the left face with a fluctuant mass palpable over the left cheek anterior to the masseter muscle. The patient has a history of poor dental hygiene and a recent left lower molar extraction. Intraoral examination reveals purulent drainage from the extraction socket. Which anatomical space is most likely involved, and what is the primary route of spread of infection in this case?

Explanation

## Buccal Space Infection and Odontogenic Spread **Key Point:** The buccal space is a potential space bounded by the buccinator muscle medially and the skin/subcutaneous tissue laterally. Odontogenic infections from lower molars commonly spread to the buccal space via violation of the alveolar bone. ### Anatomy of the Buccal Space | Boundary | Structure | |----------|----------| | **Medial** | Buccinator muscle | | **Lateral** | Skin and subcutaneous tissue | | **Superior** | Zygomatic arch | | **Inferior** | Mandibular body | | **Anterior** | Modiolus (angle of mouth) | | **Posterior** | Anterior border of masseter | ### Odontogenic Spread Pathway ```mermaid flowchart TD A[Lower molar extraction/infection]:::outcome --> B[Perforation of alveolar bone]:::action B --> C{Bone perforation site}:::decision C -->|Buccal plate perforation| D[Buccal space infection]:::outcome C -->|Lingual plate perforation| E[Sublingual/submandibular space]:::outcome D --> F[Facial swelling anterior to masseter]:::action E --> G[Floor of mouth swelling]:::action ``` **Clinical Pearl:** The location of facial swelling depends on where the alveolar bone is perforated. Lower molars typically perforate the buccal plate because the buccal cortical plate is thinner than the lingual plate in the posterior mandible. **High-Yield:** Odontogenic infections are the most common source of deep space neck infections. The route of spread is determined by the anatomy of the tooth and the direction of bone perforation, not by lymphatic or vascular channels. ### Clinical Features of Buccal Space Infection - Facial swelling anterior to the masseter muscle - Fluctuant mass over the cheek - Intraoral swelling of the buccal mucosa - Trismus (if masseter involvement) - Origin: lower molars (most common) **Mnemonic: BUCCAL** — **B**uccinator medial boundary, **U**sually from lower teeth, **C**heek swelling anterior to masseter, **C**ause is odontogenic, **A**lveolar bone perforation, **L**ateral to buccinator muscle. [cite:Clinically Oriented Anatomy 8e Ch 8]