Structure
The cheeks are flexible muscular walls which form the anterolateral boundary of the oral vestibule. They are lined on the superficial surface by skin and on their deep surface by mucosa. The cheeks are continuous with the lips medially and the soft tissue of the face in other directions. The mucosa of the cheeks is firmly adherent to the mouth, wrinkling when the cheek is relaxed and taut when the cheek is distended.
Posteriorly on the internal surface, a fold of mucosa containing the pterygomandibular raphe (the point of attachment for buccinator and the superior constrictor) is usually apparent. The parotid duct empties into the oral cavity at a small opening lateral to the 2nd molar tooth.
Relations
Medially, with the teeth, alveolar processes, oral cavity and lips
Superiorly with the zygomatic process and orbit
Inferiorly with the mandible
Posteriorly with the parotid gland
Macroscopic Appearance
The external cheek is usually covered by normal skin. A buccal fat pad may be prominent but is usually most visible in newborns. The internal cheek is pink-red in hue.
Microscopic Appearance
The cheeks are covered by normal skin on their external surface. Their internal surface is usually non-keratinising stratified squamous epithelium. This internal epithelium contains numerous submucosal buccal salivary glands.
Physiological Variations
The cheeks may be distended by increasing pressure in the oral cavity and relaxing the buccinator muscles. In cachetic patients the cheeks may appear sunken due to the loss of the buccal fat pad and muscle wasting.
Neurovascular Supply
Arterial Supply
The buccal artery arises from the maxillary artery (2nd part) and runs anteriorly between the medial pterygoid and the temporalis muscle. It supplies the skin and muscle of the cheek. The facial artery supplies small unnamed vessels
Venous Drainage
Buccal veins converge on the pterygoid venous plexus, between the temporalis and the lateral pterygoid. This plexus communicates widely, including with the cavernous sinus. Most blood is returned to the internal jugular vein via deep facial vein.
Lymphatics
Lymphatic drainage from the cheek is complex. The inferior and medial parts usually drain to submandibular nodes, whereas the lateral and upper parts may drain to parotid (pre-auricular) nodes. Buccal nodes may be present in the soft tissue of the cheek.
Innervation
The superior cheeks are primarily innervated by the infraorbital and zygomaticofacial branches of the maxillary nerve. The inferior skin of the cheeks is instead innervated by the buccal nerve, a branch of the mandibular.
Routes of Cancer Spread
Local Invasion
Tumours of the cheek may erode through the mucosa of the internal surface or the skin of the external surface. They may extend into the maxillary or mandibular bones, or cause obstruction of the parotid gland by invading the duct that passes through the cheek.
Lymphatic Spread
The upper and outer parts of the cheek usually drain to parotid nodes. The lower and medial parts of the cheek usually drain to submandibular nodes. Buccal nodes within the cheek may also be present.
Neurological
Tumours may invade and follow nerves back to the cranial cavity. For the medial part of the cheek, this usually occurs along the infraorbital nerve to the maxillary nerve. The buccal nerve supplies the lower part of the cheek and leads back to the mandibular nerve. Muscles of the cheek are supplied by the facial nerve which emerges from the styloid foramen.
Haemotogenous Spread
As for the lips, SCC usually spreads to lung, bone and then liver.
