A "mucous cyst of the oral mucosa" (also known as a "mucocele") is a clinical term that refers to two related phenomena: mucus extravasation phenomenon, and mucus retention cyst. The former is a swelling

Swelling (medical)

In medical parlance, swelling is the transient enlargement or protuberance in the body and may include tumors. According to cause, it may be congenital, traumatic, inflammatory, neoplastic or miscellaneous....

 of connective tissue

Connective tissue

"Connective tissue" is a fibrous tissue. It is one of the four traditional classes of tissues . Connective Tissue is found throughout the body.In fact the whole framework of the skeleton and the different specialized connective tissues from the crown of the head to the toes determine the form of...

 consisting of collected mucin

Mucin

Mucins are a family of high molecular weight, heavily glycosylated proteins produced by epithelial tissues in most metazoans. Mucins' key characteristic is their ability to form gels; therefore they are a key component in most gel-like secretions, serving functions from lubrication to cell...

 due to a ruptured salivary gland duct

Duct (anatomy)

In anatomy and physiology, a duct is a circumscribed channel leading from an exocrine gland or organ.-Types of ducts:Examples include:-Duct system:...

 usually caused by local trauma, in the case of mucus extravasation phenomenon, and an obstructed or ruptured salivary duct (Parotid duct

Parotid duct

The parotid duct, also known as Stensen's duct, is the route that saliva takes from the parotid gland into the mouth.It passes through the buccal fat, buccopharyngeal fascia, and buccinator muscle then opens into the vestibule of the mouth next to the maxillary second molar tooth. The buccinator...

) in the case of a mucus retention cyst.