Type:
Educational Exhibit
Keywords:
Neoplasia, Inflammation, Diagnostic procedure, Ultrasound, MR, CT, Salivary glands, Management, Head and neck
Authors:
B. S. D. Flor de Lima, E. F. M. P. Negrao, J. Rebelo, C. Sousa, J. N. C. Lobo; Porto/PT
DOI:
10.26044/ecr2019/C-3483
Background
The parotid gland is the largest salivary gland in the body.
It lies in the parotid space,
which is located posteriorly to the masticator space and laterally to parapharyngeal and carotid spaces.
It is composed of fat and glandular components,
both in the same amount.
Parotid can be divided into two lobes by a surgical cleavage plane composed by the facial nerve: a bigger superficial lobe,
and a smaller deeper lobe.
Since the facial nerve is hard to depict on imaging,
the gland may be divided by the retromandibular vein,
which lies medially to the nerve.
Lymph nodes are normally incorporated in the gland during embryogenesis,
unlike other major salivary glands.
Their short axis must be inferior to 5-6 mm.
The parotid gland is drained by the Stensen duct.
This duct leaves the gland and runs along the lateral border of the masseter muscle,
then curves medially through the buccinator muscle and,
finally,
opens at the vestibule,
near the second molar tooth.
The Stensen duct is hardly depicted on imaging unless it is dilated.
An ectopic accessory parotid gland is seen in 20% of the population,
placed anteriorly to the main gland and superiorly to the Stensen duct.
Parotid swelling may be caused by several different disorders and is more frequently unilateral.