Citation, DOI & article data
The parotid gland is wrapped around the mandibular ramus and extends to a position anterior and inferior to the ear. It has superficial and deep lobes, separated by the facial nerve. Both superficial and deep lobes are connected through an isthmus located behind the ramus of the mandible 13.
The facial nerve and its branches pass through the parotid gland, as does the external carotid artery and retromandibular vein. The external carotid artery forms its two terminal branches within the parotid gland: maxillary and superficial temporal artery 13.
The gland usually contains several intraparotid lymph nodes. These lymph nodes are the first station of lymphatic drainage of the skin of the pinna and peri-auricular skin.
A fibrous capsule surrounds the gland, formed by the superficial (investing) layer of the deep cervical fascia, creating the parotid space. Posteriorly, this fascia condenses to form the stylomandibular ligament.
The inferior projection of the parotid is often referred to as the "tail", which overlies the angle of the mandible. The tail is not distinct from the rest of the gland, but it has been defined as the inferior 2 cm of the gland 11.
Anteriorly, there is often an accessory parotid gland, which may be separate from the main gland.
There is fatty infiltration or fatty replacement of the parotid glands with age 6.
lateral surface: subcutaneous tissue
anterior border: formed by the lateral edge of the anterior surface where it meets the masseter
deep surface: indented by the mastoid process and its attached muscles (sternocleidomastoid and posterior belly of the digastric), styloid process and its attached muscles (stylohyoid, styloglossus, stylopharyngeus) and two ligaments (stylomandibular, stylohyoid)
arterial: external carotid artery and a specific branch of the artery, the transverse facial artery
venous drainage: the retromandibular vein drains the parotid gland and eventually into the external jugular vein
Intraparotid nodes drain into the deep cervical chain.
sensory: auriculotemporal nerve, greater auricular nerve
facial process: anterior extension of glandular tissue along the parotid duct continuous with the main gland
ectopic parotid tissue
parotid duct duplication 7
congenital agenesis: either unilateral and bilateral 10
Ultrasound is often the first diagnostic procedure to evaluate morphological and structural changes of the parotid gland; for small (<3 cm) and superficial lesions, ultrasound and cytology are often sufficient for a definitive diagnosis 2.
appears homogeneous with increased echogenicity compared to nearby muscle 1
intraparotid lymph nodes are normally seen (unlike the submandibular gland)
limitations of ultrasound are:
difficulty visualizing deep lesions: the deep lobe is not able to be assessed as it is protected by the mandibular ramus
difficulty visualizing deep extension 3
CT and MRI provide useful additional diagnostic imaging if malignancy is suspected 4, with the sensitivity approaching 100% for detecting parotid neoplasms 5
the parotid duct and retromandibular vein are usually seen and approximate the plane separating the superficial and deep lobes 12
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