Parotid bed

Question 1

Development of parotid

Answer 1

Weeks 6-7, three salivary glands start to develop from future oral cavity as solid epithelial buds. derived from neural crest cells, secretary portions of gland come from oral epithelium. Parotid 1st to appear.

Question 2

Parotid duct development

Answer 2

Solid cord of cells develop b/w maxillary/mandibular prominence, proceeds to ear but maintains connection with corner of mouth, 10th week the cord develops a lumen and becomes the parotid duct. terminal ends of cord become the secretory portions of gland, fully functional at 18th week and starts secreting saliva.

Question 3

Parotid structure

Answer 3

Largest salivary gland, contains serous acini,triangular, wedged between ramus of mandible and mastoid process.

Question 4

Parotid duct

Answer 4

two inches long, quarter inch in diameter. leaves anterior edge of gland, courses superficial masseter muscle and pierces buccinator to enter oral cavity. acts as a valve, opens in oral cavity opposite 2nd maxillary molar at parotid papilla. accessory parotid gland.

Question 5

CN VII and parotid gland

Answer 5

CN VII, enters posteriomedial after existing stylomastoid foramen, most superficial structure in parotid gland. gives off two branches before entering gland. posterior auricular nerve,motor nerve to poster belly of digastric and stylohyoid muscles. then gives of 5 branches within.

Question 6

Retromandibular vein

Answer 6

Lies deeper to CN VII, formed in the substance of parotid gland by junction of superficial temporal and maxillary veins. Retromandibular vein divides into anterior and posterior part. posterior part joins with posterior auricular vein to form external jugular vein, anterior joins with facial vein to drain into internal jugular.

Question 7

external carotid artery

Answer 7

lies deeper to retromandibular vein. external carotid enters the gland from its inferior surface, terminates in the parotid gland by giving off two terminal branches(maxillary and superficial temporal)

Question 8

Maxillary artery

Answer 8

proceeds anteriorly to enter the infratemporal fossa

Question 9

Superficial temporal artery

Answer 9

proceeds superiorly to supply the scalp

Question 10

Sympathetic innervation of parotid

Answer 10

Postganglionic fibers come from superior cervical ganglion and travel to parotid with external carotid. stimulation produces thick saliva

Question 11

Parasympathetic innervation of parotid

Answer 11

Branches of CN IX, tympanic nerve and lesser petrosal nerve, bring preganglionic fibers to otic ganglion. postganglionic fibers go from otic ganglion to parotid via auriculotemporal nerve, stimulation produces thin watery saliva.

Question 12

Infections of parotid gland

Answer 12

Mumps - acute, communicable viral infection of salivary glands(mainly parotid), glands swell causing severe pain because of parotid sheath.
Tumors - 80% of salivary gland tumors in parotid, parotidectomy can sometimes result in injury to facial nerve or its branches.