Station - parotid gland

[admin]

1 Where do the secretions of the parotid gland drain?

Spoiler

The secretions of the parotid gland pass into the oral cavity via Stensons duct whose oral opening is opposite the second upper molar tooth.

2 Which structures pass through the parotid gland?

Spoiler

Facial nerve
External carotid artery
Retromandibular vein
Auriculotemporal nerve

3 What is the lymphatic drainage of the parotid gland?

Spoiler

It contains lymph nodes within the substance of the gland itself. It then drains to the deep cervical nodes.

4 Which nerves supply the parotid gland?

Spoiler

Parasympathetic-Secretomotor
Sympathetic-Superior cervical ganglion
Sensory- Greater auricular nerve

5 Outline where you would place the incision for a superficial parotidectomy.

Spoiler

The incision runs posterior to the mandible and up inferior to the tragus of the ear. Loss of cutaneous sensation to the ear lobe is therefore a risk of the procedure.

[Shamzy2020]

1/ Stenson's duct
2/ Main trunk of facial nerve, retromandibular vein, external carotid artery, auricular temporal nerve, parotid lymph nodes
3/ Superficial and deep parotid lymph nodes, which then empty into the superior deep cervical lymph nodes
4/ Facial nerve
5/ Modified Blair Incision

[Shamzy2020]

@admin said in Station - parotid gland:

The incision runs posterior to the mandible and up inferior to the tragus of the ear. Loss of cutaneous sensation to the ear lobe is therefore a risk of the procedure

The incision is called Modified Blair and the loss of cutaneous sensation is due to the sacrifice/ injury to the great auricular nerve (a branch of the facial nerve)

[Shamzy2020]

@admin said in Station - parotid gland:

Parasympathetic

Parasympathetic (secretomotor) innervation
The parasympathetic supply increases the production of watery saliva. Its pathway is long and complex, beginning with the glossopharyngeal nerve (CN IX).

1. Origin: The preganglionic parasympathetic fibers arise from the inferior salivatory nucleus in the brainstem.
2. Course: The fibers travel along the glossopharyngeal nerve and a small branch called the tympanic nerve, which passes through the middle ear.
3. Synapse: The fibers continue as the lesser petrosal nerve and synapse in the otic ganglion, which is a collection of nerve cell bodies near the base of the skull.
4. Supply: The postganglionic fibers then "hitchhike" along the auriculotemporal nerve (a branch of the trigeminal nerve) to reach and innervate the parotid gland. (Hence sometimes post parotidectomy when the great auricular nerve is sacrified or injured - it causes Frey's syndrome - where regenerating of parasympathetic fibers accidentally "rewire" themselves to connect with the sympathetic pathways that lead to the skin's sweat glands and blood vessels

Sympathetic innervation
The sympathetic supply reduces saliva production, causing a thicker, more viscous saliva via vasoconstriction.
• The postganglionic sympathetic fibers originate from the superior cervical ganglion and travel to the gland along the external carotid artery.

Sensory innervation
The parotid gland receives its sensory supply from two nerves.
• Auriculotemporal nerve: This nerve provides general sensory innervation directly to the substance of the gland.
• Great auricular nerve: This nerve, a branch of the cervical plexus (C2 and C3), supplies the sensory innervation to the tough fascia or capsule of the parotid gland.