Here is a term paper on the ‘Parotid Gland of Ear’. Find paragraphs, long and short term papers on the ‘Parotid Gland of Ear’ especially written for school and college students.
Term Paper on the Parotid Gland of Ear
Term Paper Contents:
- Term Paper on the Meaning of Parotid Gland of Ear
- Term Paper on the Boundaries of Parotid Bed
- Term Paper on the Relations and External Features of Parotid Gland of Ear
- Term Paper on the Capsule and Structures Present within the Parotid Gland of Ear
- Term Paper on the Parotid Duct (Stensen’s Duct)
- Term Paper on the Applied Anatomy of Parotid Gland of Ear
Term Paper # 1.
Meaning of Parotid Gland of Ear:
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This is a Greek word comprising para means near or around and otos – Ear.
This is the largest salivary gland and is a compound tubulo-acinar-serous type of gland. It secrets water saliva.
Weight- About 15 to 30 gms
Shape- Irregular-wedge shaped
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Development- Buccal ectoderm
Situation- Parotid bed in parotid region is bony, muscular and fascia lined space.
Term Paper # 2.
Boundaries of Parotid Bed:
Anterior:
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Posterior border of ramus of mandible
Medial pterygoid muscle
Masseter muscle.
Posterior:
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Mastoid process
Anterior border of sternocleido mastoid muscle.
Superiorly:
Capsule of temporo-mandibular joint
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External auditory meatus.
Inferiorly:
Posterior belly of digastric
Stylohyoid.
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Floor:
Styloid process
Styloglossus, stylopharyngeus and stylohyoid muscle
Gland overflows out of structures of parotid bed.
Term Paper # 3.
Relations and External Features of Parotid Gland of Ear:
1. Superficial Surface:
It is related to:
i. Skin
ii. Superficial fascia
iii. Great auricular nerve (C2 and C3)
iv. Pre-auricular lymph nodes
v. Parotid masseteric fascia.
Apex:
Lower end of superficial surface is called apex. It crosses the posterior belly of digastric muscle and enters the carotid triangle. It is pierced by cervical branch of facial nerve, anterior and posterior divisions of retro-mandibular vein.
2. Superior Surface (Base of the Gland):
It is concave upper aspect of the gland and is related to:
(a) Temporo mandibular joint
(b) External auditory meatus.
This surface is pierced by:
(a) Superficial temporal vessels
(b) Auriculo temporal nerve
(c) Temporal branch of facial nerve.
An abscess formed in this surface may burst and open into the external auditory meatus.
It is not covered by parotid fascia.
3. Antero-Medial Surface:
Posterior border of ramus of mandible grooves this surface.
Surface is related to:
(a) Masseter muscle
(b) Posterior border of ramus of mandible
(c) Capsule of temporo mandibular joint
(d) Medial pterygoid muscle.
(e) Branches of facial nerve leave the gland through this surface.
4. Postero-Medial Surface:
It is a large surface and related to:
(a) Mastoid process of temporal bone
(b) Sternocleido mastoid muscle
(c) Posterior belly of digastric muscle
(d) Styloid apparatus
(e) External carotid artery enters the gland.
Styloid process separates the gland from the following structures:
(i) Internal jugular vein
(ii) Internal carotid artery
(iii) Glossopharyngeal, vagus and accessory nerves.
Anterior Border:
Separates the superficial surface from the antero medial surface.
From this border following structures are emerging:
(i) Zygomatic branch of facial nerve
(ii) Transverse facial vessels
(iii) Upper buccal branch of facial nerve
(iv) Parotid duct
(v) Lower buccal branch of facial nerve
(vi) Marginal mandibular branch of facial nerve.
Accessory parotid gland (Sociaparotid) when present it may be situated above the parotid duct.
External Features of Parotid Gland of Ear:
Surfaces – There are four surfaces of this gland.
1. Superficial surface – lower end is called apex.
2. Superior surface or base
3. Antero medial surface
4. Postero medial surface.
Term Paper # 4.
Capsule and Structures Present within the Parotid Gland of Ear:
Investing layer of deep cervical fascia splits at the lower pole of the gland divides into superficial and deep layers. Deep layer passes deep to gland and attached to the base of the skull. Superficial layer is called parotido-masseteric fascia, it is attached to the lower border of zygomatic arch. This fascia is not elastic and hence inflammations of the gland are highly painful.
Superior aspect of the gland has no proper capsule, posteriorly the capsule is defective. Here parotid space communicates with pharyngeal space.
Structures Present within the Parotid Gland:
(i) Facial nerve with its branches
(ii) Retro mandibular vein
(iii) External carotid artery.
Facial nerve is sandwiched between superficial and deep lobes of the parotid gland. An isthmus connects the two lobes.
Facial nerve crosses superficial to the retro-mandibular vein and external carotid artery.
(i) Facial Nerve:
Divides into following branches:
A. Temporo facial branch divides into:
(a) Temporal branch
(b) Zygomatic branch.
B. Cervico facial branch divides into:
(a) Upper and lower buccal branch
(b) Marginal mandibular branch
(c) Cervical branch.
(ii) Retro Mandibular Vein:
This is formed by union of superficial temporal vein and maxillary vein within the lower part of the gland and it divides into anterior and posterior divisions.
(iii) External Carotid Artery:
This is deeply situated within the gland. It terminates by dividing into superficial temporal and maxillary arteries.
Posterior auricular artery may be formed from the external carotid artery within the gland.
Term Paper # 5.
Parotid Duct (Stensen’s Duct):
Length- 5 cm
Formation- Formed within the gland by fusion of two ducts.
Emergence- It emerges through the anterior border of the parotid gland.
Course- It runs forwards on the lateral surface of the masseter muscle.
It is situated in between the upper and lower buccal nerves.
At the anterior border of the masseter muscle it turns medially and pierces the following structures:
i. Buccal pad of fat
ii. Bucco pharyngeal fascia
iii. Buccinator muscle
iv. Mucous membrane of the mouth.
Termination:
It terminates in the vestibule of the mouth at the level of upper second molar tooth. The terminal part of the duct is oblique. This oblique direction is acting like a valve.
Blood Supply:
From branches of external carotid artery.
Venous Drainage:
External jugular vein.
Lymphatic Drainage:
Parotid lymph nodes.
Nerve Supply of Parotid Gland:
A. Sympathetic Supply:
Plexus around external carotid artery. These fibres are vasomotor in function and derived from the superior cervical sympathetic ganglion.
B. Parasympathetic Supply (Secretomotor Supply):
Inferior salivatory nucleus → glossopharyngeal nerve → tympanic branch of glossopharyngeal → tympanic plexus → lesser superficial petrosal nerve → otic ganglion → postganglionic fibres join auriculo temporal nerve → parotid gland.
C. Sensory Supply:
Auriculo temporal nerve
Great auricular nerve.
Important Structures that Radiate from the Periphery of the Parotid Gland:
1. Superiorly:
i. Superficial temporal vessels
ii. Auriculo temporal nerve
iii. Temporal branch of facial nerve.
2. Anteriorly:
i. Transverse facial vessels
ii. Zygomatic branch of facial nerve
iii. Upper buccal branch of facial nerve
iv. Parotid duct
v. Lower buccal branch of facial nerve
vi. Marginal mandibular nerve (VII).
3. Inferiorly:
i. Cervical branch of facial nerve
ii. External jugular vein
iii. Great auricular nerve.
4. Posteriorly:
i. Occipital vessels
ii. Posterior auricular vessels and nerve.
Microscopic Structure of Parotid Gland:
i. Serous type of salivary gland.
ii. Glandular mass is covered by fibrous capsule.
iii. Capsule invades the gland as fibrous septae and divides the gland into lobes and lobules.
iv. Each lobule is formed by collection of alveoli.
v. Each alveolus has pyramidal shaped cells containing zymogen granules.
vi. Nucleus is kept along the base of the cell.
vii. Cells are anchored to the basement membrane.
viii. Zymogen granules are utilized in the synthesis of enzymes of the saliva.
ix. Basket cells support the serous cells of the alveolus. They help in squeezing the alveoli while releasing the saliva.
x. Secretory canaliculi open into the lumen of follicle, and are lined by cuboidal epithelium.
Term Paper # 6.
Applied Anatomy of Parotid Gland of Ear:
1. Swelling of parotid gland causes severe pain because of non-yielding tough parotid masseteric fascia.
2. Tumours arise usually from the lateral portion of the gland. Mixed tumours are commonest.
3. Parotid abscess may burst superiorly into external auditory meatus or may run medially towards the pharynx or it may perforate the fascia inferiorly and enter the neck.
4. Mumps- This is a viral infection of the parotid gland and involves both sides.
5. Calculus formation.
6. Parotid sialography – radiopaque dye is injected into the duct – to study the anatomy of parotid duct and gland.
7. While draining parotid abscess horizontal incision should be given to save the branches of facial nerve – Hiltons Law.
Infection from mouth can spread by parotid duct and involve parotid gland.