1. PAROTID REGION
STEVEN J. ZEHREN, PH.D.

2. GENERAL REMARKS

3. GENERAL REMARKS AND RELATIONSHIPS
Sublingual fold
Parotid gland
Cervical branch of VII
The PAROTID GL. is the largest of the three major salivary glands (~ 25 gm) . It is wedge-shaped in outline with the base of the wedge superior and the apex inferior (near the angle of the mandible).
The SUBMANDIBULAR GL. is intermediate in size (walnut) and shaped like the letter U lying on its side. The larger, superficial part of the gland is continuous with the smaller, deep part around the post. border of the mylohyoid m. The SUPERFICIAL PART of the gland fills up the submandibular triangle and is RELATED TO the ant. and post. bellies of the digastric. Lying medially are the mylohyoid and hyoglossus mm. (which form the floor of the submandibular triangle). Laterally the superficial part of the gland is related to the submandibular fossa of the mandible, the cervical br. of VII and the facial v. The DEEP PART of the gland has the SUBMANDIBULAR DUCT emerging from it.
The SUBLINGUAL GL. is the smallest (almond) sized and is elongate. Its RELATIONSHIPS are as follows: INFERIORLY is the mylohyoid m. and SUPERIORLY is the sublingual fold (of mucous membrane).
Sublingual gland
Digastric m.
(posterior belly)
Mylohyoid m. (cut)
Digastric m. (anterior belly)
Facial vein
Submandibular gland

4. SALIVARY GLANDS (HISTOLOGY)
Parotid gland is totally serous.
2. Submandibular gland is mostly serous, partly mucous.
3. Sublingual gland is almost completely mucous.
PAROTID GLAND:
Totally serous
SUBMANDIBULAR GLAND:
Mostly serous; partly mucous
SUBLINGUAL GLAND:
Almost completely mucous

5. Palatine glands Molar minor salivary glands
In addition to the three major salivary glands, there are accessory salivary glands including those in the palate, behind the molar teeth, and in the lips and tongue.

6. RELATIONSHIPS
OF THE PAROTID GLAND
(PAROTID BED)

7. PAROTID BED (RELATIONSHIPS OF PAROTID GLAND)
Ext. auditory meatus
Mastoid process
Ramus of mandible
Styloid process
Sternocleidomastoid m.
Stylohyoid m.
Post. belly of digastric m.
Carotid sheath (& contents)
The PAROTID "BED" is the "resting place" for the gland. The parotid bed can be thought of as an irregular-shaped "mold" (formed by bones and muscles) in which the gland ("cast") lies. Anteromedially the parotid bed is formed by the ramus of the mandible and two muscles (not shown) --- the masseter and medial pterygoid. Posteromedially the bed is formed by the mastoid and styloid prs. and their associated muscles (SCM, post. belly of digastric, stylohyoid). The styloid pr. and its muscles separate the parotid gl. from the int. carotid a., IJV and IX - XII. Superiorly the bed is formed by the ext. acoustic meatus.

8. PAROTID BED (HORIZONTAL SECTION)
Masseter m.
Ramus of mandible
Medial pterygoid m.
Facial n. (VII)
Retromandibular v.
A HORIZONTAL SECTION THROUGH THE PAROTID GL. AND BED reveals that the gland is wedge-shaped in cross section as well. The lateral surface of the gland is subcutaneous. The anteromedial and posteromedial surfaces meet at the medial border of the gland. Note how the ramus of the mandible, masseter and med. pterygoid indent the anteromedial surface of the gland whereas the SCM and post. belly of digastric indent the posteromedial surface.
Ext. carotid a.
Parotid gland
Stylohyoid m.
Sternocleidomastoid m.
Post. belly of digastric m.
Carotid sheath & contents

9. LATERAL PHARYNGEAL SPACE
Oropharynx
Superior constrictor
of pharynx
Lateral pharyngeal space
The anteromedial and posteromedial surfaces of the parotid gland meet at the medial border of the gland which is closely related to the wall of the pharynx (formed at this level by the sup. pharyngeal constrictor). Tumors of the parotid gl. may grow medially (through the lateral pharyngeal space) and push into the pharyngeal wall.
Medial pterygoid
Parotid gland

10. STRUCTURES WITHIN
THE PAROTID GLAND

11. Facial n. Retromandibular v. External carotid a.
THREE IMP. STRUCTURES PIERCE THE PAROTID GL. They are VII, the retromandibular v. and the ext. carotid a. (from superficial to deep). The retromandibular vein and ECA provide blood supply to the gland.
External carotid a.

12. FACIAL NERVE (VII) WITHIN PAROTID GLAND
Temporal branches
Zygomatic branches
Note how VII, after penetrating the parotid gl., divides into its terminal brs. These branches of VII (“To Zanzibar By Motor Car”) fan out from the margins of the gland to supply the muscles of facial expression. Malignant tumors of the gland destroy VII causing facial paralysis. Benign tumors usually do not invade VII. Hence, surgical removal of these tumors requires great skill to avoid damaging VII. For this reason VII has been called the "hostage of parotid surgery".
Main trunk of VII
TO ZANZIBAR BY MOTOR CAR
Buccal branches
Marginal mandibular branch
Cervical branch

13. Temporofacial division Temporal br.
Medial pterygoid m.
Ramus of mandible
Main trunk of facial n.
Masseter m.
Mastoid process
Parotid gland
Temporofacial division
Temporal br.
Zygomatic brs.
Main trunk of facial n.
Buccal brs.
Again, note how the main trunk of the facial n. penetrates the parotid gland. The nerve divides the gland into superficial and deep lobes.
Cervicofacial division
Marginal mandibular br.
Cervical br.

14. Superficial temporal v. Maxillary v.
Facial v.
Posterior auricular v.
Retromandibular v.
Common facial v.
(to IJV)
External jugular v.
The retromandibular v. is formed within the parotid gland by the junction of the superficial temporal v. (draining the scalp) and the maxillary v. (draining the infratemporal fossa).

15. Superficial temporal a.
Maxillary a.
External carotid a.
The external carotid a. terminates within the parotid gland by dividing into the superficial temporal a. and maxillary a. (Note that the maxillary a. (and vein) pass deep to the ramus of the mandible and are difficult to see until the ramus is removed.)

16. PAROTID FASCIA

17. PAROTID FASCIA Parotid fascia Investing layer of deep cervical fascia
The PAROTID FASCIA forms a strong capsule around the gland and limits its swelling (eg, in "mumps"). Pain from mumps is also evident during chewing because movement of the mandible impinges on the swollen gland. The parotid fascia is continuous with the investing layer of cervical fascia.

18. Stylomandibular lig. Stylomandibular lig. Submandibular fossa
The stylomandibular ligament is a thickening of the deep part of the parotid fascia. It separates the parotid gland from the submandibular gland (point out submandibular fossa of mandible).
Stylomandibular lig.
Submandibular fossa

19. PAROTID DUCT
(STENSON’S DUCT)

20. RELATIONSHIPS OF PAROTID DUCT
Zygomatic arch
Transverse facial a.
Accessory parotid gland
Parotid duct
Buccinator m.
Masseter m.
Parotid gland
The PAROTID DUCT, branches of VII and various vessels (superficial temporal, transverse facial) radiate from the margins of the gland. The parotid duct crosses superficial to the masseter (~ a finger’s breadth below the zygomatic arch) where it can be palpated when this muscle is clenched. At the ant. border of the masseter the duct bends medially, pierces the buccinator and opens into the oral vestibule opposite the crown of the second maxillary molar.
After piercing the buccinator, the parotid duct passes forward for a short distance between the muscle and the mucous membrane and finally opens into the oral vestibule on a small papilla, opposite the upper second molar. The oblique passage of the duct forward between the mucous membrane and the buccinator serves as a valve-like mechanism and prevents inflation of the duct system during blowing. (However, with prolonged violent blowing, as occurs in Venetian glass blowers and trumpet players like Louis Armstrong, air may enter the duct system and cause “puffy cheeks.”)
The parotid duct may become occluded by a mineral deposit (calculus). Such a deposit can be visualized radiologically by injecting an opaque dye into the opening of the duct (SIALOGRAM). The dye will flow retrogradely to the point of obstruction. Obstruction can also be detected by asking a patient to suck on a lemon. This will be painful because the increased secretions can not reach the oral cavity and the gland becomes swollen.
Optional note:
Sometimes a part of the parotid gland is detached from the main portion (accessory parotid gl.) as shown here.

21. TERMINATION OF PAROTID DUCT
Parotid papilla
(opposite maxillary 2nd molar)
The opening of the parotid duct is marked by a PAPILLA. Viral inflammation of the parotid gl. ("mumps") can also affect the duct and papilla causing the latter to be red. A red papilla may therefore indicate parotid disease although the patient may complain of a tooth ache. Bacteria from the oral cavity can spread retrogradely to the parotid gl. via its duct.

22. NERVE SUPPLY TO THE
PAROTID GLAND

23. AUTONOMIC INNERVATION OF PAROTID GLAND
Otic ganglion
Lesser petrosal n.
IX (Glossopharyngeal n.)
Auriculotemporal n.
Inf. salivatory nucleus
Parotid gland
Medulla
Tympanic plexus
Tympanic n.
Note Key: Parasympathetic blue, presynaptic fibers solid blue
The PARASYMPATHETIC INNERVATION OF THE PAROTID GL. INVOLVES IX. Presynaptic fibers have their somata in the INF. SALIVATORY NUCLEUS. These fibers travel in IX and then branch off (TYMPANIC N.) at the level of its inf. ganglion. The tympanic n. enters the tympanic (middle ear) cavity through a tiny canal, the tympanic canaliculus. Within the middle ear the tympanic n. contributes to the TYMPANIC PLEXUS. Beyond the plexus the tympanic n. becomes the LSR. PETROSAL N. which leaves the middle ear through its own hiatus. After a short course in the middle cranial fossa the lsr. petrosal n. leaves through the f. ovale. It then enters the infratemporal fossa where it synapses in the OTIC GANGLION. From the otic ganglion postsynaptic fibers travel in the nearby AURICULOTEMPORAL N. (br. of V3) to the parotid gl. Parasympathetic innervation stimulates secretion of the gland. (It is interesting that VII, which penetrates the gland, is not involved in its innervation).
Optional:
The SYMPATHETIC SUPPLY TO THE PAROTID GL. involves the UPPER THORACIC SPINAL CORD, SUP. CERVICAL GANGLION (SYNAPSE) and the EXT. CAROTID PLEXUS. Sympathetic innervation decreases secretion.
Presynaptic parasympathetic
Postsynaptic parasympathetic

24. AUTONOMIC INNERVATION OF PAROTID GLAND (DISSECTION, MEDIAL VIEW)
Tympanic cavity
V3 (Mandibular n.)
Otic ganglion
Orient: Note upper and lower jaws w/teeth, muscle of mastication (medial pterygoid), tympanic cavity, cranial cavity. IX, tympanic nerve, and tympanic plexus are NOT shown.
Lesser petrosal nerve (w/presynaptic parasympathetic fibers) emerges from tympanic cavity, enters cranial cavity, then leaves cranial cavity to enter infratemporal fossa where its fibers synapse in the otic ganglion. Postsynaptic fibers then travel via the auriculotemporal n. to reach the parotid gland behind the ramus of the mandible (not shown).
Auriculotemporal n.
Lesser petrosal n.

25. SENSORY INNERVATION TO THE PAROTID GLAND
Auriculotemporal n. (V3)
The AURICULOTEMPORAL N. IS SENSORY TO THE PAROTID GL. As its name suggests, this nerve is also sensory to the auricle (ext. ear) and temple, and to the TMJ. Pain from parotid disease can therefore be referred to these areas.

26. FREY’S SYNDROME
(GUSTATORY SWEATING)

27. FREY’S SYNDROME Auriculotemporal n. (V3) Great auricular n. (C2,3)
FREY'S SYNDROME (gustatory sweating) is an interesting complication that sometimes develops following penetrating wounds of the parotid gl. or after parotid surgery. When the patient eats beads of perspiration appear on the skin over the gland. The cause of this condition is damage to the auriculotemporal and gr. auricular nn. During healing parasympathetic fibers in the auriculotemporal n. grow out and join the distal ends of the gr. auricular n. (which supplies the skin over the gland). Eventually these fibers reach the sweat gls. in the skin (recall that sweat gls. receive a cholinergic innervation). Thus, a stimulus intented for saliva production produces sweating instead!
Great auricular n.
(C2,3)

28. Gustatory Sweating (Frey's Syndrome)
This woman had undergone a parotidectomy for a benign mixed tumor of the parotid gland a year before this photo was taken. The picture was taken just as she was taking some food by mouth.
Note that upon gustatory stimulation there is localized sweating over the area where the skin flap was raised for the parotidectomy. With removal of the parotid the secretory fibers carried by the auriculotemporal nerve were cut. These unsatisfied nerve ends regrew to join the sympathetic nerve ends on the elevated skin flap. When parotid secretion is called for the sweat glands respond.
From Mosby, “Clinical Anatomy Interactive Lesson”

29. TREATMENT & PREVENTION OF FREY’S SYNDROME
MEDICAL
1. Topical anticholinergic creams/lotions.
2. Intracutaneous injection of Botulinum toxin A.
SURGICAL
1. Transmeatal tympanic neurectomy.
2. Procedures which involve the interposition of a
tissue barrier (eg., fascia lata or fat grafts).
3. Sternocleidomastoid muscle flap.
Treatment of Frey’s syndrome:
a Medical
1. Topical anticholinergic or antiperspirant creams/lotions. Drawbacks include only temporary relief, visibility when applied, and side effects such as local irritation to skin, blurred vision, and tachycardia.
2. Intracutaneous injection of Botulinum toxin A. Drawbacks include pain at the site of injection and
temporary weakness of the upper lip.
b Surgical
1. Transmeatal tympanic neurectomy. This procedure aims to interrupt the parasympathetic fibers running in the tympanic branch of IX. Drawbacks include the technical difficulty of the procedure and recurrence of symptoms have been reported.
(see next slide).
2. Procedures which involve the interposition of a tissue barrier, e.g., facia lata or fat grafts. These procedures aim to interrupt the anastomotic communication between the secretomotor fibers and adjacent sweat glands. Drawback is risk of damage to VII.
3. Sternocleidomastoid muscle flap. (see later slide).

30. TYMPANIC NEURECTOMY Promontory of middle ear cavity with
Orient (middle ear cavity, lateral view; tympanic membrane has been removed):
Transmeatal tympanic neurectomy. This procedure aims to interrupt the parasympathetic fibers running in the tympanic branch of IX. Drawbacks include the technical difficulty of the procedure and recurrence of symptoms have been reported.
Promontory of middle ear cavity with
tympanic nerve (branch of IX) and plexus
under mucosa
Mastoid process

31. STERNOCLEIDOMASTOID MUSCLE FLAP ROTATED
ONTO THE DEEP LOBE OF THE PAROTID GLAND
Because the treatments listed above are not always effective and often have unwanted risks and adverse effects, there has been a shift toward preventing Frey’s syndrome with prophylactic procedures at the time of parotidectomy. These procedures include the use of sternocleidomastoid (SCM) muscle flaps and temporoparietal fascia flaps (TPFFs). The advantage of these procedures is that they use tissue from regions adjacent to the parotidectomy site both to prevent Frey’s syndrome and to reconstruct the associated retromandibular contour deformity.
SCM muscle flaps—The SCM receives its blood supply from the occipital artery superiorly, from the superior thyroid artery in its mid-portion, and from the transverse cervical artery inferiorly. Therefore, the muscle can be partly divided and its superior part rotated over the parotid bed in a fan-like manner. The muscle is sutured over the parotid gland bed from the zygomatic arch to just below the mandible. It is important to cover as much of the parotid bed as possible because any area left uncovered leaves a potential unobstructed pathway for regrowth of aberrant fibers into the sweat glands of the skin. Potential complications of using the SCM flap include injury to XI and bleeding leading to hematoma formation.

32. BLOOD SUPPLY &
LYMPHATIC DRAINAGE
OF THE PAROTID GLAND

33. Superficial temporal a.
Maxillary a.
External carotid a.
The ARTERIAL SUPPLY TO THE PAROTID GL. is via the ext. carotid a. and its terminal brs., the superficial temporal and maxillary aa.

34. Superficial temporal v. Maxillary v.
Facial v.
Posterior auricular v.
Retromandibular v.
Common facial v.
(to IJV)
External jugular v.
The VENOUS DRAINAGE OF THE PAROTID GL. is into the retromandibular v.

35. Parotid nodes Deep cervical nodes
Lymphatic drainage of the parotid gland is to the parotid and deep cervical nodes.

36. END OF LECTURE