Parotid region and facial nerve

Question 1

Where is the parotid gland located?

Answer 1

the parotid gland extends between the zygomatic arch and the lower border of the mandible (between SCM, external acoustic meatus and masseter)

Question 2

What is the parotid sheath?

Answer 2

The parotid sheath encloses the parotid duct and is part of the investing layer of deep cervical fascia

Question 3

Where does the parotid duct enter the oral cavity and which muscle does it pierce to do so?

Answer 3

The parotid duct travels horizontally and pierces the buccinator before enter the oral cavity near the upper 2nd molars

Question 4

Where does the parotid duct enter the oral cavity and which muscle doe it pierce to do so?

Answer 4

The parotid duct travels horizontally and pierces the buccinator before entering the oral cavity near the upper 2nd molars

Question 5

The parotid gland is the largest of the salivary glands, what type of secretions does it produce?

Answer 5

almost entirely serous secretions

Question 6

There are 4 key structures embedded in the parotid gland, name these

Answer 6

Retromandibular vein (from superficial temporal and maxillary)
ECA (posterior auricular, maxillary and superficial temporal)
Parotid lymph nodes
CN VII

Question 7

describe the parasympathetic control of the parotid gland

Answer 7

preganglionic fibres from CN IX travel to the otic ganglion in the tympanic nerve and lesser petrosal nerve
post ganglionic fibres from the otic ganglion pass to the auriculotemporal branch of CN V3

Question 8

Describe the sympathetic control of the parotid gland

Answer 8

Sympathetic innervation of the parotid gland is derived from the superior ganglion and the nerve plexus on the ECA- results in vasoconstriction and reduction in saliva production

Question 9

What is the intratemporal portion of CN VII?

Answer 9

The intratepmoral portion of CN VII is the first part of the nerve which travels through the temporal bone.
CN VII exits pons as 2 roots (motor and nervus intermedius) which fuse together to form the geniculate ganglion.
greater petrosal branches off here - sympathetic innervation of lacrimal glands
CN VII then runs downwards and gives off 2 branches before exiting the skull
The nerve to stapedius
The chorda tympani (runs with lingual nerve to supply taste and sensation to anterior 2/3 tongue

Question 10

Through which foramen does CN VII exit the skull

Answer 10

CN VII exits the skull via stylomastoid foramen

Question 11

After exiting through the stylomastoid foramen, the facial nerve immediately gives off which branches?

Answer 11

The facial nerve immediatley gives off the digastric branch (supplies posterior belly of digastric) and the posterior auricular nerve (auricularis posterior and occipital belly of occipitofrontalis muscle

Question 12

Name the 5 main branches of CNV II and where they branch

Answer 12

CN VII splits into 5 main branches in the parotid gland (parotid plexus). These are:
Temporal
Zygomatic
Buccal
Marginal mandibular
Cervical

Question 13

What does the temporal branch CN VII supply?

Answer 13

The temporal branch of CN VII supplies the muscles of the temple, forehead and supra-orbital area

Question 14

What does the zygomatic branch of CN VII supply?

Answer 14

The zygomatic branch of CN VII supplies the muscles of infra-orbital area, lateral nasal area and upper lip

Question 15

What does the buccal branch of CN VII supply?

Answer 15

The buccal branch of CN VII supplies the upper lip, muscles of the cheek and the corners of the mouth

Question 16

What does the marginal mandibular branch of CN VII supply?

Answer 16

The marginal mandibular branch of CN VII supplies the muscles of lower lip and chin

Question 17

What does the cervical branch CN VII supply?

Answer 17

The cervical branch of CN VII supplies the platysma

Question 18

Bells palsy is the most common type of facial paralysis.
Describe the clinical signs

Answer 18

temporary/ permanent unilateral facial paralysis
patient cannot wrinkle forehead (to distinguish from a stroke)
the cause is unknown- may be viral infection

Question 19

What are the treatment options for long term paralysis (+2 years)?

Answer 19

After 2 years with no improvement, static reconstruction may be considered for aesthetic purposes- creation of a sling that is attached to the mouth and side of face to create symmetry.
This is created using tensor fascia latae muscle from the lateral leg.
A small gold weight may be placed in the upper eyelid to assist in eye closure

Question 20

Which nerve can be used as a graft for CN VII?

Answer 20

The great auricular nerve (from ventral rami of C2 and C3).

Question 21

What is mumps?

Answer 21

Viral infection of the parotid gland.