The Mouth and Face 5

Question 1

What does the facial nerve lie superficial to in the parotid gland?

Answer 1

• retromandibular vein
• external carotid artery
• terminal branches of the external carotid artery

Question 2

What are the terminal branches of the facial nerve?

Answer 2

• temporal branches - the facial nerve that passes upwards to the temporal region
• zygomatic branches - across the zygomatic arch
• buccal branches - across the cheek
• mandibular branches - along the mandible
• cervical branches - into the neck

Question 3

What does the cervical branch of the facial nerve innervate?

Answer 3

It innervates the platysma.

Question 4

What does the small posterior auricular branch supply?

Answer 4

It passes back to supply the posterior belly of the digastric and the stylohyoid muscles.

Question 5

What is sensory supply to the skin of the face and the forehead through?

Answer 5

It is through cutaneous branches of the 3 divisions of the trigeminal nerve.

Question 6

How is light, touch, pressure and temperature and pain conveyed to the trigeminal nuclei in the brain?

Answer 6

Via the 3 divisions of the trigeminal nerve and each of these sensations can be tested clinically and mapped out on the face in the distributions of each distributions of each division of the nerve to its dermatome.

Question 7

What is another name for swallowing?

Answer 7

This is also called deglutination.

Question 8

What is swallowing controlled by?

Answer 8

It is controlled by ref;exes that involve the 9th, 10th and 11 cranial nerves in the brainstem.

Question 9

What are 2 things that are fundamental to the swallowing mechanism?

Answer 9

Food must be prevented from entering the nose and the airway.

Question 10

What are choking and food passing up into the nose symptoms of?

Answer 10

These are both symptoms of bulbar palsy.

Question 11

What is balbar palsy?

Answer 11

This is degeneration of the cranial nerves 9 and 10.

Question 12

Is the first stage of swallowing voluntary or involuntary?

Answer 12

It voluntary.

Question 13

What does the first stage of swallowing involve?

Answer 13

It involves movements of the tongue in the mouth.

Question 14

Describe what happens during the first stage of swallowing.

Answer 14

• tongue is raised and pressed against the roof of the mouth
• bolus of food is moved back towards the oropharynx
• teeth come together to stabilise the mandible so that muscles can act together the mandible

Question 15

What happens during the second stage of swallowing?

Answer 15

• soft palate is raised and tensed against the posterior wall of the pharynx
  
  • prevents food from entering the nose
• pharynx constricts at the pharyngeal isthmus
• bolus of food passed back to the oropharynx by the tongue
• contractions of the pharyngeal constrictor muscles move the bolus down through the oropharyx towards the laryngopharynx
  
  • as this happens there is first an anterior movement of the hyoid bone in the neck. This is followed by elevation of the larynx by the equivalent of 2 cervical vertebral segments. Therefore the larynx is pulled upwards and forwards to the back of the base of the tongue.

Question 16

What is the action of the aryepiglottic muscles during the second phase of swallowing?

Answer 16

These muscles have a really important sphincteric action around the laryngeal inlet.

Question 17

What else contributes the sphincteric action of the laryngeal inlet?

Answer 17

There are also other muscle fibres in the wall of the inlet that contribute to this sphincteric tightening of the laryngeal inlet.

When contracted these can also help to guide food and drink either side of the laryngeal inlet.

Question 18

What occurs in the 3rd stage of swallowing?

Answer 18

Inferior constrictor muscle squeezing the bolus of food out of the laryngopharynx through the cricopharyngeal sphincter and into the oesophagus.

Question 19

Cleft lip and cleft palate are ………………………….

Answer 19

Congenital abnormalities.

Question 20

Why do cleft lip and cleft palate arise?

Answer 20

They arise through the incomplete fusion of the maxillary processes of the mandibular arch during development.

Question 21

What are the 2 types of clefts that occur?

Answer 21

They can be either unilateral or bilateral.

Question 22

Clefts occur when what fails to fuse?

Answer 22

Failure of fusion of the embryonic process.

Question 23

What is one cause of the failure of fusion of the embryonic process?

Answer 23

The maxillary processes are held apart by the developing tongue which remains high if the fetus fails to unflex. Therefore the tongue is unable to drop into the mouth in this circumstance.

Question 24

How are clefts best described and classified?

Answer 24

With reference to the structures that they affect - they may involve the lip only = hare lip, lip and alveolar process of the maxilla, or they could extend into the hard palate and the soft palate.

Clefts may be as small as bifid uvula which is of little consequence

Question 25

When are cleft lips repaired?

Answer 25

These are repaired soon after birth.

Question 26

When are cleft palates repaired?

Answer 26

They are repaired a bit later than the cleft lip, initially they are repaired by freeing the mucosa from the bone of the hard palate on each side and bringing them together in the midline. Attempts of bony repair are carried out later in childhood.

Question 27

In what bone are fractures common?

Answer 27

Fractures of the mandible are common.

Question 28

Which fractures are left to remodel without any treatment?

Answer 28

Fractures of the mandibular condyles - these typically follow a blow to the chin.

Question 29

Describe the more serious fractures.

Answer 29

These can occur in many places along the body or the chin or across the ascending ramus. Fractures such as these require fixation.

Question 30

What does the direction of the fracture line determine?

Answer 30

It determines whether or not the muscles of mastication hold the broken ends of the bone in place.

Question 31

What happens to favourable fractures?

Answer 31

These are held together.

Question 32

How are favourable fractures held together?

Answer 32

These are held together by the contraction of the masticatory muscles.

Question 33

How can we test the facial nerve?

Answer 33

Asking patients to screw up their eyes and show their teeth.

If the patient is not able to do this then this could indicate that they have facial nerve palsy or Bell’s palsy - this follows the inflammation of the facial nerve in the facial canal in the petrous temporal bone.

Question 34

How does an upper motor neurone lesion affecting the facial nerve, such as a stroke, present?

Answer 34

Since fibres from the right and left sides of the brain both innervate the muscles above the level of the eye, the orbicularis oculi remains unaffected in UMN lesions on one side of the brain.

Lower facial muscles only recieve muscle fibres from only one side of the brain and therefore they are unable to produce voluntary movements in UMN lesions of the same side of the brain, as they are in Bells palsy.

Therefore patients that suffer damage to the 7th cranial nerve due to stroke can still voluntariliy move the muscles around the eye and the forehead but those with Bells palsy cannot do this.

Question 35

Why is it important to be able to recognise the dermatomes of the trigeminal nerve?

Answer 35

The Herpes zoster virus can survive in the satellite cells surrounding the trigeminal ganglion for years.

In older people or those who are immunocompromised, the virus can travel down one or the other division of the 5th cranial nerve and present as a vesicular rash in the exact distribution of the dermatome involved.

A precise and instant diagnosis is aided by dermatomes.