The Infratemporal and Temporal Fossa 4

Question 1

How do the medial pterygoid muscles run?

Answer 1

They run superioinferiorly at right angles to this.

Question 2

What usually happens when we chew?

Answer 2

We usually chew on one side for a while and then switch to the other side in a rhythmic manner.

Question 3

Why do we only chew on one side at a time usually?

Answer 3

This concentrates all of the muscle force from both sides of the skull between the teeth of the chewing side.

Question 4

Describe what happens during the process of chewing?

Answer 4

To chew on one side the mandible swings over to that side so that the condyle of the opposite side then slides down on top the articular eminence.

But on the chewing side, the condyle remains against that back of the eminence.

Therefore whe patients fracture their condylar necks, it hurts most when they try to chew on the opposite side.

Question 5

Which muscles act to close the mouth and occlude the teeth?

Answer 5

• temporalis
• masseter
• medial pterygoid muscles

Question 6

When is the upper head of the lateral pterygoid muscle active?

Answer 6

It is active during jaw closure since it steadies the disc while it returns to the glenoid fossa.

Question 7

What is opening of the mouth against resistance brought about by?

Answer 7

It is brought about by the lower head of the lateral pterygoid and the digastric muscle.

Question 8

What type of gland is the parotid gland?

Answer 8

It is a serous salivary gland. q

Question 9

What is there an absence of in the parotid gland?

Answer 9

Mucous secreting acini.

Question 10

Where is the parotid gland?

Answer 10

It squeezes into the space available around the ramus of the mandible.

Question 11

What are 2 of the parts of the parotid gland called?

Answer 11

• superficial lobe –> the part that lies on the surface
• deep lobe –> the deep tapering edge

Question 12

What is the glenoid lobe of the parotid gland?

Answer 12

There is a part of the parotid gland that extends up to the neck of the mandible and this part is given the name of the glenoid lobe.

Question 13

What is the parotid gland surrounded by?

Answer 13

By the deep investing fascia of the neck.

Question 14

What happens when there is swelling of the parotid gland?

Answer 14

Because of the envelope of deep investing fascia around the parotid gland, swelling of the gland produces a considerable amount of tension and considerable pain, hence why mumps is so painful.

Question 15

What is another name for mumps?

Answer 15

Viral parotitis.

Question 16

How far does the superficial lobe of the parotid gland extend?

Answer 16

It extends forwards onto the surface of the masseter.

Question 17

Where does the parotid duct emerge from?

Answer 17

It emerges from the convex anterior edge of the parotid gland.

Question 18

How does the parotid duct enter the mouth?

Answer 18

It pierces the cheek to enter the mouth near the second upper molar tooth at the level of its neck or cervix.

Question 19

Why is the parotid duct quite high up?

Answer 19

Because if it were any lower in the cheek then it would be prone to being chewed when we eat.

Question 20

Branches of what nerve are embedded into the parotid gland?

Answer 20

Branches of the 7th cranial nerve.

Question 21

How do branches of the 7th cranial nerve emerge from the parotid gland?

Answer 21

They emerge from the anterior edge of the gland and they pass to the facial musculature.

Question 22

Where does the glenoid lobe lie?

Answer 22

It lies behind the temporomandibular joint in contact with the bony part of the external auditory meatus

Question 23

What nerve does the glenoid lobe lie in close relationship with?

Answer 23

It lies in close relationship to the auriculotemporal branch of the mandibular nerve

This nerve is the final pathway for parasympathetic fibres to reach the parotid gland.

Question 24

Where do parasympathetic neurones originate from?

Answer 24

They originate from the glossopharyngeal nerve = 9th cranial nerve.

Question 25

After originating from the glossopharyngeal nerve what is the path of the parasympathetic neurones?

Answer 25

They leave the petrous temporal bone as the lesser petrosal nerve and drop down to the foramen ovale and then synapse in the otic ganglion.

Postganglionic parasympathetic neurones jump inot the auriculotemporal nerve.

Question 26

When stimulated, what do the postganglionic parasympathetic neurones in the auriculotemporal branch cause?

Answer 26

They promote secretion of saliva into the mouth.

Question 27

What is the function of sympathetic fibres to the parotid gland?

Answer 27

They are also involved in secretomotr activity in the salivary glands and a balance of the different constituents of saliva results from this dual autonomic innervation.

Question 28

What does the volume of salivary flow over time depend upon?

Answer 28

It depends upon the blood flow through the gland and this is under vasomotor sympathetic control.

Question 29

What is the parotid gland related to posteriorly?

Answer 29

It is related to the mastoid process and the sternocleidomastoid muscle.

Question 30

What is the deep part of the parotid gland related to?

Answer 30

It is related to the styloid process and its muscles and to the internal carotid artery and the internal jugular vein and their related cranial nerves.

Question 31

What structures pass through the substance of hte parotid gland.

Answer 31

• external carotid artery
• retromandibular vein
• facial nerve

Question 32

What is a consequence of the fact that important structures pass throght he substance of the parotid gland?

Answer 32

This makes removal of cysts or tumours from the parotid gland much more difficult.

Branches of the facial nerve have to be identified carefully and removed during surgery.

Facial nerve is superficial in the parotid gland.

Retromandibular nerve lies deep to the facial nerve.

Branches of the external carotid artery lie deepest in the parotid gland.

Question 33

What is the bucchinator muscle?

Answer 33

This is a muscle of facial expression.

Question 34

What is the nerve supply to the bucchinator muscle?

Answer 34

It is supplies by the 7th cranial nerve = the facial nerve

Question 35

Where does the bucchinator muscle arise from?

Answer 35

It arises from the pterygomandibular raphe.

Question 36

What muscle is posterior to the pterygomandibular raphe?

Answer 36

the superior constrictor muscle.

Question 37

Where does the bucchinator muscle run to?

Answer 37

It runs forwards to the angle of the mouth and is attached above and below to the molar and premolar teeth to the maxilla and the mandible for most of its course.

Question 38

What happens to the upper and lower fibres of the bucchinator muscle?

Answer 38

These cross as they approach the angle of the mouth at the modiolus.

Question 39

What is the modiolus?

Answer 39

This is the point where muscles of facial expression intermingle and is called the modiolus.

Question 40

What is an important function of the bucchinator muscle?

Answer 40

It is used to squeeze food from the cheek back between the teeth and into the mouth again for more chewing before being swallowed.

It also controls the flow of saliva through the parotid gland and prevents food or debris or air being squeezed back into the duct – this occurs due to the bucchinator muscle contracting around the duct as the duct enters the mouth.