Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BDS2 BAMS > Local Anaesthetic > Flashcards

Local Anaesthetic Flashcards

0
Q

Which structures enter the mandible at the mandibular foramen?

A

inferior alveolar nerve and vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

Where is LA deposited during an IAN block?

A

Deposited around the nerve trunk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Give examples of a local anaesthetic.

A

Lidocaine, prilocaine, articaine (amides)
cocaine, procaine (esters)

Lidocaine + 1:80,000 epinephrine
Prilocaine + felypressin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the advantages of using a vasoconstrictor?

A

Vasoconstrictor constricts blood vessels. Most LA are vasodilators and increased blood flow will increase the ‘wash-out’ of LA. Vasoconstrictors therefore increase the duration of action.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Give examples of a vasoconstrictor.

A

Epinephrine (adrenaline)

Felypressin (prilocaine)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the pterygomandibular raphe?

A

Ligamentous (fibrous) band attached to the hamulus of the medial pterygoid muscle and the mylohyoid line of the mandible. Lies between the superior constrictor and buccinator muscles.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Where in the mouth is this situated and how is it recognised?

A

Situated posteriorly the last standing tooth and is recognised by stretching the cheek and palpating the coronoid notch.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Sometimes the advancing needle may encounter the lingula of the mandible. What is this?

A

Prominent bony ridge at the entrance to the mandibular canal (margin of the mandibular foramen), that attaches the sphenomandibular ligament.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Before injecting, the dentist allows the plunger to retract slightly. Why is this done?

A

To aspirate - this ensures the needle is not within a blood vessel.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

When the anaesthetic is injected, the tip of the needle will lie in the pterygomandibular space. Between which part of the mandible and which muscle does this lie?

A

Between the ramus of the mandible and the medial pterygoid muscle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

The dentist may also infiltrate LA into mucosa on the buccal side of the tooth. Which sensory nerve supplies this region?

A

Buccal nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why is no infiltration of the gingivae necessary on the lingual side?

A

The lingual nerve (which supplies this area) branches from the mandibular nerve anteriorly to the inferior alveolar nerve - it is often anaesthetised at the same time as the IAN during the nerve block.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Once the LA has been administered, the dentist waits a few minutes for the IAN block to work. What clinical sign indicates that the anaesthetic has been effective?

A

Numbness of the lower lip and chin - patient cannot feel pain when this is squeezed but can still feel pressure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the anatomical basis of this sign?

A

The mental nerve (which supplies sensation to the lower lip) is a branch from the inferior alveolar nerve, therefore will be anaesthetised too.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

In this patient, however, the anaesthetic does not work as planned. Instead, the corner of the patients mouth starts to droop. What has happened?

A

Facial palsy - the needle has penetrated the parotid gland and anaesthetic has been injected into this, causing paralysis of the facial nerve.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What would be your immediate concern?

A

To protect the patient’s eye - they can no longer blink, therefore there is a risk of the cornea drying out, or dirt getting into the eye - an eye patch must be worn to protect it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What clinical test would you carry out to check this danger?

A

Ask the patient to blink and check if they have full control over blink reflex.

17
Q

Where is LA administered during infiltration?

A

Around the terminal branches of nerves

18
Q

Where is the needle placed in relation to the apex of the tooth?

A

Over the apex of the tooth at the mucobuccal fold and slightly distal.

19
Q

What branch of the trigeminal nerve innervates the maxilla?

A

The maxillary branch (V2) - which branches into superior alveolar nerve, which branches into posterior superior, middle superior and anterior superior alveolar nerves.

20
Q

What anaesthetics are esters? How are these broken down in the body?

A

Benzocaine, cocaine - broken down by tissue esterases and action is quite brief.

21
Q

What anaesthetics are amides? How are these broken down in the body?

A

Lignocaine, articaine, prilocaine - broken down by liver amidases and have a longer duration than esters.

22
Q

What are examples of preservatives used in local anaesthetics?

A

Bisulphite

Propylparaben

23
Q

What is infiltration used for?

A

Used to anaesthetise soft tissues and to produce pulpal anaesthesia where alveolar bone is thin (maxilla, lower anterior teeth)

24
Q

What are nerve blocks used for?

A

Used to produce soft tissue anaesthesia and used where bone is too thick to allow infiltration (mandible)

25
Q

What do you check for on the LA cartridge?

A

Batch number and expiry date

26
Q

Which needle lengths are used for each LA technique?

A

35mm needle used for IAN block

25mm needle used for infiltration

27
Q

When finished with LA syringe, where does each part go?

A

Needle/cartridge/syringe = sharps box
Bung = clinical waste
Plunger handle = dirty box for decontamination

28
Q

Where is a mental block administered?

A

Between apices of lower premolars

29
Q

What are the important landmarks for an IAN block?

A

Coronoid notch of the mandibular ramus, posterior border of mandible, pterygomandibular raphe, lower premolar teeth of the opposite side

30
Q

Describe the action potential sequence.

A

Membrane potential reaches threshold at -55mV - triggers action potential
Sodium M-gate opens: depolarisation, sodium ions diffuse into cell, potential increases rapidly and peaks at +35mV
Sodium H-gate closes and potassium voltage-gated channel opens: repolarisation, potassium ions diffuse out of cell, potential decreases rapidly
Voltage-gated potassium channels close: potential overshoots briefly, resting potential reinstated

31
Q

What is the function of the refractory period?

A

stops rapid firing

32
Q

During an action potential, when are the sodium M-gates and H-gates open or closed?

A

At rest: M-gate closed, H-gate open
When action potential is triggered: M-gate open, H-gate open
At action potential peak: M-gate open, H-gate closed
During the refractory period: M-gate open, H-gate closed
At rest: M-gate closed, H-gate open

33
Q

What are the 3 main components of a local anaesthetic molecule? What else does a LA solution contain?

A

hydrophobic aromatic end, ester/amide bond, hydrophilic amide side chain
LA molecule in hypochlorite solution, reducing agent (provides electrons), fungicides and preservatives (provides longer shelf life - possible allergies), vasoconstrictor

34
Q

What is trismus?

A

A possible complication of LA use. Onset within hours of IAN block. Occurs when injected too far down or when injected too quickly - damages the medial pterygoid muscle, therefore causing limited mouth opening.

36
Q

What are two alternative methods of administering an IAN block?

A 
Gow Gates technique (where LA is administered at head of condyle, open mouth)
Akinosi technique (closed mouth, LA administered above lingula)
37
Q

What are the maximum doses for LA?

A 
lidocaine = 4.4mg/kg
prilocaine = 6mg/kg
38
Q

Where is the pterygomandibular space?

A

Space that lies between the medial pterygoid muscle and the medial surface of the ramus of the mandible.

39
Q

What are the possible complications of LA?

A

trismus, facial palsy, fainting, intravascular injection

40
Q

What is the site of action of a local anaesthetic?

A

voltage gated sodium channels

41
Q

Which nerve fibres are anaesthetised by LA and in which order?

A

A delta (anaesthetised first)
C
A beta
A alpha (anaesthetised last)

BDS2 BAMS (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions