Anatomy and Physiology Flashcards
- Which cranial nerve provides sensory innervation to the teeth, bone and soft tissues of the oral cavity?
a. Oculomotor
b. Trochlear
c. Trigeminal
d. Facial
e. Hypoglossal
c. Trigeminal
The right and left trigeminal nerve provides the sensory innervation to the teeth, bone and soft tissues of the oral cavity. This nerve is the fifth cranial nerve.
After administering a left inferior alveolar nerve (IAN) block to your patient, #23 and #24 are still sensitive, even though the other teeth in the quadrant are numb. It appears these teeth have not received adequate anesthesia. What could be the cause of this?
a. overlap of sensory fibers from the right side
b. a long buccal injection is needed to anesthetize #23 and #24
c. inadequate volume of anesthetic was administered
d. insertion of the needle was too superior
e. insertion of the needle was too inferior
a. overlap of sensory fibers from the right side
This problem arose because in this patient there was partial anesthesia caused by the overlap of sensory fibers from the opposite side.
While this situation rarely occurs, the mandibular incisors may need to be infiltrated (supraperiosteal injection) in order to be anesthetized. Alternately, a PDL injection can be given to each of these teeth.
- After administering a right inferior alveolar nerve (IAN) block to your patient, the first molar is still sensitive, even though the other teeth in the quadrant are numb. What could be the cause of this?
a. insertion of the needle was too superior
b. insertion of the needle was too inferior
c. the local anesthetic agent that was used lacked a vasoconstrictor
d. innervation of this tooth is being supplied by the mylohyoid nerve
e. cross-over innervation from the inferior alveolar nerve on the opposite side
d. innervation of this tooth is being supplied by the mylohyoid nerve
In some individuals, the mylohyoid nerve provides accessory innervation to the first molar, usually the mesial portion of the tooth. In this situation, there are two options to obtain anesthesia to the first molar:
administer a PDL injection to the first molar
using a 25-gauge needle, administer local anesthesia on the lingual side of the mandible to the apex of the tooth just posterior to the tooth in question, in this case to the apex of the second molar
- Name the nerve which provides sensory innervation to the palatal gingiva of the maxillary first molar:
a. nasopalatine
b. greater palatine
c. anterior superior alveolar
d. middle superior alveolar
e. lingual
b. greater palatine
The greater palatine nerve (GP) innervates the palatal gingiva of the maxillary first molar, as well as the palatal gingiva of the other molars and both premolars.
- Name the nerve which provides sensory innervation to the buccal gingiva of the mandibular molars and the mucobuccal fold in that region:
a. inferior alveolar
b. incisive
c. massateric
d. long buccal
e. lingual
d. long buccal
It is the long buccal nerve (LB) which provides sensory innervation to the buccal gingiva of the mandibular molars and the mucobuccal fold in that region.
- Name the nerve which provides sensory innervation to the lingual gingiva of the mandibular molars:
a. inferior alveolar
b. lingual
c. mental
d. incisive
b. lingual
The lingual nerve provides sensory innervation to the gingiva on the lingual side of the mandible, as well as the anterior 2/3 of the tongue and the mucous membranes of the floor of the mouth.
- Name the nerve which provides sensory innervation to the pulp of the maxillary 1st molar:
a. posterior superior alveolar
b. anterior superior alveolar
c. infraorbital
d. mental
a. posterior superior alveolar
It is the posterior superior alveolar (PSA) nerve which provides sensory innervation to the pulps of all the maxillary molars, as well as the buccal periodontium and bone overlying these teeth.
However, in some cases, the mesiobuccal root is not innervated by the PSA. In that situation, the mesiobuccal root can be infiltrated or a middle superior alveolar nerve block can be given.
- If a hematoma appears after the posterior superior alveolar injection (PSA), it is most likely due to:
a. anesthetic agent was injected too quickly
b. lack of a vasoconstrictor in the anesthetic agent
c. needle inserted too far posteriorly into the pterygoid plexus of veins
d. a 25 gauge needle was used instead of a 27 gauge needle
c. needle inserted too far posteriorly into the pterygoid plexus of veins
A hematoma produced from a PSA injection is due to inserting the needle too far posteriorly into the pterygoid plexus of veins. Perforation of the maxillary artery may also occur.
To minimize the chance of this occurring, be certain to use a short needle. Also, remember to insert the needle at the height of the mucobuccal fold above the maxillary second molar and advance slowly in an upward, inward and backward direction.
- What significance does the coronoid notch have when administering the inferior alveolar nerve block:
a. the operator places their index finger or thumb in the coronoid notch to help determine the height of the injection
b. the operator places their index finger or thumb in the coronoid notch to help determine the penetration depth of the injection
c. the coronoid notch helps determine the site to administer the lingual nerve block if that is to follow the inferior alveolar nerve block
d. the coronoid notch has no importance in determining anything of significance for the inferior alveolar nerve block
a. the operator places their index finger or thumb in the coronoid notch to help determine the height of the injection
When administering an inferior alveolar nerve block (IANB), the operator should place their index finger or thumb in the coronoid notch.
They then should draw an imaginary line extending posteriorly from their finger tip to the pterygomandibular raphe as it turns upward toward the maxilla. This imaginary line will be approximately 6 - 10 millimeters above the occlusal plane.
- Because the mandible consists of denser cortical bone than the maxilla, the incidence of clinically adequate anesthesia is higher in the mandible.
a. Both parts of the statement are true
b. Both parts of the statement are false
c. The first part is true, the second part is false
d. The first part is false, the second part is true
c. The first part is true, the second part is false
Since the maxilla consists of more porous bone than the mandible, this leads to a higher incidence of clinically adequate anesthesia in the maxilla than what is attained in the mandible. The denser cortical bone present in the mandible accounts for this.
- The posterior superior alveolar nerve provides sensory innervation to:
- pulp of the maxillary teeth to the midline
- palatal gingiva to the midline
- pulp of the maxillary molars excluding the mesiobuccal root of the maxillary first molar
- buccal gingiva overlying the maxillary molars
- anterior 2/3 of the tongue
a. 1 and 2 only
b. 2, 3 and 4 only
c. 3 and 4 only
d. 1, 2 and 3 only
c. 3 and 4 only
The posterior superior alveolar nerve (PSA) provides sensory innervation to:
pulp of the maxillary molars excluding the mesiobuccal root of the maxillary first molar buccal gingiva overlying the maxillary molars
Additionally, the PSA innervates the buccal periodontium overlying the maxillary molars.
- A local anesthetic can be injected into areas of inflammation and infection, and adequate anesthesia will be achieved.
a. This statement is true
b. This statement is false
b. This statement is false
In areas of inflammation and infection, the tissues have a lower pH making them more acidic. This affects the ability of the local anesthetic agent to work properly.
- In areas of inflammation and infection, what can be done to maximize the effectiveness of the local anesthetic agent:
a. move away from the area of inflammation and inject further up the nerve branch
b. deposit a larger amount of anesthetic agent than normal
c. deposit a smaller amount of anesthetic agent than normal
d. avoid using topical anesthetic
e. both a. and b.
e. both a. and b.
Answers a. and b. were both options to employ when local anesthetic needs to be administered in areas of inflammation and infection.
In this situation, it is recommended to:
move away from the area of inflammation and inject further up the nerve branch
deposit a larger volume of anesthetic into the region than what would normally be injected
- When administering the ___ injection, there is risk of traumatizing the lateral pterygoid muscle; whereas, when administering the ___ injection, there is risk of trauma to the medial pterygoid muscle.
a. MSA…Buccal
b. PSA …Buccal
c. PSA… IAN
d. IO …Incisive
c. PSA… IAN
When giving the PSA injection, there is risk of inserting the needle into the lateral pterygoid muscle which is located more superiorly and inserts onto the mandibular condyle. When administering the IAN injection, there is risk of trauma to the medial pterygoid muscle, which is located more inferiorly and inserts onto the angle of the mandible.
- The myelin sheath and the nodes of Ranvier on a myelinated nerve fiber enable a nerve’s impulse to:
a. conduct impulses at a much faster rate than an unmyelinated nerve of equal size
b. conduct impulses at a much slower rate than an unmyelinated nerve of equal size
c. the myelin sheath and nodes of Ranvier have no effect on a nerve’s impulse
a. conduct impulses at a much faster rate than an unmyelinated nerve of equal size
The myelin sheath and the nodes of Ranvier (gaps) on a myelinated nerve fiber enable a nerve’s impulse to conduct impulses at a much faster rate than an unmyelinated nerve of equal size.
- When a stimulus excites a nerve, the following sequence of events occurs:
a. slow depolarization, followed by rapid depolarization, and then reversal of the electrical potential across the nerve membrane leaving the interior of the nerve electrically positive in relation to the negative exterior
b. slow depolarization, followed by a neutralization of the interior and the exterior of the nerve
c. rapid depolarization resulting in the nerve achieving its resting potential
a. slow depolarization, followed by rapid depolarization, and then reversal of the electrical potential across the nerve membrane leaving the interior of the nerve electrically positive in relation to the negative exterior
When a stimulus excites a nerve, the following events occur in this sequence:
slow depolarization whereby the electrical potential in the nerve becomes slightly less negative
when this electrical potential reaches a critical level, there is then a rapid phase of depolarization called threshold potential or firing threshold
this depolarization brings about a reversal of the electrical potential across the nerve membrane - the interior of the nerve is now positive in relation to the negative exterior
- The phase of conduction affected by local anesthetics is the repolarization phase.
a. This statement is true
b. This statement is false
b. This statement is false
The phase of conduction affected by local anesthetics is the depolarization phase, not the repolarization phase.
- The process of saltatory conduction:
a. is the manner in which impulse conduction occurs in myelinated nerves
b. produces faster and more energy-efficient conduction
c. is more rapid in a thicker axon
d. progresses from one node to the next in a stepwise fashion
e. all of the above
e. all of the above
In a myelinated nerve, the impulse leaps from node to node - this is called saltatory conduction. When the nerve is myelinated, this conduction is more rapid and energy efficient than in an unmyelinated nerve. And the greater the diameter of the axon, the thicker is the myelin sheath, therefore saltatory conduction occurs more rapidly in thicker axons.
- When administering local anesthesia to a pediatric patient, the following is true:
- maxillary and mandibular bones are less dense than in an adult patient, therefore the anesthetic solution will diffuse through the bone more rapidly
- maxillary and mandibular bones are more dense than in an adult patient, therefore the anesthetic solution will not diffuse readily through the bone
- an increased depth of penetration is necessary than in an adult patient
- a decreased depth of penetration is necessary than in an adult patient
a. 1 and 3
b. 2 and 4
c. 1 and 4
d. 2 and 3
c. 1 and 4
The maxillary and mandibular bones in a child are generally less dense. This will allow the anesthetic solution to diffuse more rapidly to the site.
Additionally, since children are smaller than adults, a decreased depth of penetration is necessary to reach the correct deposition site.
- The periodontal ligament injection (PDL) is contraindicated for deciduous teeth because:
a. the injection technique is too painful for children
b. innervation of the deciduous teeth is unpredictable, therefore the PDL injection is unreliable
c. it can cause enamel hypoplasia in the permanent tooth that is developing just beneath the deciduous tooth
d. the decreased density of the bone surrounding deciduous teeth will not allow diffusion of the anesthetic solution
c. it can cause enamel hypoplasia in the permanent tooth that is developing just beneath the deciduous tooth
Administering a PDL injection for a deciduous tooth can cause enamel hypoplasia in the permanent tooth that is developing just beneath the deciduous tooth.
- For a pediatric patient, in which of the following situations may it be difficult to achieve anesthesia:
a. inferior alveolar nerve block
b. nasopalatine nerve block
c. buccal nerve block
d. infiltration of maxillary first molars
e. infiltration of maxillary central incisors
d. infiltration of maxillary first molars
Infiltration of maxillary first molars poses special challenges in a pediatric patient. This is because in some children the zygomatic process is very prominent and lies close to the alveolar bone, hindering local anesthesia administration.
In these cases, it is acceptable to either:
administer a posterior superior alveolar nerve block, or administer buccal infiltrations at both the mesial and distal of the maxillary first molar
