Download Inferior alveolar n. (cut)

DENTAL GROSS ANATOMY
CASE 4.1
(INFERIOR ALVEOLAR NERVE BLOCK)
HISTORY
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A 23 yo man went to a dentist to have a mandibular 3rd molar extracted.
The patient requested that plenty of anesthetic be given because he was
extremely sensitive to pain.
The dentist inserted the needle through the mucous membrane on the
inside of the patient’s mouth, just lateral to the ridge produced by the
underlying pterygomandibular raphe. After penetrating the adjacent
muscle the tip of the needle came to rest near the lingula.
In a few minutes the patient stated that his gum, lower lip, chin and tongue
on the affected side were numb.
During the extraction the patient said he felt pain; the dentist injected more
anesthetic. The tooth was removed without further incident.
As the patient was leaving the dentist’s office he happened to look in a
mirror and was surprised to find that he was unable to close his eye and
that his mouth sagged on the affected side. He also noticed that his ear
lobe was numb.
The dentist explained that because of the large amount of anesthetic
injected, other nerves in addition to those supplying the teeth had been
anesthetized. He assured his patient that these effects would disappear
in 3-4 hours.
1. Name the nerve supplying the mandibular
3rd molar tooth. What is this nerve a branch
of (be specific)? In what region of the head
does it arise?
NERVE SUPPLY OF THE TEETH
V3 (POST. DIVISION)
INFERIOR ALVEOLAR N.
2. The pterygomandibular raphe is used as a
landmark when giving this type of nerve
block. What is the pterygomandibular
raphe and what are its bony attachments?
Pterygoid hamulus
Buccinator m.
Pterygomandibular raphe
Superior pharyngeal constrictor m.
Mandible
PTERYGOMANDIBULAR FOLD CAN BE SEEN AND PALPATED
Maxillary anterior teeth
Pterygomandibular fold
Uvula
Dorsum of tongue
3. What muscle was penetrated by the
needle?
Buccinator m.
4. What is the lingula of the mandible?
What fibrous structure attaches to it?
What function does the lingula and the
fibrous structure have when giving this
type of nerve block?
Lingula
Mandibular foramen
Sphenomandibular lig.
5. Why was the patient’s chin and
lower lip on the injected side also
anesthetized?
Anterior division (V3) (mostly motor)
Posterior division (V3) (mostly sensory)
Temporalis fascia
and m.
Posterior and
anterior deep temporal nn.
Foramen ovale
Masseteric n.
Lateral pterygoid n.
and m.
Auriculotemporal n.
Chorda tympani n.
Buccal n.
Lingual n.
Inferior alveolar n. (cut)
Mylohyoid n.
Mylohyoid m. (cut)
Mental n.
Inferior alveolar n. (cut)
Digastric m. (anterior belly)
6. Why was the patient’s tongue on the
injected side numb? Specifically, what
part was affected? Were the tongue
muscles paralyzed? Why or why not?
Anterior division (V3) (mostly motor)
Posterior division (V3) (mostly sensory)
Temporalis fascia
and m.
Posterior and
anterior deep temporal nn.
Foramen ovale
Masseteric n.
Lateral pterygoid n.
and m.
Auriculotemporal n.
Chorda tympani n.
Buccal n.
Lingual n.
Inferior alveolar n. (cut)
Mylohyoid n.
Mylohyoid m. (cut)
Mental n.
Inferior alveolar n. (cut)
Digastric m. (anterior belly)
INNERVATION OF TONGUE MUSCLES
XII
Styloglossus m.
Genioglossus m.
Hyoglossus m.
7. What is the relationship between the
sensory nerve identified above (#6) and
the mandibular 3rd molar? Is this nerve
liable to be injured by the clumsy
extraction of this tooth?
Lingual n.
3rd Molar
8. Describe the innervation of the gingiva
of the mandibular teeth. In view of your
answer, should the dentist have
anesthetized any other nerve before
performing this extraction?
INNERVATION OF TEETH & GINGIVAE
9. What caused the patient’s facial paralysis
and loss of sensation in his ear lobule?
INFERIOR ALVEOLAR NERVE BLOCK
Parotid gl.
& facial n.
Medial pterygoid m.
Sphenomandibular ligament
Lingual n.
Inferior alveolar n.
Ramus of mandible
Temporalis m. insertion
Masseter m.
Buccinator m.
Pterygomandibular raphe
10. What complication might have arisen
if the dentist had injected too far laterally?
Too far medially? (Hint: what muscle
might be pierced?)
INFERIOR ALVEOLAR NERVE BLOCK
Parotid gl.
& facial n.
Medial pterygoid m.
Sphenomandibular ligament
Lingual n.
Inferior alveolar n.
Ramus of mandible
Temporalis m. insertion
Masseter m.
Buccinator m.
Pterygomandibular raphe
END OF CASE 4.1