Anatomy of Local Anesthesia Flashcards

1
Q

Where does the trigeminal nerve arise from?

A

Arises from the lateral pontine region

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2
Q

What are the two roots of the trigeminal?

A

• Sensory root:
- Bears the large trigeminal ganglion (semi lunar or gasserian)
- Three branches: ophthalmic, maxillary, mandibular
• Motor root
- Passes deep to the ganglion and joins the mandibular division as it exits the foramen ovale

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3
Q

Meckel’s cave

A
  • The Gasserian (Trigeminal) ganglion sits in the anterior medial portion of the posterior cranial fossa
  • As the divisions cross the petrous ridge they are surrounded by an invagination dura and arachnoid which also contains CSF (Meckel’s cave)
  • Until they exit the skull
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4
Q

Ophthalmic division (V1)

A
  • Runs through the lateral wall of the cavernous sinus
  • Gives off the meningeal branch
  • Divides into three branches as it leaves the orbit
  • Leaves via the superior orbital fissure
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5
Q

Maxillary divison (V2)

A
  • Runs along the lower portion of the lateral wall of the cavernous sinus
  • Leaves the skull by way of the foramen rotundum
  • Enters the pterygopalatine fossa
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6
Q

Mandibular nerve (V3)

A
  • Passes through the foramen ovale with the motor root, which is medial to it
  • They join immediately outside the skull to form a mixed nerve
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7
Q

The ophthalmic nerve is what type of nerve?

A

• Purely sensory

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8
Q

What are the direct three branches of the ophthalmic nerve?

A

Divides into three branches as it leaves the superior orbital fissure:

 - Nasociliary
 - Lacrimal
 - Frontal
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9
Q

Lacrimal branch of ophthalmic nerve…

A
  • Passes most lateral above the lateral rectus
  • Joined by the lacrimal artery
  • Innervates the lacrimal gland
  • The nerve divides to innervate the conjunctiva and lateral skin of the eye
  • Tear secretion
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10
Q

Preganglionic and postganglionic fibers associated with tear secretion

A
  • Lacrimal branch of ophthalmic nerve
  • Preganglionic parasympathetic fibers concerned with tear secretion run with the facial nerve via the greater petrosal nerve to the pterygopalatine ganglia.
  • Postganglionic fibers from the ganglia join the maxillary nerve and then join the zygomatic nerve to the zygomatico- temporal nerve to the lacrimal nerve via the communicating branch to the gland
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11
Q

Frontal branch

A
  • The frontal nerve passes near the roof of the orbit
  • Above the levator palpebrae
  • It divides into the supraorbital and supratrochlear branches
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12
Q

Supraorbital branch

A
  • Branches from frontal branch of ophthalmic nerve

* Innervates the skin of the forehead frontal sinus and upper eyelid

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13
Q

Supratrochlear nerve

A
  • Branch of the frontal branch of the ophtalmic nerve
  • Runs forward and medially
  • Supplies the upper lid conjunctiva and skin on the upper lid and skin on the lower medial forehead
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14
Q

Nasocilliary nerve

A

• Posterior ethmoidal nerve branch

- Enters the posterior ethmoidal foramen with the ophthalmic artery and supplies the ethmoid and sphenoid sinus’

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15
Q

Ciliary ganglion associated with…

A
  • Long ciliary nerves
  • Short ciliary nerves
  • Infratrochlear
  • Anterior ethmoidal nerve
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16
Q

Long ciliary nerve

A
  • Associated with ciliary ganglion
  • Pierce the sclera medial and lateral to the optic nerve
  • Mostly sensory
  • Also contain most of the sympathetic fibers for pupillary dilation
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17
Q

Short ciliary nerve

A
  • Associated with ciliary ganglion
  • Run with oculomotor nerve
  • Originate from the Ebinger Westphal nucleus
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18
Q

Infratrochlear

A
  • Associated with ciliary ganglion
  • Medial upper and lower eyelids
  • Lacrimal sac
  • Upper lateral nose
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19
Q

Anterior ethmoidal nerve

A

• Associated with ciliary ganglion
• Passes through the anterior ethmoidal foramen
• Goes through the foramen into the cranial vault across the cribriform plate back down to the nose and divides into the internal and external branches.
- Internal nasal branch: upper part of the nose
- External nasal branch: supplies the lower part of the dorsum of the nose

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20
Q

Maxillary Nerve

A
• Leaves the skull through foramen rotundum
• Enters pterygopalatine fossa
• The pterygopalatine ganglion is suspended from it and gives off branches to:
     - The nose
     - Palate
     - Pharynx
     - Lacrimal gland
• Out the inferior orbital foramen
• Terminal branches are:
     - Superior labial 
     - Lateral nasal
     - Inferior palpebral
• The accompanying arteries follow
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21
Q

Pterygopalatine ganglion

A

• Connected to the maxillary nerve by the pterygopalatine nerves but the sensory branches do not synapse in the ganglion they just pass through and suspend it
• Location:
- Lateral nasal wall
- Posterior and above the middle concha
- Branches are secretory sensory and vasomotor

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22
Q

Zygomatic nerve

A

• The zygomatic nerve branches from the maxillary nerve as it passes through the infraorbital canal

 - It divides and leaves the zygoma as the zygomaticofacial and zygomaticotemporal nerves
 - The zygomaticotemporal and communicating branch gives a secratory branch to the lacrimal gland
 - The maxillary nerve gives off the posterior superior alveolar nerve passes through the infraorbital canal and gives off the middle superior alveolar nerve and anterior superior alveolar nerve
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23
Q

Contributions to the pterygopalatine ganglion…

A

• Motor root from geniculate ganglion (greater petrosal nerve)
• Sympathetic root from carotid/cervical plexus (deep petrosal nerve)
- Join in the vidian or pterygoid canal to form the vidian nerve and join the pterygopalatine ganglia
• Sensory to the ganglia area are from branches of V2.

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24
Q

Distribution of pterygopalatine ganglion…

A
• Sphenoid sinus
• Posterior ethmoid cells
• Nose
• Hard and soft palate
     - Greater and lesser palatine nerves
• Choanae
• Pharynx
• Lacrimal gland
     - Parasympathetic secratory
     - Sympathetic
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25
Q

Contents of the pterygopalatine fossa…

A

• Pterygomaxillary fissure leads to pterygopalatine fossa
• Maxillary nerve as it exits foramen rotundum
• Maxillary artery
• Pterygoid plexus of veins
- Pterygopalatine and infratemporal fossa
• Vidian nerve and pterygopalatine ganglion

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26
Q

Nasopalatine nerves

A
  • Nasal branches of the pterygopalatine ganglion
  • Branches of the anterior superior alveolar arteries
  • Innervate the anterior hard palate along with the greater palatine nerve
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27
Q

Mandibular nerve

A

• Leaves the foramen ovale as two roots:

 - Large sensory with fibers from the gasserian ganglion
 - Smaller motor root
 - They unite to form the mandibular nerve between the lateral pterygoid and tensor veli palatini
 - The otic ganglion lies medial to the nerve and at this point the nerve divides
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28
Q

Anterior branches of the mandibular nerve

A
  • Masseteric
  • Anterior and posterior deep temporal nerves
  • Buccal branch of the mandibular nerve
29
Q

Buccal branch of the mandibular nerve

A
  • Sensory to the lateral pterygoid, skin of the cheek, mucosa
  • It passes between the 2 heads of the lateral pterygoid
  • Runs across the medial surface of the temporal muscle
  • Then forward and down through the buccal fat pad and the buccinator muscle (VII)
  • Innervates the posterior buccal mucosa
30
Q

Otic ganglion

A

• Medial to the mandibular nerve
• Parasympathetic, connected with the parotid gland
• Two branches pass through
- Tensor tympani
- Tensor veli palatini
- Medial pterygoid may be related but not always
• They are from the motor root of the mandibular nerve
• The otic ganglia receives preganglionic fibers from the ninth cranial nerve (lesser Petrosal)
• Most of the postganglionic fibers are given off into the auriculotemporal nerve to the parotid
• Frey’s syndrome

31
Q

Auriculotemporal nerve

A

• Travels posterior medial carrying fibers to:

 - TMJ
 - External auditory meatus
32
Q

Inferior alveolar nerve

A

• Gives off the mylohyoid branch which runs downward through the groove on the inner surface of the mandible to the muscle
• The inferior alveolar nerve enters the mandible through the mandibular foramen
- foramen lies 1.5 to 2 cm below the mandibular (Sigmoid) notch
• The main trunk leaves at the mental foramen (mental nerve)
• The mental foramen may be found by drawing a straight line down from the supraorbital notch

33
Q

Mandibular foramen location

A

Lies 1.5 to 2 cm below the mandibular (sigmoid) notch

34
Q

What supplies the incisors?

A

Supplied by the incisal plexus which crosses over the midline

35
Q

Lingual nerve

A
  • After leaving the inferior alveolar nerve the lingual nerve receives the chordi tympani fro, the facial nerve
  • Travels downward medial to the medial pterygoid
  • Anterior to the inferior alveolar nerve
  • Leaves the masticator space goes down lateral to the styloglossus muscle and lingual to the third molar area
  • 5-10% of the time it courses above the level of the ridge
  • The nerve travels under the submandibular duct
  • Then travels upward through the mylohyoid into the tongue
  • Close to the gland there is a submandibular ganglion which is suspended from the nerve
  • Parasympathetic fibers (chordi tympani) enter the ganglion then the gland and innervate the gland
36
Q

First part of maxillary artery

A
• Posterior auricular
• Anterior tympanic
• Middle meningeal 
     - Foramen spinosum
• Inferior alveolar
37
Q

Second part of maxillary artery

A
  • Masseteric
  • 2 deep temporal
  • buccal
  • medial and lateral pterygoid
38
Q

Third part of maxillary artery

A
• posterior superior alveolar
• Infraorbital artery
     - Middle superior alveolar
     - Anterior superior alveolar
• Descending palatine
• Pharyngeal
• Artery of the pterygoid canal
• Sphenopalatine
     - Epistaxis
39
Q

Facial artery

A

• Originates from external carotid
• It courses upward in the neck deep to the posterior belly of the digastric and styloid muscles
• It crosses above them and over to the medial surface of the mandible
• Passing through the submandibular gland (branches of facial artery):
- Submental
- Muscular
- Glandular
- Ascending palatine
- Tonsilar
• Running under the mandible in the antigonial notch then upwards becoming the angular artery

40
Q

Labial arteries

A

• Facial artery gives off branches to the labial artery
• Inferior
• Superior
- Tortuous

41
Q

Angular artery

A

• Terminal portion of the facial artery
• Alongside nose to the medial angle of the eye
• Gives rise to:
- Lateral nasal artery
- Anastomoses with dorsal artery from ophthalmic artery

42
Q

Collateral circulation

A
  • The facial artery gives off branches to the labial artery and becomes the angular artery.
  • So the face has a rich vascular supply.
  • Hence, if you cut the facial artery, the face still lives versus cutting the femoral artery, the leg dies.
43
Q

Lingual artery

A

• Arises from external carotid
• Gives a tonsilar branch
• Found deep to the hypoglossal nerve in Lesser’s triangle
• At the posterior border of the hyoglossas muscle a suprahyoid branch is given off
• Other branches:
- dorsal lingual
- deep lingual or ranine
- sublingual
• anastomoses with the submental branch of the facial artery

44
Q

Types of maxillary injections

A
  • Infiltrations - bone is porous that anesthetic will just infiltrate the bone and anesthetize the nerve
  • Nerve blocks
45
Q

Maxillary nerve blocks type…

A
  • Nasopalatine
  • Greater palatine
  • PSA
  • Infraorbital
  • Infratrochlear
  • Zygomaticofacial
  • Zygomaticotemporal
46
Q

Complications with maxillary injections

A
  • Pain
  • Swelling
  • Hematoma
  • Hemorrhage
  • Intravascular injection
  • Tissue necrosis
  • Inadvertent nerve injury
  • Blindness/globe injury
  • Ophthalmoplegia
  • Infection
  • Over dosage/drug sensitivity/allergy
47
Q

Mandibular injections include…

A
  • Inferior alveolar block
  • Gow-gates
  • Akinosi
  • Accessory innervations
48
Q

Inferior alveolar block

A
  • Opposite side between premolars
  • Inject in fossa made by the buccinator and superior constrictor
  • Use finger to palpate most posterior part of anterior ramus bisect finger and inject
49
Q

Gow-gates

A
  • Open mandible
  • DP cusp of 2nd maxillary molar
  • Insert needle to condyle
50
Q

Akinosi

A
  • Closed mandible technique

* Mucogingival junction maxilla towards condyle

51
Q

Accessory innervations

A
  • Mylohyoid - comes under mylohyoid muscle so need to go into the floor of the mouth
  • Cervical plexus
  • Lateral ramus - go into lateral side where 3M is and give an infiltration in inferior border of mandible
52
Q

Division of facial nerve (CN VII) as it enters the parotid…

A
As it enters the parotid it divides into:
• Temporofacial
     - Temporal
     - Zygomatic
     - Buccal
• Cervicofacial
     - Buccal
     - Marginal mandibular 
     - Cervical
53
Q

Segments of the facial nerve…

A

• Intracranial segment
- Brain stem to temporal bone
• Intratemporal segment
- Temporal course
- Internal acoustic meatus to the stylomastoid foramen
• Extratemporal (extracranial) segment
- Stylomastoid foramen to its terminus

54
Q

Fibers of the facial nerve…

A
• Motor
• Parasympathetic secretomotor
• Somatosensory
     - General sensation
     - Special sense of taste
55
Q

Intracranial segment of the facial nerve

A

• Arises from the ventral part of the pons in the posterior fossa as 2 distinct fibers
- 10,000 neurons
• large motor root (7,000 neurons)
• nervus intermedius (nerve of Wrisberg)
- smaller trunk (3,000 neurons)
- parasympathetic (taste, secretion general sensation)

56
Q

Intratemporal segment of facial nerve

A

• Internal acoustic meatus to the stylomastoid foramen
• Branches in the intratemporal segment are:
- greater petrosal nerve
- chordi tympani
- nerve to the stapedius

57
Q

Greater petrosal nerve

A
  • Carries parasympathetic fibers
  • Branches from the facial nerve exists via the greater hiatus
  • The greater petrosal nerve runs medio-anteriorly to the foramen lacerum
  • At the level of the foramen lacerum the greater petrosal picks up sympathetic fibers from the deep petrosal coursing with the carotid artery
  • The two enter the nerve of the pterygoid canal (vidian) and become the vidian nerve
  • The canal ends in the pterygopalatine fossa and the nerve enters the ganglia
58
Q

Chordi tympani

A
  • Special sense of taste
  • Para sympathetic fibers to the submandibular gland
  • Leaves the facial nerve within the facial canal
  • Exists the petrous portion of the temporal bone via the petrotympanic fissure which is anterio-medial to the stylomastoid foramen
  • It enters the infratemporal fossa and joins the lingual nerve
59
Q

Extratemporal (extracranial) segment of facial nerve

A

• As the nerve leaves the stylomastoid foramen its branches in order are:

 1) Posterior auricular
 - Motor to the posterior muscles of facial expression
 - Sensory to the skin over the mastoid and ear
 2) Posterior belly of the digastic
 3) Stylohyoid
60
Q

Q1. What is the first nerve affected by cavity sinus thrombosis?

A

ANSWER: Abducens nerve - CN VI

Background:
Before the advent of antibiotics, cavity sinus thrombosis is the deadly infection that can occur from dental infection because a lot of facial veins have no valves, so infection backs up and goes into the sinus area. The first consequence affects the nerve with the longest course, abducens, which does Lr6 (lateral movement). So, the first thing you cannot do is move the eye out, lateral ophthalmoplegia. The other nerves will also be affected as the cavity of the sinus swells and impinges on them, inhibiting their respective functions.

61
Q

Q2. Where do the preganglionic parasympathetic fibers for tear secretion come from?

A

Vidian nerve - CN VII

62
Q

Q3. What are the terminal branches of V2?

A

Inferior palpebral, lateral nasal, and superior labial

63
Q

Q4. What 2 nerves join together to form the vidian nerve?

A

Greater petrosal and deep petrosal nerve

64
Q

Q5. What nerve needs to be anesthetized in order to get anesthesia in the buccal mucosa in the posterior mandibular molar area?

A

Buccal nerve

Key: V3 innervates the posterior buccal mucosa. You are going to have to anesthetize this nerve when doing extractions.

65
Q

Q6. Where do preganglionic fibers associated with parotid gland come from?

A

Otic ganglion or CN IX

66
Q

Q7. Which nerve is 5-10% in the 3M area?

A

Lingual nerve

67
Q

Q8. What else does chorda tympani do?

A

Taste to anterior 2/3 of tongue

68
Q

Q9. All of these are branches of the facial artery as it goes through submandibular gland except?

A

Superior labial artery (other choices are submental, muscular, glanular, tonsillar)

69
Q

Q10. What branch of the lingual artery anastomoses with the submental branch of the facial artery?

A

Sublingual branch