Anatomy Flashcards
Branches of External Carotid-8
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S: superior thyroid artery
A: ascending pharyngeal artery
L: lingual artery
F: facial artery
O: occipital artery
P: posterior auricular artery
M: maxillary artery
S: superficial temporal artery
Branches of Maxillary artery? 17
rom EXTernal carotid
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1st portion: mandibular or bony
Deep Auricular
Anterior Tympanic
Middle Meningeal
Inferior Alveolar
Accessory Meningeal
2nd: pterygoid or muscular
Masseteric
Pterygoid
Deep Temporal (ant, post)
Buccal/ Buccinator
3rd: Pterygopalatine
Sphenopalatine (terminal branch)
Descending Palatine
Infraorbital
Posterior Superior Alveolar
Middle Superior Alveolar
Pharyngeal
Anterior Superior Alveolar
Artery of Pterygoid Canal
Facial nerve CN7
Zygomaticotemporal and Cervicofacial divisions:
- Temporal
- Zygomatic
- Buccal
- Marginal Mandibular
- Cervical
Dingman and Grabb (1961) relationships
In 81% of specimens, marginal mandibular n. (CN VII) nerve ABOVE inferior border before crossing facial a.
98% nerve was SUPERFICAL to the posterior facial v.
Al-Kayat (1979) findings
Mean distance between temporal branch and anterior border of bony external auditory canal 0.8 – 3.5cm Temporal branch located beneath superficial muscular aponeurotic system (SMAS) layer/ temporoparietal fascia Becomes superficial to SMAS layer: 1.5-3cm ABOVE zygomatic arch 1.5cm LATERAL to orbital rim
Hayes Martin maneuver
facial vein is divided and slung superiorly to protect the marginal mandibular nerve (Hayes Martin maneuver)
Distance from inferior border of mandible to IAN canal:
7mm at first molar 7mm at second molar 11mm at base of coronoid notch
Where does the IAN enter the mandible?
IAN enters the mandible 8.3 +/- 0.22mm below the tip of the lingula; 4mm above the occlusal plane
Buccal and lingual cortex thickness at first molar, second molar, and coronoid?
Trigeminal Nerve Fibers
A alpha- biggest, fastest, position, fine touch
A beta- proprioception
A delta- superficial (first) pain, temperature
C unmyelinated- deep (second) pain, temperature
Roods Criteria-7
- Darkening of root*
- Deflection of root*
- Narrowing of root
- Dark and bifid root apex
- Interruption of white line of the canal*
- Diversion of the canal
- Narrowing of the canal
*most significant predictors
Up to 10% of possible IAN injury: 1 or more radiographic findings
What is the diameter of IAN?
2.4mm
When is the IAN closest to the buccal cortex?
In third molar region and ascending ramus
Where is the lingual n.(V3) located in the region of the third molar?
In third molar region (Miloro et al.):
- 2.5mm medial to lingual plate
- 2.5mm inferior to lingual crest
- Above lingual crest in 10% of cases
- In direct contact with lingual plate in 25% of cases.
Lingual nerve function
Sensory, supplies the mucous membranes of the mandibular lingual gingiva, floor of the mouth and the ipsilateral two-thirds of the tongue.
Chorda tympani=taste
Sunderland Nerve Injury Classification-5
- 1st degree=to endoneurium (rapid recovery w/in days to months)
- 2nd=through endo
- 3rd=to perineurium
- 4th=through peri
- 5th=through epineurium
injury from inside out
Sunderland versus Seddon Classification
neurapraxia= 1st degree
Classification correlate histo changes of nerve injury w/ expected clinical outcomes
axonotemesis=2-4 degree
neurotemesis= 5th degree
What type of nerve injury causes the different levels of classification?
neuropraxia= first degree block- conduction block, resulting from mild nerve manipulation, traction or compression
Classification correlate histo changes of nerve injury w/ expected clinical outcomes
Axonotmesis- difference in degree of axonal damage
- 2nd –traction/compression resulting in ischemia, edema, or demyelination –thru endoneurium
- 3rd – peritneurium intact- recovery variable, may take months and be incomplete
- 4th –epineurium intact, near complete transection injury- spont recovery unlikely, min improvement may occur in 6-12 months
Neurotmesis- complete transection, traverses entire fascile, loss of epineurium
What are the three layers of the nerve?
Epineurium: outermost layer, surrounds peripheral bundles and blood vessels.
- Vasa nervorum
- Protects against compressive and stretching forces.
Perineurium: surrounds groups of fascicles.
- Provides structural support and acts as a diffusion barrier.
Endoneurium: surrounds individual nerve fibers and Schwann cells.
3 levels for neurosensory test results and how are they tested?
Level A: 2pt discrimination and brush stroke, closest distance pt can tell there are two points- boley gauage, greater than 2mm=abnorm – norm= 1st deg
Level B: Contact detection, Semmes Weinstein monofilaments, narrowest diameter filament that requires the least amount of force to detect. -norm=2nd degree, mod impaired
Level C: Pain sensitivity, norm= 3rd deg, mod impairmenmt; abnorm=4th deg, severely impaired
What fibers does each level of neurosensory tests test for?
Level A: large myelinated fibers (last to regain fxn in recovery phase)
- 2pt discrimination- A alpha
- Brush stroke- A alpha and A beta, slowly adapting large myelinated axons.
Level B: quickly adapting large myelinated fibers, A alpha
- Contact detection
Level C: small myelinated A delta and non myelinated C fibers (most resistant to injury)
- Pain sensitivity
Warm= A delta
Cold= C fibers
Recovery times after injury, IAN versus lingual n?
IAN needs more time b/c it lies in a bony canal or physiologic conduit that can guide spontaneous regeneration.
- consider surgery after 3-6 mon of no improvement
Lingual n. lies in soft tissue, NO conduit for recovery
- consider surgery after 1-3 mon
What is the diameter of lingual n?
3.2mm
What donor nerve is best to graft for lingual n and IAN?
Greater Auricular cable, most similar in diameter=3.0mm
lingual n.=3.2mm
IAN=2.4
How fast does a nerve regenerate?
1mm/day, 3cm/month
delayed w/ graft and indirect conduit repairs
How many months does it take for most nerve injuries to resolve?
3-9 months, but only if improvement was observed within the first 3 months
What 2 nerves are usually used for interpositional nerve grafting?
- Sural (S1-S2)=2.1mm, can harvest up to 20cm in length
- Greater Auricular (C1-C2)= 1.5mm/3.0mm cable, advantage if can be harvested from same incision for another procedure
- patients are opposed to sacrificing sensation in the facial area
How is the House-Brackmann score calculated and what do the measurements mean?
measurement is determined by measuring the upwards (superior) movement of the mid-portion of the top of the eyebrow, and the outwards (lateral) movement of the angle of the mouth.
1pt=0.25cm of movement to max 1cm
add for a max of 8pts
1=normal 8/8
2=slight 7/8
3=moderate 5-6/8
4=moderately severe 3-4/8
5=severe 1-2/8
What order of layers are encountered when dissecting at level of TMJ? 8
- skin
- subcutaneous
- SMAS, superficial musculoaponeurotic system
- temporal branch of facial n
- temporoparietal fascia
- temporalis fascia (splits inferior to this point into superficial and deep)
- periosteum
- TMJ
temporoparietal fascia- lateral extension of galea and is continuous w/ superficial musculoaponeurotic (SMAS) system
When does the temporal n. cross zygomatic arch?
nerve crosses 8-35mm from ANT concavity of external auditory canal to zygomatic arch
What does the marginal mandibular nerve innervate?
Innervates muscles:
- Depressor labii inferioris
- Depressor anguli oris
- Mentalis
According to Dingman and Grabb, what % of cadavers had 2 major branches?
67%
52.9% had 2 branche in Ziarah Atkinson study
3 parts of nose that make up MAJ nasal tip support
- Size, shape, and strength of lower lateral cartilages
- Attachment of medial crura to caudal septum
- Attachment of lower lateral cartilages to upper lateral
FACE NEAR PAROTID/CONDYLE - retromandib approach
skin
subQ
Smas (DONT HAVE TO CLOSE)
parotidomasseteric fascia/parotid capsule (HAVE TO CLOSE or get sialocele/herniation)
Pterygomasseteric sling
periosteum
Purpose of Al-Kayat study and safety measures?
-80% of cases neurovascular bundle (auriculotemporal n. and superficial temp vein/artery) 5-8mm anterior to midportion of tragus
Mahan Sign
bite on tonger depressor w/ canines, if pain=positive
causes pain in contralateral joint= orthopedic jt problem and inflammation in joint space
IL-1beta, IL-6, TNF alpha
