CRACK ADC

Applied Anatomy

29 bones of the head and neck o 8 cranial bones

o 14 facial bones

o 1 hyoid bone (only non-articulated bone of body)

o 6 auditory ossicles (stapes, incus, malleus)

Cranium divided into 2 portions:

o Anterior Visceral:

the facial cranium, made up of derivatives of the upper end of

primitive gut and its associated branchial structures. Consists of

14 bones

includes maxilla and mandible

Intramembranous calcification

o Posterior Somatic

The neurocranium and consists of 8 bones

Forms from 3 midline bones from Endochondral bones:

o ethmoid, sphenoid, and occipital

3 pairs of lateral dermal bones (Intramembranous):

o frontal, temporal, parietal

Typically, Intramembranous bone is used to augment the

face. It is a source of bone that can be graphed to the

face. could be procured from temporal and/or parietal

bone.

Typically break up the face into thirds:

o Upper third

Super-orbital rim and frontal bone and a piece of the nasal-

orbital-ethmoid region

Foramen in the frontal bone is longitudinally right above or just

medial to the pupil

o Middle third

Orbit and the orbital adnexium (eyeball and associated

structures), cheekbones, and maxilla

Maxilla contains a foramen that is a midline foramen that is in the

area of the infraorbitcalled the infraorbital foramen

o Lower third

Mandible and the chin

Mandible contains a foramen on the lateral aspect of the body of

the mandible (mental foramen)

Three foramens that open in a straight line on the face:

o Based on the pupil, those three foramens are

Supraorbital

Infraorbital

Mental

Face Proper

Largest bone of the facial cranium is the maxilla

Anterior visceral/Facial cranium: o 14 bones

o Brachial structures are associated with the brachial arches

o Derivatives of upper end of the primitive gut and associated brachial

structures

Posterior somatic/Neurocranium: o 8 bones

o Bulk of this is referred to as the calvaria

Unpaired frontal bone

Unpaired occipital bone

Paired parietal bones

o Forms from 3 midline endochondral bones:

Ethmoid

Sphenoid

Occipital

o 3 pairs of lateral dermal bones (intramembranous)

Frontal

Temporal

Parietal

Trigeminal Nerve starts in Pons and Medulla Oblongata.

It is a mixed nerve. Has both sensory and motor functions.

It is a tripartite nerve: it has three branches.

First and Second branch are purely sensory.

Third branch is sensory and motor.

Motor branch starts in middle cranial fossa, then joins the sensory branch once

it exits the foramen ovale.

Three branches arise from the ganglion

The trigeminal ganglion = semilunar ganglion = Gasserian ganglion

Ganglion is located in Meckels Cave (BOARD ?)

Sphenoid Bone

Most important as it relates to where the trigeminal nerve exits the skull are

associated with the sphenoid bone

4 foramina of interest in the sphenoid bone (transmit branches of trigeminal

nerve):

o Superior orbital fissure

V1 (ophthalmic branch)

o Foramen Rotundum (Latin for the round foramen)

V2 (maxillary branch)

o Foramen ovale (Latin for the oval foramen)

V3 (mandibular branch)

o Foramen spinosum

Two wings:

o Greater and Lesser Wings.

There is a curvilinear relationship of these foramen of the sphenoid bone

o Specific portion of the sphenoid bone that contains the foramen is the

greater wing of the sphenoid bone

Foramina and associated structures:

Cavernous sinus

o Internal Carotid Arter

o Contains cranial nerves:

III

IV

V1 and V2

VI

o A cavernous sinus thrombosis would affect which nerves?

Anesthesia of forehead via V1.

Ocular palsy (eyeball does not move)

o How does the eyeball move?

LR6SO4

Lateral Rectus is innervated by VI

Superior Oblique is innervated by IV

All other extraocular muscles are provided by III

Superior orbital fissure

o Contains cranial nerves:

III

IV

VI

Branches of V1:

Frontal nerve

Lacrimal nerve

Nasociliary nerve

o Superior ophthalmic vein

o Superior orbital fissure syndrome: an infection

Symptoms:

palsy of ocular muscles III, IV, VI, and V1

Inferior orbital fissure transmits

o Zygomatic nerve (branch of V2) and its branches that provide sensation

to the lateral cheek (injury results in numb cheek)

Zygomaticotemporal

Zygomaticofacial

o Sphenopalatine branches

o Inferior ophthalmic vein

o Trauma to the orbit can affect: Infraorbital nerve (runs on floor of orbit)

Maxillary front teeth become numb

Optical Canal (contained within the sphenoid bone) transmits

o Optic nerve

o Central retinal artery

Vascular constriction affects central artery of the retina.

o Ophthalmic artery

Jugular Foramen:

o BOARD ?: Cranial nerves:

IX

X

XI

Foramen ovale transmits:

o V3

o Small meningeal artery

o Small petrosal nerve o Emissary vein

Foramen Rotundum

o Transmits V2

Foramen spinosum

o Middle meningeal artery

branch of carotid arterial system

avenue by which infects of face can gain access to the meninges

o Lymphatics

o Important because the artery that is at risk of the medial aspect of the

glenoid fossa is the middle meningeal artery

What nerve supplies sensation to the dura mater?

o Middle meningeal nerve.

Pneumonic to remember 2nd and 3rd divisions: MR. MO (max rotundum, mandibular ovale)

Cranial Nerves

I Olfactory n Smell (Purely Sensory)

II Optic Sight (Purely Sensory)

III Oculomotor Moves the eye (Motor)

IV Trochlear Superior oblique (Motor)

V TG Sensory nerve to the face

3 divisions: ophthalmic, max, and mandibular

mixed n. (motor + sensory)

Largest Cranial Nerve

VI Abducens Lateral rectus (purely motor)

VII Facial Facial movement

Mixed (motor + some sensory) CHECK THIS***

In particular sensation of gestation via chorda tympani

VIII Vestibulocochlear Hearing and balance

Purely Sensory

IX Glossopharyngeal Swallowing and elevation of the soft palate and posterior

pharyngeal wall

Mixed N.

X Vagus Longest distribution in the body of ANY cranial nerve

XI Accessory Shoulder shrugger (purely motor)

XII Hypoglossal Movement of the tongue (purely motor)

There are 6 muscles that move the eyeball: LR6 SO4 (all others are by cranial nerve 3)

Four recti muscles (medial, lateral, superior, inferior)

Two obliques (superior, inferior)

Topography things of note

Mandible

Heavy cortical plate lingually and buccally (in between, there are marrow spaces)

o Does not allow infiltration to provide pulpal anesthesia of the teeth Composed of:

o Condyle-ramus unit

2 foramina of interest:

o mandibular

o mental

Pulpal anesthesia of mand = inferior alveolar n. (IA)

At approx. apex of PM1 and PM2 = mental foramen

o IA continues thru the foramen = incisive n.

o To remove the PM2? = anesthesize IA (pulpal anesthesia)

o To remove PM1 mental nerve, can remove w/OUT anesthetize IA

Dont want to deliver bilateral lingual anesthesia to IA to kiddos

Can perform lingual infiltration via mental n.

Some of the soln will go to the foramen and anesthetize

the incisive n.

Mental nerve breaks up into 3 branches (extension from IA?)

Maxilla

Thin cortical plate that is very porous

o Infiltration works best on maxilla due to thin cortical plate.

Mainly cancellous bone.

All the teeth on a maxilla can have pulpal anesthesia merely from infiltration

Any injection near anterior teeth will affect nasal sensation.

Cheekbone can deflect the needle.

o Most maxillary anesthesia will cause some sensory deficit of the nose and

upper lip

On the posterior aspect of the maxilla lie two plates:

o Lateral and medial pterygoid plates

o Board Q: muscle attached to lateral pterygoid plate is the superior

pharyngeal constrictor

o Board Q: muscles attached to medial pterygoid plate are the medial and

lateral pterygoid muscles

No tooth on the maxilla I cannot get numb!

There is a piriform rim that is intimately associated with the apex of the

central, lateral, and canine teeth

o Anytime you anesthetize these teeth, there will be nasal consequences

The roof of the maxillary sinus is the floor of the orbit

o There is a nerve that runs across the floor of the orbit infraorbital

nerve

o Within the infraorbital canal, branches to the first and second

premolar, the mesial-buccal root of the first molar, and the

maxillary anteriors are given off

o The branch to the premolars and the MB root of the first molar is called

the middle superior alveolar nerve (MSA)

o The branch to the anterior teeth is the anterior superior alveolar nerve

(ASA)

In the posterior maxilla, the pterygopalatine fossa, the branches to the

maxillary posterior teeth are given off

o This branch is called the posterior superior alveolar nerve (PSA)

o Guarding the entrance to the pterygopalatine fossa is the malar bone

(zygoma)

Root of the zygoma can potentially affect your ability to give

anesthesia to the posterior maxilla

Just distal to the root of the canine lies the canine fossa

Posterior aspect, you can see all the porosities

o Several foramina that transmit the PSA

o When you give a maxillary injection PSA, the depth of penetration is

16mm

o There is some vascularity associated with the posterior aspect of the

maxilla, called the pterygoid plexus

Infraorbital foramen is contained within the maxilla

o You can see from an inferior view what the maxilla looks like

Two vascular structures at posterior of maxillary:

o Pterygoid Plexus (a venous structure)

short needles are used to prevent nicking of the pterygoid plexus

o Internal Maxillary Artery

close to neck of mandible

ALWAYS ASPIRATE NEEDLE BEFORE YOU INJECT LOCAL

o if you get a positive aspiration, withdraw needle, change carpule, then

reinsert

Palate Two nerves innervate:

o Greater palatine nerve (associated with hard palate)

o Lesser palatine nerve (associated with soft palate)

Lesser palatine foramen is poster to greater palatine foramen.

At the palatal root (lingual root) of the second molar lies the greater palatine

foramen

o Greater palatine foramen encompasses the greater palatine nerve that

sends sensations to the hard palate and distal aspect of the canine bilaterally

o Anterior to the lesser palatine foramen

Soft palate innervation is provided by the lesser palatine nerve o This is right next to the greater palatine, so if you anesthetize one, you

will anesthetize the other!

o Posterior to the greater palatine foramen

Palatal sensation of the premaxilla: o Provided by the nasopalatine nerve (the nerve of the premaxilla)

Only sensory nerve that crosses the midline!

o Nasopalatine nerve is about 5-7mm posterior to the central incisors

Maxillary sinus

o Supplied by V2

o Any time you have an infection in the maxillary sinus, the pt will complain

of pain in the posterior maxillary teeth

Typically all the molars, the 2nd PM, and on occasion the 1st PM

Posterior maxilla:

o Pterygopalatine fossa

o Inferior orbital fissure

Nerve associated with pulpal sensation or premolars and anteriors

o terminal branch of V2 (Infraorbital Nerve)

ASA (anterior superior alveolar)

supplies anterior incisors and canine

MSA (middle superior alveolar)

premolars and mesiobuccal root of first molar.

PSA (posterior superior alveolar)

Travels through two small foramina to enter maxillary

off of V2 from pterygopalatine fossa

1st, 2nd, and 3rd molars

A way to anesthetize all V2 is via the greater palatine foramen.

Mandible Composed of condyle-ramus unit (flares outwardly/laterally)

Mandibular Nerve provides sensation to teeth, mucosa, tongue AND MOTOR

INNERVATION

o Motor innervation to 8 muscles.

Muscles of mastication

medial and lateral pterygoid

masseter

temporalis

Mylohyoid

Anterior belly of digastric (posterior via CN VII)

Tensor tympani

*******Tensor Veli Palatini*****

Contains two foramina of interest:

o Mandibular foramen and the mental foramen

Lingula

o little spick of bone on the medial aspect of mandible associated with

mandibular foramen.

Pulpal anesthesia is provided by the inferior alveolar nerve (IA)

At approximately the apex of the two PMs lies the mental foramen

o IA continues through the symphysis area

o At this point the IA is called the incisive nerve

Question: To remove the second PM, what nerve should be anesthetized? IA

Question: To remove the first PM, what nerve should be anesthetized? Can

perform lingual infiltration.that means anesthetize the mental nerve, hoping

that some of the solution reaches the foramen and anesthetizing the incisive

nerve good when working on kids

o Dont want to provide bilateral sensory loss on children because they

cant swallow then

o Can remove the two first premolars and not have bilateral anesthesia

Mental nerve is a continuation of the IA that exits at the mental foramen

o Mental nerve breaks up into three branches without names

Trigeminal Nerve

Ganglion associated with trigeminal nerve (all same thing, just three different

names)

o Trigeminal ganglion

o Semilunar ganglion

o Gasserian ganglion

Most important nerve of the middle cranial fossa

Largest of all cranial nerves except optic

From the ganglion, the three great branches emerge (V1, V2, V3)

Has two roots that arise from the lateral pontine region of the ganglion:

o Sensory (portio major)

o Motor (portio minor)

Great afferent nerve of the face, of the mucous membranes of the head

(meninges, paranasal sinus, and conjunctiva of the eye), internal cranial

structures, afferent nerve of the teeth and TMJs, and the efferent

(motor) nerve of the first branchial arch

o Implies the muscles of mastication (4 muscles)

medial and lateral pterygoid, masseter, and temporalis

o Mylohyoid, Anterior Belly of Digastric, Tensor Veli palatini, Tensor

Tempani

Sensory root bears largest TG (or semilunar, Gasserian) ganglion and is like the

dorsal root ganglion of a spinal nerve

o NO nerve synapses within the ganglion

o Fold of dura mater (called Meckels cage) is site of nerve synapses

3 great branches:

o V1 (smallest division), V2, V3 (largest division)

o arise from the ganglion. It should be noted that there is 1 ganglion for

each side of the face.

****BOARD ?: Primary sensation to TMJ is the auriculotemporal nerve*****

If a pt has trigeminal neuralgia, where would you section the TG nerve?

Meckels cage

Cell bodies of Trigeminal nerve embryologically arises from the NEURAL CREST

CELLS.

The type of nerve cell in the Trigeminal nerve is a PSEUDOUNIPOLAR CELL.

Like a spinal (dorsal root) ganglion i.e. it consists of a collection of pseudo-unipolar

cells, each of which has an axon passing into the brainstem and a dendrite extending

peripherally to a sensory nerve ending.

4 Nuclei:

Main Sensory Nucleus-located in pontine tegmentum. Sensation of touch.

Spinal V Tract and Nucleus-has 3 parts: Pars oralis, Pars interpolaris, Pars

caudalis. Fibers concerned with pain and thermal sensitivity

Motor nucleus-branchiomotor component

o Muscles of mastication

o BQ: the only muscle of the soft palate supplied by the trigeminal nerve

comes off the otic ganglion (the tensor veli palatini)

Mesencephalic nucleus-responsible for proprioception/jaw position and

movement

Cranial nerve V Responsibilities

Motor:

o Muscles of mastication (masseter, temporalis, med/lat pterygoid),

mylohyoid, anterior belly of digastric, tensors tympani and veli palatini

Sensory:

o to entire face

o V1: scalp anterior to ears, mucous membranes of cranial viscera, nose and

sinuses, cornea and conjunctiva

o Board ?: obliteration of corneal reflex (blink reflex)

V1:

o Accessory muscles of mastication: mylohyoid, anterior belly of digastric,

tensor tympani and veli palatini

o Motor innervation is ONLY supplied by V3

V2:

o Sensory to the gingiva/teeth and midface: maxilla, upper lip, orbit

V3:

o Sensory to lower face: gingiva/teeth of mandible, tongue, check, lower

jaw, lip (motor)

The 3 divisions embryologically supply:

o V1 frontonasal process

o V2 maxillary process

o V3 1st branchial (pharyngeal) arch

Arch Associations: ON FINAL AND BOARDS

Most common questions involve branchial arches 1 and 2

Arch 1 CN V

Arch 2 CN VII

Arch 3 CN IX

Arch 4 CN X/XI superior laryngeal

Arch 6 CN X/XI recurrent laryngeal

Ophthalmic division

Exclusively sensory

Smallest of the three branches

3 branches:

o Frontal branch comes out and exits onto the face and breaks into

Supraorbital

Supratrochlear

o Nasociliary smallest branch of V1

Ciliary ganglion with the long and short ciliary nerves

Anterior/posterior ethmoidal nerve

Infratrochlear nerve

o Lacrimal branch

Exits the cranium via the superior orbital fissure

If paralyzed, will have an insensate conjunctiva

Why does a pt have tearing in the eye during injection? Stimulation of lacrimal nerve

Maxillary Division

Comes into the orbit in the inferior orbital fissure and lies in infraorbital groove

to exit via the infraorbital foramen

Ganglion is the ciliary ganglion

Exclusively sensory

Exits the skull at foramen rotundum (greater wing of sphenoid bone)

Branches into 4 regions

o Cranium (middle meningeal nerve to dura)

o Pterygopalatine fossa (maxillary nerve with pterygopalatine ganglion)

o Within infraorbital canal

o Upon the face (via infraorbital foramen)

Parasympathetic ganglion is the pterygopalatine ganglion

o Just anterior to this is the posterior superior alveolar nerve

o Located in pterygopalatine fossa

o PSA is located just anterior to the ganglion goes to 1st, 2nd, 3rd molars

While in the pterygopalatine fossa, gives off 3 branches:

o Pterygopalatine nerves

Has branches to the orbit, nose, palate, and pharynx

o PSA (supplies 3rd molar, 2nd molar, and 1st molar, EXCEPT MESIOBUCCAL

ROOT OF 1ST MOLAR)

o Zygomatic

Zygomatic nerve is in the inferior orbital fissure gives sensation to skin of

cheek bone via Zygomaticotemporal and zygomaticofacial

o Where does this come from?

Nerve of premaxilla is ultimately derived from nasopalatine nerves

Branches to the nose:

o Branches to nose pass through sphenopalatine foramen just behind the

middle nasal concha and divides into the medial and lateral posterior

superior nasal branches

o The nasopalatine nerve is a branch of the medial posterior superior nasal

branch and runs through the incisive canal to end in the incisive (or

nasopalatine) foramen, covered by the incisive papillae

o Nasopalatine foramen and incisive nerve will be seen

o Nasopalatine nerve is the only nerve that crosses the midline.

Branches to palate:

o Lesser palatine

Mucous membranes of the soft palate

o Greater palatine

Sensory to soft tissues of the palate up to the area up to the 1st

PM where it anastomoses with branches of the nasopalatine nerve

o Nasopalatine

to premaxilla

o Can you give a greater palatine injection without numbing up the soft

palate? Nope because always knock out the lesser palatine (sensory nerve

to the soft palate)

o Anesthetize MSA, PSA, and Greater palatine to remove the Maxillary

first molar.

Branching within the infraorbital canal:

o Within the infraorbital canal, the branches of MSA and ASA are given

off to the anterior and premolar teeth

o MSA goes to MB root of 1st molar and both premolars

o ASA goes to canines, laterals, and central incisors

o Infraorbital nerve exits onto the face at the infraorbital foramen and

branches into three parts:

One to upper lip called superior labial One to lateral nose called lateral/external nasal One to lower eyelid called inferior palpebral

PSA, ASA, MSA have small terminal filament nerves called the superior dental

plexus that goes to the pulp

Within the orbit is located in the inferior orbital fissure

Look at summary chart!!!

Sensory innervation to the palate by three cranial nerves

o V: GP/LP/NP

o VII: greater petrosal

o IX: tympanic (or tonsillar) plexus or lesser petrosal

In the cranial cavity Meningeal

In pterygopalatine fossa Ganglionic, zygomatic, posterior superior

alveolar

Infraorbital MSA, ASA

Mandibular Division

Largest branch of trigeminal nerve

Exits the skull through foramen ovale

A mixed nerve

Nervous Spinosus?

When it exits foramen ovale, it is in intimate contact above the condyle

2 roots emerge separately out of the Foramen Ovale then unite, but ultimately

split into anterior and posterior divisions

Prior to the split into anterior/posterior divisions, the otic ganglion is attached

Anterior division:

o Mostly motor with branches like

Muscles of mastication

Anterior/posterior deep temporal

Buccal (both sensory and motor to lateral pterygoid muscle)

Long Buccal with CN V (sensory and motor; DOES NOT GO TO

BUCCINATOR)

Posterior division:

o Includes the following branches:

Auriculotemporal

Inferior alveolar and its terminal branches

Mental nerve

Incisive nerves

Lingual

Mylohyoid (mixed nerve; ALSO PROVIDES ACCESSORY

INNERVATION TO THE MANDIBULAR INCISOR AND

MESIAL ROOT OF MANDIBULR FIRST MOLAR)

Mandibular foramen is 1.5 to 2 cm beneath mandibular notch or 1-19mm above

the occlusal plane

o Notch can be used as site to perform Inferior alveolar block

o Inject 20 mm above mandibular notch

Sphenomandibular ligament attaches to lingula.

Stylomandibular ligament goes from Styloid process to angle of mandible.

NOTE: When it comes out of the foramen, before the split into anterior and

posterior division, it is 4.5 mm in length (what were shooting for with a Gow

Gates one shot knocks the whole mandible out)

o The distance from the sigmoid notch to the lingula is about 15 mm

o Where is the lingula located? At junction of posterior third and middle

third of the mandible

Little projection of bone above the mandibular foramen

Located 1-19mm above the occlusal surfaces of the mandibular

teeth

So if you shoot 20 mm above the occlusal surface, 99% of the

time you will get profound anesthesia (shoot 20 mm or higher)

What is the most common reason for missing the mandibular

block? You shot too low

Parotid gland receives secretomotor innervation from auriculotemporal nerve

from branches from OTIC GANLGION. Auriculotemporal nerve also supplies

sensation to TMJ. Also supplies external auditory meatus and tympanic

membrane.

Exits foramen ovale and has two ganglions associated with it:

o Otic ganglion (medial aspect of mandibular nerve that sends a twig to the

tensor veli)

o Submandibular ganglion

Before inferior alveolar nerve goes into the mandible, it sends a branch called

the mylohyoid branch

o When you do inferior alveolar nerve block, you withdraw 2/3 of the

needle you will knock out the lingual nerve

o Lingual nerve has an association with CN VII chorda tympani

o Why important? Taste to anterior 2/3 of tongue

o If have a lingual nerve dysfunction, you will have a taste disturbance on

that side

Inferior alveolar nerve exits mandible at mental foramen

o Supplies sensation to lower lip and chin

Difference between Gow Gates and IANB?

o 95% success rate with GG; knocks out the whole damn thing

o 80-85% success rate with IANB

Headache of meningitis is mediated by GSA fibers of trigeminal nerve.

Components of Trigeminal Nerve Component Function

Branchial Motor (SVE) Muscles of mastication, tensor tympanis,

tensor (veli) palatini, mylohyoid, and anterior

belly of digastric

Other mandibular division notes

The buccal nerve: comes off the facial nerve; goes to the buccinators muscle

The long buccal nerve: comes off the mandibular nerve and provides sensory

innervation

o Also supplies motor to lateral pterygoid muscle

Auriculotemporal nerve supplies sensation to TMJ!

Cant really feel the notch, so know that mandibular foramen is 1-19 mm above

the occlusal plane

Three holes that open in a straight line on the face:

Supraorbital foramen

Infraorbital foramen

Mental foramen

Maxillary Artery

Passes horizontally between ramus of mandible and the sphenomandibular

ligament and is embedded in the pterygoid plexus of veins

1 of terminal branches of external carotid? along with superficial temporal

Has three parts:

o 1st:

Deep auricular

Anterior tympanic

Middle meningeal

Inferior alveolar

o 2nd:

Masseteric

Deep temporal branches to pterygoids

o 3rd:

PSA

Infraorbital

Descending palatine and sphenopalatine (most common source of

bleeding from max artery)

Medial to the neck of the condyle

Most common source of epistaxis (nose bleeding) is from nasopalatine artery.

Oral Surgery:

Key area to achieve anesthesia is on LOWER ARCH

Anatomical series of questions for board

o anesthetize lower arch

Where is tip of needle?

pterygomandibular space

What are the boundaries of pterygomandibular space?

medial = medial pterygoid muscle

lateral = mandibular ramus

superior = lateral pterygoid

posterior = parotid gland

What are the structures within the pterygomandibular space?

inferior alveolar nerve, artery, and vein

lingual nerve

sphenomandibular ligament

What are the relationships?:

lingual nerve is anterior and medial to inferior alveolar nerve

lingula is where sphenomandibular ligament is attached