Oral surgery lac innervation



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oral surgery 
lac. innervation
-the posterior  superior  alveolar  nerve.
it decending from the main trunk of maxillary n.in the pterrgopalatine fossa before  the maxillary devision inter infra orbital fissure. this n. will pass down ward through the pterigoplatin fossa. they reach the post. surface of maxilla.gives 2 branchs.
one remains external of bone& supply sensory innervintion to the buccal gingival in the max. molars& odjacent facial sursafe.
the other branch the maxilla along with a branch of internal max. artery to inter  maxillary sinus.
branches in the infra orbital canal
within the canal ,the v2 gives the middle sup.& ant. sup. alveolar nerves. the n in the infra orbital grove& canal is called infra orbital nerves .
denal plexuse
  terminal  branches of long nerves forms anerve network to inn. root of teeth,bone & pdl in both maxilla and mandible.
?summary of the branches of v3
1-undevided n.(main trunk)
 
a-nervous spinosus
 
b-n. to med pterygoid muscle.
 
2-devided nerve
a-ant. division
•  n. to lateral pterygoid muscle.
•  n. to the masseter muscle.
•  n.to the temporal muscle .
•  n. to buccal .or buccal nerve
b-posterior division.
i.  articulo temporal nerve.
ii.  lingual nerve.
iii.  mylohyoid nerve.
iv.  inferior alveolar nerve (dental branches)
v.  mental nerve.
vi.  incisive branch.
 
 



  long buccal nerve
?  wholly sensory , branch of ant.division of v3.
?  passes between 2 head of the lat. pterygoid muscle at  the  level of occlusal plane.
ligual nerve
?  the  2end branch of the posterior division of v3
?  it passes downwards medial to the lateral pterygoid muscle.
?  it lies between the ramus of mandible& the  medial pterrygoid muscle.
?  reach the side of the base of the tongue.
?  slighty below & behind the mand.3rd molar
?  provide general  sensation for
 
?  all ligual gingival
?  mucosa of  the floor of mouth.
?  the ant. two third of the tongue(sens& taste) 
 
the inferior alveolar nerve
?  abranch of mandibular division,
?  it passes medial to lateral pterygoid muscle.
?  posterior to lingual nerve.
?  it gives the mylohyoid m.
?  with the inferior alveolar artery& vein inter the mandibular canal
?  through the mandibular foramen.
the mental nerve
?  it exite the man. through mental foramen
?  located several mm inf. to the apex of the 2nd premolar
?  or slightly anterior or posterior.
?  it devided into 3 branches
?  inn. the skin of the chin+lower lip+mucos membrane of lower lip.


    the incisive nerve
    it remains within the man. canal
    form anerve plexus
    innervat the pulpal tissue of  the mand. 1st premolar ,canine& incisor via dental branches.



  local anesthesia
 
history
 
the leaves of the coca plant were traditionally used as a stimulant in peru. it is believed[by whom?] that the local anesthetic effect of coca was also known and used for medical purposes. cocaine was isolated in 1860 and first used as a local anesthetic in 1884. the search for a less toxic and less addictive substitute led to the development of the aminoester local anesthetic procaine in 1904. since then, several synthetic local anesthetic drugs have been developed and put into clinical use, notably lidocaine in 1943, bupivacaine in 1957 and prilocaine in 1959.
shortly after the first use of cocaine for topical anesthesia, blocks on peripheral nerves were described. brachial plexus anesthesia by percutaneous injection through axillary and supraclavicular approaches was developed in the early 20th century. the search for the most effective and least traumatic approach for plexus anesthesia and peripheral nerve blocks continues to this day. in recent decades, continuous regional anesthesia using catheters and automatic pumps has evolved as a method of pain therapy.
intravenous regional anesthesia was first described by august bier in 1908. this technique is still in use and is remarkably safe when drugs of low systemic toxicity such as prilocaine are used.
spinal anesthesia was first used in 1885 but not introduced into clinical practice until 1899, when august bier subjected himself to a clinical experiment in which he observed the anesthetic effect, but also the typical side effect of postpunctural headache. within a few years, spinal anesthesia became widely used for surgical anesthesia and was accepted as a safe and effective technique. although atraumatic (non-cutting-tip) cannulas and modern drugs are used today, the technique has otherwise changed very little over many decades.
 
 
local anesthetics are used in dentistry to anesthetize teeth and portions of your jaw so as to maximize comfort during dental procedures.
 
dental anesthetics are dispensed in individual, sterile cartridges into which a sterile needle is inserted.
 
typical dental anesthetics are "-caine type agents" such as xylocaine, lidocaine, carbocaine, and marcaine.  novocaine was perhaps the first widely used local anesthetic but it is no longer available. some anesthetics contain epinephrine (adrenalin), a vasoconstrictor (reduces blood flow), to decrease bleeding in the site and increase anesthetic potency.
 
dentists inject anesthetic into spaces near nerves that innervate (supply sensation) the area to be treated.  the goal is to let the anesthetic gently diffuse into the desired region.
 
as a patient, you will feel the needle go in and the pressure of the solution being injected into the tissues.  generally, the slower the injection, the less the discomfort.
 
topical anesthetic is a -caine type ointment applied before the injection to diminish the prick of the needle.
 
each patient is anatomically unique therefore, it is possible to inject directly into a nerve.  this situation causes sudden, sharp "shock" followed by immediate anesthesia.
 
it is also possible to inject into a blood vessel.  in those circumstances, you may feel your heart pound faster.  this is due to the epinephrine (adrenalin) in the anesthetic.  you may also swell and bruise (hematoma).
 
local anesthetic can block almost every nerve between the peripheral nerve endings and the central nervous system. the most peripheral technique is topical anesthesia to the skin or other body surface. small and large peripheral nerves can be anesthetized individually (peripheral nerve block) or in anatomic nerve bundles (plexus anesthesia). spinal anesthesia and epidural anestem merges into the central nervous system.
injection of local anesthetics is often painful. a number of methods can be used to decrease this pain including buffering of the solution with bicarb and warming.[1]
  surface anesthesia - application of local anesthetic spray, solution or cream to the skin or a mucous membrane. the effect is short lasting and is limited to the area of contact.
infiltration anesthesia - injection of local anesthetic into the tissue to be anesthetized. surface and infiltration anesthesia are collectively topical anesthesia.
field block - subcutaneous injection of a local anesthetic in an area bordering on the field to be anesthetized.
peripheral nerve block - injection of local anesthetic in the vicinity of a peripheral nerve to anesthetize that nerve s area of innervation.
plexus anesthesia - injection of local anesthetic in the vicinity of a nerve plexus, often inside a tissue compartment that limits the diffusion of the drug away from the intended site of action. the anesthetic effect extends to the innervation areas of several or all nerves stemming from the plexus.


physiology
to achieve conduction anesthesia a local anesthetic is injected or applied to a body surface. the local anesthetic then diffuses into nerves where it inhibits the propagation of signals for pain, muscle contraction, regulation of blood circulation and other body functions. relatively high drug doses or concentrations inhibit all qualities of sensation (pain, touch, temperature etc.) as well as muscle control. lower doses or concentrations may selectively inhibit pain sensation with minimal effect on muscle power. some techniques of pain therapy, such as walking epidurals for labor pain use this effect, termed differential block.
pathophysiology
reviewing the physiology of nerve conduction is important before any discussion of local anesthetics. nerves transmit sensation as a result of the propagation of electrical impulses this propagation is accomplished by alternating the ion gradient across the nerve cell wall, or axolemma.
in the normal resting state, the nerve has a negative membrane potential of -70 mv. this resting potential is determined by the concentration gradients of 2 major ions, na+ and k+, and the relative membrane permeability to these ions (also known as leak currents). the concentration gradients are maintained by the sodium/potassium atp pump (in an energy-dependent process) that transports sodium ions out of the cell and potassium ions into the cell. this active transport creates a concentration gradient that favors the extracellular diffusion of potassium ions. in addition, because the nerve membrane is permeable to potassium ions and impermeable to sodium ions, 95% of the ionic leak in excitable cells is caused by k+ ions in the form of an outward flux, accounting for the negative resting potential. the recently identified 2-pore domain potassium (k2p) channels are believed to be responsible for leak k+ currents.
  dentistry (surface anesthesia, infiltration anesthesia or intraligamentary anesthesia during restorative operations or extractions, regional nerve blocks during extractions and surgeries.)
 
techniques of dental local anesthesia
regional dental anesthesia can be divided into component parts,
depending on the technique employed. there are three different
techniques used in dental anesthesia: local infiltration technique,nerve block and periodontal ligament injection in local infiltration technique,
small nerve endings in the area
of the dental treatment are flooded
with local anesthetic solution,
preventing them from becoming
stimulated and creating an impulse.
local infiltration technique
is commonly used in anesthesia
of the maxillar teeth and
the mandibular incisors
\in nerve block anesthesia
  (conduction anesthesia), the local anesthetic
solution is deposed within close proximity to a main nerve
trunk, and thus preventing afferent impulses from traveling centrally
beyond that point. nerve block is used in anesthesia of the
inferior mandibular nerve, the lingual nerve, the buccal nerve, the
greater palatine nerve and the nasopalatine nerve
 
in periodontal ligament (pdl) technique
(= intraligamentary injection),
the local anesthetic solution is injected into the desmodontal
space. the pdl technique is useful for anesthesia of
mandibular molars as an alternative to the nerve block technique.
the injection is painless and the anesthetic effect is limited to the
pulp and desmodontal nerve of the tooth anesthesized. duration
of anesthesia is in the range of 15 to 20 minutes, which allows
most routine dental treatment. the pdl injection is useful for extremely
anxious patients and
children, who do not tolerate
conventional technique. the
dose of anesthetic solution, which is required for complete anesthesia,
is lower than in infiltration technique. for pdl technique, 
 
a high concentration of the local anesthetic is required due to the
limited volume, which can be injected into the narrow desmodonta lspace ,
surface anesthesia - application of local anesthetic spray, solution or cream to the skin or a mucous membrane. the effect is short lasting and is limited to the area of contact.
infiltration anesthesia - injection of local anesthetic into the tissue to be anesthetized. surface and infiltration anesthesia are collectively topical anesthesia.
field block - subcutaneous injection of a local anesthetic in an area bordering on the field to be anesthetized.
peripheral nerve block - injection of local anesthetic in the vicinity of a peripheral nerve to anesthetize that nerve s area of innervation.
plexus anesthesia - injection of local anesthetic in the vicinity of a nerve plexus, often inside a tissue compartment that limits the diffusion of the drug away from the intended site of action. the anesthetic effect extends to the innervation areas of several or all nerves stemming from the plexus.
epidural anesthesia - a local anesthetic is injected into the epidural space where it acts primarily on the spinal nerve roots. depending on the site of injection and the volume injected, the anesthetized area varies from limited areas of the abdomen or chest to large regions of the body.
spinal anesthesia - a local anesthetic is injected into the cerebrospinal fluid, usually at the lumbar spine (in the lower back), where it acts on spinal nerve roots and part of the spinal cord. the resulting anesthesia usually extends from the legs to the abdomen or chest.
intravenous regional anesthesia (bier s block) - blood circulation of a limb is interrupted using a tourniquet (a device similar to a blood pressure cuff), then a large volume of local anesthetic is injected into a peripheral vein. the drug fills the limb s venous system and diffuses into tissues where peripheral nerves and nerve endings are anesthetized. the anesthetic effect is limited to the area that is excluded from blood circulation and resolves quickly once circulation is restored.
local anesthesia of body cavities (e.g. intrapleural anesthesia, intraarticular anesthesia)
adverse effects
 
adverse effects depend on the local anesthetic agent, method, and site of administration and is discussed in depth in the local anesthetic sub-article.
overall the effects can be:
1.  localized prolonged anesthesia or paresthesia due to infection, hematoma, excessive fluid pressure in a confined cavity, and severing of nerves & support tissue during injection,
2.  systemic reactions such as depressed cns syndrome, allergic reaction, vasovagal episode, and cyanosis due to local anesthetic toxicity.
3.  lack of anesthetic effect due to infectious pus such as an abscess.
uses
 
acute pain
acute pain may occur due to trauma, surgery, infection, disruption of blood circulation or many other conditions in which there is tissue injury. in a medical setting it is usually desirable to alleviate pain when its warning function is no longer needed. besides improving patient comfort, pain therapy can also reduce harmful physiological consequences of untreated pain.
acute pain can often be managed using analgesics. however, conduction anesthesia may be preferable because of superior pain control and fewer side effects. for purposes of pain therapy, local anesthetic drugs are often given by repeated injection or continuous infusion through a catheter. low doses of local anesthetic drugs can be sufficient so that muscle weakness does not occur and patients may be mobilized.
some typical uses of conduction anesthesia for acute pain are:
•  labor pain (epidural anesthesia)
•  postoperative pain (peripheral nerve blocks, epidural anesthesia)
•  trauma (peripheral nerve blocks, intravenous regional anesthesia, epidural anesthesia)
chronic pain
chronic pain of more than minor intensity is a complex and often serious condition that requires diagnosis and treatment by an expert in pain medicine. local anesthetics can be applied repeatedly or continuously for prolonged periods to relieve chronic pain, usually in combination with medication such as opioids, nsaids, and anticonvulsants.
differences of esters and amides
•  all local anesthetics are weak bases.  chemical structure of local anesthetics have an amine group on one end connect to an aromatic ring on the other and an amine group on the right side.  the amine end is hydropinghilic (soluble in water), and the aromatic end is lipophilic (soluble in lipids)
•  two classes of local anesthetics are amino amides and amino esters.
o  amides:        esters:
o  amide link b/t intermediate  ester link b/t intermediate chain and chain and aromatic ring          aromatic ring
o  metabolized in liver and very  metabolized in plasma through soluble in the solution            pseudocholinesterases and not
stable in the solution cause allergic reactions
 
structures of amides and esters
the amine end is hydropinghilic (soluble in water), anesthetic molecule dissolve in water in which it is delivered from the dentist’s syringe into the patient’s tissue.  it’s also responsible for the solution to remain on either side of the nerve membrane.
 
the aromatic end is lipophilic (soluble in lipids).  because nerve cell is made of lipid bilayer it is possible for anesthetic molecule to penetrate through the nerve membrane.
 
the trick the anesthetic molecule must play is getting from one side of the membrane to the other.
           
 
?  three special drugs used in dental anesthes bupivicaine (marcaine®
produce very long acting anesthetic effect to delay the post operative pain from the surgery for as long as possible
0.5% solution with vasoconstrictor
toxicity showed by the pka is very basic
onset time is longer than other drugs b/c most of the radicals (about 80%) bind to sodium channel proteins effectively
most toxic local anesthetic drug
?  prilocaine (citanest®)
identical pka and same conc. with lidocaine
 
almost same duration as lidocaine
 
less toxic in higher doses than lidocaine b/c small vasodilatory activity
?  articaine (septocaine®)
 
newest local anesthetic drug approved by fda in 2000
same pka and toxicity as lidocaine, but its half life is less than about ¼ of lidocaine
 
used with vasoconstrictor.
enters blood barrier smoothly
the drug is widely used in most nations today
 
 
 
anesthetic  pka  onset  duration (with epinephrine) in minutes  max dose (with epinephrine)
procaine  9.1  slow  45 - 90  8mg/kg – 10mg/kg
lidocaine  7.9  rapid  120 - 240  4.5mg/kg – 7mg/kg
bupivacaine  8.1  slow  4 hours – 8 hours  2.5mg/kg – 3mg/kg
prilocaine  7.9  medium  90 - 360  5mg/kg – 7.5mg/kg
articaine  7.8  rapid  140 - 270  4.0mg/kg – 7mg/kg
adverse effects of epinephrine
depending on the dose, sympathomimetic amines can evoke a variety
of systemic reactions. the major systemic effects of injected
sympathicomimetic amines involve the cardiovascular system.
heart rate and contractile force increase under the influence of epinephrine.
arterioles and veins are constricted or dilatated,
depending on the total dose of epinephrine and the receptors
activated (tab. 8).
cardiovascular responses of epinephrine often include tachycardia,
mild hypertension, and occasionally premature ventricular
contractions. the majority of adverse reactions are mild and short
of duration. headache can result in the rare occurrence of a severe
hypertensive response. since moderate doses of epinephrine lower
total peripheral resistance, the mean arterial pressure may remain
unchanged or become slightly reduced. in sensitive patients or
under certain conditions, epinephrine may cause
•  pronounced tachycardiaor
•  hypertension and may
•  elicit dangerous cardiac
 
•  arrhythmias,
angina pectoris attack or myocardial infarction


 


serum levels of epinephrine
following submucosal
injection and
systemic effeccts on cardiovascular system 


 

 


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