Anatomy of 3 rd cranial nerve

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Anatomy of 3 rd cranial nerve

  1. 1. A N A T O MY OFT HI RD CRANI AL NERVE Dr.HASIKA BHIMALA M.S.OPHTHALMOLOGY ( 1ST YR) 24-3-13
  2. 2. The cranial nerves 12 in number. Are part of the peripheral nervous system. The craniocaudal sequence of cranial nerves is as follows• 1- Olfactory• 2- Optic• 3- Oculomotor• 4- Trochlear• 5- Trigeminal• 6- Abducent• 7- Facial• 8- Vestibulocochlear• 9- Glossopharyngeal• 10- Vagus• 11- Accessory• 12- Hypoglossal All exit the cranial cavity through foramina or fissures. All originate from the brain. Contain sensory, motor or both components
  3. 3. 1- MOTOR (EFFERENT) PARTS OFCRANIAL NERVES:• Ar i se w t hi n br ai n f r om gr oup of ner ve i cel l s, w ch const i t ut e t hei r nucl ei of hi or i gi n.• They ar e connect ed w t h cer ebr al cor t ex i by cor t i conucl ear f i br es, t hese ar i se f r om cel l s of m or ar eas of t he ot cor t ex, descend chi ef l y i n geni cul ar par t of i nt er nal capsul e t o br ai nst em w e , her m any but not al l cr oss t he m an pl ane edi and end by ar bor i zi ng r ound nucl ei of or i gi n of m or cr ani al ner ves. ot
  4. 4. 2- SENSORY (AFFERENT) CRANIAL NERVES:•Ar i se f r om ner ve cel l s out si de br ai n, t hese ner vecel l s m be aygr ouped t o f or m gangl i a on t r unks of t he ner ves, orm be si t uat ed i n per i pher al sensor y or gans such as ayt he nose, eye & ear .•The cent r al l y di r ect ed pr ocesses of t he cel l s r uni nt o br ai n & t her e end by ar bor i zi ng ar ound ner vecel l s, w ch ar e gr ouped t o f or m t hei r nucl ei of hit er m nat i on. i• Fi br es ar i se f r om cel l s of t hese nucl ei and,
  5. 5. The nucl ei of t hecr ani al ner ves.Thesensor y nucl eiar e i l l ust r at edon t he l ef t , andt he m or nucl ei oton t he r i ght .
  6. 6. Dorsal aspect of brain stem showing locationsof Afferent cranial N. nuclei (left) , andEfferent cranial N.nuclei (right) , in which thesame colours have a common embryological
  7. 7. • Thi r d cr ani al ner ve.• I t i s t he l ar gest of t he ocul ar m or ner ves. ot• I t cont ai ns som 15,000 axons, i ncl udi ng m or e ot f i ber s and par asym het i c m or f i ber s. pat ot• Ent i r el y m or i n f unct i on. ot• Suppl i es LPS and al l ext r a ocul ar m uscl es except l at er al r ect us and super i or obl i que.• Al so suppl i es t he i nt r aocul ar m uscl es nam y el sphi nct er pupi l l ae and ci l i ar y muscl e
  8. 8. FUNCTIONAL COMPONENTS• Som i c ef f er ent com at ponent i s concer ned w t h i t he m ovem s of t he eyebal l – m or suppl y ent ot to m uscl es der i ved f r om head m om yot es-LPS, SR R R and I O ,M ,I .• Gener al vi scer al ef f er ent (par asym het i c) pat com ponent of t he ner ve i s m eant f or accom odat i on and cont r act i on of t he pupi l – m m or suppl y t o ci l i ar i s and sphi nct er ot pupi l l ae.• G ener al som i c af f er ant com at ponent of t he ner ve i s associ at ed w t h pr opr i ocept i ve i i m ses f r om t he ext r aocul ar m pul uscl es suppl i ed by t he som i c ef f er ent com at ponent of
  9. 9. OCULOMOTOR NUCLEAR COMPLEX• Locat ed i n m dbr ai n at t he l evel of super i or i col l i cul us, i n t he vent r om al par t of t he cent r al edi gr ey m t er t hat sur r ounds t he cer ebr al aqueduct . at
  10. 10. • I t i s a l ongi t udi nal col um of about n 10m l engt h. m RELATIONS:• Dorsomedial: central grey zone surrounding aqueduct.• Ventrolateral: medial longitudinal bundle.• Superior: approaches floor of third ventricle.• Inferior: continuous with trochlear nucleus
  11. 11. • The nucl eus of t he t hi r d cr ani al ner ve i s l ocat ed i n t he i nf er i or per i aqueduct al gr ay m t er of t he at m esencephal on.• I t i s a com ex of bot h pai r ed and pl m dl i ne m or cel l s. i ot• These cel l s ar e f ound f r om t he post er i or com i ssur e super i or l y t o t he m pont omesencephal i c j unct i on caudal l y i n t he dor sal m dbr ai n. i
  12. 12. • C assi cal l y, t hi s com ex has been l pl descr i bed w t h f our pai r ed subnucl ei i suppl yi ng i nner vat i on t o t he i nf er i or , m al , and super i or r ect us edi m uscl es and t o t he i nf er i or obl i que m uscl e.• Ther e i s a si ngl e caudal , dor sal m dl i ne i nucl eus pr ovi di ng i nner vat i on t o t he l evat or m uscl e.• I nner vat i on of t he ext r aocul ar m uscl e f r om t he pai r ed nucl ei i s i psi l at er al f or t he i nf er i or and m al r ect us m edi uscl es and t he i nf er i or obl i que m uscl e.• H ever , i nner vat i on of t he super i or ow r ect us i s cont r al at er al .• The m or f i ber s t o t he super i or r ect us ot decussat e w t hi n t he t hi r d ner ve nucl eus i
  13. 13. • I n addi t i on t o t he ext r aocul ar m uscl e m or f i ber s, t he Edi nger -W phal ot est nucl ei suppl y t he par asym het i c pat pr egangl i oni c neur ons t hat pr oj ect t o t he ci l i ar y gangl i on.• These nucl ei ar e posi t i oned dor sal and m al t o t he m edi uscl e m or nucl ei . ot• They ar e com posed of t w cel l gr oups, o a m al unpai r ed col um and a l at er al edi n pai r ed col um n.• Al l evi dence suggest s t hat t hese f i ber s pr oj ect i psi l at er al l y.
  14. 14. OCULOMOTOR NERVE NUCLEI:I ncl ude t w m or nucl ei : o ot M n M or N eus: ai ot ucl Si t e : vent r al par t of cent r al gr ey m t er at "sur r oundi ng t he cer ebr al aqueduct ", of m dbr ai n, at t he l evel of super i or col l i cul us, i cl ose t o m an pl ane. edi Suppl y : al l ext r i nsi c m uscl es of t he eye except super i or obl i que & l at er al r ect us. The l evat or pal pebr ae super i or i s muscl es of bot h si des ar e suppl i ed by si ngl e cent r al gr oup of cel l s "cent r al caudal nucl eus". The super i or r ect us m uscl e i s suppl i ed by cont r al at er al ocul om or nucl eus. The r em ni ng m ot ai uscl es ar e
  15. 15. • I t i s com posed of subnucl ei suppl yi ng i ndi vi dual ext r aocul ar muscl es as f ol l ow : s1. D sol at er al N eus : I psi l at er al I nf er i or or ucl R us ect2. I nt er m al N eus : I psi l at er al I nf er i or edi ucl O i que bl3. Vent r om al N eus : I psi l at er al M al edi ucl edi R us ect4. Par am al (Scat t er ed) N eus : C r al at er al edi ucl ont Super i or R us ect5. C audal C r al N eus : Bi l at er al Levat or ent ucl Pal pebr ae Super i or i s
  16. 16. W w cks ar r angem ar i ent of t he I I Icr ani al ner vesubnucl ei , i l l ust r at i ng t hepat t er n of m or cel l s i n t he otbr ai n st em t hat sends f i ber s t o
  17. 17.  Accessor y par asym het i c (ED N ER ESTPH L) pat I G W A nucl eus: Si t e : i t l i es dor sal t o t he m n m or nucl eus. ai ot Suppl y : t he axons, w ch ar e pr egangl i oni c hi accom pany ot her ocul om or f i br es t o r el ay w t hi n ot i ci l i ar y gangl i on i n or bi t and suppl y sphi nct er pupi l l ae & ci l i ar y muscl es vi a shor t ci l i ar y ner ves. I t consi st s of a m an and t w l at er al com edi o ponent s. Per haps, t he cr ani al hal f of t he nucl eus i s concer ned w t h l i ght r ef l exes and t he caudal hal f i w t h accom odat i on. i m
  18. 18. FASCICLE• The f asci cul ar por t i on of t he ocul om or ner ve ot descends as i t s m oves vent r al l y and l at er al l y t hr ough t he mesencephal on.• The f asci cl es pass t hr ough t he m al l ongi t udi nal edi f asci cul us, t he r ed nucl eus, and t he m al por t i on edi of t he cer ebr al peduncl e.• D i ng t he passage t hr ough t he vent r al m dbr ai n, ur i t her e appear s t o be t opogr aphi c or gani zat i on of t he f asci cl es so t hat a di vi si onal par esi s i s possi bl e even w t h i nt r i nsi c l esi ons. i• The ocul om or ner ve exi t s t he br ai n st em i nt o t he ot i nt er peduncul ar f ossa as a hor i zont al ar r angement of m t i pl e f i ber bundl es t hat r api dl y coal esce t o ul
  19. 19. C oss-sect i ons of t he br ai n st em (A) Thr ough super i or r .col l i cul us, show ng cr ani al ner ve I I I nucl ei w t h i ii nt r amedul l ar y f i ber s.
  20. 20. CONNECTIONS1. C ebr al cor t ex er• M or cor t ex (pr ecent r al gyr us) of bot h ot si des t hr ough cor t i conucl ear t r act s.• Vi sual cor t ex t hr ough t he super i or col l i cul us and t he t act obul bar t r act .• Fr ont al eye f i el d.2. N ei of 4t h, 6t h and 8t h cr ani al ner ves ucl t hr ough t he m al l ongi t udi nal bundl e. edi3. Pr et ect al nucl eus of bot h si des (f or l i ght r ef l ex)4. Ver t i cal and t or si onal gaze cent er s t hr ough t he m al l ongi t udi nal bundl e. edi5. C ebel l um t hr ough t he vest i bul ar nucl ei . er
  21. 21. D EEP O I G N : R I• The ocul om or f i br es r un f or w ds f r om nucl ear ot ar com ex passi ng t hr ough M t egm um r ed nucl eus pl LF, ent , & m al par t of subst ant i a ni gr a, f or m ng ser i es of edi i cur ves w t h l at er al convexi t y. i• They em ge f r om sul cus ocul om or i us on m al er ot edi si de of cer ebr al peduncl e.
  22. 22.  SU FI C AL O I G N PER I R I :• The ner ve em ges as 10-15 r oot l et s at sul cus er ocul om or i us cl ose t o upper bor der of pons, near ot t er m nat i on of basi l ar ar t er y. i• As i t em ges f r om br ai n i t i s i nvest ed by pi am er & er at l i es i n t he subar achnoi d space.• I t passes bet w een super i or cer ebel l ar & post er i or cer ebr al ar t er i es.• Bet w een t he t w ner ves i s t he post er i or per f or at ed o subst ance (f i g. N 4).
  23. 23. COURS E ANDDI S T RI BUT I ON
  24. 24. Fasci cul arBasi l arI nt r acaver nousI nt r aor bi t al
  25. 25. The Fascicular part :• Fasci cul us consi st s of ef f er ent f i br es w ch pass f r om t he t hi r d hi ner ve nucl eus t hr ough t he r ed nucl eus and t he m al aspect of t he cer ebr al edi peduncl e• They t hen em ge f r om t he m dbr ai n er i and pass i nt o t he i nt er pedencul ar space
  26. 26. Oculomotor nerve. Axial oblique 0.8-mm-thick SSFP MR image shows thenerve (small arrows) where it emerges from the interpeduncular cistern(large arrow), which lies medial to the cerebellar peduncle (p).
  27. 27. The Basilar part :• St ar t s as a ser i es of 15-20 r oot l et s i n t he i nt er peduncul ar f ossa.• These coal ase t o f or m a l ar ge m al and a edi sm l l at er al r oot , w ch uni t e t o f or m a al hi f l at t ened ner ve, w ch get s t w st ed br i ngi ng hi i t he i nf er i or f i br es super i or l y and super i or f i ber s i nf er i or l y; and t hus t he ner ve becom aes r ounded cor d.• The ner ve t hen passes b/w t he post er i or cer ebr al ar t er y and t he super i or cer ebel l ar ar t er y and r uns f or w d i n t he i nt er peduncul ar ar ci st er n ( r unni ng l at er al t o & par al l el w t h i t he post er i or com uni cat i ng ar t er y) t o r each m
  28. 28. M or bl ood ajvessel s and t hei rr el at i onshi ps t ot he ocul ar m orotner ves. N e t he otpassage of C I I I Nbet w een t hesuper i orcer ebel l ar ar t er ybel owand post er i orcer ebr al ar t er yabove. Thevascul ar suppl y t oC I I I com f r om N esbr anches of ft he post er i orcom uni cat i ng mar t er y, w ch i s hii n cl osepr oxi m t y. i
  29. 29. Oculomotor nerve. Coronal 0.8-mm-thick SSFP MR image shows the oculomotornerve (white arrow) in cross section between the posterior cerebral artery (whitearrowhead) and the superior cerebellar artery (black arrowhead), which are distalbranches of the basilar artery (black arrow).
  30. 30. The Intracavernous• part ent er s t he caver nous si nus by pi er ci ng t he The ner ve : post er i or par t of i t s r oof on t he l at er al si de of t he post er i or cl i noi d pr ocess.• I t t hen descends t o t he l at er al w l of t he al si nus, w e i t l i es above t he t r ochl ear ner ve. her• I n t he ant er i or par t of t he caver nous si nus, t he ner ve di vi des i nt o super i or and i nf er i or di vi si ons w ch ent er t he or bi t t hr ough t he m ddl e par t of t he hi i super i or or bi t al f i ssur e w t hi n t he annul us of Zi nn. i• I n t he f i ssur e, t he nasoci l i ar y ner ve l i es i n b/w t he t w di vi si ons, w l e t he abducent ner ve l i es o hi
  31. 31. l nt r acaver nous cour se of t he ocul ar m or ner ves. C I I I and C I V r un ot N Ni n t hel at er al w l of t he caver nous si nus al ong w t h C V di vi si ons VI and al i Nv2. C VI r uns i n cl ose appr oxi m i on t o t he car ot i d ar t er y w t hi n t he N at icaver nous si nus i t sel f . A t he ner ves cour se t ow d t he ant er i or aspect s arof t he caver nous si nus and t he super i or or bi t al f i ssur e, V1(opht hal m c) di vi des i nt o 3 br anches: t he l acr i m , f r on t al , and i alnasoci l i ar y ner ves. The l acr i m and f r ont al ner ves cr oss over t he t op alof C I I I and C I V. C I I I di vi des i nt o super i or and i nf e r i or N N N
  32. 32. The Intraorbital part :• I n t he or bi t , t he sm l er super i or di vi si on al ascends on t he l at er al si de of opt i c ner ve & suppl i es t he super i or r ect us and t he LPS .• The l ar ger , i nf er i or di vi si on di vi des i nt o t hr ee br anches :1. N ve To The M al R us passes i nf er i or er edi ect t o t he opt i c ner ve.2. N ve To I nf er i or R us passes dow ar d er ect nw and ent er s t he m uscl e on i t s upper aspect , and3. N ve To I nf er i or O i que (l ongest of t he er bl t hr ee br anches) passes i n b/w t he I R & LR and suppl i es t he I O f r om i t s post er i or bor der . I t gi ves of f t he m or r oot t o t he ot
  33. 33. CILIARY GANGLION• Descr i pt i on : Per i pher al par asym het i c pat gangl i on and i t s const i t uent cel l s ar e m t i pol ar . ul• Si ze : Sm l , about t he si ze of pi ns head. al• Shape & col or : Fl at & r eddi sh-gr ey.• Si t e : Near or bi t al apex i n som l oose f at e bet w een opt i c ner ve & l at er al r ect us, l yi ng usual l y on l at er al si de of opht hal m c ar t er y. i
  34. 34.  R s : r eci eves post er i or l y t hr ee ootr oot s or r ami Parasympathetic (motor) root Sympathetic root Sensory root
  35. 35. Par asym het i c (M or ) R : pat ot oot• C r i es pr egangl i oni c par asym het i c ar pat f i br es w ch ar i se f r om cel l s of hi Edi nger -W phal nucl eus and r un est t hr ough ocul om or ner ve & i t s br anch ot t o i nf er i or obl i que t o r each t he gangl i on.• These f i br es ar e r el ayed i n t he gangl i on and post gangl i oni c f i br es t r avel i n t he shor t ci l i ar y ner ves.
  36. 36. Sym het i c R pat oot :• I s br anch f r om i nt er nal car ot i d pl exus w ch ent er t he or bi t t hr ough SO and hi F r each t he gangl i on by ei t her : (a) j oi ni ng i t di r ect l y, (b) j oi ni ng t he sensor y r oot , or (c) t r avel vi a opht hal m c ner ve i & i t s nasoci l i ar y br anch.• I t consi st s of post gangl i oni c f i br es f r om t he SC w ch t r aver se t he ci l i ar y O hi
  37. 37. Sensor y Root :• cont ai ns sensor y f i br es f r om t he eyebal l , w ch r each t he gangl i a vi a hi shor t ci l i ar y ner ves and pass t hr ough i t w t hout i nt er r upt i on. i• I t l eaves t he gangl i on backw ds t o ar j oi n nasoci l i ar y ner ve near t he poi nt w e t hat ner ve ent er s t he or bi t . her
  38. 38. Br anches:• These ar e t he shor t ci l i ar y ner ves, 8-10 del i cat e f i l am s w ch em ge f r om t he ent hi er gangl i on.• They r un f or w ds i n w ar avy cour se i n company w t h shor t ci l i ar y ar t er i es, i above and bel ow t he opt i c ner ve.• They subdi vi de i nt o 15-20 br anches w ch pi er ce scl er a ar ound opt i c ner ve hi and pass f or w ds i n del i cat e gr ooves on ar
  39. 39. • They car r y:1. Par asym het i c f i br es: suppl y sphi nct er pat pupi l l ae & ci l i ar y muscl es (m e t han 95% or of t hese f i br es ar e di st r i but ed t o ci l i ar y muscl e w ch i s m hi uch l ar ger i n vol um e).2. Sym het i c f i br es: di st r i but ed t o bl ood pat vessel s of eyebal l and m i ncl ude t he ay f i br es w ch suppl y t he di l at or pupi l l ae hi w hen t hese f i br es do not f ol l ow t hei r usual cour se i n t he opht hal m c, nasoci l i ar y and l ong ci l i ar y i ner ves.
  40. 40. BLOOD SUPPLY• The bl ood suppl y t o t he m al aspect of t he edi br ai nst em i s f r om vessel s di r ect l y of f t he Basi l ar ar t er y.• Sm l per f or at or s of f ci r cum l ex ar t er i es (post er i or al f cer ebr al , super i or cer ebel l ar ar t er y) m al so suppl y ay t he f asci cul ar por t i on of t he t hi r d ner ve as i t cour ses t hr ough t he vent r al m dbr ai n. i• The vascul ar suppl y of 3r d ner ve i n subar achnoi d space i s vi a vascul ar t w gs f r om t he post . C ebr al A., t he i er sup. C ebel l ar A., and t he t ent or i al and dor sal er m ngeal br anches of t he m ngohypophyseal t r unk of eni eni t he I CA.• I n t he caver nous si nus, t he t ent or i al , dor sal m ngeal , and i nf er i or hypophyseal br anches of t he eni m ngohypophyseal t r unk suppl y t he ner ve al ong w t h eni i
  41. 41. • Al l ner ves ar e suppl i ed w t h bl ood f r om adj acent vessel s, w ch ar e i hi usual l y sm l and var i abl e. al• Such a nut r i ent ar t er y di vi des i nt o ascendi ng and descendi ng br anches w ch anast om hi ose i n t he epi neur i um w t h si m l ar br anches i i f r om ot her s.• Fr om t hese epi neur al vessel s f i ne br anches penet r at e i nt o t he per i neur i um w t h f ur t her anast om , i oses, and t hei r t er m nal i ar t er i ol es ent er f asci cul i t o f or m r i ch l ongi t udi nal capi l l ar y pl exuses al ong t he f ul l l engt h of t he ner ve.• These ar e r ei nf or ced by ot her nut r i ent ar t er i es, but no par t of t he i nt r af asci cul ar pl exus i s dom nat ed by any one ar t er y. i• The bl ood suppl y of t he ocul om or , t r ochl ear and abducent ner ves ot i s si m l ar l y ar r anged, t he nut r i ent ar t er i es bei ng der i ved f r om any i adj acent sm l er ar t er i es. al
  42. 42. CLINICALLY APPLIED ASPECTS
  43. 43. ANATOMICAL BASIS OF CLINICALFEATURES OF THIRD NERVE PALSY• A com et e & a t ot al t hi r d ner ve pl pal sy i s of com on occur r ence. m• M be congeni t al or acqui r ed. ay• C i ni cal f eat ur es of com et e t hi r d l pl ner ve pal sy i ncl ude :
  44. 44. (b) complete left ptosis;(a)after manual elevation ofupper left eyelid, we canobserve left exotropia andhypotropia, and mid-dilatedpupil.
  45. 45. 1. Pt osi s - par al ysi s of LPS muscl e.2. D at i on – out , dow and i nt or t ed – unopposed evi n act i on of LR and SO .3. O ar m cul ovem s : ent• Adduct i on – M R• El evat i on – SR and I O• D essi on – I R epr• Ext or si on – I R and I O4. Pupi l i s f i xed and di l at ed – par al ysi s of sphi nct er pupi l l ae m uscl e.5. Accom odat i on i s com et el y l ost – par al ysi s of m pl ci l i ar y muscl e.
  46. 46. 6. C ossed di pl opi a – par al yt i c r di ver gent squi nt .7. Head post ur e – i f t he pupi l l ar y ar ea i s uncover ed, head t akes a post ur e consi st ent w t h t he di r ect i ons of i act i ons of t he par al ysed m uscl es, i .e., head i s t ur ned on t he opposi t e si de, t i l t ed t ow ds t he sam si de and chi n ar e i s sl i ght l y r ai sed.
  47. 47. FEATURES AND CAUSES OF THIRDNERVE LESIONS AT VARIOUS LEVELS1. Supr anucl ear l esi ons• Lesi ons of t he cer ebr al cor t ex and supr anucl ear pat hw pr oduce ay conj ugat e par esi s w ch af f ect bot h hi eyes equal l y.• I n supr anucl ear l esi ons al t hough posi t i on and m ovem s of t he eyes ent ar e abnor m , t hey m nt ai n t hei r al ai r el at i ve co-or di nat i on and pr oduce no di pl opi a
  48. 48. 2. N ear l esi ons ucl• Lesi ons i nvol vi ng pur el y t he t hi r d ner ve nucl eus ar e r el at i vel y uncom on. m• C m causes i ncl ude ; vascul ar om on di seases, dem i nat i on, pr i m y t um s and yel ar or m ast asi s et• Lesi ons i nvol vi ng ent i r e nucl eus cause an i psi l at er al t hi r d ner ve pal sy w t h i psi l at er al i spar i ng and cont r al at er al w eakness of el evat i on.• Lesi ons i nvol vi ng pai r ed m al r ect us edi subnucl ei (vent r om al nucl eus) cause a w l - edi al eyed bi l at er al i nt er nucl ear opht hal m egi a ( opl
  49. 49. 3. Fasci cul ar l esi ons• Causes are similar to nuclear lesions. Benedikt syndrome involves the fasciculus as it passes through the red nucleus and is characterised by ipsilateral 3rd nerve palsy and contralateral extrapyramidal signs such as hemitremor. Weber syndrome involves the fasciculus as it passes through the cerebral peduncle and is characterised by ipsilateral 3rd nerve palsy and contralateral hemiparesis. Nothangel syndrome involves the fasciculus and the superior cerebellar peduncle and is characterised by ipsilateral 3rd nerve palsy and cerebellar ataxia. Claude syndrome is a combination of Benedikt and Nothangel syndromes
  50. 50. Lesion in cerebral peduncle , Weber Syndrome (B)Lesion in red nucleus , Benedikt Syndrome (C)
  51. 51. 4. Lesi ons i nvol vi ng basi l ar par t of t he ner ve• As t he ner ve r uns i n t he subar achnoi d space at t he base of skul l unaccom pani ed by any ot her cr ani al ner ve, i sol at ed t hi r d ner ve pal si es ar e f r equent l y basi l ar .• Causes :1. Aneur ysm at t he post er i or com uni cat i ng s m ar t er y cause i sol at ed t hi r d ner ve pal sy w t h i nvol vem i ent of pupi l .2. Ext r adur al hem om w ch m cause at as hi ay t ent or i al pr essur e cone w t h dow ar d i nw her ni at i on of t he t em al l obe. Thi s por com esses t he t hi r d ner ve as i t passes pr over t he t ent or i al edge. I ni t i al l y t her e occur s f i xed, di l at ed pupi l , w ch i s hi f ol l ow by a t ot al t hi r d ner ve pal sy. ed rd
  52. 52. 5. Lesi ons i nvol vi ng i nt r acaver nous par t of t he ner ve • Because of i t s cl ose pr oxi m t y t o i ot her cr ani al ner ves, i nt r acaver nous 3r d ner ve pal si es ar e usual l y assoc. w t h i nv. of t he 4t h and 6t h ner ves, and i t he 1st di vi si on of t r i gem nal ner ve. i • I n i nt r acaver nous 3r d ner ve pal sy, pupi l i s spar ed. Som i m pupi l m be const r i ct ed et es, ay ow ng t o i nv of sym het i cs. i pat
  53. 53. • Causes :1. D abet es m cause vascul ar pal sy. i ay2. Pi t ui t ar y apopl exy – m cause a t hi r d ay ner ve pal sy as a r esul t of hem r hagi c or i nf ar ct i on of a pi t ui t ar y adenom a (af t er chi l d bi r t h), w t h l at er al i ext ensi on i nt o caver nous si nus.3. I nt r acaver nous l esi ons – aneur ysm m ngi om car ot i d- s, eni as, caver nous f i st ul ae and Tol osa-H unt syndr om (gr anul om ous i nf l am at i on) e at m
  54. 54. 6. Lesi ons of t he i nt r aor bi t al par t of t he ner ve • M cause i sol at ed ext r aocul ar m ay uscl e pal si es or m i nvol ve ei t her ay super i or di vi si on or i nf er i or di vi si on or bot h. • C auses : or bi t al t um s, pseudot um s, or or t r aum and vascul ar di seases. a
  55. 55. 7. Lesi ons of pupi l l om or f i br es ot• B/w t he br ai nst em and t he caver nous si nus, pupi l l om or f i br es ar e l ocat ed ot super f i ci al l y i n t he super i or m an edi quadr ant of t he ner ve.• They der i ve t he bl ood suppl y f r om t he pi al bl ood vessel s w eas t he m n her ai t r unk of t he 3r d ner ve i s suppl i ed by vasa ner vor um .
  56. 56. • Sur gi cal l esi ons such as aneur ysm s, t r aum and uncal her ni at i on a char act er i st i cal l y i nv t he pupi l by com essi ng t he pi al bl ood vessel s and pr t he super f i ci al l y l ocat ed pupi l l ar y f i br es.• M cal l esi ons such as di abet es and edi hyper t ensi on usual l y spar e t he pupi l . Thi s i s because t he m cr oangi opat hy i assoc. w t h t hese di seases i nvol ves i t he vasa ner vor um causi ng i nf ar ct i on , of t he m n t r unk, but spar i ng t he ai
  57. 57. CAUSES OF ISOLATED THIRD NERVE PALSY1. I di opat hi c - I n about 25% cases2. Vascul ar di seases – di abet es and H , i s TN t he m ost com on cause of pupi l -spar i ng m 3r d ner ve pal sy. I n m ost cases spont aneous r ecover y occur s w t hi n 3 i m hs. D abet i c 3r d ner ve pal sy i s of t en ont i assoc. w t h per i or bi t al pai n and m i ay occasi onal l y be t he pr esent i ng f eat ur e of di abet es. The pr esence of pai n i s t her ef or e not hel pf ul i n di f f er ent i at i ng rd
  58. 58. 3. Aneur ysm of t he PC at i t s j n w t h t he A i I C i s ver y i m cause of i sol at ed A p pai nf ul 3r d ner ve pal sy w t h i i nvol vement of pupi l .4. Tr aum bot h di r ect and secondar y t o a, subdur al hem om w t h uncal at a i her ni at i on, i s al so a com on cause. m5. M scel l aneous. O her r ar e causes i t i ncl ude t um s, vascul i t i s assoc. w t h or i col l agen vascul ar di sor der s, syphi l i s
  59. 59. T HA NK Y OU ..

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