Some aspects of the vagal innervation of the canine esophagus : an anatomical study : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science at Massey University

Copyright is owned by the Author of the thesis. Permission is given for

a copy to be downloaded by an individual for the purpose of research and

private study only. The thesis may not be reproduced elsewhere without

the permission of the Author.

SOLf: ASPECT;:)

OF

THE VAGAL INiffiRVATION 0? 'ri-lE CMIINE ESOPHAGUS MJ AHATOEICLL STUDY

by

Alastair Gordon llatson B ^•. \gr.Sc. (Cantuar)

A t hesis present ed in part ial fulfilment of t he requirements for t he Degree of Nas t er of Agricultural Scienc e in Animal Sc ienc e at Eassey Univ ersity.

1974

ABS"rltAC'l'

The anatomical dislJOs i t ion of the branches from the vagus nerves to the entire canin e esopha�u.s w ere inves tit;at ed and. the effects of various nerve ^transecti^{ons 011 eso}p^hageal function uere observed radio&;raphically.

'l'uenty one aclult uongre l clotjs trere carefully dissected;

f ou::.'tGGi.l were dissecte1 as fresh s pec iuens and seven -.;.rere forn.J.lin ernbalmod anu dissocted lator. 'c.'en of thc::;o do.::;s hc.d previotl.:Jly undergone various s"J.rgical nc17e tl'd.,_l.scc tions: bilatcJ·.:::. l

phar:y11goosophat_;oal neurcc t ony, bila toral cranial thorr1cic vagotomy, t r:::msoct.!_on of recurrent lal'YTleoal nerves at thci:;.· oricins, clouble bila torul cranial thor.:::.cic vagotouy, and ^caudal tlwr8.cic va::;otouios.

The sur:.:;ical approachetJ for transc:::ction of these esopl1c.geal aGl"'Tes hei·v-8

beun

iEvos tig.ltocl 2.�1d the vo.1·ious t eclEliques are dc[:c rib ed.

Lsopha0eal funct ion before and after nc:::rvc transection ;m .. J s tudied radiographically, G::>pe:ciu.lly by cineradiography; all radiographs were made on c o nscious deG;�J, t rained to ::d;ancl

L1

a non:nal p o s it i on freely eating bari"LU•i iwpre(.)'latod ^{illeal frora a bm;l}

placed innediately in fro:..1t of tlleir forepaws. ili.l.dioe:;r2.phic

cbs crvati ons Oi.l esophagcal motilHy Here i!!ade on fifteen additioD.:::.l app...1rently normal dogs .

C^ontrary to st.::mda:tu texts , it vras found in the present study that each parent recurrent laryngeal nerve was always divided int o tv1o trunl.:s: the recurrent laryngeal n erve proper ullich coursed directly to and tennin.ated in the ipsilateral intrL.1sic la^ryngeal muscles (excludine:; cricothyroideus), and a more dorsally lying pararecurrent laryngeal nerve I'Thich coursed parallel to the

recurrent proper but freely supplied many

branches

to the esoplW.f,'1.tS and trachea.

'�hesc es ophagoal

branches vfere ^especially numerous on the left side, as the left pnrarecurrent nerve richly supplied the

c

rani::.l thoraci

c

e;Jo;_>

ha

gus as uoll as the cervical portion.

Ho1-wver, the r^ight

pararoc urrent

nerve supplied the cervic-'3.1 esophag·us only. Bach pnrarocu2.·rent n<:!lVe thon toriilLJ.a.tod in ·cho

ana

s

toLJ.oti

c

rru,:us from the inturnal branch of ^{tho ipc;}i^lato

r

o.l crani.'.cl lai"J11[;eal nerve.

From the exporiilental s tuJies it ^{\·Ta:J con}c^lu^decl that the recurrent ^laryngenl nGlvos vrere f1.mctiunnlly in^-volved uitll tll(;

c ra..fli8.l

t>^.o

r

a

c

ic osophagt�G, since this rogio11 vras co,ipleto:;_y po.ral:_yrscd follouing bilateral rec·Llrront lary

n

go.:-'.1 neurecto::..::;r.

;:)oulG dysfunction \:c.s ^aloo aoGn L1 the ccrvic:.::.l esop·�J.agus after this operation.

The ^cervicccl esorhaQ.ill ^{\'TU.S vrimarily} innc:rvc.tcd and fcmctionally controllocl by t�1e pair of pharyngocsophaccal nerves 1-1l1icll arose

solely from t:·w pharyngeal br.:1nch of eac}l vs.c;us nerve.

Cauclal to the o

r

ii:!.·ins of the rocu

r

:cent ^nerves, t he tl^lor:.:;.ci

c

aud

a

bdo^uinal va;;:;i supplied and cont^ro^lled the

caudal

thoracic a1J.d abdominal portio^{ns of the} 03o�ha�1s.

The vagus ^nerves in..'lervate and are invo^lved

in

thG nor_al function of t^he gastroesophc,.::_;cal j1.m

c

tio

n

, since bi

l

ateral c:canial thoracic vagotomy COi1Sidcrably ^altered

the

ar::tivity of c�1is region.

Hm-revcr, double caudal thor^a

c

i^c vatsotomy appeared only slightly to affect the function of the gastroesophageal junction.

In addition, the course and the histologica l structure of the canine esophaG�lS has been obse:;_�ed and described.

Durine this stu<ly, ro.dioGraphic observatior:s 1:ore

repcatecll::,r lllude,

on apparently noJ.--r:lnl do:r,s, tha. t put ⁱⁿ question the va lidity

of the ct:rrmt ly hel<l concepts o:f esopL8.GG.::t l p�lj"siolo�y.

G3opho.gcL'.l c^o:.1t^{r, .c}ti^on ^1-m.vcs did ^:1ot ncceD3D.rily d^{irectly follou} oacl1 orophar:y-ngual cleg lutitioll se.1ue;::ce. Suo..lloHcd bolu�ec ^uu:re

frequently delayed in the crania l c;}rvical, thorJ.cic inlet, o.ncl cr·anial thOl'<.'..Cic ro:;ions of tb.e oso]Jha[;us. Tuenty tuo of the

ruflt..u:: of material ^frolli the stol,u.lch into the ^cetuclo.l t�1or:J.cic

eso1)ho.gus. ^{lwr·o detailed} J:•.:diogrupllic stu<lios of thG nGrll18.l canine esophugus under trul�r physiolo[_;ic£:.J conditi oi1.'3 arc

ACKNO\TillDGEriENTS

The op

p

or

tunity

for

t

h

is study

a

r

o

se

through the

encouragement of I'ir.D.A.Dowd and

Dr.:S.E.Goulden ,

and

t he

generous p

ro

visi

o

ⁿ of facili tie.J by t

h e

Departruo!'Ib3

cf 2h

^ysi

o lo

g

y and

Anatmty, and Veteri

n

ary Clinical Sciences at La;;;:;oy University.

I

^a1..1 gre.J.tly indebted to my two

suporvisOl'G

^{for their} �;uidance and C011Dtmlt interest.

I

uould

lite to extend r.'.y sincc;ro gra.ti tudo to .�r. J ,c;

.:,;·o-vihook

for his helpful aclvico in tbo procluction of this ^{tlwcic nl1d for} :lis con:::;tructivo cri tici.su1 dtu·inz tho ^course

of

_{this studJr.} 'I':·:a"ll--:s ^n:..·o

co:aocting the draft copy. i UJ:i

e1lso

grutoful to � r .^. �.,J. ·.J:;-bur:cl and Lrs. 1.1�. I"tofc for· their a:J::::i:Jtance in oporatine tllc rudio::::;r.::�pllic

()Cluiprucmt 1nd i11tcrproti:�; tho radioeraphs, to r:r. I:. J. :Jirtl,;s ^for

I.r.I1,JatunLJ.itavulci

for

Oll'balfilL1C the clog::;, to Lr.J,]).Au::;-LL: and

�"r.T.G.Lm: ^for the prolJ8.racioi1

of

ph^ot

o

g

r

_aph::;

,

^to Dr.:S.E.Dm:-d for drm;-j_ng -�'igurcs 19b and 23b, to Lrs.ll.i'IcComish for labelling the

diacrmts,

ancl to

Dr.H.!�;.l3atte:n for his com..monts

on

-�ppo:1clix H.

'rhanks arc a

l

s

o duo to

tl1o lll&s�..:oy U

n

ivorsi

ty l ibrary

_staff,

eupoc iall y

^Hiss

E.K . Greon for obtaining many of

_the references.

I<�y

sinc ere

thanl�s

are clue to

f�iss Suo Shi

r

rif^fs

for iwr

patience and

careful typing of

the thesis.

I am

part icularly

indebted

to

Naung

Sha

Ban

for

his f

r

iendship

,

great interest and valuable enc o uragement

th

ro

ugh

o u t this study, and to my 1-rife Jenny, f or her -vril lingnoss to acc ompany me on this long, often trying, but always interesting, road.

TABLE OF COHTENTS

Al3STHACT

ACKHO\JLEDGEL:Wr'rS TJl.Bi,B OF C OIJTEI:?S LIC.J'r

OP

_:B'IGURES

HJTR0:91JC'l' I

OH ^{. . ..... ..}

.

^.........

.

^{. .....................}

..

^.. . .

IiAT1'RIALS :'Jm u..;·l'HOD3 ^.

.

^....

.

^{.. . .. .. . . .... ..... ...... .......}

.

^{. .}

3

Exper imental I1ethod ^{. .}

.

^...

.

^.

.

^.

.

^{... .}

.

^.

.

^{. ..}

.

^{. . . .}

.

^.

.

^{. .. .. ..}

.

^. ₃

Experimental Animals • • • • • • • • • • • • • • • • • • • • ' • • • • • e • • • • • • • • • • 3 Dissec tion Techniques ^.......

.

^.

.

^.

.

^{. ..... ... . . .}

.

^{.. .}

...

^..... _4-

Emba

^l

m

ⁱ

ng and Sp

^ec

irucn P

^re

p

ⁿration ^.....

.

^...

.

^{... ..........} ₅

Experimental Gro ups ^{... ..... ...}

.

^.

.

^........

.

^{. . ... ..... . ....}

7

Surgical Techniques ^{••• c ••••• •••••• ••••• ••• • • • • • •• •• ••••• •}

8

Radiographic Techniques

10

Photographic 'l'echniques ^{•• ••••• • • • • •• • •••} 0 • • • ••• ••• •• • ••••

12

1\futri tio11 ^.

. . . 1 3

Post llorte!n Technique ^{.. ....... . . .. ... ..}

.

^{. .. . . . ......}

.

^....

Histo logical 'l'echniques ^{. . .. ... .... ..... . .. ..... .. .. ..}

.

^{. . .}

RESULTS ^{..... . ......... ..... ... .. .. ..... ........ . . . . ... ... .....}

Anatomical Observations ^{.. .. ... .... . .}

.

^{. . ... . . ... .. ..}

.

^{. . ...}

Pharyngoesophageal nerves Recurrent laryngeal nerves

righ t left

. . . .

.

^{. .}

.

^{.... .. .}

..........

.

^...

Thoracic vagus nerves right

left

. . . . . . . . . ....

.

Dorsal and ventral vagal trunks ^{. . . .}

.

^{.. ... ......}

.

^{.. . .}

13 14

16

16

16

20

2 1

24

27

27

28

30

Radiographic Observations ^{• . • . • ••.•• ..•..} . . . • . •...•...• •• .

!\foma.l dogs ... ^. After bilateral phC::.l"'YJ.'lgoesophaceal neurectomy ^{• •. . • • •} ..tlfter bilateral cranial thoracic vagotomy ^{••• . •.} • . • . •

.c'l.fter recurrent larJilGea.l neurectomies

.-�.fter do1.1..ble

bilc.ter·al

cr::mial thorc.�.cic

vag·oton;;r

^{•• . •} After

caudu.l

thoracic va0otol!lies ^•.•• • . • . • • • • .•• . • .. •

Clinical Obs ervatio·n.s ^{• • • • . .•. ••} JJaryngeal ^{function •. . •.}

. . . ..^..^{.. .. . .}

:Cc:Lting behaviour ^{•. •} I'ost i:Iortem Observationo

. ^{. .. . . ..}.^{. ..... .. . .. ... . .. . . .}

... .. . ..........^{. . .. . .... . .}.^.. l'Teurec to my sit o

Esophacieal dilatation

Neyve

degeneration histology

Structural Considerations

Cervical osophc:c;_,'l.l::l • . . • . . . . . . . ..•.

Crani::.:.l thoracic csopha::;-us • • . . . • •. . .. • · • • • · · · · • · · · • •

Pa:rarocurrent lo.ryn�_:eal nerves ^{• . • . ..••• . •. .. •••..•..} Co.udal thoracic and o.bdoiJim.l esophagus ^{• . •• ••.• •• . • •} Embryonic development ^{• •.•. . . . • •• •..•.} . . . . • •. • • • •• • . •

Functional Considerc.tions Nethods of s tucly ^{• . • .} Cervical esophagus

Crania::!. thoracic es ^ophagus

Thoracic

and

abdoru.inal esophaQ..'..S normal esophageal motility ^{• • • .• •}

Slli·il·IP

^{... RY} ••• •• • • • •••••• • • . • • • • • • •• •• •••••. • • . • • • • • .• ••••• •.•• • . •

APPEifOIX ^I

Course of the Canine Esophagus

Page

32

32 32 33 35 38 40 41

41 41 44 '�4

44 45

46 47 47 51

52 54 55 60 60 62 65 67 70 72

74

Pnge

APPEHDIX II

0tructu�e of ^{the Canine 8sophn�us •••.• • ••••• . • • • • .••• ••• •} 78

APPENDIX III

Surgical '.rechniqucs fo1· i;:::rerimontal I:·eu:cectomios ^{• •} • • • • • • 37

APPElWIX IV

Schedule of

Postoperati-ve

BxLl.Illi:n.::!.tion Days • • . • • • • • • ••• •••

93

APPBliDIX V

Histolocic�l St�inin� Teclmiques ^{•••• ••••.•••• .• ••• • .•. •• .}

94

lt,JGU��S

^{.•• •.•} . . . . ... .... . .... ••.•.. .. . ..• .. .... . . o • • • • • • • • • • 95 J:ll.;p..:::TIEITCE3 ^{••• •• • •••••• •••• ••• •• ••• • , • • • • • • • • . • • • • • •} • • • • • • • • • • • 1

28

PUBLISJQ:,) iiORK

v!atson,

( 1 973).

Structure of tho ^ca!lin.; oe3opha1-;us.

LIS'r OF li'l GURES

Figure

1 ^• Photograph, radiographic equipment

2. D ia0ram, vago.l n e rve

branches to

^{esophagus .•••.• ..• • • • •}

3.

^Diagram, phar:,mgocsophc.geo.l nerve • . • . • . • . . . ••• . . . • . . . .•

4. Diagr.J.hi, or^icin of plnryn::;ocsophc..geal nerve,

c orr..L1on putt ern. ^{•..• ..•.• •• 0 .. ••} • • • • • • • • • • • • , •^{• ••••• •} 5 . Di::tgralil, o rigin o f pharyngoosophagoal nerve, V[<.riant ^{• . .} 6. DiagrruiJ., right par0.recurron ^{t and} rec urrent laryngeal

Page

95 96 97

98 98

nerr.Te;:; ^{• • • . • .. .. • . . • • • • • • • • • • • • • . . • • • • • • .} • • • • • . . • • • • • 99

7. Diagra;:a, left pararecurront and. recurrent laryngeal

no rv es ^{...•. •. ..•• .. ..• .•. • .. ..•.... ..... "} .... , . . . . 1 00

8. Diagrrua, origin of left rec urrent laryngeal nerves, s ingle origin ^{....... .. ........ ...... ........ ..... ...} 9. Diagrc1m, oric;in of loft rec urrent lar;y-n..:;eal nerves,

1 01

mul tiple origin ^{. .•.• .• . • .. "........} .^........... ^... 101 1 0. Transverse sec t i on of recurrent laryngeal nerves,

11 ^•

12.

14 .

c ommoE n erve sheath ^{• . • • • . . . . . . . . . . . . . • .} • . • • • . • . • • • 1 02

Transverse sec tion of recurrent larynge.J.l nerves ,

s eparate nerve t runlrs • . •••.. • . . . ..••...•.. • . • . . •• . 102 Diagram, vagal nerve branches t o thoracic esophagus 103

Diagrrua , vagal nerve branc hes to thoracoabdominal

esophagus, righ t side . . . . ... . .. . . ^.

104

Diagram, vagal nerve branc hes to thoracoabdominal

es ophagu.s, 1 eft side ^{.•........•. .}. . . . ..• .. ... 105 15 . Radio graph, c ervical esoph agus of dog 05, before

neurectomy ^{..... � .} . . . . . . . . . . . . . . . . . . . 1 06

Figure Page

1 6. Radiograph, cervical esophag;us of dog 05, tvro days after bil.:J.ternl ph_,ryngoasophageal neurectomy

1 7. Radiograph, thoracic osophac:us of dog

05,

hw ^days

after bilateral pharync-oesopha.geal neurectomy

1 G. Radiograph, cervical esophagus of do;:�·

05,

nine du.ys after bilateral phar-JnsoesophD{;eal ncurectolily 1 9a . Hadiograph, thoracic c::30phat5,1..lS of dog 06, ono day

106

1 07

107

after bilateral cr<m:i.al thoracic vu.gotomy . . • • • . . . • 108

19b.

Diagram of the �bove ru.diograph ^{.••.•..•...• .• ...•.•• • • •} 108

20. P�diograph, caudal thoracic esophagus of doG 06, one d a y

after bilateral cra;1ial t11oracic vago cmny ^{• ••, • • • • •} 109

21 ^. Iia.J.iograph, cranial thol'&cic esophagus of dog 06, one

day after bilatera.l c:;.�u.Dial thoracic va;:;·otomy .

. . . . 109

22. fludio,:sraph, gnstroesOlJila:_;o.-... 1 junction of dog 06, one day

a�·tcr bilateral cranial thor2.cic vu.gotoEty ^{• • • . • • • • •} 110

2)o.. �iadiogralJh, thoracoa �do�1L:c.l eso})llc."�·u:J of do,:; 10 , ono

day aftc::r bilater:ll c1·anial thorncic vagotomy ^• . . • • 1 1

1

23b. Diagram of the above ro.r.lio::;raph . • . • • . . • • • • • . . • • • . ^{• . • . • •} 1 11 24. lbdiograph, thoracic inlet of dog 15, before nourectony

25. Radiograph, cranial thoracic esophagus of dog

15,

before

112

neur·ectomy . . . . • . . . • . . . . • . . . . 1 1 2

26. Radiograph, cervical esophagus of dog 1 5 , one day after right recurrent laryngeal neurectomy ^..^{.. .. . . .. . .}.^.

I

27. Radiograph, cervical esophagu^{s of dog} 1 4 , one day after right recurrent laryngeal neurectomy ^{. . '} .^....^...^{.. .} 28. l�diograph, cervical esophagus ^of dog 1 4, one day after

1 1 3

1 13

right rec urrent laryngeal neurectomy ... . ... 114

Figure Page

29 . Radiograph, cervical e^sophagus of dog 1 4, one day after right recurrent laryngeGl neurectomy

30. fu\diograph , craⁿi^o.

l

thoracic esophagus of dog

14,

eight

11 4

days after bilateral recurrent laryng·eal neurectomy 115

1bdiogra�h, cervicothoracic esophagus of dog 14, eight d<-1ys after

bilatorc:.l

recurrent laryngeal net:rectomy 32. R .. ^1diograph, cranial thoracic esophagus of dog

14,

oic;ht

1 1 5

days after bilaturc:tl recurrent lm:,:-:'l[;·oal ncuroctoiJy

1 16

33. Radiograph, cranic.l thoracic esoph

a

^r;u

s

of dog

14,

^eiL;ht

clays after bilL:.teral recurre;.1t larync;eal ncmroctm:1y 116

3L�.

P.adiograph, c rani.:::.l thoracic esophagus of dog 14, eight

days after bilateral recurrent lo.ryngcal neurectowy 117

35.

}b.diogrclph, cervicothoro.cic esophat,rus of dog

15,

^eight

day::; after bilateral recurrent la:qngeal neurectoruy 117

36. r,adiograph, thoracic esopha;;us of dog 12, hro days after

bilatercJ.l cranial thoracic vagotony ...

118

37. nadiogro.ph, thor

a

^coa

bdominal

esopllLl.:_;US of dO(; 04, before

neurectomy, no rc�flux • • . . •

.

^{. . • . . •} . ^{. . . •} . ^{. • . . .} • • • . . • 1 19

38.

P.adiograph, thoracoabdoLlir:al esophag-u.::; of dog

04,

^before

l!.eurectomy, reflux • • • . . • • . • . ^{. • •} . ^• . . . . • . . • . . . • • • 11 9

39.

Padiograph , thoracoabdm:1inal osophagus of dog 04, fifteen days after double t runk caudal thor-acic

vagotony . . . . . . . . . . . . . . . . . . . . . . . . 1 20

40 . Radiograph, thoracoabdoruinal esophagus of dog 04, f ift een days afte r doubl e trunk caudal thoracic

vagotomy ..^{. . . .}.^.. . .^{. .}.. . ^{. .}.^{.. �} . ^. . . . • . . . . . . . . 1 20 41. Hadiograph, thorncoabdominal es ophagus of dog 02 , four

days after do1�nl trunk caudal thoracic vagotomy .. 121

Figure Page

42.

Radiograph, thoracoa bd.ominal es ophagus of dog

02,

fourteen days afte:;.' double trunk caudc..l

thori:.lcic vo.gotoH!.y ^{• ••.•• •.•••••• ••.• o . . .. ... .... ...} 121

43.

Photogra.ph, dilated esophagus ^{of dog 1}

0

^, thirty one dnys after bilator2.l cranial thor.J.cic vaGotomy 4-..J.. T r1:msverse section of :rec·c1.:rroat llll'J11gCal nervGs,

1 22

nor.u1al . . . . • . • . . . • . . . . • . . • . . . . . . . • . . . . . . • .

1 23

45. Trnnsvers c section of r..)curre:tlt laryn;sc.J.l narvos,

postnourcctomy, de&,·on.c:r .... -..tive ch::mges ^{• . .} . . • • • • . . • . . . . • • • 123

46. Transverse section of csopl1neoal eiJi thelin:J. ^{••• .• . • .•..•} 124

47n. Transverse section of esophueus 125

47b. ^{Dio.gram of tho c.�.bovo f;oction . • .} • • . • . • . . . . . . . . . . . • . ^{. . . • .} 125 L�8a. Longi tudino.l section of gastroosophn,:;oLll j1..u1ction . . . . ·1 2G L�8b. Diagram of the above section ^{•• • • . . .. . ..••......, . . .} . • • • 1 Z7