Understepuort Journal of r·eterinary Science und A n-im(ll lnduslr}J, Folw11e 14, :r1nnbers L and :!, .Tanttory and April. 19-W.
!'rinted in tlH' Cnion of South Africa by tile C:on'rtlmcni. l'rinter. P1·0toria.
Anatomica l Studies No. 64.
Anomalous Course of the Left Phrenic Nerv e 1n a Donkey.
Hy CECIL J ACKSOK aud \V. C. Y ILHJI.<:~, Si>cl ion of Anatomy, Onderst epoort.
\\'nt::--; during dissediun ul a one-.Year-old fenwle donkey ( JJ.U.H. ;\o . . 214li9) the thorux \\'a~ opened, it \\·as ub~Pl'Yed that the left plu-eni(' nen-e follo1Yed an unu:wal eour:;e and had peculiar relationships,
!']'OSsing tlw costal ;;ul'face of the left lung, and that thi~ :lnvm<.tly was associatf'il \Yith an irregular arranp·emeut of the pleura on the lPH ,;ide.
The orin·iu of t lw llt'l'H' and its en( ry into the thorax are as Llciual, but after it l1:H passPd beneath the- left .·wlwb,·iun :nter~· its
(~om·se beeome::; ahnormal. Instead of <·rossing- thf' cost·oeerYical YPin and eonhnuing- llWI'(' or l<•s,; horizontally along- the lateral face of the llt':t(·hiot·<·phalit· trunk, it inclinPs ,·Pntrally, ,·ro::>sing- the dm·,;:d part of th(' t-lt_ylllll.~ ohliqurl.\· a11cl aniYi11g- :d· 1 ht• pt>ril':trdiulll ,-J ''"'·
ht•Jm,· tbe orig·in of 1·\Jt• hr:whiot·Pph:dil' trunk.
It l'nntinue~ <l('l'o~~ the peri<·anliuitl i11 :1 110~iliou IlltU'h lo\H'l'
th:tll nornwl and ,,·ith <I JII'IJJIOtiiiCPd n·nlral inl'l.inatioll. -~~· lbat it
n•ad10~ the 1<-n'l of lht· fourth rib o11l\· .-J l'lll. :lho\·e thr sh-·mal ex- tremit\· of ilw htiln. !.':1iling- to rP(tll'l·, fro111 IH'11eath t-itP peri1·urdiae pleura to tht• (po~t-t·ardi:tl) II!Pdi:l.~tiii\1111. it conlinUI'S to IHTllp\· :1
lateral position, l>Ping- I'I'Lih•d lo t ht• tllllr:H·il' ,,·;~ll alld no,~ing- i·he t·o.-d:il c;udat·l' of iheo lung·.
rn thi.-< part of ih ('()llr.~t· it ll\Tll]iit• . ..; thP do1·~aJ lJoH1PI' of a ..;peci;tl told of plPura \Yhieh i~ rPfiPdP1l ll]l\Y:H(L hom tht· diaphr:tgm i11 the regiou of thP phrPni('o-t·o~lal ~illll". is c-o11tiuuous c;rauialh ,,·ith lh(•
]Wl'i(·anliae plnrra :111d io< of a lat·r-lik<·' tf'xttii'P. ln thP~e :re~pt•f'h thr arntnp-Pmenl of lhe plt•ura i..; r·on1panthl<' with th:d nonnallY obtaining on tiH• right si(lf'. ,,·lu·n· thr phrenil' llPI'\.1' i" t•nl'lnsf'(l i;, thP l'aval fold.
.\\'.\TU\1 ll.\L "'ITDY :'\0. !i.f.
The nerve re<.u.:he,; tLe luug li em. aboYe the junction of the Yeutral and basal honl<'r,.; (lnng .. ; fixed iu t-•xpiratory pbatw), crosses the cost:d ~udact> of the org-an, ou whil'h it ]e;_n·e~ a di.;tinci intpression, and ;tt tht• le,·el of tlw c;eYenth 1·ib pa:-il"il'" through a ,.;nwll fissure (] em. in depth) in the h;t~al hordPr of the lull.!.! io reach tht·· di;tphragm, not at tlu~ h·udiuottll t·PntrP, hut at the cotltal 1111.1~cular portion opposite the nanial border and -+ t·m. :1 boYe the tltenJal extremii ,. of the eightlt 1ib. Tht> JlOI"it-t·;Jnlial Jlledia..-dinum is normal, excPp( for thP faet that. it dot>s not acCt>lllllltHlntt• t ht• phrPnir· nei'\'P.
At a cli~Ltuce of 1 ntl. tt':-ipPc!iYeh- in fro1Jt· of ;tud ht·hind the
fissurP iu the hordPr of fit!• lung- ot·l·UJ' 1 "·o ot hl'1· sintiLtr fi~surt>:<
Sinct~ thPre i.-< 110 adltt>,.;inn hef\\·t·t'll tht· pulniOil<tr~· ]tlPul'il and the
~pecial fold i11 which llw nPJ'\·e j, atTOJIIJIJod:tied :111(1 in r·on~equeut:t-•
ilte lung- Jw . .; frpe lllOJ.j]jjy I'(•I.JfiYt·h· (t> j}tp llPI\l', it ciPl'IIIS likely that. at pre,·ious tintP.s (e.g-. during- pre-n<~btl lite) tlw tH'I'Ye maY ha\'t' or·<·upit·d otlt' o1· t>ther of fht~ . .;p fi,;surt·:'. \\·hil'h pt·e:-;umah]:,- tlPYPiorw<l in nr<kr to ill't·ontnJt>datP it.
The ntaltortn<tlit>n de~crilwd i.~ ilflflilll'ltfly liJJl'l'<:orLlPd 111 tl~t·
Yoluminotts litPr<lilll'\' dt>;tling- with t·t>ng·pnit.tl iiJlOIIJ:diPCl of tltt> lung·.;.
plt•urae, diapht·;tg·tn. and nPrn•,.;.
~fr. Tb. ~[<·.n·J· kindly took thP photogTaplt \l·hil'h at·t·onlpani<'ci
jJtj, Jtoh• .
. lnumu/u11s ,.IJiff':SI' ()j lit!' /,f'/f l)hrenic -~Yen·,'.-'J"'he 11('1'\'e is seen passing obliquely OI'Pl' thP thymus anu p<:>ricardium and then 0\·er tJw JateraJ Surface of tlw lung. Tht• ~pet·Jal fold of pleura in 11·hos•• dorsal border· it is conta111ed is ,·isible behind the cardiac Hotch of the June;; its lo11·er part has sagged downwards latt>ral to the eostal !'artilages (artefac·t). The fourth and eighth rilJ>: are dPrJOtPcl hy mlmbers.
490
