No. 442.

LONDON, SATURDAY, FEBRUARY 18. [1831-32.

LECTURES

ON

VETERINARY MEDICINE, E,DELIVERED IN THE

UNIVERSITY OF LONDON,BY

MR. YOUATT.

LECTURE XVIII.

OX THE MUSCLES, NERVES, BLOOD-VESSELS,AND LINING MEMBRANE OF THE LARYNX.

THE beautiful mechanism of the larynx,which occupied our attention in the lastlecture, is governed or worked by a some-what complicated system of muscles. If in

describing them I should vary, and thatvery considerably, from the account givenus by our best veterinary anatomists, Imust refer you to the dissections on thetable, and particularly to a very elaborateone by my talented pupil and friend Mr. ISimpson, as my apology. I

Action of the Mztscles of the Larynx.-Theaction of the muscles of the larynx is prin-cipally confined to the dilatation or contrac-tion of the openings into the trachea, whe-ther between the arytenoid cartilages or thevocal ligaments, and thus adaptmg them tothe varying purposes of respiration, andthe formation and modulation of the voice.

As, in describing the cartilages of the

larynx, I commenced with the cricoid carci-lage, placed at the base of the machine, sowe will first consider the muscles of thatcartilage.

The Crieo. ar1jlenoidells Porticlls. - Thefirst pair of muscles that presents itself,is attached to the spine of the cricoid carti-lage, and to the whole of the roughened de-pressed surface on either side, and com-pletely covers the posterior surface of thecartilage.

The Posterior-Crico-arytenoid Muscles ap-pear, when first observed, to consist of twopairs, with distinct origins and insertions,and a different direction of the fibres of each.

It is, however, so difficult to dissect the onefrom the other, that veterinary anatomistshave agreed to consider them as one pair.If I were disposed, and I almost am to

separate them, I should speak first of theinferior portion, arising by a fleshy bodyfrom the base and side, and lower partof the spine, and surface of the cricoid,cartilage on each side and the fibres takinga direction upwards, the muscle is insertedby a tendinous expansion into the summitof the tubercle at the base of the spine ofthe arytenoid cartilage. The fibres of thesuperior portion, arismg from the upper partof the spine and general surface of the samecartilage, take a direction upwards and ob-liquely outward, and are inserted by athick Beshy attachment into the inner sideof the same tubercle. It is, however, diffi-cult to establish a perfect separation be-tween them.

They evidently possess great power,for they are thick, and many tendinousfibres mingle in their composition, butinserted at the very base of the arytenoidspine, they act with considerable mechani-cal disadvantage. Adheriug throughoutthe whole of their development to thecricoid cartilage, their action must be verylimited. Their function is evident-toelevate and to draw backward the arytenoidcartilages ; but, acting upon them in anoblique direction, these cartilages are

opened while they are raised. The glottisis also dilated, and the vocal ligamentstightened.

This muscle is not so large or so power-ful in the ox. In the swine it is morepowerful, and has a greater proportion oftendinous substance in its composition.

The Crico-thyroideus.—Placed laterallyat the base of the larynx on each side, occu-pying the whole of the side of the cricoid

cartilage, and filling the depression in it,and also attached to the side of the base ofthe thyroid curtilage from the inferior cornerposteriorly to the interposed ligament be-tween the aloa of the cartilage anteriorlv,and running along the hoop of the cricoidring yetmore anteriorly, is the crico-thyroidmuscle. It approximates or brings togetherthe two cartilag-es, or, according as either

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of them is considered, or made, the fixed I be relaxed, and the rima glottidis widenedpoint, it depresses the thyroid or elevates and shortened. If the arytenoid cartilagethe cricoid, and in either case separates is the fixed point, the interposed ligamentthe arytenoid cartilages and relaxes the is drawn a little backward, and the lips of

vocal ligaments. The trachea itself is also the glottis are somewhat opened and thusshortened by the action of this muscle, and at their apex or ncute angle, and thusthus the voice is in some degree affected. more air will be thrown on that membraneThis muscle is also ot small size in the ox, which I have described as placed over theand more developed in the bog. point of the angle, and connected with the

The Crico-arytenoideus Lateralis;—In order act of neiglzing. Accordingly, as the whole,to bring the next muscle belonging to the or only a portion of this membrane, is af-cricoid cartilage fully into view, we must fected by the opening or closing of thedetach one side of the thyroid cartilage ; angle, the neighing may be more rapid orand there, inserted into the anterior side of distinct. If the membrane is the fixedthe tubercle at the base of the spine of the point, we have an adjuvant to the musclearytenoid cartilage, and arising from the last described, drawing forward the base ofupper edge of the side of the cricoid carti- the arytenoid cartilages, and thus bringinglage, and extending as far as the interposed forward and separating the upper edges.ligament of the thyroid cartilage, is the The Ligamento-arytelloideus Medius.-lateral crico-arytenoid m’uscle. This is in This arises from the spine of the arytenoidsome measure an adjuvant to the crico- cartilage a little above the tubercles, andarytenoid, and also an evident antagonist to after pursuing the same course as the lastits too powerful action. By drawing for- along the external face of the lining mem-ward the base of the arytenoid cartilages, brane, but a httle higher and above theit brings forward and elevates the upper vocal ligaments, and also being very looselypart of them, and thus separates them, and connected with the thyroid cartilage whichalso dilates the rima glottidis, and relaxes covers this muscle, it is inserted into thethe vocal ligaments. central thickened portion of the same liga-And now, having this portion of the larynx ment just above the interior. The office of

under the thyroid cartilage exposed, we this muscle is clearly the same as the pre-will examine the other muscles which are ceding. When, however, we consider theirhere brought into view. I use the term in situation tied down upon the lining mem-the plural number, for although no vete- brane of the larynx, and the one a very littlerinarv anatomist that I have met with, above, and the other as short a distance

English or foreign, tlescribes more than one, below the vocal ligaments, we can scarcelyhere are evidently three. A very slight help connecting their function with that ofdissection will bring them plainly into the ligaments. They would seem to be theview. They are nearly parallel. You ob- moving power by which these ligaments areserve that they all spring from the anterior chiefly influenced. The other muscles act

edge of the arytenoid cartilage. As we are directly on the cartilages of the larynx, andtravelling upward, I will take the lowest only indirectly on the vocal ligaments.first. These appear to act directly upon them,

The Ligamento-arytenoideus Inferior.—It they are bound down upon the very mem-arises from the anterior face of the tubercle brane of which these ligaments are a du-of the spine of the arytenoid cartilage plicature-they influence the length andwithin the lateral crico-arytenoid muscle. the tenseness of the ligaments, and are theltis not connected with the cricoid cartilage, principal agents in effecting all thoseand only with the thyroid by the loosest cel- changes on which the character of the voiceular membrane, but pursues its course an- depends. These two muscles are not found

terwrly, closely bound to the lining mem- in any other domesticated animal, becausebrane of the larynx by denser cellular sub- there is no interposed ligament betweens.tance, and running parallel with, and the alae of the thyroid cartilage for their

nearly opposite to, but a little below the insertion.vocal ligaments, is inserted into the lower The Ligamento-arytenoideus S’uperior-thepart of the oblique edge of the crico-tlyroid thyro-arytenoideus of Mr. PercivaU and

ligament, or the ligament interposed be- other anatomists.-This pair of muscles, ly-tween the al2 of the thyroid cartilage. ing above the two which I have just de-

If we consider this muscle as contracting scribed, arises from the upper and thinnerat its centre, the form of the larynx is portion of the spine of the arytenoid carti-somewhat altered ; its posterior and anterior lage, and, taking a course parallel to thatportions are evidently approximated, and of the others, is also connected with thethe elastic yielding nature of the ligament, lining membrane of the larynx, and withand the moveableness of the arytenoid car- the interposed ligament, and at length in.tilages, will permit this to some consider- serted near the summit of the interposedable extent theu the vocal ligaments will ligament. Tliis muscle may assist in thia

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last function which I have attributed to the I The Thyro-arytertoideus.-This is a very

preceding ones, for it likewise is connected short pair of muscles, extending from thewith the lining membrane of the larynx, but middle of the inside of the posterior edgeit is situated further above the vocal liga- of the thyroid cartilage, to the arytenoidments: another office however is discharged, muscle’!, among the fibres of which it is

supposing the thyroid cartilage to be the lost. Its function is to approximate the ’fixed point, namely, to separate the aryte- thyroid and cricoid cartilages, and to limitnoid cartilages, and so enlarge the opening the action of the arytenoideus muscle. ,

into the larynx. The Thyro-epialottideus.-This is a pairThe Elasticity r f the Cartilages.-All these of somewhat expanded but thin muscles,

muscles are, more or less, closely combined climbing up the inside of the thyroid carti-in the performance of one function, the en- lage, and opposite to the hyo-thyroideus.largement of the opening into the larynx, or and is inserted into the base of the epi-of that between the vocal ligaments into the glottis, which is thickened, and tubercu-trachea. It is a very complicated piece of lated, and roughened for the purpose. Theymachinery, though the importance of the are weak muscles, and act at mechanical ,offices to be discharged, would justify any disadvantage. They assist in depressingintricate combination of power and action. the epiglottis, in order to cover the apertureThere is however another duty to be per- into the larynx.formed-the bringing together again of the The Aryteno-epiglottideus is another paircartilages and ligaments, and the reduction of small muscles, running from the lowerof the apertures to their natural dimen- and anterior angle of the arytenoid cartilagesions; and we have, in the construction of to the slips of cartilage at the base of thethe machine, an agent so pcwerful as to re- epiglottis. Their action is doubtful ; theyquire very little aid in effecting this pur- seem to contribute to the support of the

pose. The larynx is composed of cartilage, epiglottis, by connecting it more with thea substance highly elastic, and exhibitmg other cartilages, and to keep it steady inthe very perfection of elasticity. The carti- the extensive motion which it undergoeslages yield to the force impressed upon when closing upon the aperture into thethem, but that force removed, the muscle trachea.

ceasing to act, they return by their inherent Other :Muscles common to other parts.-elasticity to their natural situation and form. These are all the muscles peculiar to theThis principle is the antagonist power, larynx. But there are others connectedwhich stands instead of complication of also with other parts which have consider-muscular action. able influence in the proper performance of

The A rytettoide us. -There is however one the functions of the larynx. The hyo-thy-little muscle to complete the closure of roidells was described, in the 15th lecture,these apertures, or rather to bring them arising from the whole of the inferior bordercloser together than they are found to be in of the body of the os hyoides, extendinga state of inaction, and that is the arytenoid over and attached by cellular substance to amuscle. They cover the posterior part of considerable portion of the side of the thy-the arytenoid cartilage, arising on either roid cartilage, and inserted into the tubercleside from the spine of the arytenoid carti- at the postero-inferior portion of that carti-lage, occupying the whole of the posterior lage Its office is to raise the thyroid cartilage,surface of that spine, filling the depression and with it the larynx, or to depress the osat the base of it; diminishing in width as hyoides, accordingly as we consider the onethe cartilage diminishes ; in the centre, or the other the fixed point. The hyo-epi-where the cartilages are connected together glottidetts 1 also described in that lecture, asby cellular membrane, becoming thinner, being the frasnum, or stay of the epiglottis ;and exhibiting many tendinous fibres,-en- extending from the back of the epiglottis tolarging again with the enlargement of the the base of the spur of the os hyoides;cartilage on the other side, and so extend- sufficiently yielding to suffer the cover of £ing from the spine of one of the cartilages the aperture into the larynx to be deliressedto that of the other, and occupying as I have when the peilet of food passes, assistingsaid the whole of their posterior surface, the inherent elasticity of the cartilage inThe function of this muscle is immedi- raising it again immediately for the pur-

ately evident; it presses the arytenoid car- pose of respiration, and, with this excep-tilages closer together, and so closes the tion keeping the aperture always open thataperture between them, and also that be- the animal may breathe freely. This mus-tween the vocal ligaments. It is a mus- cle, you will observe, is bifurcated in thecle of no great power, but it is sufficient ox, and the two hyoideal origins are foundfor the purpose. It is an antagonist to all near, or generally upon, the internal face ofthe dilators, and it affects the farther ob- the ioint uniting the smaller cornua; it isject of contracting these apertures even also bifurcated in the dog.within their natural dimensions. There are therefore nine pairs of muscles

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proper to the larynx,, and one single muscle, tinned to act, and the glottis was contract-and one pair and a single muscle, common ed, and the vocal ligaments were renderedto the larynx and the os hyoides. tense, and they vibrated sufficiently rapidly

The Nerves of the Larynx.—These muscles, and po:,erfully; and the animal could tellare abundantly supplied with nervous the pain he suffered under the cruel expe.energy, but from the respiratory system, the riments.

per vagum, or eighth pair. If they could In another case the laryngeal branch ofnot be traced by anatomical demonstratior., 4 the par vagum wa3 left untouched, but tl.enot be traced by anatomical demonstration, the par vagum was left untouched, but thetheir mode of action would abundantly prove recurrent branch was divided. The con-

their origin, for they are partly under the sent ofrnotion between the respiratory mus-control of the will, and partly involuntary. cles, and the natural process of respiration,I am not assured that they are not indebted were very little interrupted, but the voicefor their power of voluntary motion to their was destroyed, for neither the arytenoid car.frequent anastomosis with the motor nerves tilages nor the glottis could contract.of the spinal chord. However this may be, The common sensibility of the larBnx iswhile the whole process of respiration is derived partly from anastomoses ’.Bith de-

partly under the control of the will, the scending branches of the iifth pair of nerves,muscles of the larynx concerned in one but more from the first and second cervical

atage of it are likewise so ; but then they nerves.

act independently of the will, for during The Bloodsessels.-Theoribin of the laryn-sleep and unconsciousness the machine con- geal artery is not always uniform. In a fewtinues to work. instances it is derived from the main tru’,k

Derived from different Sources.—We have of the carotid; but in the majority of casesseen that although very unequally divided, it is a branch of the thyroicleal artery. Itthe muscles of the larynx may be classed pierces the ligament between the thyroidunder two heads, the dilators and the con- and cricoid cartilage, about the middle ofstrictors. They are both supplied by the the side of the larynx, and is diffused overparvagum, but, singularly enough, by differ- the ltning membrane of the larynx, and theent branches of it. The laryngeal branch muscles of this organ. The ascending pha-of the eighth pair gives some fibres to the ryngaal however affords some branches toexternal muscles of the thyroid cartilage, the larynx, and other small branches mayif 1 may so term them, and then passes be traced. The veins follow nearly thethrough the foramen, while you will observe same course’asthe arteries, and empty them.the base of the superior cornu of this selves into the jugular.cartilage to be distributed over all the otimr The Sensibility of the lIIembrane, how regu-dilator muscles ; but the arytenoid muscle, lated, and the consequence of this.-The lin-and also the thyro-epiglottideus, are sup- ing membrane of the larynx is a continu-

plied by a branch of the recurrent nerve, ation of that of the pharynx above and ofwhich, climbing behind the trachea, passes the trachea below. It is covered with in-

through the same foramen and is distributed numerable follicular glands, from who;eover the constrictor muscles. This is a mouths there oozes a mucous fluid that mois-curious and interesting fact; it must, how- tens and lubricates its surface. It is pos-ever, be admitted with some limitation. sessed of very great sensibility; its fune-The broa(l assertion, first made 1 believe tion requires it. It is, as I have stated,by M. Majendie, of this distribution of the innor guard of the luugg, and the larynxnervous influence to the dilators and con- must undergo a multitude of changes ofstrictors, from different branches of the par form in order to adopt itself to certainvagum, is thus far true, that none of the changes in the respiratory act, and in orderlaryngeal branches have been traced to the to produce the voice. The voice of ourconstrictors ; but I am sure that I have patients is strangely limited compared withtraced many fibres of the recurrent nerve to that of the human being. The same sensi-the dilators. Still I say the fact is singular bilily therefore is not required, and natureenough. never gives that which the animal

does notThe Experiments of Le Callois.—Experi- d. Exposed as our quadruped slaves

ments, and most satisfactory, are related by are to absurd and barbarous usage, too greatSir Charles Bell. Le Gallois found that a sensibility of any part, and particularly ofdivision of the laryngeal branch stopped’ this, would be a curse to the animal.the consent of motion between the muscles Connected with some Symptoms of Rubies.—of the glottis and the muscles of the cle st. This decrease of sensibilitv enables us

The innumerably varied expansion of the satisfactorily to account for an importantglottis;, and of the anterior cartilages, ceased fact, viz. the true bydophobia, or dread ofat once ; all the cartilages of the larynx! water. in rabies in the human being-thebut one had lost the power to move. The almost total absence of it in the brute. Thevoice, however, remained, for the arytenoid degree of morbid sensibility generally bearsmuscle, derived from another source, con- a strict proportion to that which is natural

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to the animal or the part. To producethousand delicate intonations of the humanvoice, the highest degree of sensibility isgiven to the larynx; but incomparably lesswill suffice for the animal, the compass andintonations of whose voice are so limited.We can imagine that in the one the morbidirritability may be so great, that no fluidcan pass over the membrane without excit-

ing the mo3t horrible spasm ; that even thevery thought of it shall produce the spasm,md even a current of air, in increased

quantity, or of altered temperature, passingthrough the glottis, shall be followed by thesame horrible consequence, while in theother, no marked ettect shall be producedby the same agents. This will be more

fully discussed, when, under the sensorialsystem, I trat of rabies. It is now men-tioned incidentally as satisfactorily account-ing for the fact, that the principal distin-guishing symptom of rabies in the humanbeing is wanting in the quadruped.

LONDON HOSPITAL.

CLINICAL LECTUREDELIVERED BY

DR. BILLING,PHYSICIAN TO THE HOSPITAL,

Dec. 31, 1831.

2TESV FEVER. -

Additional Cases of Petechial Synorha.SixcE last lecture, Gentlemen, I have

admitted three more cases of the petechialsynocha. The two remaining of the formerpatients, F. W. and J. ’1’., are now alsoperfectly convalescent ; there is nothingwoith mentioning’ in the reports, exceptthat J. T. continued to have troublesomecough and headach, which were removedby a blister to the che-;t, and leeches to thetemples two or three times, and ipecac. gr. i,ter die as an expectorant, added to the qui-nine. In those cases where you find deli-rium, or even headach, continue after the

eruption has come out fully, you must applyleeches to the temples, or the patient willbecome typhoid, and if you find that statecommencing, the leeches will relieve thehead, and make the pulse fuller.

Case 1.—J. H. æt. 32. Febris.

Dec. 29. One P.M. Complains of head-ach, weakness in his limbs, and cough;rhonchus sonorus gravis and sibilans; is in-coherent. His friends state that lie has Ibeen ill about a week. Tongue white;

! thirst, anorexia; pulse 120, strong, and! hard; skin and forehead hot and dry;, bowels confined. Had copious bleedingfrom the nose yesterday, and the day be-fore ; he has been bled from the arm, and

had some medicine ; he shows great morbid! anxiety, and objects to being bled.

V.S. ad 3xvi. statim. Abraso capillitio lo-tio frigida fronti. Capt. magnes. sulph.,3ss; Ex inf. sennœ, 3iss. statim; et posteamagnesiœ, sulph, 3j; Antimoniitart.g.1;Ex aquœ, 3ies, 4tis horis.

Five P.M. Pulse much softer ; tonguemoister.You had here an opportunity of seeing

the synocha in its full character, and par-ticularly the sensoi,ii J’anctio7zes pS)’MM tur-

batœ; for though incoherent, he was think-ing anxiously about his family and himself,and was offended because I referred to hisfriends to confirm his statement, and par-ticularly because I ordered him to be bledimmediately afterwards, thinking it impos-sible I should do so had 1 believed his ac-count of the quantity of blood lie had al-

ready lost; you do not see this activity ofmind in typhus, nor in synocha, when thebrain and viscera are oppiessed for want ofdepletion; compare, for instance, the caseof J. 1’. with this, or a case which I havenext to remark upon ; observe also the re-port of profuse bleeding from the nose,which kind of occurrence was one of the

things that formerly gave a hint to Syden-liam and others to relieve apparent debility,by taking off the load from the viscera,having observed spontaneous haemorrhageto afford relief, when they had not venturedto bleed.

30. Feels much better ; lies on his side ;still rather confused, and his manner hur-ried and anxious ; eyes more lively ; sayshe does not sleep petechiæ fading pulse120, soft, rather full; tongue whitish, nearlyclean ; thii-at; but little cough ; no headachbowels opened once. Perstet.

’, 31. Says he is very bad, very low ; feelsno better, and his head worse ; hopes weare not going to bleed him again. But the

petechiæ are gone ; he slept in the night;skin temperate ; is perfectly collected ;pulse 94, soft ; tongue clean, rather dry ;he has been purged six or seven times

to-day.Habt. tinct. opii, ltixv .Ex aq. menthœ,

3j. stutim; Capt. decocti hœmatoxyli,3iss. ter die. Omitt. cœtera.

You have in this day’s report, Gentlemen,the disTinction between complaint and dis-ease ; his disease is gone, but he is full of

complaints. The reason is that, in the firstplace, besides his own feebleness, he hasmuch cause for domestic anxiety, and hisfeeling of weakness makes him dread being